AJ I have a 28Hz length mode (1.0.0) in my room, at the moment I use EQ to knock it down, are you saying multiple subs could ameliorate that resonance?
Keith.
Keith.
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Wanted: Proof of multiple subs and sub EQ
- Thread starter Ethan Winer
- Start date
dallasjustice
Major Contributor
If it's really 1,0,0, you could totally eliminate it with only one sub as long as you use a crossover with your speakers.
Mike Hi, yes I am sure it is a length node, room mode calculators and REW's frequency generator confirm, much higher pressure at either end of the from.
So how do I use the Sub ( out of phase) I can cross to the main speakers no problem.
I thought you still had to use EQ for you low bass peak?
Keith
So how do I use the Sub ( out of phase) I can cross to the main speakers no problem.
I thought you still had to use EQ for you low bass peak?
Keith
dallasjustice
Major Contributor
Place one sub at the exact halfway point between the front and back walls. This position is called the antinode for the 1,0,0 mode. You can easily confirm its the antinode using a mic and REW. You can generate a 28hz tone. Walk with you mic while looking at the REW SPL meter. When the mic gets to the 28hz antinode, the SPLs will be substantially reduced. Place you sub in this position and measure again at MLP. You will see there's no more 1,0,0 ringing. Of course, you'll need to setup a crossover between your R/L and the sub to implement.
This is not my recommendation for best results though. It's better to use four subs, if possible. For most rectangularish rooms the 1,0,0 and the 2,0,0 will be the most dominant modes and relatively immune from fiberglass panels.
The frontwall/backwall sub configuration Welti recommends will take out only even order axial modes between those two walls. The sidewall midwall subs he suggests in a four sub setup will not excite the the 1,0,0 and also helps a little with even order width modes. The Welti four sub setup does a lot of good. One of the nice things about it is that it distributes 1,0,0 and 2,0,0 mode excitation between different speakers. This reduces their effect.
This is not my recommendation for best results though. It's better to use four subs, if possible. For most rectangularish rooms the 1,0,0 and the 2,0,0 will be the most dominant modes and relatively immune from fiberglass panels.
The frontwall/backwall sub configuration Welti recommends will take out only even order axial modes between those two walls. The sidewall midwall subs he suggests in a four sub setup will not excite the the 1,0,0 and also helps a little with even order width modes. The Welti four sub setup does a lot of good. One of the nice things about it is that it distributes 1,0,0 and 2,0,0 mode excitation between different speakers. This reduces their effect.
Mike Hi, ok, understood, and would that sub be in phase with the bass of the main speakers?
I can see how injecting bass there would fill the null but how will it cancel the main resonance, unless the fill in subs antinodes are now at the front and back walls?
Thanks as always,
Keith.
I can see how injecting bass there would fill the null but how will it cancel the main resonance, unless the fill in subs antinodes are now at the front and back walls?
Thanks as always,
Keith.
dallasjustice
Major Contributor
The subs should always be in phase with the R/L at the crossover.
Speaker placed in the antinode will simply not excite that particular room mode. Try it out. It will just play flat at that frequency. I posted earlier in this thread four subs each at the 4 midwalls. My 1,0,0 is 24hz. You can see the effect the the sidewall subs (in the antinode) has on this mode. It speaks for itself. Give it a try!
Speaker placed in the antinode will simply not excite that particular room mode. Try it out. It will just play flat at that frequency. I posted earlier in this thread four subs each at the 4 midwalls. My 1,0,0 is 24hz. You can see the effect the the sidewall subs (in the antinode) has on this mode. It speaks for itself. Give it a try!
Mike I will thanks, one last question ,in your set up are you using four mid wall subs and two further subs to extend the bass of the JBLs?
Keith.
Keith.
dallasjustice
Major Contributor
No I use four midwall subs. They are all low passed with a 2nd order NT crossover. The JBLs are also crossed with a symmetrical crossver to the subs. All speakers are time aligned and Acourate applies a final correction filter in the end. It all sounds wonderful. The bass is mega.
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Thanks Mike, ,never uses subs before any recommendations?
Sealed,ported ?
BWKeith.
Sealed,ported ?
BWKeith.
dallasjustice
Major Contributor
Nah I want four of those , might making getting into the room tricky though,
Keith
Keith
OP
- Thread Starter
- #72
I haven't tried that model, but active bass traps can absolutely work. And they can target very low frequencies efficiently. Bag End (known for pro loudspeakers) has sold such a system for many years. I haven't used that one either, but I understand from others who have used it that it works well. The main problem with the Bag End unit is it's tedious to set up. I've heard of newer models from other companies that adjust themselves automatically. Great idea!
--Ethan
OP
- Thread Starter
- #73
I think we are about equally loved by audiophiles.
LOL.
There's a big difference between this, versus testing for subtle things like the importance of sample rates higher than 44.1 KHz, or demagnetizing vinyl LPs, or comparing speaker wires. Even the difference between 256 kbps and 320 kbps MP3 bit-rates is very subtle even if real. But adding absorbers at reflections points makes such a humongous improvement I can't imagine why blind tests are needed. You don't need a blind test to tell the difference between Auratone and Barefoot loudspeakers.
I've seen more than a few AES papers that are demonstrably wrong! One classic (for me) example is the Bucklein paper about the audibility of narrow response nulls that I disproved here:
Audibility of Narrow-Band EQ
Another paper that's not from the JAES paper but is (I assume) considered peer reviewed and based on real science is the infamous Oohashi paper that "proved" humans can perceive ultrasonic content. That paper was debunked a year later when it was shown they goofed by not accounting for IM difference products in their tweeter "aliasing" down into the audible range. So just because a paper is in the JAES, or was written by a bunch of PhD types, doesn't mean it's correct.
