Dutch & Dutch 8c Speakers

[tmallin]

Just to clarify, my D&D speakers are now 30 cm from the wall behind them and 40 cm from the near side wall. such distances are easy (or at least easier) to measure is you don't toe the speakers in toward the listening position. Many audiophiles seem to prefer to face their speakers "straight ahead," as in with the speaker sides parallel to the room walls (at least if the speakers have a rectangular shape).

Here's how these distances can be reliably measured with the D&D 8c's if, like me, you want to toe your speakers in to face your ears while sitting in the sweet spot. But before I get to measuring those distances, I'll include general set up instructions for these speakers first as well.

To begin at the beginning, first, determine your ear height when you are sitting in your listening chair. This is not a trivial task!

One good way is to recruit an assistant to manipulate the boom arm of a microphone stand. Place the stand on the floor beside your listening chair. Then have your assistant arrange the end of the boom arm so that it is touching the outside of your ear canal. Have your assistant lock the boom arm in place at that position and then move the boom arm away from your head. Measure the distance between the end of the boom arm which touched your ear canal and the floor. That distance is how far your ears are above the floor.

Without an assistant, the best way I've found to determine the height of your ears above the floor is to use a shiny bodied, squarish tape measure. If you have a ceiling light or high window in your room, make sure the light is on and/or coming into the room. As you sit in your listening seat extend the tape to the floor. Raise the tape measure body keeping the tape vertical to the floor. Watch the top edge of the tape measure body in the light. When that shiny top surface just disappears from view, you know the top of the tape measure is at your eye height. Glance at the tape measure to see how many inches are visible on the tape. Add the size of the body of the tape measure (often three inches) to that number and you have your eye distance above the floor. To compute your ear distance, face a mirror, put a ruler vertically beside your heard and determine how far it is vertically between your pupil to your ear canal. In my case that measurement is about 1.25 inches. Subtract this distance from the eye-to-floor distance you computed with the tape measure and you have your ear-to-floor distance in the listening position.

You then want to mount your speakers on a stand which is the right height so that the reference listening axis of the speakers is that many inches above the floor. For the D&D 8c speakers that listening axis is specified by the manufacturer to be 26.5 cm above the bottom of the speakers (see the manual, page 14). That's about 10.43 inches, but I would allow at least 10.5 inches since (unless you bolt the speakers to stands such as D&D's own) you will have to elevate the speakers a bit above the stand to prevent the screwheads sticking out of the bottom plate of the speaker from contacting the top plate of your speaker stand. If your stands have a top plate roughly the size of the 8c speaker's footprint, the OEM rubber feet of the speakers are about 1/4 inch high.

In my case, I know that my listening chair puts my ears about 34" above the floor if I take out the seat cushion. That's the way I used the chair with my short Gradient 1.4 speakers. As I get older, it is less and less comfortable to get in and out of a chair this low. I wanted to be get a stand of such a height as would allow me to use the seat cushion of the chair and still get my ear height to the design axis of the speakers.

Some users have used 24-inch stands with the D&Ds. However, in my set up, such stands will only get the design axis about 34.5 inches above the floor. Now, you can increase this distance by raising your speaker stands with spikes or feet and/or raising the speakers with sizable spacers (Mitch Barnett mentioned using Vibrapods in both spots). I prefer to use minimal spacers below the stand and between the stand and speaker. I know that with my seat cushion in place, my ears are about 37 inches above the floor. Thus, 24-inch stands would not be tall enough. I thus chose 28-inch stands. Those put the reference axis of the speakers about 38.5 inches above the floor. I know that if I use my seat cushion plus a Target shelf below the cushion, my ears are at about 38.5 inches above the floor, a near ideal match.

Next, if the stand pillars should be filled with sand, cat litter, or some other damping material, do that and tightly assemble the stand after filling. Place the stands in approximately the spots you intend to use them. Unless your stands have spikes which are easily adjustable for height while the stand is loaded with the weight of a heavy speaker, now is the time to level the top of the speakers stand. Since I did not plan to use spikes at all, I used my BMI level to measure the top plate of the stand for level both side to side and front to back. I adjusted the level by adding pads to the bottom corners of the speaker stand. This worked reasonably well, allowing me to level both stands so that the bubble remained within the crosshairs both front to back and side to side.

Next, you should add the interface between your speakers and the stands. I prefer to mount such an interface to the stand rather than the bottom of the speakers because it's just easier that way, especially when as with my Monlith stands and the 8c speakers, there is quite a disparity between the size of the speaker bottom and the top plate of the stand. For each speaker I'm using four small circular, self-adhesive hemispherical clear vinyl bumpers with uncompressed depth of about 1/8", less when compressed by the weight of the speaker. Nothing fancy, available at any hardware store. I mount one near each corner of the speaker stand top plate.

A trick you can use when you have such a large disparity between the speaker size and the stand top plate size, a trick which will allow you to easily center the speakers on the top plate of the stand is, before you assemble the stands, trace around the top plate of the stand onto a piece of cardboard. Cut out that piece of cardboard to use as a template for the speaker stand top plate. Turn your speakers upside down on a carpeted surface and center the cardboard cutout on the bottom of the bottom plate of the speaker in the same orientation the top plate of the speakers stand will have. In the case of the Monolith stands, the short dimension of the stand top and template should be parallel to the speaker front and back and the long sides parallel to the speaker sides. Tape the template cut out in place with masking tape at the center of all four sides of the cut out. Then get some 1/8-inch thick heavy duty adhesive felt strips and mount those to the bottom plate of the speaker at the four corners of the cut-out. Remove the cut out from the bottom of the speaker. Turn the speaker over and place it atop the stand so that the felt strips are just outside all four corners of the top plate of the speaker stand. Your speaker is now centered on the speaker stand top plate. Leave the felt strips on the bottom of the speaker just in case you have to remove and remount the speaker at a later date.

At this point, connect all your cables to the speaker. If you use contact enhancers, remember to treat the cable sockets and plugs with your preferred contact enhancer before you make these connections. I currently use JENA Electrical Contact Enhancement Fluid.

 

[tmallin]

Now that the speakers are mounted on their stands and cabled, the next step, believe it or not, is to move your listening chair into the proper position for your planned speaker set up. You can't properly toe in your speakers unless you know where your chair will be first. This is all math--geometry and trigonometry--and you have to "back into" the listening positioning, so to speak.

For my set up, I am assuming an equilateral (equal angles, equal side length) triangle set up between the listening position and the center of the tweeters. In equilateral triangles, all the angles are 60 degrees. Such assumptions automatically create a 60-degree subtended angle between the tweeters as viewed from the listening position, which is the "standard" angle for stereo separation with two-channel stereo recordings.

The only trigonometry you need to know for such a speaker set up is that the cosine of a 30 degree angle (cosine being the length of the adjacent leg to the angle divided by the length of the hypotenuse of the triangle) is 0.866 and the sine of a 30 degree angle (sine being the length of the opposite leg to the angle divided by the length of the hypotenuse of the triangle) is 0.5.

Remember that in my set up I wanted the speakers to be 40 cm from the side wall and 30 cm from the wall behind them. It's important to know that this distance, according to D&D, is to be measured from the center back of the speaker cabinet. That corresponds to the center of the subwoofers. Converting to inches (one inch = 2.54 cm), 40 cm = about 15.75 inches and 30 cm = about 11.81 or about 11 13/16 inches.

Now my room is 132 inches wide. Since each sub center is to be 15.75 inches from the side wall, the sub centers are 132" - (2 x 15.75") = 100.5" apart.

If the speakers are each toed in to face the listening position, their toe in angles will each be about 30 degrees. This follows from the fact that for an equilateral triangle, from the listening position the two speakers subtend a 60 degree angle; each must be toed in half this amount. This is why 30 degrees becomes the relevant angle for all the trigonometric calculations.

