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kmcintyre
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How to determine what is needed - and can you have too much?

I'm looking at acoustic treatments for my office, which doubles as a DAW music room and home of my latest stereo acquisition.

The engineer in me thinks I should precisely test my room and figure out if I have acoustic issues. Then I should "fix" the issues via specific measures.

The engineer in me thinks that to accurately measure the acoustic characteristics of my room will take a significant investment of time and money. (How accurate can a Radio Shack microphone recorded via a Sound Blaster be...) (Ok, I have better recording gear than that, but the point remains.)

The pragmatist in me thinks that sounds like a lot of investment for something I'll do once.

The pragmatist in me (or maybe it's the slacker in me) thinks that sounds like a pain it the ass and wants to go buy stuff to throw it at the problem. (A problem I'm not sure even exists...)

Looking at various sites, it appears there are only general guidelines for treating a room. Essentially it comes down to "buy as much of our treatments as you can cram in your room. Stick 'em in the corners, on the walls, on the ceiling, on the doors, and enjoy!"

So -

1) How can I tell if I really need additional acoustic treatments?

2) Can I over do it? How will I know if I do?

*******

My "problem" - my system sounds good at low ro moderate volumes. But when I turn the volume to go for the "big" sound what I get is "loud but muddy" sound.

*******

What would be very useful (perhaps) is a "reference" recording/headset pair that could set the baseline for the "acoustically perfect" room. (like that exists...) Then one could listen to the cans, listen to the speakers/room and compare. Based on the findings one could add reflective and absorbent materials to "tune" the room.

Keith

Elk
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Re: How to determine what is needed - and can you have too much?

I can fully relate to every aspect of your analysis.

Room treatment will absolutely improve the sound, guaranteed. It will get you more improvement per dollar (yuck/buck ratio) than buying new equipment.

It is annoying in a way; it's not fun to research and buy room treatments.

And it is true, you almost can't put too many treatments in a room.

Now for the good news: add some room treatments and you will immediately hear the improvement. You will enjoy listening more, the room will have a better "feel" to it even when not listening to music, and mixing and editing on your DAW will be a lot easier.

The only way to overdo it is to make it hard to move . . .

kmcintyre
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Re: How to determine what is needed - and can you have too much?

My room is 12 x 11 x 10 (l x w x h) with two doors leading to other spaces and windows on the other two walls.

My current plan calls for -

24 x 48 x 4 panels - 4 each (hung 4 inches off ceiling)
24 x 48 x 2 panels - 4 each (rear wall)
24 x 24 x 2 panels - 14 each (front and side walls)

I really don't have room to diagonal the corners. All wall panels will affix flat to the wall.

Does this sound like enough?

Thanks

Keith

ethanwiner
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Re: How to determine what is needed - and can you have too much?


Quote:
The engineer in me thinks I should precisely test my room and figure out if I have acoustic issues. Then I should "fix" the issues via specific measures.


That's the old school method, but in truth it doesn't matter what you measure because the solution is always the same - as many bass traps as you can manage.


Quote:
How accurate can a Radio Shack microphone recorded via a Sound Blaster be.


Plenty accurate for low frequencies, which is the main problem in all domestic size rooms.


Quote:
1) How can I tell if I really need additional acoustic treatments?


If you have a room, you need bass traps and first reflection treatment.


Quote:
2) Can I over do it? How will I know if I do?


You can probably have too much absorption at mid and high frequencies, but not below 300 Hz or so. The correct approach is to measure RT60 in third octave bands. Small rooms don't really have reverb though, but you can still look at the decay times which are similar. The ideal is for all frequencies to decay at the same rate. This won't happen in practice, but you can get close enough. However, it's still not necessary to measure. Simply choosing the right materials or products will ensure the desired broadband results.


Quote:
my system sounds good at low ro moderate volumes. But when I turn the volume to go for the "big" sound what I get is "loud but muddy" sound.


As I said, if you have a room, it needs treatment.

