Do you time align your drivers ?

[jcrobso]

R. Heyser's excellent Klipschorn review from Audio, 1986:

http://forums.klipsch.com/forums/sto...n%20Review.pdf

This came out soon after I had built my K-Horns, I forgot the the length is 8'.
It would be interesting to see how my JBL loaded K-horns would test. I know because of the mid horn I'm using the horizontal dispersion would be better.
The Beyma CP21 tweeter I use is much better than the EV-T35 that K uses.
I love my JBL K-horns and the is what matters,,to me.

As others have stated DON'T LOOSE SLEEP OVER THIS!

[ginetto61]

This is an interesting question and one that I hope to someday do some serious studying of.
First of all, audio is full of pseudo scientific BS and worse.
Bearing that in mind, if a speaker is advertised as being time aligned, I wouldn't assume it necessarily to be true.
So what is time alignment?
As far as I know there are three types....
So how important is time alignment?
That is a huge question. as Mr. BMW said, .....
That said, when you take a system like the 4345 and correct it's time alignment, it will sound different... better? I am not sure.
This is an area that I find most interesting.
Widget

Thank you very much Mr Widget
I am fascinated by this issue, but also confused
Nevertheless I am gathering extremely interesting information from this discussion
Someone think that some time disalignment can be tolerate in the real world.
Thank you very much again.
Kind regards,
gino

[rdgrimes]

I think it's fair to say that there are a lot of OTHER things you can be looking at first, to improve audio in your listening room. Such as room treatments, careful layout of the components and furniture and of course the hardware itself. The room can introduce massive time and phase issues very easily which would render moot any speaker adjustments in that realm.

All that being equal, I think time and phase aligned speakers are worth it based on what my ears tell me.

[toddalin]

I believe that my 4430s are time aligned and they do image better than my quasi-L300s, though I do prefer the overall sound of the quasi-L300s. Maybe that imaging is partially a benefit of the time alignment.

[1audiohack]

First of all, audio is full of pseudo scientific BS and worse.

That's for sure!

A full frequency driver such as a single full range cone. These will inherently be time aligned.

Well,,, kinda,,, it will have frequency dependant delay products caused by that long wire coiled in the magnetic gap. Why this seems less offensive I don't know but will speculate that since it is a single driver you don't have another reference creating a step. In effect its acoustic center will not be stable, it will move forward and back in space.

If your speakers have all cone drivers, most of the VCs will be within a few inches of each other.

This gaurantees you nothing, a fact overlooked by many "speaker enfineers." It's back to that inductor in the gap, a woofer or subwoofer is not "slow" due to it's moving mass, that makes it inefficient however, they are slow due to the huge inductor that is the voice coil. In more than a few projects I have done and measured the woofer will still be "later" than the compression driver who's VC is a foot behind the woofers.

This subject is still pretty hotly debated as to how audible it is, here is my experience with time aligning multiway systems.

An example,when the woofers sound slow on say kick drums, it's likely because you heard the tweeter or midrange first. A time aligned system sounds tight and fast.

As some have touched on, the interaction with the room is a large part of what you hear, a time aligned powerflat speaker system sounds better in a much larger sweet spot, sounds much more natural even in another room and seems much more imune to the sonic abberations imposed by the room.

We are currently prepping for the Baje 1000, it is the busiest time of the year for us. I have a lot of measurments I can share when I get my life back in a couple of weeks if there is still interest. Sorry to be short and not well worded.

My opinon on time alignment is it is important.

All the best, Barry.

[MikeBrewster77]

I have a lot of measurments I can share when I get my life back in a couple of weeks if there is still interest.

I'm pretty sure there absolutely is, at least on my part. This is really interesting stuff for a layman like me.

[Oldmics]

An example,when the woofers sound slow on say kick drums, it's likely because you heard the tweeter or midrange first. A time aligned system sounds tight and fast.
__________________________________________________ ____________

Usually time alignment consists of applying delay to the componets in the box that have there acoustical centers closest to the leading edge (front) of the cabinet.

This allows the rear most componets producing sound to pass thru and catch up to the delayed componets.

The term "time alignment" is not an absolute term.

It should be more along the description of "All devices producing sound will arrive at a specified distance simutainiously".

I have found by manipulating the arrivals of different frequency producing band devices that a sound system can be "taylored" for specific applications.

E.G.-Delaying the low freq section give a system a loose (almost to a point of sloppy if so choosen) rolling low end that is excellent for reggie music.

Thats one of the reasons that a horn loaded system sounds the way they do.

Delaying all but the vocal region gives a "forward" sounding system-great for speech-bad for music.

Delaying all but the tweets gives a pretty bad sounding shrill system.

I dont recommend applying these techniques.Its just some observations we have come to over the years.

So the only real way to understand what a "time aligned" system is is to measure one and see if all bands of freqs are arriving simutainiously-or not.

Oldmics

[Mr. Widget]

Delaying all but the vocal region gives a "forward" sounding system-great for speech-bad for music.

I'm not so sure...

I have noticed that my TAD 4003 midrange drivers on their TAD horns tend to sound deeper than a typical JBL system... deeper in stage depth not tone. Well, this combo is physically deeper or more delayed than say a 2440 or 2441 on a short fog horn... OK so that kinda backs up what you are saying, however when Bo and I swapped out his 2421s on his 4345s with a pair of TAD 2002s, the geometry didn't change but the sound stage grew deeper. We didn't measure the impulse response, but I doubt there was a significant change.

Now, one might argue that the JBL sound has a peak in the mids that make it sound forward and the TAD is more neutral so perhaps this sends the stage depth back into the room... well, maybe, but in both cases Bo very carefully EQed each configuration so a simple tonal shift is unlikely the cause.