Now if each speaker is toed in 30 degrees and each speaker measures about 10.5 inches wide 13.5 inches from back to the mounting surface for the tweeter (this doesn't include the molded plastic front baffle), each speaker's tweeter center will be about 6.75 inches further from the side wall than the subwoofer center. Sine 30 degrees = 0.5 = hypotenuse / opposite leg of 30 degree angle = 13.5'' / length of leg opposite the 30 degree angle. If we define the length of the leg opposite the 30 degree angle as L, then solving for L, we have L = 13.5" x 0.5 = 6.75". For a 30 degree angle, the opposite leg of the triangle will always be half the length of the hypotenuse.

This means that the two tweeter centers are 6.75" x 2 = 13.5" closer together than the two subwoofer centers. If the sub centers are 100.5" apart, then the tweeters will be 100.5" - 13.5" = 87 inches apart. The length of each side of the equilateral triangle set up is thus 87 inches. Each tweeter is 87" from the other and from the listening position.

If the speakers were not toed in, the distance between the wall behind the speakers and the tweeter would be simple addition of 11 13/16 inches of wall to back of speaker and 13.75 inches from back of speaker to tweeter. But since the speakers are toed in 30 degrees, the tweeter is less than this extra 13.75 inches from the wall behind the speakers. How much less is determined by the cosine ratio, 0.866. Thus the tweeter is 13.75" x 0.866 = about 11.69 inches.further from the wall behind the speakers than the back of the speaker is. The tweeter is thus about 11.81" + 11.69" = about 23.5" from the wall behind the speakers.

The easiest way to position the listening seat is to measure from one's ears when sitting in that seat to the wall behind the speakers with a laser measuring device. What should that distance be? Well, we now know that the tweeter is 23.5 inches from the wall behind the speakers. How far should our ears be from a line connecting the two tweeters? Again we use the cosine ratio. If the tweeters are 87 inches from our ears, than the line connecting the tweeters is cosine 30 degrees times 87 inches from our ears or 0.866 times 87" = 75.34 inches. Adding that distance and the 23.5 inches from tweeter to wall behind the speakers means that we should adjust the chair so that the distance between the ear and the wall behind the speakers is 23.5" + 75.34" = about 98.84" or about 98 27/32".

I move the chair so that it is centered in the room. Getting the listening seat centered side-to-side in the room is easy. The carpet has a right/left symmetrical pattern with strong center figuring. I carefully placed the carpet in the left/right center of the room. I align the front legs of my listening chair so that they are symmetrical with respect to the carpet pattern--very easy. My rack and the equipment on it are also carefully centered in the room. The Music Direct catalog on top of the Lumin X1 has an X white cross which is exactly centered in the room. Thus, all the visual cues are also there. I listen to monophonic music. My head will then auto-center between the speakers. I hold my Disto laser measuring tool so that it's back edge is against my ear canal as I sit in my natural listening position. I aim it at the center of the wall between the speakers and at a height of 38.5 inches above the floor. I keep adjusting the listening chair position forward and backward until multiple trials cluster around the 98 27/32" distance.

Only now am I ready to physically position the speakers for distance from the walls and toe in angle.

 

[steve59]

Congratulations on a great system. Reading your thread was a lot like my own experience once I decided to try dsp active speakers. I must admit tho' I'm a bit less exact in my placement, to be fair tho mine weigh nearly 250 lbs each and don't have near the user configurations yours do.

 

[tmallin]

Yes one significant problem with huge heavy speakers is that it is exceedingly difficult to get them into exactly symmetrical positions. And, if you want to use spikes, unless there is a way to add the spikes AFTER you move them into position WITHOUT changing the position, well, once spiked a multi-hundred-pound speaker is almost impossible to move with any significant amount of control, even for two or more people.

I know from experience that small (I mean on the order of 1/16 inch) distance and angle differences are quite audible. You'll never really know what your system is truly capable of until you get things just right. This is measurable as well. For example, when measuring the 8c speakers with a monophonic short sine sweep test tone so that the tone is going through both speakers at once, to get the impulse response peaks to exactly overlay each other on the OmniMic 2 graph requires adjusting the microphone position to a small fraction of an inch.

Of course, the same goes for oddly shaped speakers like the Gradient 1.4s (or any of the other Gradients for that matter), where there are no straight parallel-to-the-walls surfaces to measure from. But at least they are small enough and light enough that you can experiment with placement iterations to your heart's content without any muscle or back strains at all.

 

[steve59]

sigh, rolling up my sleeves.

 

[tmallin]

Now for the speaker positioning. First put a piece of masking tape across the top back center edge of each speaker so that it wraps around a bit over the back top edge to prevent getting ink on the speaker in the next step.

Then using a pen, make a short mark parallel to the speaker sides and normal to the speaker back at the exact midpoint of the back top edge of the speaker. With the D&D 8c, since the speakers are 270 mm wide, that point should be 135 mm or 13.5 cm from either edge.

The back side of the speaker is rebated about 1/8 inch from the top back edge of the wood veneer. To take this into account when measuring, draw a line bisecting on the tape parallel to the back edge which is about 1/8 inch from the back edge. Make sure that line bisects the other short line you drew. Now you can measure from the intersection of these two lines confident that this line intersection represents the top center of the back wall of the cabinet, not the back edge of the wood veneer.

Next use masking tape to attach a small circular mirror (2-inch, or 1-inch diameter; the 1-inch will yield more accurate results but is more difficult to use) so that it is vertically in line with the center of both the tweeter and woofer. If you have difficulty finding such mirrors, try a local craft store, such as Michaels or Hobby Lobby.

Attach the mirror at the design axis point, about 26.5 cm above the bottom of the cabinet. This will be just about where there is a visible horizontal ridge on the front baffle between the tweeter and woofer. This ridge makes mounting the mirror a bit tricky, but with several iterations of adjusting the masking tape you can aim the mirror properly so that you will be able to see your ears in the mirrors when sitting in your listening seat.

The toe-in procedure using such mirrors is fully described in my ancient post, "Mirror, Mirror on the wall . . . or Speaker." I'll repeat the procedure here for convenience.

For adjusting speaker toe in, ideally you want a small flat circular mirror. I find that a 1- or 2-inch-diameter circular mirror is ideal for adjusting speaker toe-in. The smaller the mirror (at least up to some point), the more accurately you can judge that the toe-in is toward your ears since with a small mirror you really have to have the speaker aimed just about right before you see your ear's reflection. With larger mirrors, you have to judge whether the image of your ear is centered in the mirror.

When adjusting speaker toe-in to aim the speakers at my ears, I sit in my listening chair and aim my head straight ahead by listening to a monophonic recording. Listening for a centered image will automatically orient my head into the sweet spot facing straight ahead. Then I glance to the side without moving my head to see if my left ear is reflected in the mirror attached to the left speaker looking only with my left eye (I cover up or close my right eye). I glance right without moving my head to see if my right ear is reflected in the mirror attached to the right speaker looking only with my right eye (I cover up or close my left eye). When everything is just right, you should see your ear canals reflected in the centers of the mirrors.

Even this procedure is not really exact; there is a bit of parallax because you are viewing your ears with your eyes which are not at the same angle to the speaker front as your ears are since your ears are further apart on your head than your eyes are. But even with non-flat speaker baffles, this mirror method consistently produces superior audible results from me than other methods I've tried.

I suggest roughly positioning the speakers where you want them, and then get the toe-in angle just right so that you can see your ears in the mirrors on the speakers using the procedure described above. Note that this mirror procedure can also be used to set the toe in if you prefer to over-toe the speakers a bit so that their axes cross a bit in front of the listening position. You can set the toe in so that you see your eye, nose, or opposite shoulder depending on how much you want to over-toe the speaker angle.

Then, using a tape measure, get the distances from the mark you made on the masking tape just the distances you want. In my case, the measurements are 11 13/16" inches from the wall behind the speakers and 15.75 inches from the near side wall.

