Wanted: Proof of multiple subs and sub EQ

[AJ Soundfield]

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.

Amir, how many links must I provide for you not to read?
The one above relates to both Ethans sighted preferences and Tooles work. Please read it along with this travesty he/Sean is referring to!

 

[AJ Soundfield]

and this is the place where I live ...

I would have thought it more padded, perhaps a bit isolated?
Ok, all kidding aside Frank, when do we get the thread about how you coaxed audio nirvana from a Sharp HTIB? So we can clearly see the "methods"?

 

[March Audio]

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.

Hi Mike

I have no argument with the multiple sub / positioning methodology, speakers placed at the anti mode will not excite it. However my L&R are not there!

Whilst their excitement of my lowest mode at 30Hz is fairly low, they certainly do excite the one at 60Hz. So unless you have a brick wall xo between sub and mains how do you stop this issue? I have had a good play with sub placement and dual subs - certainly helped with filling out the FR, but had little success in dealing with the modes.

Second problem I have is I seem sensitive to sub location. When xo at 80Hz I can definitely locate where the sub is and worse than this I can easily detect "phasey" effects if the sub is not in the right place. If I xo at 40Hz this is reduced to fairly acceptable levels, but still noticeable.

 

[dallasjustice]

There are studies. I don't have them now. Bottom line is that you can't localize the sub below about 80hz. Now that's not to say you will not notice a poorly integrated sub or distortion. The problem with subs is that folks often don't use a crossover, don't time/phase align at the crossover.

I'm not sure about all the modes in your room. Subs can't eliminate all of them. Keith asked about a particular mode and I explained how to reduce it with one sub. But one would need to use a crossover. Trust me, crossovers do work.

There's a lot of opinions about sub crossover points. All I can say is what I've tried and what the research says about bass localization. If you can localize your sub at 40hz, there's something seriously wrong with your sub. Think about the wave lengths and the size of your head. It's impossible.

When we talk about bass, it's always a balancing act. So the only question is better or worse.

If you have two subs, you can eliminate all the even order axial modes for the length of your room. If your room is rectangular, you could run them both mono and place each at the midwall point of the front and back walls. That will eliminate all the even order axials. It will NOT eliminate the 1st axial or the the other odds. The only way to do that with 2 subs is to run the two subs in opposite polarity, which I wouldn't really recommend.

Hi Mike

I have no argument with the multiple sub / positioning methodology, speakers placed at the anti mode will not excite it. However my L&R are not there!

Whilst their excitement of my lowest mode at 30Hz is fairly low, they certainly do excite the one at 60Hz. So unless you have a brick wall xo between sub and mains how do you stop this issue? I have had a good play with sub placement and dual subs - certainly helped with filling out the FR, but had little success in dealing with the modes.

Second problem I have is I seem sensitive to sub location. When xo at 80Hz I can definitely locate where the sub is and worse than this I can easily detect "phasey" effects if the sub is not in the right place. If I xo at 40Hz this is reduced to fairly acceptable levels, but still noticeable.

 

[fas42]

I would have thought it more padded, perhaps a bit isolated?
Ok, all kidding aside Frank, when do we get the thread about how you coaxed audio nirvana from a Sharp HTIB? So we can clearly see the "methods"?

Don't confuse systems! Philips HTIB, now dead; and NAD combo with Sharp speakers: first can be found here, http://www.whatsbestforum.com/showthread.php?2966-A-Search-for-Truth-and-Tonality, and the second here, http://artofaudioconjuring.blogspot.com.au/search/label/Tweaking.

People will whinge that they don't have everything, but it shouldn't matter. What they show is how I go about the process.

 

[amirm]

Amir, how many links must I provide for you not to read?

As I keep saying, it is not our job to read your links to make your point. You need to quote the appropriate section to read.

That is also how we make the forum more informative, i.e., having summary points from research papers. You have seen me do that. You need to do the same thing.

The one above relates to both Ethans sighted preferences and Tooles work. Please read it along with this travesty he/Sean is referring to!

I have read it. This is the conclusion:

While Reflection garnered maximum number of testers who preferred it (and we know that many recording mixing/engineers like that when not working), good number also preferred absorption in the middle. So Ethan could very well be in that camp.

Note that what I am talking about here is what *Ethan* prefers. This is not what I think the general public prefers. Your thesis is that Ethan must just be confused by sighted testing with respect to his own preference. The paper you cite does not support this.

 

[amirm]

Second problem I have is I seem sensitive to sub location. When xo at 80Hz I can definitely locate where the sub is and worse than this I can easily detect "phasey" effects if the sub is not in the right place. If I xo at 40Hz this is reduced to fairly acceptable levels, but still noticeable.

Last time I did this test, localization came from other elements rattling in the room. In my case was the AC vent.

