Dutch & Dutch 8c Speakers

[steve59]

I use a meridian 218 which is a very basic pre/dac for my active dsp speakers it lists for $1000. I use the RJ45 master/slave outputs but it has coax analog and digital outs. streams to 24/96 and takes up very little space.
I'd be interested in what the approximate spl's are that you notice the D&D system start to sound stressed.

 

[tmallin]

The D&Ds low bass is the first thing which will start to sound a bit stressed as volume increases. That's to be expected given the extension all the way down to 20 Hz out of a small box. Most reviewers haven't commented much about audibly or measurably increased bass distortion with level at all. But it's there if you care to be picky. When I say "a bit stressed," I mean just that. Not gross obvious distortion or doubling, just a bit more compressed, a bit richer and less detailed, a bit more "wooly," just not as "clean" as it sounds at lesser volumes.

To my ears, even the bottom octaves stay clean up to about 95 dB at the listening position. This is an approximate measurement using the Audio Tools app on my iPhone 11 Max phone held in my hand just in front of my face when I sit in the listening position. The meter is set on C weighting, slow. This applies even with music with heavy low bass, such as pipe organ and electronic music with heavy synth bass.

While that may not seem like all that loud compared to measured rock concert levels, at home in a small, not very damped listening room like mine, it is loud enough for me. I would not want to listen that loudly for very long. I usually listen down around 83 - 85 dB measured the same way with that sort of material.

I'm not sure how translatable this is to other systems, but using either the Lumin or Roon volume controls with the D&D speaker gain set at the nominal 0 (no boost, no cut) level, 84 dB corresponds to around 64 on the volume control with a lot of fairly compressed material, while 95 dB is at most about 82 on the volume setting with that same sort of material. Both these volume controls have a maximum setting of 100. I listen from about eight feet away from the speakers and the room is quite small, about 11' x 13' x 8.5'.

 

[kaka89]

Lumin recently released a remote for their device.
For those who don't like to use 8C's web app for volume control now they have a great option.

 

[tmallin]

I'm not really sure what you mean, kaka89. Both the Lumin App and Roon contain volume controls which will control the volume of what you hear out of the D&D 8c speakers. This has been so from long before the D&D speakers were released.

In fact, I have never used the volume control built into the speakers to adjust the volume of what I hear out of the D&D 8c's. I just set it at unity gain (0 dB) and leave it there. I always adjust the volume via the Lumin's Leedh DSP volume control, either directly through the Lumin App, or via Roon. I have Roon set up so it uses the Lumin's Leedh volume control.

 

[kswanson27]

I'm not really sure what you mean, kaka89. Both the Lumin App and Roon contain volume controls which will control the volume of what you hear out of the D&D 8c speakers. This has been so from long before the D&D speakers were released.

In fact, I have never used the volume control built into the speakers to adjust the volume of what I hear out of the D&D 8c's. I just set it at unity gain (0 dB) and leave it there. I always adjust the volume via the Lumin's Leedh DSP volume control, either directly through the Lumin App, or via Roon. I have Roon set up so it uses the Lumin's Leedh volume control.

I'm using a U1 Mini with my 8C's and controlling the volume for Roon with my iPad. I have Leedh enabled so I assume I'm controlling the 8C volume with Lumin's Leedh volume control? The iPad shows "lumin U1 Mini" at the bottom right with a volume slider.

 

[tmallin]

Assuming that you have the Lumin volume control also enabled, then I think you are correct. The Lumin App does not control the volume of the D&D 8c speakers, just the digital volume control in the Lumin U1 Mini itself. In Roon, make sure you have Roon set up to allow the Roon endpoint, in this case the Lumin U1 Mini device, to control volume. I believe that is the better sounding way to do it. Roon's built-in volume control is very good for a digital volume control, but the Lumin's Leedh DSP volume control is the best way to handle the volume of a streaming system--forget analog preamps!

 

[kaka89]

I'm not really sure what you mean, kaka89. Both the Lumin App and Roon contain volume controls which will control the volume of what you hear out of the D&D 8c speakers. This has been so from long before the D&D speakers were released.

In fact, I have never used the volume control built into the speakers to adjust the volume of what I hear out of the D&D 8c's. I just set it at unity gain (0 dB) and leave it there. I always adjust the volume via the Lumin's Leedh DSP volume control, either directly through the Lumin App, or via Roon. I have Roon set up so it uses the Lumin's Leedh volume control.