Once you do that, you most likely will have to slightly adjust the toe in again, then readjust the distance from your mark to the walls, then toe in again, round and round until everything is correct. It should only take a few iterations once you get used to the process. Once the distances are correct and you can see your ears in the mirrors on the speakers as described in my old post, the set up should be complete.

I would mark your chair position on the floor or carpet. Chairs tend to slide a bit over time as you get up or down. For me they tend to slide a bit backwards. I attach masking tape to the carpet to outline the front and outside edges of the front two chair legs on the carpet. If the chair slips backwards, it's then a simple matter to move it so the legs are back against the masking tape and thus in its original position.

 

[steve59]

As you describe the process I am curious how it can be applied to different speakers in different rooms? mine are sealed pyramid similar to the watt puppies with 3x8'' woofers on each side. I know from experience with different side firing models this room has smoother and deeper bass with this style.

 

[tmallin]

Picking up again on the time-coherence aspect of the design of the D&D 8c's I raised above, I can't help but think that the audiophile world (or much of it, at least) has been misled for decades about the importance of time coherence. It is rather obvious when this feature is defeated. The difference in sound between the low latency mode of the speakers and the time coherent higher latency mode is rather obvious. And this is so even though the low latency impulse response is not all that out of time sync and is quite clean compared to other speakers.

No, we've been fooled by the shortcomings of most prior examples of time coherent speakers. In the analog domain, to produce time coherence--where the sound of all the drivers arrives at your ears at the same moment and with the same acoustic phase when listening on the design axis--if the speakers have a crossover, that crossover has to have the gradual 6 dB/octave roll off and there has to be either a physical offset of the drivers to align the voice coils of the drivers in a vertical line, or some sort of electrical analog delay line to line up the driver outputs in time at the listener' ears. Thus the common form factor of such speakers with either a sloping baffle (e.g., Thiel, Spica, Meadowlark) or stepped baffles (e.g., Vandersteen). The Quad 63 and its descendants are unique in using an electrical analog delay line to time align the tweeter and woofer sections of the "flat" electrostatic diaphrams.

Note that both the physical driver offset to align voice coils and the 6 dB/octave crossover are necessary elements for producing a time coherent speaker if the crossover of a multi-driver system is done in the analog domain. Thus, without DSP, there is no way for multidriver speaker incorporating a steeper crossover slope to achieve time coherence. Thus, even if speaker has a sloping baffle, if it doesn't have 6 dB/octave analog crossovers, it will not be time coherent. And even if a speaker has a 6 dB/octave crossover (such as the old EPI 100 single-cap crossover), it will not be time coherent if it does not incorporate some means of physically aligning the drivers in space.

The proof of this is there in the measurements. For example, despite the marketing claims and the tremendous expense and apparent engineering ingenuity and precision which goes into the design and construction of Wilson speakers with their physically-adjustable-in-the-field driver arrays, those speakers are NOT time coherent because they use analog crossovers which have higher slopes than 6 dB/octave. Just look at the step response of any Wilson speaker tested by Stereophile. For example, see Figure 4 on this page for the step response of the Wilson Alexx. If the speaker were time coherent, there would be a single peak, not multiple peaks and there would be no talk about the drivers being connected some with positive polarity and others with negative polarity. The polarity differences among drivers are evident in the graphs from the direction of the initial pulse from each driver--some pulse initially go up, others initially go down form the reference line.

But there is actually more going on here. Many reviewers obfuscate the lack of time coherence in the speakers they test. They either don't mention it at all (e.g., the SoundStage NRC tests do not show impulse or step responses) or they act as if time coherence doesn't matter. John Atkinson of Stereophile, for example, in the text accompanying Figure 4 linked to above, says: "In the time domain, the step response on the tweeter axis (fig.4) reveals that the tweeter and midrange units are connected in positive acoustic polarity (footnote 1), the woofers in negative polarity (footnote 2). More important, the output of each drive-unit can be seen to blend smoothly with that of the next lower in frequency, suggesting good crossover design." Right. The language used belittles the importance of true time coherence. Having the output of each driver "blend smoothly" in time with the outputs of the drivers above and below the range of any given driver is regarded as good enough.

It gets worse. In Footnote 2 of the Alex review, Atkinson mentions remeasuring the step response of the Wilson Alexx. This time his new graph shows that the upper and lower midrange drivers are out of phase with each other and time displaced, but he still sees no problem with this.

Even where the driver outputs are separated by about 3 milliseconds, Atkinson apparently sees/hears no problem. See Figure 5 in his measurements of the Aerial 10t speaker.

Atkinson has his limits, however. In his measurements of the latest Klipschorn, where the outputs of tweeter and woofer arrive about 8 milliseconds apart, he says: "Does this matter? In theory, even the woofer's output is within the hearing system's tolerance for different arrival times" based on the precedence effect. But then in the following paragraph he notes: "But from my own experience with truly time-coincident, multi-way loudspeakers like Quads and Vandersteens, where the outputs of all the drive-units arrive simultaneously at the ear, I feel such time delays smear and obscure stereo imaging precision." Well, which is it? Is time "blending smoothly" good enough, or must the drivers be time and phase aligned to avoid smearing of imaging?

I would note that it's not just smeared images which are at stake here. Compared to all the other speakers I've had in recent years, the integrity of individual notes is also smeared. As I mentioned in a prior post, leading transient edges of all tones from all instruments just seem to be more a part of the tone and specifically associated with their particular instruments. With other speakers, by comparison, leading transients tend at least a bit toward sounding like undifferentiated and detached noise.

With the DSP-implemented crossover of the D&D 8c, we can have true time alignment of the driver output on the design axis and still have a 24 dB/octave crossover and not need any sloping or stepped baffle. Moreover, the controlled and similar dispersion of the wave-guided tweeter, passive cardioid bass/midrange driver, and near wall 2-pi dispersion of the subwoofers, creates the "constant directivity" which reduces the audibility of bass room modes and keeps reflections from the walls from being obnoxious since the reflected sound has a similar tonal character to the on-axis output, just more rolled off in the upper frequencies.

The 8c speakers sound very "open" and balanced from all over the room whether sitting or standing since they are not focusing the highs with laser-like precision (a la Janszen or Sanders) and since the room surface reflections are not severely colored. The only speakers I've had in this room achieve a somewhat similar effect in terms of freedom from wall reflections combined with a sense of openness are the Gradient 1.4s, and even those Gradients sound closed in and colored by comparison once you move around the room away from the sweet spot.

I'm not saying that the Dutch & Dutch 8c speakers are the be-all and end-all of speakers. But they point the way to what can be accomplished with current technology within the confines of a form factor which can fit into even a small room and at a price which is not egregious for all the performance and system components included in the package. Add size and more subwoofer driver area and one could have a system which could produce full-range high levels in an even larger listening room. Add more sophisticated response correction tools to the software like Audiolense or Acourate and the attainable response could be even smoother than with the current software with its parametric equalizer filters. But with those additions the size and cost of the speaker would probably at least double.

 

[tmallin]

As you describe the process I am curious how it can be applied to different speakers in different rooms? mine are sealed pyramid similar to the watt puppies with 3x8'' woofers on each side. I know from experience with different side firing models this room has smoother and deeper bass with this style. View attachment 68597

The set up methods I've described work well with the 8c since we know from the manufacturer's recommendations and built-in software how the rear and sides of the speaker cabinet should be oriented with respect to back and side walls. These methods also work well with speakers which, like the 8c, have their drivers arranged in a vertical line or are concentric (e.g., Tannoy Dual Concentric speakers). The methods are also largely applicable to any rectangular box-shaped speaker. The methods I've described are at least somewhat relevant to other speakers, but once the driver layout gets complicated or the shape of the speaker gets unusual, it will be more difficult to apply the methods I've discussed here. However, even with speakers as unusually shaped as the Gradient 1.4, this method can work; you just need to improvise and think more carefully about reference points on the speaker cabinets from which to measure.