That's a straw man argument because I never said otherwise. I've made it clear several times now that I welcome proof. But it has to show ringing reduced not just at the one location the measuring mic was placed. And it has to be real measurements in a room, not some simulation. I explained clearly why I require that as proof. Unless I missed something, none of the articles you linked show what happens a foot or two away from the calibration position. I have dozens of graphs showing ringing being improved at all locations in a room after adding bass traps.
Also, just as important, nothing you do with multiple subwoofers affects frequencies above the standard 80 Hz crossover, so that leaves half the bass range full of peaks and nulls and ringing. Even the most staunch EQ proponents agree you can't use EQ either much above that range. The range from 80 to 300 Hz is the "speaking" range for bass instruments where clarity and minimal ringing are most important. I know I already mentioned that fact, but in your zeal to prove me wrong you glossed over it as if it never happened.
As is disturbingly typical lately, you call my article wrong but don't give even one example of why it's wrong. Sean Olive (who I respect a lot) did that a week ago on Facebook. He said this same article has numerous factual errors, but failed to list even one. Are you telling me that you don't agree that absorbing early reflections is beneficial? That might explain a lot. I'm curious AJ, what is your background with audio and music? I didn't see any bio information here or on your speaker company's web site.
--Ethan
OP
- Thread Starter
- #74
Also, I still don't understand why you feel the need to be condescending. I noticed several "embarrassing" things on your web site, but I didn't feel the need to point them out.
--Ethan
AJ Soundfield
Major Contributor
Yes and I thought I had answered this. Déjà vu?
You would not consider the "Active Room Absorption Module" to be a subwoofer but something else?
AJ Soundfield
Major Contributor
Because you're beliefs are wrong as Toole has shown and that is exactly why we need blind tests. Even when you move the goalposts to "studiophiles" and their "critical listening" needs, which are irrelevant to home listeners: http://www.aes.org/e-lib/browse.cfm?elib=16640
This is exactly the type of audiophile Red Herring and Wishful Thinking fallacies you should be embarrassed about. The fact is Tooles work and all he references have not been refuted like the Oohashi nonsense. You have zero counter argument, in the form of reliable listening tests regarding early reflections, just your "personal experience/heard this/heard that". Any wonder why I coined the term "Studiophile"?
Preaching to choir, go argue with Amir there.Also, just as important, nothing you do with multiple subwoofers affects frequencies above the standard 80 Hz crossover, so that leaves half the bass range full of peaks and nulls and ringing. Even the most staunch EQ proponents agree you can't use EQ either much above that range. The range from 80 to 300 Hz is the "speaking" range for bass instruments where clarity and minimal ringing are most important. I know I already mentioned that fact, but in your zeal to prove me wrong you glossed over it as if it never happened.
Though I find your iso-ward solution non-optimal, to put it mildly.
Not surprised Sean noticed the same thing. You've been shown all the Toole/related papers on why innumerable times, the added power to speech/clarity, the phantom center combing fill, etc, etc, but like any true believer, you dismiss them all for your "personal experience". With zero reliable counter evidence.
Einsteins definition of insanity, like Sean, I'm not listing them all again.
It is irrelevant to the argument Studiophile.
cheers,
AJ
Dr. Toole completely agrees that people who record and mix music develop sensitivities to early reflections and consider it "bad" as opposed to us, the listeners. From his book,This is exactly the type of audiophile Red Herring and Wishful Thinking fallacies you should be embarrassed about. The fact is Tooles work and all he references have not been refuted like the Oohashi nonsense. You have zero counter argument, in the form of reliable listening tests regarding early reflections, just your "personal experience/heard this/heard that". Any wonder why I coined the term "Studiophile"?
"Why do recording and mixing engineers prefer to listen with
reduced lateral reflections (higher IACC)? Perhaps they
need to hear things that recreational listeners don’t. This is
a popular explanation, and it sounds reasonable, but experiments
reported in Section 6.2 indicate that we humans
have a remarkable ability to hear what is in a recording in
spite of room reflections—lots of them. But there is an
alternative explanation, based on the observation that some
listeners can become sensitized to these sounds and hear
them in an exaggerated form. Ando et al. (2000) found that
musicians judge reflections to be about seven times greater
than ordinary listeners, meaning that they derive a satisfying
amount of spaciousness from reflections at a much lower
sound level than ordinary folk: “Musicians prefer weaker
amplitudes than listeners do.” It is logical to think that this
might apply to recording professionals as well, perhaps
even more so, because they create artificial reflections electronically
and manipulate them at will while listening to the
effects. There can be no better opportunity for training
and/or adaptation. In fact, it is entirely reasonable to think
that acousticians who spend much of their lives moving
around in rooms while listening to revealing test signals can
become sensitized to aspects of sound fi elds that ordinary
listeners blithely ignore. This is a caution to all of us who
work in the field of audio and acoustics. Our preferences
may reflect accumulated biases and therefore may not be
the same as those of our customers."
This is the case with me and hearing compression artifacts. My ability to do so is well above others due to training. So it would be natural to accept that Ethan hears the reflections as artifacts that we don't. He does not need to provide proof of this.
To that end, I have little doubt that he hears the effect of an absorber. But I am very doubtful that many would. Instead, they see the reflector and imagine an improvement in sound whether there or not.
and this is the place where I live ...
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