--Ethan

fitzcaraldo215
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Re: How to determine what is needed - and can you have too much?

I think you can easily wind up with too much or too little. Acoustics is tricky and a little bit of knowledge is a dangerous thing. More is not always better, but it sure does cost a lot, and it can look like hell if you do too much. If I were you, I would first treat the side early reflection points with absorbers or diffusers. Which is best? Who in the hell knows? You could also do the same for mid front and rear walls, but that's probably less inportant.

Second, the best investment you will make in treating the room will be to get a receiver or pre-pro with Audyssey MultEQ room correction built in. Audyssey's automatic room calibration determines an amount of equalization that is just right. Denon, Integra or Onkyo are your best bets. NAD does not appear to be features competitive, and Marantz appears to be pulling away from Audyssey in favor of an in-house solution. Do not go with a Yamaha or Pioneer in-house solution, either. Audyssey has the reputation, the reviews, the research, and the pedigree (Tom Holman of THX fame). Some of these receivers list for about $1,000 or even less, possibly. Audyssey works in 2-channel or multichannel mode, and I think even the estimable Kal Rubinson has understated how great it truly is. In addition to Kal in Stereophile, see also The Absolute Sound's review of the stand alone Audyssey Processor ($2,500) or also many, many web forums and reviews.

Consider the stand alone Audyssey processor if vinyl is primarily what you will be playing, but that does not sound like a good choice for the office.

Carefully read Kal's reviews involving Audyssey of the Integra DTC 9.8 controller, the Oppo universal players and the Pioneer Elite universal player. I myself have the DTC 9.8 coupled to an Oppo 980 H via HDMI. Listening to this combination with the Audyssey correction inside the Integra wih multichannel SACD's is the best sound I have ever heard in my life by a whole lot. In terms of musical truth and emotional involvement in the music, it easily beats any megabuck 2-channel system I have ever heard, even the sacred cow of vinyl. My own system cost about $50K before the multichannel upgrade, and I hardly listen to 2-channel anymore, because it pales by comparison. Audyssey room equalization is a vital part of this equation.

Elk
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Re: How to determine what is needed - and can you have too much?

Good EQ is indeed neat and can work well to trim a room. EQ on top of a well setup system is fun.

However EQ cannot solve basic room problems. For example, if there is a suckout in the bass it is becasue of phase cancellations. No matter how much boost one applies through EQ this suckout will not go away - and you have now energized the room with excess energy in this region, causing other problems.

Thus it is best to fix the room. A few bass traps and a few absorption panels to tame first order reflections will do wonders.

I would not use EQ in the room for mixing, editing and mastering on your DAW however. There are good reasons that mastering engineers and studios do not use EQ first to attempt to address room problems; they fix the room.

fitzcaraldo215
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Re: How to determine what is needed - and can you have too much?


Quote:
Good EQ is indeed neat and can work well to trim a room. EQ on top of a well setup system is fun.

However EQ cannot solve basic room problems. For example, if there is a suckout in the bass it is becasue of phase cancellations. No matter how much boost one applies through EQ this suckout will not go away - and you have now energized the room with excess energy in this region, causing other problems.

Thus it is best to fix the room. A few bass traps and a few absorption panels to tame first order reflections will do wonders.

I would not use EQ in the room for mixing, editing and mastering on your DAW however. There are good reasons that mastering engineers and studios do not use EQ first to attempt to address room problems; they fix the room.

I agree completely about absorbtion panels to tame obvious first order reflections, and I said so in my initial response. Nothing else can be done about reflections, certainly not EQ. Thick rugs on the floor are also required to nulify the floor reflection. If you can do it, I have always liked high ceilings which are not "live", because they take the ceiling reflections out of the equation.