With speakers other than the 8c, you probably are not trying to place the speakers so as to meet a manufacturer's placement recommendations. You may try moving the speakers and listening position around a bit before settling on approximate locations for both. Lacking speakers specifically designed for near-wall placement, the general rule is to move the speakers into the room a fair distance, away from walls and corners.

An L-shaped open floor plan room like yours is considerably more difficult to deal with since the asymmetry of the room will tend to make the left speaker louder than the right one and the bass modes will be more complex because of the adjoining room than in a nice tidy rectangular space like mine.

The basic plan would be similar, however. You want the driver positions and the listening position to form an equilateral triangle. That implies equal distance from your ears to the speakers and between the left and right speaker drivers.

You want your ears to be on the vertical reference axis which ideally means adjusting your chair height and/or speaker stand height to get your ears at the proper height above the floor for your speakers. That is so for all speakers. The only alternative is to tilt the speaker backwards or forwards and I know from experience that while such tilting can get you on the treble axis, that method also usually results in either looking up or down at images on the stage, an effect I do not like.

The small-mirror-on-speaker-baffle method for adjusting toe in will work with many speakers. Measuring with a tape measure or laser device from reference points on the cabinet to the side and back wall will also work well with many set ups.

There are certainly any number or other set-up methods which could work fine, but I prefer the methods I've described because they are adaptable to a wide range of speakers in rectangular rooms, which has usually been my situation. Some people use direct laser or tape measurements from speakers to ears with the aid of an assistant. I prefer not to aim lasers at my eyes, ears, or speaker drivers. I also don't like touching tape measures to drivers or body parts for the same reason--fear of accidental damage to the drivers, my eyes, or ears.

Some use set up methods which aim to get the smoothest bass response at the listening position without the need for equalization by first picking a listening position, then putting a speaker or subwoofer there and crawling around near the floor to find the spot where the speaker's bass output sounds or measures the smoothest. This method uses the principle that there is a reciprocal relationship between the listening position and speaker position in terms of bass response. It can work, but you may end up compromising stereo separation or imaging this way.

Another method is to set up the speakers and listening position along a room diagonal. This is a method frequently used by Sanders to demo their speakers at shows. Yes, this can work if your listening room is quite large. You will probably need to measure distances from your head to the speakers and the speakers to each other directly rather than with respect to the walls. In any shape room other than a square, your left and right speakers will not be the same distances from the side or back walls, possibly making the left and right channels have considerably different bass response. If the room is pretty large, however, these differences may not matter much. It certainly works well in the larger rooms Sanders uses at shows.

For rectangular rooms, good methods are shown by this speaker placement calculator. You plug in your wall lengths and the calculator spits out where you should put the speakers and listening seat. I find both the Cardas method and the Rule of Thirds (29% version) to work well in my room.

 

[tmallin]

More comments and comparisons of the D&D 8c to speakers I've recently used in the same room:

My Gradient 1.4 comments are at https://www.whatsbestforum.com/thre...rs-downsizing-simplifying-and-changing.29155/. My extensive comments about the M40.2, including a lot of comparison with the M40.1, are at https://www.whatsbestforum.com/threads/harbeth-monitor-40-2.25222/.

The M40.2, in my opinion is a much different speaker from the earlier M40.1 I also owned. It goes much further down the path of being practical to use in a lot of rooms without a ton of electronic bass EQ. I think REG is one of very few people on the planet who has a listening room that can get the bass balance of the original M40s to sound and measure well without such EQ. The M40.1 was, by my measurements, about 8 dB less bass heavy than the original, and was manageable for rooms with a moderate amount of bass leakage through windows, archways, open floor plans, etc. The M40.2 finally made the big Harbeths have a bass balance which could work in a small rectangular room, even one with solid plaster walls like mine.

In addition, the M40.2 has a high frequency balance which is more forgiving than the earlier M40 or M40.1 of the usual excesses in the highs of many program sources, especially early Golden Age classical and modern pop and jazz. The M40.2 balance makes a much wider swath of program material sound acceptable from a tonal balance standpoint. The M40.2 is also considerably more capable than the 40 and 40.1 in terms of its ability to "rock out" on modern pop and electronic music. Unlike the earlier versions, the 40.2 does not begin to sound strained on such music at appropriately loud volumes.

The M40.2 and Gradient 1.4 are two of the most natural sounding passive (as in not internally amplified) speakers I know of at anything like a reasonable price. The Harbeth is warmer sounding, the Gradient is clearer, but both have enough of both qualities to sound satisfying. Electronic equalization can move the sound of either toward that of the other, but the Gradient will always be considerably more independent of the room and position within the room. It will sound more like itself, in other words, wherever you place it, so it is very easy to place for truly excellent results.

There is nothing "wrong" with the Gradient 1.4s. In moving to the Dutch & Dutch speakers my initial goal was the desire to further simplify my system. But as it turns out, I've found speakers that are way better yet than either the Harbeth M40.2 or the Gradient 1.4, which were previously my two favorite speakers for this room (or any room I've had stereos in, for that matter).

If you like the big Spendor SP100, you'd be happier with the sound of the big Harbeths than with the Gradient 1.4, I'd say. It's not that the Harbeths are any more full range. If you noticed my measurements of the Gradients, see https://www.whatsbestforum.com/thre...ng-simplifying-and-changing.29155/post-660506, they produce flat bass to well below 20 Hz in my room, deeper than the M40.2s. The highs are equally extended.

However, the Harbeths have no floor dip in my room and generally have a warmer, fuller upper bass/lower midrange. They are not as full and warm as the big Spendor SP100, though.

Thus, unless you equalize out the floor dip on the Gradients (and this IS possible in my room--I did it with no ill effects) the Harbeths will sound "bigger" and have more "authority" on big music because of this tonal balance difference. With that equalization, the Gradients sounded as well balanced as any speaker I'd heard--certainly as well balanced as the Harbeth M40.2. But then I heard the D&D 8c . . . .

The Gradients, on the other hand, image and stage at least as well as the Harbeth M40.2, sound clearer yet without brightness, need less room treatment, and are WAAAAAY easier to move around and change the toe in. The Gradient head unit can not only be toed in or out, but up or down as well. It's a simple matter of orienting a 10-pound head unit by hand on three rubber bumpers in the bass cabinet. The Gradients will play almost as loud cleanly as the Harbeths, given sufficient input power--I used bridged Benchmark AHB2 amps with both speakers and never ran out of juice with either speaker. The Gradients will sound more like themselves wherever you place them, though, so what you hear is more or less what you will get in terms of tonal balance unless you apply electronic equalization. Like all Gradients, the 1.4s ignore your listening room acoustics much more than most speakers.

I would not say that the Harbeths sound any more dynamic than the Gradients, either in terms of macro dynamics or micro.

As to price, the Gradient 1.4s cost less than half the price of the Harbeth M40.2, much less the anniversary edition.

But, again, if you really like the tonal balance of, say, the Spendor SP100, I doubt that the Gradients would be your cup of tea. Even the M40.2 will have at least a bit leaner sound. I've owned a number of Gradient speakers. They all have a leaner-than-Harbeth sound, but the 1.4 can be nudged into sounding full blooded with some judicious electronic EQ.

But my new Dutch & Dutch 8c's are just in a different league altogether. The tonal balance is exemplary. The promise of time coherent speakers has finally been fulfilled by removing the colorations and lack of power handling which has handicapped prior such designs. The radiation pattern seems truly ideal for a small room. For an eclectic listener like me, these are the bee's knees. And, while expensive, you get a lot more than just speakers for the $12,500 price.

Of course, the whole idea of locking the user into the speaker designer's choice of amps, crossover, EQ, room placement, and a 48 kHz downsampling DAC is antithetical to many audiophile precepts. Thus, I doubt whether many non-pro-audio listeners will ever take the D&D plunge. Where's the fun if the speaker hamstrings your choices?