So what causes the TAD drivers to sound like they are playing music from a spot deeper in the sound stage and the stock JBL to sound more forward? I am not sure.


Widget

[Oldmics]

So what causes the TAD drivers to sound like they are playing music from a spot deeper in the sound stage and the stock JBL to sound more forward? I am not sure.


Widget[/quote]

Its gotta be materials difference.

AAHHHHH,The quest for audio

Oldmics

[Robh3606]

Its gotta be materials difference.

I was wondering about that as well Be vs Ti or Al. The Be is better damped and should have a cleaner ETC/CSD plot. Could be you are better able to hear whatever ambiance clues there are so you get a better sense of space and depth??

Face it any JBL speaker using a 2307 or 2312 is going to have issues in the time domain looking at the Step Response. According to the Selecting a Monitor technote on the site they are all below the audible threshhold for Group Delay. Even a 4333/L300 which has the longest midrange horn and the most offset is also below the threshhold.

http://www.audioheritage.org/vbullet...ead.php?t=4408

Rob

[ginetto61]

Hello Gino
Just to see what we are talking about here are a couple of Step Response measurements.
First one is a DIY biamped 3 way and the second a biamped 4344.
The step response from a 4345 is going to be very similar. You can see all 4 drivers with the 2405 first the 2122 a close second then the woofer out of phase with the 2425 right in the middle of the woofers response. It's the physical offset of the 2425 mounted on the 2307 that really skews the time alignment. When you start talking about soundstage and so on I would hazard to quess that "Time Alignment" may contibute but it certainly is not going to be the deciding factor.
To many other variables to consider.
Rob

Hello Rob
Thank you very much for the kind and interesting reply
I am trying to get more information on the subject
Maybe two experimet could be
1) put some increasing delay on one of the two L and R channel and listen for differences in soundstage rendition
2) listen to one speaker with a mono signal and delaying one driver in respect of the other and again listen for variation in sound

I understand it is a very raw approach... not that scientific I am afraid
But often is not so easy to correlate measurements and audio listening impressions

With the occasion I would like to thank you and all the other Members for this very kind disclosing your remarkable expertise with me
Have a nice day
gino

[ginetto61]

quote=1audiohack;269123
.... In more than a few projects I have done and measured the woofer will still be "later" than the compression driver who's VC is a foot behind the woofers....
An example,when the woofers sound slow on say kick drums, it's likely because you heard the tweeter or midrange first.
A time aligned system sounds tight and fast

Good Morning !
Very interesting points
Lately my interest in coaxial drivers has increased a lot
In these drivers the tweeter is placed behind the woofer
Even if there the center of emission of the tweeter is some cm behind that of the woofer someone argue if any delay of the woofer is necessary
It would be extremely interesting to know something more about the procedure you follow for time aligning your drivers

As some have touched on, the interaction with the room is a large part of what you hear, a time aligned powerflat speaker system sounds better in a much larger sweet spot, sounds much more natural even in another room and seems much more imune to the sonic abberations imposed by the room.

Another important point. Time alignment seems really a good thing, even if the listening environment is not that good.
Very very interesting.


We are currently prepping for the Baje 1000, it is the busiest time of the year for us.
I have a lot of measurments I can share when I get my life back in a couple of weeks if there is still interest.
Sorry to be short and not well worded.
My opinon on time alignment is it is important.
All the best, Barry.

Thank you very much Barry
You have convinced me that time alignment is worth the effort
I will wait for your further information.
And I wish you a great Baje 1000 !
Kind regards,
gino

[ginetto61]

Hello Gino
Just to see what we are talking about here are a couple of Step Response measurements. ... Rob

Please excuse me Rob could you tell me something more about the kind of test signal you use to get these very interesting plots ??
Thank you very much indeed
Kind regards,
gino

[tomee]

I don't think it can be easily generalized - a speaker with a passive crossover at 800Hz is different than one at 3000Hz, and 'time alignment' is probably more important for the design with the higher crossover if just to prevent comb filtering effects. Inductance in the crossover and voice coils alters everything with frequency, so at one specific frequency a design can be 'aligned' but then an octave above and below it's not, and this even applies for coaxial designs (eg. the Mastering lab crossover corrected the inherant mis-alignment of the stock Altec 604 using a time delay circuit for the woofer). 'Full range' or single cone speakers often use cone resonance or wizzer cones to extend the frequency range, and when a phase plot is shown it's easily seen that even these are not always 'aligned' at all frequencies. IMHO I think where the 'mis-alignment' occurs is as important as how it's dealt with - so the sound of 'mis-alignment' at 800Hz is probably not the same to our ears as one at 3000Hz (and I don't know which is better. :-))

[4313B]

According to the Selecting a Monitor technote on the site they are all below the audible threshhold for Group Delay. Even a 4333/L300 which has the longest midrange horn and the most offset is also below the threshhold.

http://www.audioheritage.org/vbullet...ead.php?t=4408

Rob

What is really interesting is the paper that came before that wherein JBL discussed that only the 4301, 4311, 4313 and 4315 met the threshold criteria and that all the larger format studio monitors were above the threshold, the 4333 being the worst offender of all. Not that any of us really care though. They all sound groovy, group delay and all.

(If I remember correctly there were two versions of that paper, one of them evidently a first draft)

Face it any JBL speaker using a 2307 or 2312 is going to have issues in the time domain looking at the Step Response.

Yeah, alot of horns aren't going to "work right" but we'll muddle through anyway.

Which reminds me... how is your Array project coming?