Bass traps are another matter. As passive devices, they cannot "know" how much to cut the bass or at what frequencies. They also cover a fairly wide bass frequency range. If you just happen to locate the device just right, it might just help cancel one or more modes, and this just might alleviate a peak or even a valley in response caused by interference. But, like most passive room treatments, it's a trial and error situation, even if you are an acoustician and know what you are doing. I know it's now fashionable for audiophiles to throw in some bass traps (the cost adds up considerably), and feel better because they did. But, is the final response actually better than it was? A Radio Shack meter will not tell you because it has notoriously poor bass response. You need to take measurements with something considerably better at multiple points. But, how do you weigh the multiple measurements? Averaging them might just give you the wrong answer everywhere.

I like Audyssey, particularly Audyssey Pro, because it has figured most of these problems out and automated them into an easy to use package. And, it works at all audible frequencies, not just the bass. Take it from Kal Rubinson and me that it works exceedingly well.

Also, as to bass response, the Bag End active device Kal just reviewed might hold a lot more promise in dealing with special bass problems than passive bass traps.

I also like today's better subwoofers that include an electronic calibration for at least the worst room mode. I am using a JL Audio Fathom f113 with great results. I calibrated the Fathom first, then I let Audyssey in my Integra DTC 9.8 pre-pro do it's thing. I will say it one more time: it's the best reproduced sound I have ever heard anywhere, and my room was pretty good before.

kmcintyre
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Re: How to determine what is needed - and can you have too much?

All,

Thanks for the posts. Everything makes sense. EQ can even out freq response of the speaker/room tuple. Panels can reduce reflections that muddy the signal the ears receive after the fact. A tuned bass trap could further help eliminate a troublesome resonate freq caused by the room.

(On the later, it seems that parametric eq could reduce the peak as well, but unless the eq device was really high quality, it might induce undesireable artifacts. A standard eq. could well have too wide a band to properly reduce a resonate peak. It seems to me fixing the problem at the root cause - the room - might be best.)

So getting back to ME (sorry)... :-)

I'm running a Velodyne SPL-1000R. It has a 6 band eq with a built in FSA that is supposed to help level the playing field (so to speak) down under 120 Hz.

So with the room size (12 x 11 x 10) and the following traps/panels, should I be in the ballpark?

4 ea - 2 x 4 x 2" on rear wall
14 ea - 2 x 2 x 2" on front and side walls
4 ea - 2 x 4 x 4" hung 4" off ceiling

Assume OC 703 or equivalent.

Thanks!

Keith

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Re: How to determine what is needed - and can you have too much?


Quote:
Bass traps are another matter. As passive devices, they cannot "know" how much to cut the bass or at what frequencies. They also cover a fairly wide bass frequency range.


Bass traps are supposed to be, and need to be, wide frequency range absorption. They do not need to "know" what frequencies to cut or boost, nor do you want them to "know".

Bass traps function by absorbing the bass that is created by the room itself (which tends to "pile up" in the corners). Their job is to absorb bass that the room acoustics create so that you can listen to the bass your speakers are putting out, not your room. As they absorb this room created bass, the peaks and nulls flatten out (this is a huge advantage over EQ which cannot fill a null.)

In this respect, bass traps are like putting absorption on first order reflection points. These products similarly do not "know" what frequencies they need to absorb. In fact, their job is to absorb all frequencies that would otherwise reflect back.

They only time that you would not want to absorb all the bass created by the room is in those rare instances where the speaker is specifically designed to couple with the wall or corner and will not function without it. Even then, bass traps in the opposite corners would be beneficial.

Another big advantage to room treatments is that the positive improvements are heard everywhere in the room. The sweet spot becomes much larger as well.

EQ does the opposite; the more EQ the narrower the sweet spot. Moreover EQ favoring the sweet spot makes the other locations worse (some EQ systems use various forms of averaging to compromise the improvements to one listening position to broaden the sweet spot. Whether this is a worthwhile trade off is up to the buyer.)

EQ is attempting to use a band-aid for a "broken" room. Fix the room and you do not need band-aids.

However, EQ is fine if you do not want to fix the room or cannot do so (spousal acceptance for example.)

ethanwiner
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Re: How to determine what is needed - and can you have too much?