I mean this new remote from Lumin. Physical volume key!

 

[tmallin]

Interesting, but useless for most people, I'd say. You REALLY NEED an iPad GUI interface for either the Lumin App or Roon. Volume control is easily accessible and operable from either. Also, for best sound you want to turn off the screen of the Lumin, even if you could read it from your listening position, which I can't comfortably. But I suppose there are folks who just must have the old physical wand type remote control with hard buttons for volume and other functions.

 

[tmallin]

I did some measurements again on the D&D’s about a week ago using Omnimic V2. As before, I really couldn’t find much to change in the overall response.

Even in the bass range, the trend line is plus or minus 3 dB all the way down to 20 Hz. When I say "trend line," I mean the desired-by-me trend of the response to slope smoothly down from 20 Hz to 20 kHz by about 10 dB. Using the D&D's built-in parametric EQ controls, I did try adding a 4 dB boost at 20 Hz with a Q of 2 to extend the trend line all the way down to 20 Hz. I later backed off to a 3 dB boost a 20 Hz with a Q of 2. I’m trying that out for a while. The bass sounds even more spectacularly extended now without the bit of excess "shudder" that the 4 dB boost was providing.

I do plan trying absorption again at all the reflection points instead of dispersion. But the system sounds so good right now that I am not in a rush to do that.

 

[tmallin]

I was never able to access the 8c's via a Windows computer. The Lanspeaker.com link works fine with an iPad or iPhone. I never called D&D about this since I use an iPad for control in the audio room anyway.

Last week I just got a new iMac computer as my new desktop work/play unit. I do not have Windows installed on it. I just tried accessing lanspeaker.com from it and it worked fine the first time. So I think it's a Windows issue. I have not tried an Android device. The D&D folks would know if it's just an unusual problem with my set-up or that it just doesn't work with Windows.

 

[kswanson27]

I was never able to access the 8c's via a Windows computer. The Lanspeaker.com link works fine with an iPad or iPhone. I never called D&D about this since I use an iPad for control in the audio room anyway.

Last week I just got a new iMac computer as my new desktop work/play unit. I do not have Windows installed on it. I just tried accessing lanspeaker.com from it and it worked fine the first time. So I think it's a Windows issue. I have not tried an Android device. The D&D folks would know if it's just an unusual problem with my set-up or that it just doesn't work with Windows.

I've had that problem on my Windows 10 desktop when I haven't accessed Lanspeaker for a while. Rebooting the 8C's solves it.

 

[tmallin]

More thoughts on the D&D 8c's in response to questions I've received:

I did not use Omnimic or REW to set up the 8c's. I used physical measurements from the top center back of the cabinet to the wall behind the speakers and the nearest sidewall. I adjusted the position of the speakers to match the available presets for those measurements in the D&D software. Those presets are every 10 cm (about every 4 inches). I ended up with 30 cm from the wall behind the speakers and 40 cm from the near side wall.

That positioning worked out best in my room in terms of giving me a 60-degree subtended angle between the fronts of the two speakers while putting my listening distance at a spot in the room which is not in bass null (e.g., not in the exact center of the room). Keeping the speakers 20 to 50 cm from the wall behind them is recommended by D&D to take maximum advantage of the bass reinforcement possible by near-to-wall-behind-them positioning. Also, my positioning allowed me to keep the speaker stand base all on the hardwood part of the floor. Any further out would put the base half on the carpet and half on the wood, making leveling a nightmare, or all on the carpet, making leveling more difficult and adjusting the toe in much more difficult, especially with the stands I have.

I have my internet connection to the audio room equipment hard-wired these days. you could use a wireless access point and do ethernet connections from there to each speaker. At least for set up you need to run separate ethernet wires from a router or ethernet switch to each speaker. I used a $25 TP Link wireless access point set up for Client Mode for a long time to feed internet signals via ethernet to my Lumin streamers before I invested $1,000 to run the ethernet cable from my router to my audio room. See my discussion of this TP Link set-up here. (Note that for some reason What's Best Forum does not make the links in my posts show up as highligted texts. You have to mouse over the text to see the links, but they are there, such as links to the description of the TP Link and the video as to how to set it up in Client Mode.)

