Time alignment

[NorthStar]

That comment was made generally on the topic and not directed at yourself nor Dunlavy, etc. I've heard and measured the SC-VI's and was quite impressed with what was achieved. I also well remember Richard Hardesty's subwoofer comparisons and measurements from the late 90s I believe.

---- Also known as Dr. Boom.

Indeed, he had a very extensive series of articles on subwoofers with many of them reviewed.
And he explored the various methods of proper settings (phase, low-order x-overs, x-over points, etc.).
Also, dual subs are better than one. And multiple subs.
{I do have all his reviews and articles on subs from Widescreen, plus the Sub bible; Subwoofer Buyer's Guide with over 50 subs reviewed, specs on 296 subs, in the Fall/Winter 2000/01 special edition.}
...You are right, that series on subs was from the late 90s.

...And for music, no bigger than 12" driver(s). ...Preferably multiple smaller drivers, like 8" or 10". ...For them subs. And for the LFE channel only (movies), 18 inchers are perfect. :b

* I knew that your comment was general, but general here. :b

________________________

I've been busy today with 'master clock', 'jitter' stuff reading, analog stages, USB asynchronus, HDMI inputs, USB inputs, ...Oppo BDP-105 Universal 3D/4K Blu-ray player.
And on how to interpret correctly graph measurements; about distortion, different orders of harmonics, THD, IMD, smoothed Frequency Response, etc.

I guess the better your source it helps too at the end of that Time Alignment's line; all part of the total equation, not just the loudspeakers.

 

[cooljazz]

A great experience for me was an afternoon spent playing with time alignment a few years back. I'll never question the value of time alignment again!

It was a two way design. JBL potatoe masher for highs and a Harry Olson titty driver for the rest in a sealed enclosure. We were able to just slide the JBL back and forth making changing distance easy. A first order crossover of course, an oscillator (set to cross freq) and a mic/amp/VU meter to look at result. Flipping phase and looking for the null shows you the alignment.

You could get a pretty deep null and sliding back and forth it became pretty clear. After playing a little, you really didn't need the metering. Interesting was the 360 out position and it's slightly less null.

But the listening before and after, or in phase and not necessarily, was extremely illuminating! The best words I could come up with was when you went in phase it was like sticking your head out of a window to where a system was playing. Out of phase was like pulling back inside and having mostly indirect sound.

While I don't at all discount the importance of all the other factors, the coherence of time alignment was very interesting. It's "correctness" seems to really go along with my experience and enjoyment of my long term reference of big electrostat's and now my playing with OB full range drivers.

CJ

 

[NorthStar]

-- Good post CJ. :b

* As an aside; the first speaker I built back in 69-70 was crossover-free (x-overless?).
Of course it was just mickey mouse in a box, but fun and pleasant nonetheless.
And it was also a Center Back Channel speaker. ...Yes, for a surround sound experience.
I kid you not; got proof (my family; Mom, bros & sis).

** I'm waiting for much more from the experts, and Amir too. :b

 

[FrantzM]

In a different thread you posted this. I thought it would be more appropriate to continue the discussion here:

Firstly i want to address an error. , i meant to say 63 not 57 in my previous response so you are correct when saying 63 , as to the rest if you read back i said it was a combination of physical and electrical properties , proper xover mix is a must , a straight first or second order xovers will not address this issue in its entirety, it requires a careful mix and combination of both electrical and physical alignment....

Frantz, less take for eg your transducer of choice , Panel speakers , (i have one too)the amount of acoustical smearing is astonishing , we can start with the lost reverberant field around instruments and voices , this is why you hear such a wide disparity between your headphones and your speakers, most panel speakers have this issue , they go from Ok to very bad , from Belafonte at 35% Carnegie Hall, to a small room ...

This is what point source speakers do better, they do suffer from dynamic compression in the mids/highs more , so there is a constant tradeoff , accuracy and detail in the recoding vs size and growth , still it's Hilarious to hear the word resolution to describe the sound of most panel speakers, big and open sounding they are , recording details , No !

The 63 is the rare exception here as it will resolve and yes it has a seriously good step and Impulse response and the upgraded ones from Wayne Pk can actually play loud enuff to have power ..


Regards ,

PS: I have yet to hear DSP out do passive xovers, i'm open to hearing it do so , the lyndorfs and others i have heard Have not convinced me they are there yet..

Seeing what they do , it's possible a melling of the two is the way to go ...

The term you used "Acoustical smearing " and the likes are they things that can be measured or your subjective evaluation? In which case they are as invalid or valid as any other opinion: Yours against the other person's.

Please do tell me the speaker that approximate the better headphones? I have a few cans .. Denon, HiFIman, Old Koss I got from e-Bay (ESL) and a Superlux(dirt cheap but surprisingly good) for travel ...