Elk is already doing a great job, so I'll add just a few bits:


Quote:
EQ can even out freq response of the speaker/room tuple.


Not really. EQ can reduce peaks, but it cannot raise nulls. EQ cannot reduce ringing either, which is just as damaging audibly as the peaks and nulls. EQ is also highly positional. If you use EQ to reduce a peak for the prime seat on the couch but the next seat over was flat at that frequency, you just created a null for that listener.


Quote:
A tuned bass trap could further help eliminate a troublesome resonate freq caused by the room.


Tuned bass traps can be useful, but they have a few problems. One problem is they take up space that might be better used for broadband bass trapping. Another is it's tough to target a narrow frequency range accurately.

--Ethan

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Re: How to determine what is needed - and can you have too much?


Quote:
So with the room size (12 x 11 x 10) and the following traps/panels, should I be in the ballpark?

4 ea - 2 x 4 x 2" on rear wall
14 ea - 2 x 2 x 2" on front and side walls
4 ea - 2 x 4 x 4" hung 4" off ceiling

Assume OC 703 or equivalent.


Keith, I'm sorry that I missed this question. I bet Ethan did also with the other discussion going on.

I do not have th experience Ethan does (no where near!) with respect to various materials, etc.

However, I think that what you propose will do a nice job diminishing reflections in the mid to highs, and to get rid of ringing (a typical problem). A great improvement.

I don't think these panels will do much for bass control however, unless you put them on top of each other so they are at least 4" thick (although suspending them from the ceiling should help bass absorption a bit.)

Hopefully Ethan will chime in as he can give you a better idea.

fitzcaraldo215
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Re: How to determine what is needed - and can you have too much?

Yes, I think your room will be too dead and overdamped. Take it slowly. Do the side walls a little bit at the first reflection points only and try it. Put your drawing pencil and checkbook away for awhile and see how it actually sounds.

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Re: How to determine what is needed - and can you have too much?


Quote:
Bass traps ... job is to absorb bass that the room acoustics create so that you can listen to the bass your speakers are putting out, not your room (this is a huge advantage over EQ which cannot fill a null.)
...
Another big advantage to room treatments is that the positive improvements are heard everywhere in the room. The sweet spot becomes much larger as well.
ethanwiner
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Re: How to determine what is needed - and can you have too much?


Quote:
there is serious disagreement about bass correction via passive bass traps.


No need for a disagreement because all of this is easily proven. Bass traps do indeed reduce the room's effect on the sound, and always for the better. Assuming good bass traps. Unless someone prefers a low frequency response that looks like a roller coaster, with a second or two of ringing at half a dozen or more frequencies. But since nobody seems to want that in their CD player or preamp, I think it's safe to say we should all strive to avoid it in our listening rooms too.


Quote:
I do not object to the use of bass traps. I just think they are a blunt instrument that can do both good things and bad things to the sound.


I'm not aware of any "bad things" bass traps can do, but I'm willing to hear you out.


Quote:
They lack the control as to frequency, magnitude and Q of correction of other approaches.


I think you misunderstand what bass traps do. In most rooms, you do not want traps that target specific frequencies. Understand that all rooms have peaks and nulls at all low frequencies, not just those related to the room dimensions. This is a common mistake, and even some professional acousticians do not understand this!


Quote:
passive bass traps do not eliminate the bass generated by your room "so that you can listen to the bass your speakers are putting out, not your room".


Elk's wording may have been ever so slightly imprecise, but the basic gist is correct. Bass traps (and other absorbers) reduce the reflections so you hear more of the direct sound from your speakers.


Quote:
how do the passive bass traps know the difference between what your speakers are putting out vs. what your room is doing? They don't, so they attenuate all of it.


They "know" by where you place them. Let's say you put bass traps on the entire rear wall behind the listening position. In this case you hear all of the direct sound from the speakers, and the only thing the traps absorb is the reflections off that wall. This is a Good Thing.