One wrinkle is that you might still need to use an ethernet switch (as I do) since you will need to run two separate ethernet wires to the speakers and the TP Link only has one ethernet output. TP Link also makes a $20 ethernet switch you could use. You would feed the switch from the access point and then feed the speakers (and possibly a streamer if you need one) from the switch via separate runs of ethernet cable. I use Blue Jeans CAT 6 or 6a ethernet cables.

As mentioned, each speaker must be separately connected to the switch. One speaker does not act as a slave to the other in this respect. Once set up, however, strictly speaker the speakers no longer need to be internet connected. However, if you ever want to check the set up or make changes to it, you will have to reconnect both to the internet. I just keep both speakers always connected to the internet. This will also be necessary if D&D ever gets the speakers certified as Roon Ready. If that happens, I technically would no longer need my Lumin streamer, but eliminating the Lumin would give up the Lumin's DSP Leedh volume control which, in my estimation, is the cat's meow of volume controls.

If you still need or want to use an external equalizer such as the DSPeaker X4 to equalize the system (remember, the D&Ds have onboard parametric EQ in addition to separate level controls for the subs, woofer, and tweeter, you would not need to feed the D&Ds an analog signal. You can definitely feed the D&D's a digital signal from the coax digital out of the X4. All you would need to do is convert the coax digital to BNC and then convert the BNC to AES/EBU either near the X4 or at the speakers so the cable can be inserted into the XLR-based AES/EBU digital input of the left speaker. I use a Blue Jeans SDI cable with BNC at each end to run from the Lumin's BNC digital output to near the left speaker. I then convert the BNC to AES at the speaker. (I'm not 100% certain as to which "sex" of BNC connector you would need. I think you will want a female BNC adaptor. But you may want to buy one each of adaptors with female BNC and male BNC. I know you'll need the other end of the adaptor to be male RCA to fit into the female RCA output jack of the X4.)

In this sense, the left speaker acts as master and the right as slave. You run a balanced digital link from the digital output of the left speaker to the balanced digital input of the right speaker. You then insert a D&D-supplied (as in it comes in the box with the speakers) termination plug in the right speaker's digital output jack.

Here are some other thoughts about things I might do differently if starting over with my D&D set up, now that I've lived with them for awhile:

• I'd consider buying the $600 D&D dedicated 24" stands. The pictures now posted look much better than the drawings they once had online. You bolt the speakers to the stands (the speakers come pre-drilled with threaded holes lined up with the holes in the D&D stands), so this would be a much more stable stand than the Monoprice. The stability would allow easy positioning of the speaker and stand even on carpet, at least unless/until you attach spikes to the bottom of the stand. See pictures near the bottom of this page.
• I would experiment with both near-wall and far-out-from-the-wall set ups to see which sounds better.
• If sticking with the Monoprice stands, I would try 24" Monoprice Monolith stands rather than the 28" version. I do find getting the listening height correct to make a nice further improvement in terms of image focus. The correct height seems to my ears to be a bit more toward tweeter level than the 10.5" above the bottom of the cabinet stated by D&D. The 24" stand might therefore be fine if your chair puts your ears no higher than about 36" above the floor.
• I would use sand instead of cat litter to fill the stands. Sand will make the stands yet deader, the added mass would benefit the stability of the stand, and the Monoprice stands don't seem to be "leaky" at all.
• With the Monoprice stands, I would use slightly taller self-adhesive vinyl bumpers atop the top plate of the speaker stand to allow more clearance for the screws which protrude from the bottom plate of the speakers. I'd try 1/4" high vinyl bumpers. I think the ones I used are either 1/8" or 3/16". With the D&D stands, the already-attached speaker feet sit atop the stand's top plate so you wouldn't need spacers.

 

[RDSChicago]

What are the differences between the 8c and 8c studio besides the studio being all MDF? Is there also a difference in streaming capabilities?

 

[tmallin]

From the description on the D&D website, the Studio version will not include built-in internet streaming capabilities. Thus, assuming D&D is ultimately successful in making the 8c a Roon Ready device, that capability will further distinguish the 8c from the Studio.

With the studio, you will need a separate streamer to feed the Studio an AES digital signal of up to 24/192. Thus, the Studio should be able to work just as I am currently using the 8c. I feed the 8c AES signals at up to 24/192 from my Lumin X1 streamer, either from the Lumin App or via the Lumin App from Roon.