 

[tmallin]

Here are some comments about the way I listen to music sources through the D&D speakers:

I no longer own many audio components except what you see in the D&D 8c thread and my electrostatic headphone system thread at https://www.whatsbestforum.com/threads/my-electrostatic-headphone-adventures.28342/

My CDs are all converted to files. I listen to them via the Lumin App which runs on the Lumin X1 streamer. The files are served up via Minimserver running on the desktop computer you see in the headphone thread. Most often these days, however, I listen to the CD files via Roon which runs on my Roon Nucleus+ with aftermarket Keces P8 linear power suppy. The CD files are all on a single 1TB USB stick which plugs into the back of the Nucleus-. The Nucleus+ and its power supply are down in my dining room next to my router. The Nucleus+ is connected via ethernet cable all the way to my Lumin X1 in the audio room. See my Roon thread at https://www.whatsbestforum.com/threads/roon-and-the-roon-nucleus.30765/ For the story on the ethernet links, see https://www.whatsbestforum.com/thre...-yet-better-sounding-system.29425/post-660929.

I also subscribe to the high res services of both Tidal and Qobuz as well as the best Spotify service. Tidal and Qobuz are fully integrated within Roon and the Lumin App. Thus, I have millions of CD-and-better-quality albums available in addition to my measly 1200 CDs.

I still have all my CDs for back up, just no player on which to play them through the audio system. Direct comparisons before I sold my Oppo UDP205 player convinced me that the files sound just as good and in some cases a bit better than the CDs played on the Oppo. Whenever I get new CDs, such as with the BBC Music Magazine every month or occasional purchases from Amazon, I immediately rip them to uncompressed WAV files via dBPoweramp and add them to my USB stick and thus to my Roon and Lumin library. I use a $30 Dell DVD ripper connected via USB to my desktop computer to rip CDs to files. I could use that ripper to play CDs through my audio system in a pinch, but I've never done it.

For broadcast radio, I use the internet streams of radio stations played through either Roon's Live Radio function or the Lumin X1's internet radio function. "Broadcast radio" in this case includes not only geographically local stations but stations from all around the world, some "broadcasting" only on the internet. I also use the Airplay functions of both Roon and the Lumin X1 to play Sirius/XM and other subscription services like Jazz Radio via my iPad Pro which is also used as the remote control for Roon and the Lumin X1 in my audio room.

 

[tmallin]

I'm cross-posting the following from my Lumin X1 thread because of its implications for the potential sound of the D&D 8c's when fronted by the Lumin X1 processing the sound of streaming via my Roon Nucleus+. If and when D&D solves the problems remaining before it can release a firmware version which makes the 8c speakers Roon endpoints I'll have to evaluate whether eliminating the Lumin X1 from the signal path will truly be an improvement or not. I have a feeling that unless Dutch & Dutch can incorporate the Leedh DSP volume processing Lumin uses and can somehow eliminate the distortion caused by copper ethernet cable connections, there will at least be pluses and minuses to running Roon directly through the speakers. See below.

***************************************************************************************************


Now that I've switched to the Dutch & Dutch 8c speakers, I need three ethernet cable connections in my audio room. Thus the need for an ethernet switch in this room. One ethernet cable is needed for my Lumin X1 streamer and one for each of the D&D speakers.

It also occurred to me that now that I had ethernet in this this room, I could also move my Roon Nucleus+ and the Keces P8 linear power supply for it to my audio room. Until now, they had been in my dining room immediately below my audio room, where the Nucleus+ could be attached via a short ethernet cable to my Xfinity Advanced Gateway modem/router. That router is in a great spot for supplying strong Wi-Fi signal throughout my old plaster-walled two-story house. I had tucked the Nucleus+ and its power supply under a hutch where they were out of the way of foot traffic. The router sits on the floor under a stationary stool right next to the hutch--I'm not sure why that location works so well for Wi-Fi in my home, but so it does.

I did not want to also move the router to the audio room for three reasons. First, the router has a fan which operates most of the time and thus would be audible during quiet passages of music. Second, I would have to route a cable connection to the audio room in addition to the ethernet connection and didn't want to incur the expense for that, given the $1,000 I just spent to get the ethernet connection to this room. Third, putting the router in this room probably would not give me the great Wi-Fi coverage I currently have in the house, necessitating some sort of mesh router system. Most of those (if not all) do not have the Wi-Fi bandwidth I currently get from my Xfinity router with Gigabit service. Even with Wi-Fi I regularly clock speeds of 600 mbps and above in my audio room. Most mesh systems are only rated for 100 to 200 mbps.

The advantage of moving the Roon Nucleus+ and its Keces P8 power supply to the audio room is that I could take advantage of the vibration isolation and purer powerlines available in the audio room, courtesy of my Salmander Archetype rack, A/V Room Service EVP isolation feet, the dedicated power lines, and P.I. Audio Group outlets and UberBusses in this room.

I also thought I'd take this opportunity to try out the fiber optical connection my Lumin X1 offers in place of the copper ethernet connection I'd been using. This type of wired connection is explained on the Lumin website at this fibre networking page. This required swapping out my TP Link gigabit switch for a switch with an SFP slot. Since I know little about fibre networking and did not want to have to learn how to troubleshoot such network connections, I followed Lumin's instructions to the letter, figuring that they know what fibre networking equipment works with their Lumin X1.

Thus, going by the recommendations on the Lumin Fibre Networking page I purchased the recommended Cisco switch (about $170 through Amazon), plus two of the 10GTek single-mode 1310nm SFP modules (about $40 from Amazon), plus a one-meter fibre optic cable from FS (about $10), for a total investment of about $220 to move from a copper ethernet connection between the Cisco switch and the Lumin X1 to a fibre optic ethernet connection between those two components.

I moved the outboard Lumin X1 linear power supply up to the top shelf of my three-shelf Salamander rack alongside the main chassis. I mounted the Roon Nucleus+ and its Keces P8 outboard linear power supply side by side on the middle shelf. I mounted the Cisco switch atop the two P.I. Audio Group UberBusses on the lower shelf. Each piece of equipment is mounted atop four A/V Room Service EVP (Equipment Vibration Protectors) of the proper weight rating for each component. All equipment, including the D&D 8c speakers, is plugged into the UburBusses.

Here's a picture of this new set up:

Note that if you want to try the fibre optic connection with the Lumin X1, I recommend that under options in the Lumin App you first select that the Network LED be on. I had it off before. While I don't know for sure, I think this is necessary for the fibre optic network connection. I did not call Lumin about this and can't find any online discussion about that option, but it makes sense that the option refers to enabling the fibre optic networking option. It does not refer to anything visible on the Lumin X1's screen display since the display stays the same with that option on or off.

So, how does it sound compared to the previous ethernet connections? More marvelous!

This system was already marvelous in sound, the best by far I've had in this room. But the combination of better vibration protection, purer powerlines, and the fibre optic connection between the switch and the Lumin moves the performance up to a level of naturalness and a freedom from distortion which I had to hear to believe. There is simultaneously an increased smoothness and transparency to the sound without any real detail being lost. What is lost is distortion which was adding just a bit of edge that was not really noticed until I heard its absence.

I did A/B the Lumin with a copper ethernet link, then with the optical link. That change in itself is a significant part of the transformation I'm hearing.

Changing from copper ethernet to the fibre optic connection between the switch and the Lumin X1 meant even less "grunge" in the background, blacker backgrounds, even less high frequency digital nasties, and a generally more open sound. This is true regardless of the quality of the program--it applies from low-bit-rate internet radio up through high-res programs from Tidal or Qobuz. Lumin and the reviewers who have commented on this type of connection's performance are correct. This is better yet than an ethernet connection, which itself was better than a single Wi-Fi link in the streaming connection.