Quote:
Secondly, they do not eliminate the room response. To do so would imply making the room an anechoic chamber, at least in the bass.


Actually, eliminating all peaks and nulls and ringing is exactly what you want at bass frequencies.


Quote:
Some subwoofer makers even want you to put their subs in the corner to get maximum room reinforcement for efficiency.


See this:

Subwoofer Placement


Quote:
As to EQ and sweet spot size, no method of active or passive room correction is going to make the room totally uniform in response or totally without peaks and nulls.


Agreed.


Quote:
Current state-of-the art equalizers such as Audyssey are specifically designed to provide a "bubble" of best response within the calibration area.


They may be "designed" for that, but they don't really achieve it. More here:

Audyssey Report


Quote:
the more EQ you do, in terms of mike positions, potentially the larger the sweet spot.


If only!


Quote:
Audyssey, in particular, works in the time domain as well as the frequency domain.


If only!


Quote:
passive traps cannot provide boost either.


Of course they do! The graphs below show a room with and without bass traps. Notice the nulls before and after:

Clearly the volume level at the null frequencies has been raised substantially. EQ cannot do this. And if you try to do this with EQ you not only strain your power amps, you also add new ringing into the room.


Quote:
They might reduce nulls indirectly by attenuating the peaks from nodes and reducing phase cancellations. How this differs from an equalizer knocking down peaks and thereby reducing cancellations is a total mystery to me.


Hopefully this post is clear enough so it will no longer be a mystery. But please follow up with any questions and I'll do my best to explain further.

--Ethan

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Re: How to determine what is needed - and can you have too much?


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Rives Audio has established an enviable reputation as room tuning consultants. Their approach uses a combination of room design, sonic measurements, passive treatments and equalization. Their PARC equalizer is a key to their view of bass equalization.

This is the best approach. Design and build the room to be the best it can be, add passive treatments to get the best possible result, then finally a bit of EQ sweetening if still necessary.


Quote:
I just think they are a blunt instrument that can do both good things and bad things to the sound. They lack the control as to frequency, magnitude and Q of correction of other approaches.


This reflects a basic, but common, misunderstanding of acoustics and the role of room treatments.

One doesn't need control of frequency, magnitude and Q with bass traps because one is not treating the peaks and nulls as EQ attempts to do.

Instead, room treatments treat the room so that the peaks and nulls do not exist in the first place. That is, no absorption of only specific frequencies is needed, nor desired.

The specific peaks and nulls exist primarily as a function of room dimension, together with measurement position. However, you do not want to try and treat only the frequencies of the peaks and nulls, you want to absorb all of the bass frequencies. This is because all of the bass frequencies interplay to create these nulls and peaks. Once these frequencies are absorbed so that they do not create havoc with the room, the peaks and nulls no longer exist.

Once again, treat the disease and the symptoms go away.

Ethan is correct: studios went through this learning curve a generation ago. I was rally excited over graphic and parametric equalizers in the late 70's. They were marketed with the promise that they solved all speaker deficiencies and room problems. We learned better.

Nothing has changed except that computers make it easier to set up EQ. In a sense it is ironic that it has taken this long to for these issues to begin to become mainstream in home audio, even more ironic that the same learning curve is being repeated when all of the information is already out there.

EQ is great when you cannot control the room, such as limiting feedback in a performance venue. EQ is great for adding final polish to one's home theater after creating a good room.

It is a blunt, inexpensive and largely ineffective tool when it is asked to do the job of good room design and treatment.

However, if EQ is working for you and making you happy this is wonderful! This is a hobby and we should all the follow the path that amuses us most.

fitzcaraldo215
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Re: How to determine what is needed - and can you have too much?

Look, ELK, by all means stay on the bass trap bandwagon. Knock yourself out! You argue fiercely, but I do not find any technical support for much of what you say anywhere, but you are fully entitled to your opinion. The graphs you provide of response before and after bass traps are, I say this as charitably as I can, anything but convincing. So, if this is what you want your room response to look like, by all means do so, and God be with you.