With the 8c, once the firmware is upgraded to become a Roon Ready endpoint, I could send Roon programming (e.g., internet radio, Spotify, Tidal, Qobuz) directly to the 8c's from my Roon Nucleus+ controlled by the Roon App on my iPad Pro. I would no longer need the Lumin X1 streamer. However, that signal path would lack the Lumin's Leedh DSP volume processing. Not being able to use the Leedh volume control might negate any sonic advantage of allowing the 8c speakers to act as the Roon endpoint without the Lumin X1 in the signal path. Only direct comparisons will settle that issue.

 

[tmallin]

I agree that the best way to use the old TacT equalizer (in my case the RCS 2.2XP, both the stock unit and the fully Maui-Modded version, both of which I owned) is to defeat the target curve above a chosen frequency, usually no higher than 800 Hz.

Here's how to identify real high frequency problems which can be treated with electronic EQ, as opposed to problems caused by room surface reflections: Measure the speaker from quite close up, not the listening position, move the microphone around a bit from that short distance, and only correct the errors which seem constant in these close-up response measurements.

I've found that for frequencies above 800 Hz or so, you are usually better off following the "old school" EQ method: just don't buy speakers which sound like they have significant high frequency problems when you audition them. In other words, don't plan to EQ-away the high-frequency problems you hear.

That's because in the small, narrow rooms I've lived with, room reflections have been the primary cause of the "brightness" problems I always seem to be kvetching about. Electronic EQ is not the satisfactory way to treat those issues since in the highs EQ only deals with the direct sound from the speakers, not the delayed, off-axis response. For most speakers, the off axis sound in the highs is colored compared to the on-axis response and this coloration is added to any obnoxiousness caused by the short delay in hearing this sound. What is needed to cure this room-reflection-caused "brightness" is diffusion or absorption in treating the room surfaces of your listening room.

This has led me to use both absorption and diffusion in my listening room to cut down on the obnoxious sound of room reflections. It also led to my adoption of near-field listening and toeing the speakers in to face my ears. All three methods reduce the ratio of reflected sound to direct sound I hear from the listening position.

This same pursuit--less second-venue sound in the upper frequencies--also led me to pursue speakers which interact less with the room above the bass while not sounding too "closed in" or "dull" away from the sweet spot. With the Gradient 1.4 and now even more the Dutch & Dutch 8c, I've found that sweet spot in high frequency dispersion for my small listening room.

Sure, even with the D&Ds I can still hear the difference in sound from the listening position when I treat the room surfaces with diffusion or absorption panels. With "bare walls" listening you get added "liveness" to the sound, a liveness which technically is not in the program, but which can impart a sense of added spaciousness and/or excitement without sounding offensive. For example, radio announcers speaking in a small, surely dead-sounding studio appear to be speaking in a larger, more reverberant room; the "clap track" test on the Sheffield/XLO Test disc has a reverb tail it does not have through headphones.

But the Gradient 1.4 and to an even greater extent the D&D 8c do not sound obnoxious in the high frequencies even at high playback levels in my small room even under such "bare walls" conditions. The off-axis sound is quite similar in response to the on axis sound and thus is not colored--see the lateral response graph in the Stereophile review of the D&D here. The earlier Gradient Revolution lateral response graph published in Stereophile showed a similar lack of off-axis coloration below the top octave--there was no "filling in" to the sides for an on-axis dip in the presence range, for example, as there is with so many BBC-legacy speakers--see Figure 5 in the Stereophile measurements of the Stirling LS3/6 here, for example.

It's not that I'm anti-electronic equalization. My D&D 8c's are heavily DSPed by the electronics built into the speaker boxes. This automatic DSP is easily user adjustable to compensate for different distances from the speaker to the wall behind it and nearest side wall. "Tone controls" are available for the subs, woofer/midrange, and tweeter, and 24 bands of parametric EQ are available for each channel. But the automatic DSP, together with the other built-in design elements of the 8c, works so well in my room that I really hear nothing "wrong" after months of listening and adjusting only for the distance of the speaker from the walls. Okay, after measuring the bass and looking at the Omnimic V2 response graphs I tried a parametric alteration of +4 dB at 20 Hz, with a Q of 2. Listening told me this added a bit too much "shudder" to the low end, so I dialed it back to +3 dB and that is what I'm now living with. But, honestly, with most material, this added bass is not needed or even significantly audible.