I can heartily recommend that those of you who have a Lumin X1 (or another streamer with a fibre connection potential built in--are there any others?) try this right away. The money spent, at least in my system, was way out of proportion to the audible improvement. What was obviously already a top streamer before in terms of sound quality is now at another level entirely, qualitatively superior to anything I've previously heard in network streaming.

 

[steve59]

I think most music lovers would be surprised at the quality of your system without having a clue of the effort that went into getting things just right.

 

[tmallin]

Further thoughts on the D&D 8c speakers:

In the context of passive speakers, where you have to/get to mix and match your electronics with your speakers, the Benchmark DAC3 and the DAC which is part of my Lumin X1 are the best sounding I've encountered.

Prior to my purchase of the Dutch & Dutch 8c, I had owned three speakers which could be regarded as "active": the Linkwitz Orion, the Gradient Active Revolution, and the Janszen Valentina Active. However, none of those prepared me for the D&D 8c and none contained as many electronic components within the speaker box as do the 8c.

The 8c speaker boxes include triamplification, DSP crossovers, DSP automatic equalization keyed to the distance of the speaker from the side walls and wall behind it, up to 24 bands of manually adjustable (or importable from REW) parametric DSP equalization, DSP level controls for the subwoofers, woofer, and tweeter, DSP crossovers allowing 24 dB/octave slopes with full time alignment of drivers, and a DAC (maybe multiple DACs?). In addition, the boxes incorporate cardioid radiation for the woofers (100 Hz up to 1250 Hz), wave guiding of the tweeter, and sealed box rear facing dual 8-inch subwoofers (below 100 Hz) which are said to leverage the Allison Effect to boost the low bass up to 6 dB in level when placed close to the wall behind them as is recommended.

Yes, the speakers seem to have a designed-in 10 dB rolloff from low bass to high treble and the high frequencies roll off yet more off axis. But it all sounds totally natural and balanced, not at all dull or rolled off in the highs. The 8c's are also designed to have a quite unusually uniform dispersion from 100 Hz up--this translates to my ears to speakers which do not sound dull off axis but do not require heroic room treatment to avoid annoying reflection of sound from room surfaces. They sound like "room fillers" without the obnoxious wall reflections which usually accompany the sound of speakers which seem so balanced when heard off axis. In this respect, the 8c's are quite better yet than the Gradient models which were my previous favorites for this quality.

Basically, all you need to complete your stereo system once you have the 8c speakers are some wires, speaker stands, and a streamer. Most everything is in the speaker boxes. A future firmware update is planned for 2021 which will make the 8c speakers Roon Ready Roon endpoints. That potentially would eliminate the need for a streamer--we shall see.

Now the downside to this sort of totally integrated system is that you get what you get. There is no mixing and matching allowed. You are dependent on the manufacturer's choice of electronic components and how well they synergize to provide the sound you desire from your audio system. Obviously, with all the provided EQ, there is considerable flexibility in terms of the final sound you hear. But you can't compare, much less actually swap out, the DAC, equalizers, power amps, etc.

If repair is needed, many problems can be diagnosed and fixed from afar by the distributor or manufacturer since each speaker is ethernet connected to the internet. If physical repair is needed, online comments indicate that the US distributor provides excellent very responsive service. The electronics box is located at the bottom of the speaker and can be physically detached by undoing a few screws. Yes, the speakers would have to be taken off their stands to do this, but for most electronics repairs, the entire speakers need not be shipped back, just the much smaller electronics module. Commenters have said that swapping out these modules is a simple process taking only a few minutes. Not as easy a process as with separate components perhaps, but not as problematic as it could be without online diagnostics and/or if the entire speaker had to be shipped back.

As I've discussed in prior posts of this thread, the end result is by far the best overall sound I've ever had in any of my home listening rooms. Whatever synergy is at work here between electronics and speaker design and manufacture works extremely well. Digital artifacts are either gone or so low in level it will take a better-yet system to hear any. Frequency response is very natural sounding to me from sub-basement bass up through the top octaves. Clarity and lack of apparent distortion are as low or lower than I've ever experienced. The transient clarity imparted by time alignment is for once divorced from any obvious frequency response errors in the on or off axis sound. Those whose tastes go beyond classical music to include pop, rock, and big-band jazz will be delighted since these go loud and clean as a whistle up to at least 95 dB. The entire bass end is a delight, offering the best combination of extension, impact, power, smoothness, and definition I've ever heard in my home listening systems. And so it goes, on and on in terms of excellences.

The only area where other speakers might (and did to me) sound initially superior is in terms of their "overt" depth of field. Due to the proximity to the wall behind them, it took me a bit of time to hear the depth which these speakers do in fact impart. This probably is a matter of re-educating only for those listeners who, like me, usually listen with eyes open rather than with eyes closed. Focusing on sonic images in depth beyond the wall behind the speakers takes some time. The trick is to listen at first in a semi-darkened room so that the wall behind the speakers is not so optically obvious. As the Stereophile reviewer helpfully said: "Unlike planars, the D&Ds didn't throw the soundstage forward — instead, it began at the plane described by the speakers' front baffles and extended deep behind them. The result was less obviously impressive but seemed more honest." With speakers placed far in front of the wall behind them (the way I've set up most speakers in this and every room) the depth dimension is easier to "see into" with eyes-open listening since you are focusing on images appearing in open space within the listening room, not behind a solid back wall.

 

[tmallin]

[Continued from above]

See my system descriptions here: https://www.whatsbestforum.com/threads/my-current-audio-systems.31269/ I no longer use any Benchmark DAC3 in the audio system with the 8c speakers since the 8c's contain their own DACs. In terms of what I can change in this "simple" system, I find ethernet connections to the Lumin to be sonically superior to any Wi-Fi links in some of the ways I mentioned in my prior message. I also find a fiber-optic link from the ethernet switch to the Lumin X1 to sound superior to an ethernet cable in this connection. Lumn recommends this type of fiber optic connection for the X1.

Why did I move away from the Benchmark DAC3B in this system? Basically I moved to using the DAC in the Lumin X1 since it, unlike the Benchmark, allowed full MQA decoding/unfolding. But after a lot of experience A/Bing the MQA Tidal version of recordings with the Qobuz High Resolution versions, I have come to the conclusion that Tidal MQA often sounds different, but not usually better than High Res PCM on Qobuz. With the D&D 8c speakers, the internal DACs don't do MQA decoding. I can get the first MQA unfold via either the Lumin's digital transport section or via Roon. I typically usually listen to the Qobuz High Resolution version of recordings these days and thus the lack of full MQA unfolding is no longer that important to me. I could take the fully decoded MQA signals from the analog outputs (full MQA unfolding ONLY occurs from the analog outputs of a DAC) of the Lumin X1 and input that analog signal to the 8c speakers, but then that would require an unnecessary A/D - D/A conversion by the D&D speakers. While reviewers say the speakers sound close to as excellent that way as they do when supplied with a digital input, most say that the digital input sounds a bit better.

In addition, the Lumin X1 digital volume control seems even more transparent than the analog relay volume control of the Benchmark HA4 headphone/line amp. That really surprised me, but allowed me to eliminate both the Benchmark DAC3B and the Benchmark HA4 from the system, allowing the Lumin X1 streamer to directly drive my amps. At first, those amps were Benchmark AHB2s. But now, with the 8c speakers, the Benchmark amps are gone as well. The volume control transparency was further enhanced with a recent Lumin firmware change which incorporated the Leedh DSP volume control processing. This can be A/Bed with the prior digital volume control in the Lumin's settings, and the difference is surprisingly audible in favor of the Leedh processing, especially at lower volume settings.

How much of the goodness I hear with the D&D 8c speakers is the speakers versus all the incorporated electronics? I would bet that much or even most of it is the speaker design of the 8c. Of course that design includes having enough power from the internal amps, as well as ensuring that all the included digital electronics work well with the acoustic design of these speakers. One example of a conscious design decision as to the digital electronics is that the internal DACs, while accepting digital program inputs up to 24/192, downsample the input to 24/48. This is done so that no program input contains sufficient high frequency energy to excite the mechanical resonance of the tweeters used, which resonance is a bit above 20 kHz.