Elk
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Re: How to determine what is needed - and can you have too much?

You are confusing me with Ethan.

And if you think this is a fierce argument you need to get out more. This is merely a group of tumbling kittens.

Just wait until I send the attack kitten!

I would be careful dismissing Ethan's measurements so cavalierly. EQ is even less effective but is rarely measured with sufficient resolution to reveal the problems, unfortunately marketing gets in the way.

However Ethan has already provided you with similar measurements of an EQ system with multiple set-up measurement points. It didn't do well when subjected to objective analysis.

If you are seriously interested in exploring the subject there is a wealth of books and technical materials available, even on the Internet. If you want the real, detailed materials, you need a decent technical library or to simply order a few books. Easy to find.

For example, you cited Rives Audio, a good group. Note that Rives' home page specifically states in bold print: No Accessory Outperforms Ideal Room Acoustics .

This from a company that sells a very good parametric EQ. How odd. Could they actually know that room acoustics is primary? Of course they do.

Rives has lots of good information on its site. If you would like basic technical data and information this is a good place to start.

I understand the appeal of electronic wizardry. It's great fun. I have played with a number of room correction systems - some hideously expensive. The problem is that a few DSP chips do not change physical acoustical properties. I wish they did. I love gadgets.

None of this matters however if you have a room in which you adore listening to music. Once this is true, you have a perfect listening room.

Thus, if you are delighted with your room and the sound you are getting you have the right setup for you.

Kal Rubinson
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Re: How to determine what is needed - and can you have too much?


Quote:
Look, ELK, by all means stay on the bass trap bandwagon. Knock yourself out! You argue fiercely, but I do not find any technical support for much of what you say anywhere,..............

Start here: http://forum.studiotips.com/index.php

Kal

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Re: How to determine what is needed - and can you have too much?

Kal, great link!

I have seen some of these things before, but not all in one place like this.

Do some digging and there is a great deal of information to be unearthed.

Thanks!

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Re: How to determine what is needed - and can you have too much?

ELK, sorry for confusing you with Ethan. The 2 of you are ganging up on me, so I misidentified.

Let me reapeat what I have been trying to say. Neither passive bass traps nor equalization are sure fire solutions to room bass problems. Case in point are Ethan's graphs, which show before and after bass trap application. While the nulls are substantially reduced, they are still there. And, while the peaks have been smoothed a little, they are still there. I think it is fair to call the final response pretty ragged. Obviously, this room has big problems, and the simple addition of bass traps did not solve them. I am certain that equalization would not, either. So, there.

I would like to think we are all saying the same thing: room treatments are not mutually exclusive with EQ, and nothing beats a well constructed room in the first place.

The point is too many audiophiles think that bass traps are a magic bullet. They throw them in without really knowing what they are doing, the more the merrier. They do not take measurements, and they have no idea what is really going on with the room response. They have no idea how many traps to put in or where to put them, except in the corners. And, really big traps that go low in frequency get pretty expensive. Many audiophiles are at the mercy of manufacturers, like Ethan's Real Traps, or ASC or somebody else, who have helped create the "bandwagon", as I call it, of unchallenged belief in the overwhelming power of these things to fix everything. As we see from the graphs, they don't; this room needs more work. I know neither you nor Ethan expected the traps to fix everything, but many audiophiles do.

EQ may have a similar bandwagon among audiophiles. It should not. But there are a few advantages to EQ. In Audyssey's case, as with several other current approaches, there is a mandatory multi-point mike calibration performed. How many bass traps are installed without this? If you do not like the EQ, you can turn it off easily. Hence, it is far, far easier to A-B compare the results by ear. Overall, it is much simpler for an audiophile to try EQ to see if it is worth keeping.