 

[March Audio]

There are studies. I don't have them now. Bottom line is that you can't localize the sub below about 80hz. Now that's not to say you will not notice a poorly integrated sub or distortion. The problem with subs is that folks often don't use a crossover, don't time/phase align at the crossover.

I'm not sure about all the modes in your room. Subs can't eliminate all of them. Keith asked about a particular mode and I explained how to reduce it with one sub. But one would need to use a crossover. Trust me, crossovers do work.

There's a lot of opinions about sub crossover points. All I can say is what I've tried and what the research says about bass localization. If you can localize your sub at 40hz, there's something seriously wrong with your sub. Think about the wave lengths and the size of your head. It's impossible.

When we talk about bass, it's always a balancing act. So the only question is better or worse.

If you have two subs, you can eliminate all the even order axial modes for the length of your room. If your room is rectangular, you could run them both mono and place each at the midwall point of the front and back walls. That will eliminate all the even order axials. It will NOT eliminate the 1st axial or the the other odds. The only way to do that with 2 subs is to run the two subs in opposite polarity, which I wouldn't really recommend.

Yep, fully aware you are not supposed to be able to localise below 80Hz, but the point is the sub when crossed over at 80 doesnt actually stop at 80Hz. Same at 40Hz, there is output above that. Maybe I wasnt clear enough but when at 40 Hz I barely notice localisation, but I am definitely aware of phase issues if I move out of the main listening position.

BTW the sub is fine The XO is done by the AVR. The sub does have variable phase, not just 0/180 deg, which I have checked is not cancelling at XO, but of course that will only be spot on correct for one frequency.

 

[March Audio]

Last time I did this test, localization came from other elements rattling in the room. In my case was the AC vent.

I will check but I wasnt concious of anything else being excited that would give the position away.

 

[AJ Soundfield]

I have read it.

Great. So now let's set the table.
When Ethan couldn't respond to a single reliable audio test that Toole presents (both his own and others) in his book/presentations, totally debunking his "Early Reflections Are Not Beneficial" nonsense, his counter is that the folks Toole and others tested, didn't have the "training" and golden ears required to hear things proper. (Tell me if that sounds familiar from audiophile woo woo world.)
To quote Ethan directly from the article he said Sean "dissed" on Facebook:

The value of absorbers at reflection points is standard for "professional" listeners, and should likewise be the goal for an audiophile or home theater enthusiast who wants a listening environment as excellent as a million dollar control room.

This next part might seem offensive and condescending, but I assure you that's not my intent. I'm convinced that most professional recording and mixing engineers have better "learned hearing acuity" than the general population, and many probably have more refined musical taste as well. I mention "professional" listeners because I believe they have a better grasp on quality and clarity, and can more readily identify when something sounds "better" versus merely different.

I'm a big fan of Floyd Toole, so disagreeing with his preference for early reflections doesn't mean I don't respect his other work.
As far as I know Dr. Toole is not a recording engineer, and he hasn't mixed music professionally if at all. I don't think he's a musician either, so that probably affect his opinions.
Floyd's statements about early reflections defy my own "personal experience", and the experience of almost every other audio engineer I know. Floyd claims that early reflections increase clarity, and cites research that proves "people" prefer the sound of music with early reflections present. But of those tested, how many were "experienced" listeners and how many were regular folk with no particular interest in audio and music? If the tests included "civilians" who don't listen for a living or even as a hobby, it's difficult to accept the results.

Ok, now to the paper.

The study of how music mixing engineers are affected by changes in reflections in the control room is thus the prime subject of this research, since such reflections are likely to be present in greater force in a home listening situation. Previous conventions include control room designs with reduced reflections for an increase in clarity. It is also known, however, that adding reflections to the direct signal can significantly increase the perceived power of an audio signal [1]. While previous research on the effect of reflections has been conducted using regular listeners, this study uses trained balance engineers to complete interactive tasks in varied acoustic settings.
0.2 Historical Context

The impetus for this research was provided by research conducted by F. E. Toole. In his recent book Sound Reproduction, he concludes that the listener can adapt to reflections in a room and can also clearly distinguish between acoustic comb filtering in the listening room

So basically, they responded to Ethans sighted belief that if "Professionals" were used, they would overwhelmingly prefer absorptive "treated" reflections, the opposite of what us poor non-professionals prefer.

Reflection garnered maximum number of testers who preferred it

Ooops.

good number also preferred absorption in the middle. So Ethan could very well be in that camp.

Sure, he could. Or he could fall into the largest group. Using his ears only, not what he believes.

Note that what I am talking about here is what *Ethan* prefers.

Actually, pretty much every discussion here is going to involve what we prefer, sighted.
Nothing wrong with that at all, within the paradigm.

cheers,

AJ

 

[Purité Audio]

Really interesting thread ,lateral reflections can increase the sense of spaciousness , 'sound reproduction'.
Presumably the degree of spaciousness, depends upon the speakers off axis response, the absorption coefficient of the side walls , and the distance away for the side walls?
Is there an 'ideal' distance range, obviously very long delays ,echoes aren't good?
Keith.