For those with other speakers, the best electronic EQ box I've used is the DSPeaker X4. It combines ease of use with a lack of undesired side effects that makes it unique in my experience. Yes, it's expensive. The old Z-Systems units also have no undesirable audible side effects. You can still usually find used Z-Systems rdp-1/rdq-1 units for around $1,000 or less. But these are strictly manual units and are relatively difficult to adjust compared to the DSPeaker X4. The parametric filters available through Roon also seem to be fine but again are strictly manual. You will need a system like OmniMic V2 to see the effect of your adjustments on system response and use the displayed graph to ball park the adjustments. Your ears should then be the final arbitor in setting your EQ curve. The DSPeaker X4 makes this so easy because even in my small room it got everything sounding correct the first time with no need for manual second-guessing and not need to involve a computer in the measurement process. For my comparative detailed and long discussion of the X4 and other electronic equalization devices I've used (pre-D&D 8c) see this thread.

 

[tmallin]

If you have not seen this AMROC room mode calculator before you should check it out. Put in your room dimensions first in either cm or feet. Using the forward/backward arrows shows different values. One of the calculators shows suggested RT60 for various uses and the amount of padding needed to achieve that RT60 result. I now have enough absorption to get the R60 way down to the .33 second value recommended for speech and education.

https://amcoustics.com/tools/amroc?l=15.25&w=14.75&h=9&sa=false&so=false&ft=true&r60=0.6

My room shape also falls within the recommended Bolt area and has the recommended increasing Bonello progression of room modes.

 

[tmallin]

Questions: Are there advantages to using a sophisticated equalization box, such as the DSPeaker X4, either in addition to or instead of the built-in equalization capabilities of the D&D 8c speakers for adjusting the 8c's? What about time-domain effects of such outboard EQ boxes or bass traps?

As far as I know, the X4 does not do anything "special" in the time domain the way the electronics from Eikon Audio and Legacy Audio are advertised to do. But, as REG has repeated many times, if you correct the frequency response of a speaker you automatically correct the phase response of it, at least the part that is minimum phase. That means that correcting the response won't fix a lack of time alignment of the drivers, for example, and won't fix resonant behavior of the room which puts out sound after the fact of being excited by bass from the speakers.

But with the D&D 8c's, you're ahead of the game since the speakers are time aligned from top to very bottom via the DSPed crossover as long as you have the Active Room Matching distances set correctly in the software to correspond to the physical distances of the subs from the room boundaries. The phase response down below 100 Hz isn't all that important anyway since the wavelengths are very long there and even large distance variations won't create many degrees worth of out-of-phase alignment. Most of what is being adjusted by the Active Room Matching distance settings relates to the Allison Effect and acoustic cancellations caused by the ratios of the distances of the drivers from the room surfaces.

I think that owners of equalization software and EQ electronics boxes like the X4 should experiment with taking that outboard software or hardwar out of the signal path entirely, then just using the D&D's settings to correct the response you measure with OmniMic. The method would be:

• measure from the listening position
• measure one speaker at a time
• use the full setting of OmniMic V2 (not blended)
• look at the 1/3-octave smoothed graph
• 2 dB per division on the graph for sufficient detail with this smoothing
• adjust overall bass level so that it smoothly slopes up a few dB from 100 or 200 Hz down to 20 Hz so that 20 Hz is at most 6 to 8 dB higher than 1 kHz; you may prefer much less bass boost than that, but try that amount first
• if the overall bass level is higher than that, use the Sub level control in Active Room Matching to lower it some before using any parametric filters
• only pull down bass peaks, don't fill in any bass dips
• exception: fill in any dips in the 100 to 300 Hz region to the extent possible--you can't add more than 6 dB anyway with any given parametric filter and you shouldn't try adding more than that to fill in a dip anyway
• don't correct anything above 1 kHz and preferably not above 500 Hz.
• If you want more or less highs, just adjust the overall treble level in small increments (0.5 dB increments are the finest available) to taste using the Active Room Matching settings for both speakers.

You should then be done and will have fixed all the DSPeaker X4 would have fixed anyway, and will have fixed any dip in the 100 - 300 Hz range that the X4 would have left alone, but which REG and I agree is important to fill in to the extent reasonable.

I'm not familiar with differing time domain effects of bass traps vs. equalization. There may be audible differences between the two since the traps actually suck bass out of the room overall whereas EQ will only correct the bass response at the measured position and may make the bass frequency response worse elsewhere in the room. Whether this is audibly important from the listening position, I don't know since I've never used bass traps.