I may be blessed with a very good room. It is large (24 x 17) with few parallel surfaces. The ceiling is high and slopes(10' to 18'). Even side walls are well broken up . And, there are tons of books on shelves providing a somewhat random pattern of absorption and diffusion, at least in the mid/high frequencies. In my experiments with passive bass traps, I did not feel that I was getting much bang for the buck. But, perhaps like many audiophiles, I was ignorant in how to apply them properly. Audyssey, however, gave me an immediate and very positive improvement; it was one of the greatest improvements in my system ever, in fact. So, I am going futher with it in Kal's footsteps by upgrading to Audyssey PRO, which my Integra pre/pro supports.

One final note, I have read carefully Ethan's white paper on Audyssey, but I am, nontheless, convinced I have done the best thing in using it. I appreciate Ethan's input, but we have to understand his Real Traps bias. That does not automatically make everything he says on the subject wrong or slanted. We just have to take it with a grain of salt.

There is one thing in Ethan's critique of my earlier post. He questions that Audyssey works in the time domain. If he has proof to the contrary, I wish he would provide it. If such evidence exists, we should be filing a class action lawsuit against Audyssey, because they sure do make a big point of this on their website and quotes from their CEO in online forums. Kal's and just about everybody else's reviews of the product contain references to it.

Elk
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Re: How to determine what is needed - and can you have too much?

"Ganging up" on you? That attack kitten really must be scary.

I'll leave it to Ethan to address his graphs. His point, as I understand it, is that bass traps will fill in nulls. I doubt the room had sufficient bass traps to satisfy Ethan. Rather the graph is there simply to illustrate a point.

OTOH, you don't want to know what a rigorous waterfall graph of a room before and after only EQ looks like.

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Re: How to determine what is needed - and can you have too much?


Quote:
The 2 of you are ganging up on me, so I misidentified.


No way do I ever gang up on anyone or toss insults! I stand for Truth, Justice, and the Scientific Method.


Quote:
While the nulls are substantially reduced, they are still there. And, while the peaks have been smoothed a little, they are still there.


Yes, it's impossible to make any normal size room perfectly flat. It won't happen. But you can easily get a room with multiple 30 dB spans throughout the bass range down to only 10 dB spans.

A 20 dB improvement is friggin' huge!

Are you saying if you can't make things totally perfect, and as flat as a power amp, you'd rather not even bother?

More to the point, EQ cannot get a room anywhere near as close to flat as bass traps can. And whatever improvement it does give is invalid only a few inches away. Yet you (and others) for some reason gloss over that severe limitation while criticizing the better approach - bass traps - as not being a total solution?


Quote:
Obviously, this room has big problems


In fact this room is absolutely typical!

Also, if you have enough bass traps you can get much closer to flat. Here's my 25 by 16 living room (peaked ceiling to 11 feet) which had 39 bass traps at the time I made this graph:

I now have 44 bass traps plus 4 diffusors that are also bass traps at low frequencies.


Quote:
nothing beats a well constructed room in the first place.


Even the most ideal room needs bass traps. All you gain from "good" dimensions is a more or less even distribution of modes. But the modes are still there. And the modes still ring. And comb filtering off the wall behind you is still there too.


Quote:
The point is too many audiophiles think that bass traps are a magic bullet. They throw them in without really knowing what they are doing, the more the merrier.


Bass traps are a serious tool, and the more you have the better. Really. It's clear you have little direct experience with bass traps.


Quote:
Many audiophiles are at the mercy of manufacturers, like Ethan's Real Traps, or ASC or somebody else, who have helped create the "bandwagon", as I call it, of unchallenged belief in the overwhelming power of these things


OMG.

Talk about bandwagon of unchallenged beliefs, please list all of your equipment, and especially the wires you own and how much each wire cost.


Quote:
In my experiments with passive bass traps, I did not feel that I was getting much bang for the buck. But, perhaps like many audiophiles, I was ignorant in how to apply them properly.