 

[Purité Audio]

AJ , Amir and Mike regarding multiple subs you appear to be all more or less in agreement , some minor disagreement regarding localisation, and mono and stereo bass , isn't all bass cut mono anyway?
But essentially you are all in agreement?
Keith.

 

[March Audio]

Just as a general point, people can use the room simulator in REW to see the effect of moving speakers, subs, multiple subs etc.

 

[AJ Soundfield]

Yep, fully aware you are not supposed to be able to localise below 80Hz, but the point is the sub when crossed over at 80 doesnt actually stop at 80Hz. Same at 40Hz, there is output above that. Maybe I wasnt clear enough but when at 40 Hz I barely notice localisation, but I am definitely aware of phase issues if I move out of the main listening position.

BTW the sub is fine The XO is done by the AVR. The sub does have variable phase, not just 0/180 deg, which I have checked is not cancelling at XO, but of course that will only be spot on correct for one frequency.

Are you using the little bookshelfs in your avatar? Asking a 6-7" midwoofer to go down to 40hz, at reasonable output levels is a stretch. Most will start to exhibit signs of distress even at modest output levels, say 90-93db/1m (so less at LP).
You most certainly should not be able to detect a sub even with a non brickwall filter, typical commercial offerings will be around 3rd-4th order electro-acoustic, which should be more than enough to suppress audibility at 40hz low pass. Perhaps other spurious resonances/distortions, but not a well designed subwoofer itself.

cheers,

AJ

 

[AJ Soundfield]

AJ , Amir and Mike regarding multiple subs you appear to be all more or less in agreement , some minor disagreement regarding localisation, and mono and stereo bass , isn't all bass cut mono anyway?
But essentially you are all in agreement?
Keith.

No.
I don't think I could be any more clear that for "stereo" music reproduction, I believe the multi-sub/EQ elixir "everyone knows it" mantra is insufficient.
Multi-sub below 50hz, mono, sure. EQ, sure. Neither is capable of addressing nulls to 500hz...or more.
So then we get to the other automatic "everyone knows it" on forums "solution"...the dreaded T word "treatments". The padded cell iso-ward approach. Create sound energy, then turn it into heat.
I find that approach insufficient also.
I'll start another thread for alternatives beyond "sub" territory.

cheers,

AJ

 

[Purité Audio]

AJ sorry to be such a duffo, I just want to understand the various options , form the large dedicated room where there are no constraints, financially or aesthetically to the much more usual ,over here at least shared family room. Where some sort of acceptable compromise hasto be reached, thanks for your patience!
Keith.

 

[AJ Soundfield]

...to the much more usual ,over here at least shared family room.

Yep, that's exactly what I'm talking about. No problem with a dedicated room resembling an iso-ward, or an "audiophile/studiophile" room, but a "living" room should bear no such semblance, imho.
We'll get there in the other thread ;-).

cheers,

AJ

 

[Thomas savage]

Yep, that's exactly what I'm talking about. No problem with a dedicated room resembling an iso-ward, or an "audiophile/studiophile" room, but a "living" room should bear no such semblance, imho.
We'll get there in the other thread ;-).

cheers,

AJ

my lounge is like a iso ward but it was a condition of my release..

 

[March Audio]

Are you using the little bookshelfs in your avatar? Asking a 6-7" midwoofer to go down to 40hz, at reasonable output levels is a stretch. Most will start to exhibit signs of distress even at modest output levels, say 90-93db/1m (so less at LP).
You most certainly should not be able to detect a sub even with a non brickwall filter, typical commercial offerings will be around 3rd-4th order electro-acoustic, which should be more than enough to suppress audibility at 40hz low pass. Perhaps other spurious resonances/distortions, but not a well designed subwoofer itself.

cheers,

AJ

Yes which is why I have been using them at 80Hz. This has just been an experiment in sub location. 40Hz has only been used to ameliorate the localisation, which as I explained earlier is not really noticeable at 40 Hz.

For example if the (single) sub is placed at the rear of the room the FR is possibly the smoothest, however at 80Hz XO I can most certainly here the sub is behind me.

The subs is fine, Paradigm Sub 12, and I have heard this with other subs.

Here are the slopes at 40Hz and 80Hz. There is plenty going on at higher frequencies at 80Hz xo.

As mentioned above I am going to look for other items in the room being excited, but I havent consciously noticed anything so far.

 

[Ethan Winer]

You would not consider the "Active Room Absorption Module" to be a subwoofer but something else?

I guess I read too little too quickly. I saw "active room absorption" and assumed it's an active bass traps. I looked more carefully now but couldn't figure out exactly what it is or what they claim it does.

--Ethan