I've never been impressed with the bass response of rooms which use ASC Tube Traps and can't say that I've ever heard the before and after effect of other kinds of bass trapping. Traps are supposed to be tuned to fundamental room resonances and are not capable of being changed to deal with Allison Effect problems or other interactions of speaker bass response with the positioning of the speakers or listener in the room. Those other problems are best addressed by changing the positions of the speakers and listener and/or electronic equalization, I believe.

To my ears, ASC Tube Traps are primarily beneficial for creating special imaging and staging effects because they can tune the absorption/diffusion characteristics of the room depending on how you rotate the trap in position--part of the cylinder is reflective and part is absorptive. I'm not really fond of those effects, either, compared to a live-end/dead-end treatment with broadband acoustic foam.

I continue to believe that the D&D 8c speakers produce some of the best bass response I've heard in any system I've ever owned and with very little effort on my part.

 

[tmallin]

I applied the method described above and measured and equalized the speakers. The first listen was promising, but I thought things sounded a bit "thick." Then I remembered that I EQed using the Blended setting of OmniMic v2 instead of the All setting. I think that the All setting gives a better match with how my ears hear the bass end of things. The "thickness" I was hearing was probably due to my having overcompensated for a measured dip in the 100 - 300 Hz range because I was using the Blended graph to make my equalization adjustments. So the next day I re-did the EQ and made the slight adjustments necessary due to the differing bass-end results between the Blended and All settings.

I guess I just like a lot of bass--a real bass-head--but I find a 6 dB slope up from the upper bass down to 20 Hz to sound best. But the overall level of bass I get below 150 Hz is totally adjustable quite easily using a combination of the Active Room Matching Sub setting and the one Parametric filter I have set to boost 20 Hz with a Q of 2. For my situation I have subtracted 2.5 dB of overall level from the drive to the Subwoofers (100 Hz and below) while boosting the 20 Hz level by about 4 dB with a parametric to make the bass continue its smooth rising slope from 150 Hz down to 20 Hz.

Attached are the results measuring and tweaking the equalization. The graphs are 1/3-octave smoothed, with 2 dB per vertical division. I find this sort of smoothing and vertical graph resolution to match well with what I hear and enable fine enough adjustment. On the one hand, our ears tend to sum sounds on a 1/3-octave bandwidth. On the other hand, the vertical scale needs to be expanded enough to show what is happening accurately enough so that you are not lulled into thinking that all is well when in fact the compression of the vertical scale is hiding problems you might hear. Many published graphs use a vertical scale of 5 or even 10 dB per vertical division and I think thus tend to mask truly audible problems.

These measurements are made with the mike at the listening position facing straight forward. They are annotated to show what EQ I have applied (I didn't include the 30 cm from back wall and 40 cm from side wall settings). As thus equalized, both channels measure basically plus or minus 1 dB from 150 Hz up to about 9 kHz, above which the response slopes off and below which I have the bass turned up. The left channel is a bit flatter than the right channel for reasons I don't really understand, but the primary difference is in the 150 - 300 Hz range which really shouldn't have any dips, but almost always does with audiophile systems. I can get the left channel flat in that range with no problem, but I'm still about a dB shy on the right channel. Still, the "power range" now sounds excellent and the speakers' entire range sounds even smoother than before.

I have not tried to fill in the dip at 50 - 60 Hz since measurements made with less smoothing show that this is a sharp deep null. Such nulls usually occur when the microphone is in an exact null position for a particular room mode. I'm pretty sure this null results from a room-width-related mode since the microphone is exactly centered on the room width. This null will fill in a bit anyway because my ears are each a bit off center whereas the mike is exactly centered on the room width. I don't hear this dip on music.

I may try adding a dB or two of level to the treble via the Active Room Matching Tweeter control. I looked at that when measuring and the whole treble range shifts up a bit with that control with even 2 dB of lift probably being too much. I can just listen to the results and see if I prefer adding a bit more treble.

I've also included Blended plots just to show the Impulse response. (OmniMic does not show the impulse response on the Full setting.) Pay no attention to the frequency response shown on these plots since they are not directly comparable to the "All" plots; for one thing, they are not normalized to be 70 dB at 1 kHz. The acoustic foam helps a lot for smoothing the result following the impulse. The nice single pulse of the impulse response is due to the time-coherent nature of the D&D 8c speakers. Other speakers do not show this "tidy" a pulse.