Point source do not necessarily suffer from dynamic compression that is a false statement ... Factually false.

Well I haven't heard he upgraded ESL 63 from Wayne PK I can't comment . The stock 63 does not play loud.


Happy Holiday People!!

 

[A.wayne]

Factually false ...?

Is this your opinion or can you provide us with Data ....
Sorry had to jab at the Irony ..

 

[FrantzM]

Factually false ...?

Is this your opinion or can you provide us with Data ....
Sorry had to jab at the Irony ..

You do have a sense of humor .. Happy you found it funny ...

You stated that point source speakers suffer from dynamic compression. That is a false statement. That is not a limitation of an arrangement in which the radiation of the different drivers constituting the loudspeaker seems to emanate from one point: Point Source as opposed to line source. That is what most dynamic loudspeakers try to achieve... with various level of success. They don't all suffer from power of dynamic compression because they are point source. If and when they do it is a driver limitations whether they are point, line source or whatever else. You can find several measurements of multi-driver speakers that suffer from no-power compression ... When I am done with my music session I may try to find some measurements in the archives of Soundstage or other places ...

 

[jeromelang]

One thing i have often noticed is that, through time & phase coherent speaker designs, the placement of certain sound images in the soundstage is usually different from the more prevalent, non time & phase coherent speaker designs. T&pc speaker designs tend to produce a very compact, vertically small image, the so-called "horizontal slit" effect. Try listening to the icy chime-like keyboard effects at the intro on the track "in a New York minute" in the eagles' hell freezes over album through a t&pc speaker design and compare it to others. Then you may realize that in most convention speakers, the vertical placement of sound images is often dependent upon the frequency makeup of that particular sound. certain sounds like chimes, bells, sibilance, etc, with predominantly higher frequencies tend to image towards the upper portion of the soundstage, while sounds with higher contents of lower frequencies tend to image lower towards the floor. With human voices, let's say Don Henley's voice, the higher frequency portion of his vocals and sibilance are "pulled" higher up while the lower frequency portion is "dragged" down, and in the process, creating a longitudinal "stretched" effect, which most people had so gotten used to, and don't begin to realize the unnaturalness of it all, that is, until they hear the same track played back on a t&pc speaker.

Another example of the sound image "tearing" effect can be heard when playing back a solo piano recording.
here's a couple of pictorial depiction to illustrate:

The first picture is the point-source example (for the sake of simiplifing, let's use a multirange driver speaker type, where all sounds are heard to come from a single spot). provided the microphone placement is supporting the pianist perspective, or pretending this is a midi synthesized playback, the soundstage of a piano is perceived to be steady on the horizontal plane:

The next picture is the 2-way, non time & phase coherent speaker design example. The soundstage of a piano is separated on the horizontal plane, with higher notes appearing higher on the soundstage, and lower notes appearing lower on the soundstage.

in this above two-way example, the upper-range notes appear higher in the air because in most all two-ways the sounds from the tweeter are not arriving at the same time as the sounds from the woofer-- the tweeter is not time-coherent with the woofer. this timing difference is mostly caused by the crossover circuit.

 

[jn229]

I have found this thread interesting, but I have a related question. When manufacturers slant or rake the front baffle backwards, are you not listening to the drivers off axis? If manufacturers slant the front baffle backwards to help time aligning are they saying off axis listening is not as bad as off time alignment listening?

 

[KlausR.]

The real question is does it matter?

In my opinion that question should be: does it make a difference? And if the answer is yes, then ask: does it matter?

My 3-way speakers (active midfields with onboard FIR-based DSP) come with 3 factory settings: all ways linear phase, all ways minimum phase, mixed. I can change from one setting to another by simply pressing a button on the remote. In the LLL setting phase shift and group delay are zero, impulse response is shown below.



To answer the question does it make a difference, the answer is yes. To my tin ears the difference is audible albeit subtle. The biggest difference is in the bass which is somewhat tighter, more precise, better controlled.

Does it matter? Since hifi is about being faithful to the source the answer is definitely yes. If you strive for the best, then you should strive for the most accurate. A stereo system is not a grand piano which should convince by how it sounds, a stereo system is for reproducing a recording of that grand piano in the most accurate manner.

Klaus

 

[DonH50]

I have found this thread interesting, but I have a related question. When manufacturers slant or rake the front baffle backwards, are you not listening to the drivers off axis? If manufacturers slant the front baffle backwards to help time aligning are they saying off axis listening is not as bad as off time alignment listening?

Time alignment requires more than physical (driver) placement, there's phase shift in the crossover network to consider. It has to be handled as a system.

@Klaus: That is very impressive impulse response from a speaker!