As REG has drilled on for years, yes, speakers and their interaction with the listening room is where it's at. I was not arguing against that. If speakers and rooms are 90% of what you hear, the question is how much does the rest matter, if it matters at all. Well, we know (and REG will readily admit) that the other end of the recording chain, what happens at the recording end, is very important indeed. Many have commented that a recording made in a favorable hall with correct microphone placement and non-peaky mikes sounds excellently natural even through truly mediocre reproduction equipment at home and with digital media of comparatively low resolution, such as the 320 kbps provided by Spotify.

 

[tmallin]

Someone pointed out to me that most speakers can be made time aligned or time coherent through the addition of processing by programs such as Acourate and (I believe) Audiolense. Thus, so it goes, the time alignment with high-slope crossover present in the D&D 8c speakers is not really a breakthrough at all.

Frankly, I've long been intimidated by the implementation of Acourate. To my knowledge it doesn't come in an add-on electronics box and is not a simple program to download and install which then just works. Considerable computer skills are involved in getting it up and running, has been my impression. See: https://audiophilestyle.com/ca/ca-a...-loudspeaker-correction-software-walkthrough/ I know Bob Katz uses Acourate with his speakers, and Mitchco has used Audiolens, but relatively few seem to have mastered the implementation of such programs.

The time coherence of the D&D 8c's comes pre-programmed in, together with a 24 dB/octave crossover. This may not be unique, but it's the first such speaker I've heard, I think, much less owned. They automatically produce time-coherent step/impulse response graphs "right out of the box" as long as you don't choose via the menu to defeat this function by selecting the "low latency" mode. You might want the "low latency" mode if you want the audio in an A/V system to be in time with the video so that the dialog is synced with the actors' lip movement. The "breakthrough" for me is that with the D&Ds you get time coherence automatically and without being tied to the shallow 6 dB/octave crossover necessary in analog-world time coherent speakers like Vandersteen. Implementing the time coherence and steeper crossover with DSP allows far greater power handling and also keeps the off-axis radiation very smooth, unlike the colored off-axis response in the Vandersteens, for example (see figures 6 and 7 at https://www.stereophile.com/content/vandersteen-audio-3a-loudspeaker-sidebar-3-measurements-page-3 ).

 

[tmallin]

In a small room like mine (13' x 11'), the off-axis output of a speaker is a particularly significant factor since there is no way to get the speakers very far from the side walls. Even listening from the near field with the speakers pointed at my ears, I've usually ended up using a lot of absorption or at least diffusion treatment on the walls since the undamped reflections seem to make the sound annoyingly bright (as in bright plus grungy or brittle distortion) and reverberant, as well as spoiling the focusing of imaging and staging.

With the D&Ds, I still use dispersion (in the form of floor-to-ceiling P. I. Audio Group AQD Sound Diffusers) on the side walls and the wall behind the listening seat, but no absorbing foam. With this room treatment, the presentation is open and large yet extremely well focused when heard from the sweet spot. It does not sound at all dull (as in excessively rolled off in the highs) outside the sweet spot. I also get a clear stereo spread even when standing to the left of the left speaker or to the right of the right speaker, something I haven't heard since my days with the Ohm Walsh speakers. It sounds wonderful from outside the listening room as well in terms of frequency balance and that feeling that the sound is "live in the next room."

If there are better dispersion characteristics for a very small listening room like mine, I have not yet heard them. Over the past six years I've had in this room at least the following speakers: vintage AR-5 and AR-3a, vintage KLH 12, Stirling LS3/6, Janszen Active Valentina, Harbeth M40.1 and 40.2, Gradient 1.4, and now these. The Gradient 1.4s were the second best in terms of non-problematic dispersion characteristics. The Janszens were the most problematic, requiring extreme care in room treatment to optimize the sweet spot without allowing harsh reflections and slap echo from the tweeter beams bouncing off the wall high up on the wall behind my head. It was also difficult to optimize the output of the side-firing Air Layer tweeters for best sweet-spot imaging and staging balanced against discomforting dullness even a foot or so away from the sweet spot.

 

[tmallin]

One correspondent on another forum noted that he found the downsampling of digital input streams from higher resolutions to 24/48 to be one of the few flaws in the Dutch & Dutch design. As I understand the designer's comments on this issue, there are two reasons for this downsampling decision. First, the designer found that the DACs he used work with greater precision when working at this resolution rather than 24/96 or 24/192. Second, the downsampling is done to prevent exciting the know 27 kHz tweeter resonance with much energy. Sampling at 24/48 will roll off the treble response like a cliff above 24 kHz, thus avoiding excitation of the 27 kHz mechanical resonance of the tweeter.

Yes, I did initially have some trepidation about the downsampling of Hi Res signals. But, upon analysis--see my experimental summary in my "CD Quality vs. High Resolution Streaming" thread--the proof is in the pudding, as they say. The D&Ds have highs which, to me, have a combination of clarity, detail, and relaxed/non-edgy sound I have not heard from other speakers. I have heard no digital artifacts from the start with these speakers.

And they seem truly transparent, clearly revealing subtle sonic changes from changes in the upstream digital streaming path. Examples include changing from the stock SMPS power supply of my Roon Nucleus+ to a Keces P8 LPS, inserting a fiber optic link at the end of the ethernet run to the Lumix X1 either the way Lumin describes here or by insertion of the GigaFOILv4 INLINE Ethernet Filter just before the Lumin X1, and changing the ethernet switch from TP Link to Cisco to a Netgear Nighthawk S8000.

Perhaps a better tweeter, one without the 27 kHz resonance, could produce better results. But to produce clean bandwidth out beyond the 40 kHz possible with sampling of 24/88 and beyond you'll need a tweeter of ribbon or electrostatic design. But the highs I hear from the D&D are at least the equal of the highs I've heard from any other tweeter, including electrostats like the Sanders 10C I once owned, or the ribbon tweeters in the Legacy Whisper or Carver Amazings. And the total system in which I used those speakers did not lack digital artifacts the way the D&Ds do. I have no doubt that better tweeters will be produced, but for now, in the D&D 8c system, the results from this tweeter are extraordinary.

Let's put it a different way. Before I got the D&D speakers, I was using the Gradient 1.4 speakers in this same room also with the Lumin X1 and Roon Nucleus+ digital streaming front end and a pair of Benchmark AHB2 amps driving the Gradients. That system allowed me to play 24/192 and MQA recordings at full resolution. Both the Roon and Lumin allowed PCM upsampling to 768 and resampling to DSD through DSD 512. As good as the high frequencies were with either native or upsampled signals through the Gradient 1.4s, the D&Ds are inarguably better sounding in the highs (and everywhere else in the spectrum for that matter) despite being "handicapped" by the mandatory downsampling of all high res streams to 24/48. The sound is just so much cleaner and more natural in balance. Even CD quality stuff sounds inarguably better in the highs through the D&Ds. Perhaps the other things the design allows, such as time alignment of the drivers, triamping, DSP foundation equalization, etc., more than makes up for any loss from downsampling.

The bass/midrange excellence of the D&Ds may not be so much from the drivers themselves, but (like in the Gradient 1.4) the use of a cardioid directional pattern and leveraging the Allison effect to provide more low bass than a small speaker has any right to do--lowering the contribution of the room to what you hear from the listening position (because of the cardioid pattern) and using the room surface near the rear-facing subwoofers to advantage below 100 Hz by keeping the subbass drivers very close to a room surface. The bass kicks like a mule on steroids and goes all the way down to below 20 Hz at full level in a speaker of "bookshelf" size at SPLs up to about 95 dB at the listening position even on electronic music with very strong bottom octave bass.