I'm really not sure what the little pulse just a millisecond or so (about one foot) after the main pulse is from. Designer Martijn Mensink suggested it may be from some part of the microphone stand. The bigger pulse 5 ms later is probably from my as-yet-untreated ceiling. The less smooth areas after 8 ms are from the areas of the walls where there is no foam but just dispersive wall treatment.

 

[tmallin]

When using parametric filters to manually smooth the measured frequency response, you need to know how to adjust the shape of your filters to match the problem peaks you see on your frequency response measurement graph before applying your manual EQ. The center frequency of any given peak is easy enough to decipher from the graph. However, you will also need to know what the Q of a parametric filter should be to match the shape of the peak you see on your response graph.

Q is a measure of the sharpness of the filter. A filter with a Q of 1 means that the width of the filter matches the center frequency of the peak/dip you are adjusting. A Q of 2 would mean the filter has half that width. In other words, the Q of a filter is defined as the peak or dip center frequency in Hz divided by the width of the peak or dip in Hz.

Thus, for example, if you see a peak in the measurement graph of 5 dB at 40 Hz and visually judge from the graph that the peak covers the range from 30 Hz up to 50 Hz, the width of that peak would be 20 Hz. For that peak you would start with a filter at 40 Hz of minus 5 dB with a Q of 2 which would be a counteracting filter with a width of 20 Hz.

When adjusting the filters manually, if you see that the areas in the graph around the peak are affected once you engage your filter, increase the Q value so that your counteracting filter gets narrower and will not affect the range outside the peak's range. If the peak isn't reduced enough for the measured response to be close to the reference/desired level, try increasing the dB value of the counteracting dip.

Yes, this may take awhile, but with speakers as inherently smooth in-room as the D&D 8c, and using 1/3-octave graph smoothing, you probably won't need more than 3 or 4 parametric filters and you only have to do the measurements/corrections once.

 

[tmallin]

My reply to someone who loves the sound of BBC-derived speakers, listens to primarily classical and jazz, but is feeling some urge for "new speakers," perhaps newer models of BBC-derived speakers:

It does not seem to me that you are at all dissatisfied with the sound of BBC-style speakers. I don't know what speakers you currently have, but if you choose to replace them at all, you probably should just look at newer models of BBC-inspired speakers. For example, Harbeth just came out with their XD line, of which the Monitor 40.3 is the new top of the line. And now that the new line is out, the prior versions should be available on the used market for considerably less.

On the other hand, you could just try to "fix" whatever you currently hear as problematic with your current speakers. Several methods include extending the bass by adding the Audiokinesis Swarm subwoofer quartet, electronic equalization, re-positioning the speakers and/or listening position in the room, or different room treatment.

When I moved on from my BBC-style Harbeth M40.2, it was not because of any perceived sonic problems. The M40.2s sounded great in my set up to the very end. But my listening room is very small and the big Harbeths, positioned as they sound best--well out into the room and well away from walls and listened to in the then necessarily quite near field--proved over the long term to be visually dominating/distracting for an open-eyes listener like me. The front panels were at most 55 inches from my ears. I was looking for speakers of equivalent quality which would not be so room dominating. The Gradient 1.4 met that goal. The D&D 8c is even better at this since they are visually smaller yet and since they work best near the wall behind them they make my small room visually quite spacious since I'm listening from about eight feet away from them as opposed to 55 inches.

While I do fancy the D&D 8c speakers as sounding considerably better yet (yes, the love affair continues), that does not mean that you would find them to be so in your room on the music you prefer. You are also correct that with a speaker which puts so many eggs within its cabinet basket, if something breaks, it might well be more difficult to fix things. Active electronics may not have nearly as long a life expectancy as the usual passive speaker components. With the D&D speaker, all the active electronics are in a drawer at the bottom of the cabinet; according to D&D that drawer can be detached and swapped out for a new one; there is no need to ship the entire speaker back for repair. I hope not to have to test this procedure; so far, everything is working just fine.

I think most people are much more reasonable and conservative about speaker replacement than I am. To say that I change speakers like I change socks is an exaggeration, but not nearly so much for me as for 99.999% of other audiophiles. I don't recommend that practice for others. Don't do as I do; do as I say: if it ain't broke, don't try to fix it. If it needs fixing, try the methods I suggest above.