Yes, if I turn the SPL yet further up on such material I can hear the bass drivers start to lose a bit of cleanliness--the harmonic distortion audibly rises, in other words. Other D&D reviewers don't talk about this, but it is surely there compared to speakers with multiple 12 or 15 inch woofers as I've used in the past (e.g., Legacy Whisper, Gradient Active Revolution with SW-T bass towers). But this happens far worse on such program material with other respected speakers (e.g., Harbeth M40.2, Gradient 1.4, Janszen Valentina Active, Stirling LS3/6, just to mention other speakers I've had in this same room) at far lower SPLs.

 

[tmallin]

On another forum some are claiming that it is unfair to compare an inherently DSPed speaker like the Dutch & Dutch 8c to the performance of a passive speaker. Such a comparison is, they argue, an unfair unlevel playing field. What should really be compared is the performance of the 8c compared to the passive speaker when ideally equalized and adjusted by the best possible external equalization electronic box or software.

I agree, at least in theory, that manual EQ, preferably with DSP as opposed to in the analog domain, can get any speaker closer to the ideal.

The D&D is a "lazy man's approach" in that almost right out of the box, with little manual tweaking at all, you get very good sounding results. At least good sounding to me.

The same is true for the Gradient 1.4. It is more immune to room effects than most speakers. Plop them down most anyplace in the room, sit centered between them at any distance you like, aim the head units toward you, and you will hear excellent sound. It's just that, to my ears, the D&Ds are even more excellent in this lazy man's approach. Yes, the price is higher, but not really, once you figure the value of the included DACs, tri-amping, crossover, time alignment, subwoofers, etc.

For the non-lazy person, the D&D has onboard 24 bands of parametric DSP equalization which you can use to tweak the sound to your heart's content. You can also adjust the overall level of each driver up or down in 1/2 dB steps. Just measure in real time and tweak away, using as much or as little parametric EQ as you like. You can also import corrections from REW if you want a more automated tweaking approach based on in-your-room measurements.

All I've done in the way of tweaking so far is the very basic set up. You measure the distance of the center back of the speaker to the wall behind the speaker and the side wall and enter those measurements in centimeters into the software. Yes, this is the ticket with these speakers to non-boomy, very extended bass. Until I hear problems, I'll stick with this basic lazy man's approach.

But while I agree in theory that manual equalization can provide yet-better results, there is something to be said for the engineering of designs like the Gradients and D&Ds which sound quite fine right out of the box, so to speak, without having to fiddle very much with room placement, room treatment, and equalization. I strongly suspect that most home speaker buyers would rather not have to fiddle too much with EQ, room placement, and room treatment in order to get their speakers to sound ball-park natural. Such clever designs should be recognized for the engineering triumphs they are.

For instance, it's a great relief not to have to fiddle to tame a midbass boom which is by far the most obvious common problem of speakers in rooms, especially small rooms. The dip in the power range of 100 to 300 Hz is even more common, but is less noticeable to most people since it's a dip, not a peak, and is so universal a problem that most people either don't notice it, or worse, don't like the result when it's corrected because the speakers may then sound less audiophile-clear in the mids.

The D&Ds come with a certain built-in DSP equalization which I'm sure is more sophisticated than the analog crossover components of the Gradient 1.4 can accomplish. Is that unfair or not a level playing field? As far as the consumer user is concerned, this part of the D&D's DSP is in the background and doesn't need to be touched. In fact it's not supposed to be touched. The same is true of the EQ built into the crossovers of the Janszen Valentina Actives I previously had in this room.

Such EQ is analogous to the foundation EQ of a Public Address (PA) system. Such EQ is usually provided at installation of the room's sound system by a professional audio engineer through parametric or graphic equalization after careful measurements of the performance of the PA speakers in that auditorium and those settings are then locked down and thus tamper-proof during ordinary use. They become the foundation from which the live sound engineer then can EQ different microphones for best sound in the room where the mikes may not be flat or ideally placed because of set-up constraints or because feedback problems are encountered which need to be "voiced out" by EQing down the offending feedback-inducing frequencies. As the D&D designer has characterized it, the D&D 8c is designed not to not need much if any "voicing" by the consumer.

There are certain constraints on placement to get the D&D sort of smooth, extended, and powerful bass performance right out of the box. D&D recommends placement within a range of about 10 to 80 cm from the wall behind the speakers to the rear of the speakers, and ideally about 20 cm to 50 cm. That's closer than most audiophiles tend to put most speakers to the wall behind them. Most speakers sound smoothest in the bass well away from the walls. Certainly the Gradient models do. As John Atkinson's 8c test results showed, when you disregard the close-to-wall-behind-them recommendation as he did, the 8c's bass smoothness can go right out the window, necessitating considerable use of the parametrics to flatten it out.

In my set up the speakers are well within the sweet spot of the design at 30 cm from the wall behind them. I just type 30 cm into the software (available as an app on my iPad control device from the listening seat) and--bingo--smooth, extended bass. And, yes, as other reviewers have found, the specified distance in the program really is the best sounding for the speakers which are physically arranged to be that specified distance from the wall. Change the distance through the program setting to a distance which does not correspond to the actual physical distance and the bass very clearly is not as smooth. It works as expected, works very easily, and works very well indeedy.

 

[tmallin]

Some have wondered if there is a less expensive streamer that would provide a near ideal front end for a Dutch & Dutch 8c-based system. Not all are able or willing to spend $14,000 for the Lumin X1 I use. Here are my thoughts on that issue.

If I were to recommend such an approach, I would stick with the Lumin streamers. The Lumin U1 Mini which I owned before my current top-of-the-line X1, is "only" $2,000 and is configured in such a way that it is a near ideal match for the D&D 8c speakers. I've written extensively about that unit in my "Lumin U1 Mini Digital Transport + Sbooster Power Supply" thread.

Since the D & D 8c speakers have their own DAC which cannot be bypassed, you are better off feeding the 8c's a digital signal rather than the analog output of your DAC. The Lumin U1 Mini has no DAC, so you are not paying for one, as you are with the X1.

In addition, unlike even the X1, the U1 Mini has an AES/EBU balanced digital SPDIF output which is a perfect match for the female XLR AES/EBU digital input of the D&D 8c speakers. With the X1, I have to use a 75 ohm to 110 ohm converter at the left 8c speaker to feed the X1's digital SPDIF output to the speakers' digital input. With the U1 Mini, no such converter is needed.

The U1 Mini has all the vital functions of the X1: the same great rock-stable firmware and GUI, the Leedh DSP volume processing, and the same first (and most important) MQA unfold from its digital output. And while the U1 Mini doesn't have the same extreme upsampling/resampling capabilities as the X1, I don't use those capabilities much anymore anyway, generally preferring the sound of native resolution, at least for CD and above quality sources.

In addition, since the DACs in the 8c speakers resample all digital inputs to 24/48 anyway and will only accept inputs up to 24/192, more extreme PCM upsampling/resampling is wasted and DSD signals can't be accepted by the 8c speakers at all. If you want to feed the speakers DSD or extreme PCM upsampled/resampled signals, you'll need to do it in the analog domain. I have not compared the sound of feeding the D&D speakers analog signals with the digital feed since in the long term I have not found such upsampling/resampling to be sonically beneficial in the first place and since the designer and most 8c owners find the speakers to sound a bit better when fed a digital signal than when fed an analog signal which must then pass through the built-in (admittedly high quality) analog-to-digital converter.

Whether you want to use an after-market power supply like the Sbooster with the Lumin U1 Mini is up to you. Many, including some whose ears I trust, find the U1 Mini to sound quite fine without it. I really never made the comparison since adding the Sbooster is not an easily reversible process once it's done and I added it before even listening to the stock version of the U1 Mini. That is to say, I didn't have the technical skills to undo the process involved in adding the Sbooster since that process involves cutting a wire inside the U1 Mini chassis.

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