Yes, ignorant is my guess, or possibly misled. I already correct several of your misunderstandings, such as the fact that bass traps can improve nulls. What bass traps did you try, and how many were there? Also, you have a very large room! To treat it properly requires at least 20 highly effective 2x4 foot bass traps.


Quote:
I appreciate Ethan's input, but we have to understand his Real Traps bias. That does not automatically make everything he says on the subject wrong or slanted. We just have to take it with a grain of salt.


I am not biased! I sell bass traps because I believe in them. Not the other way around.

Please point to everything you disagree with or don't believe is true in my article. Then we can discuss further.


Quote:
He questions that Audyssey works in the time domain. If he has proof to the contrary, I wish he would provide it.


Look at the waterfall plots in the article I already linked to.


Quote:
we should be filing a class action lawsuit against Audyssey


If you need an expert witness I'm available for a reasonable fee!

--Ethan

cyclebrain
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Re: How to determine what is needed - and can you have too much?


Quote:
I'm looking at acoustic treatments for my office, which doubles as a DAW music room and home of my latest stereo acquisition.

The engineer in me thinks I should precisely test my room and figure out if I have acoustic issues. Then I should "fix" the issues via specific measures.

The engineer in me thinks that to accurately measure the acoustic characteristics of my room will take a significant investment of time and money. (How accurate can a Radio Shack microphone recorded via a Sound Blaster be...) (Ok, I have better recording gear than that, but the point remains.)

The pragmatist in me thinks that sounds like a lot of investment for something I'll do once.

The pragmatist in me (or maybe it's the slacker in me) thinks that sounds like a pain it the ass and wants to go buy stuff to throw it at the problem. (A problem I'm not sure even exists...)

Looking at various sites, it appears there are only general guidelines for treating a room. Essentially it comes down to "buy as much of our treatments as you can cram in your room. Stick 'em in the corners, on the walls, on the ceiling, on the doors, and enjoy!"

So -

1) How can I tell if I really need additional acoustic treatments?

2) Can I over do it? How will I know if I do?

*******

My "problem" - my system sounds good at low ro moderate volumes. But when I turn the volume to go for the "big" sound what I get is "loud but muddy" sound.

*******

What would be very useful (perhaps) is a "reference" recording/headset pair that could set the baseline for the "acoustically perfect" room. (like that exists...) Then one could listen to the cans, listen to the speakers/room and compare. Based on the findings one could add reflective and absorbent materials to "tune" the room.

Keith

The engineer in you is correct.
Using a Radio Shack sound level meter doesn't work well.
Using an inexpensive computer based spectrum analyzer and pink noise generator, while not perfect, does a pretty good job.
Using music and your ears will seem to work well untill you play that one song that hits that one frequency that excites that certain room mode.
You can have too much room treatment.
Bass traps are great, but do have a narrow bandwidth.
Too many absorbors can make a room dead.

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Re: How to determine what is needed - and can you have too much?

Ethan, thanks for your resonse. And, Kal, thanks for the link to the Acoustics Forum. I now know exactly what Sabines are. You guys had better watch out. I am going to get a PhD in this stuff. The best thing I came across is Dr. Floyd Toole

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Re: How to determine what is needed - and can you have too much?


Quote:
I now know exactly what Sabines are. You guys had better watch out. I am going to get a PhD in this stuff.


Excellent!


Quote:
I understand that in a science as bewilderingly complex as room acoustics, there are going to be different points of view, different priorities.


Yes, because there's an art to it as well as science. Why is there also an art? Because small rooms acoustics are never even close to perfect, so opinions vary on which compromises are more acceptable.


Quote:
if the response isn
Elk
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Re: How to determine what is needed - and can you have too much?


Quote:
EQ is not a substitute for bass traps, though when used with bass traps it can get you that last 5 percent that bass traps have trouble delivering unless you have 20+ of them.


This accurately states the bottom line reality.

I finally took a look at Kal's review of the Audyssey.

Most interestingly, he describes TriCorner room treatments (bass traps): "I've found make a huge subjective difference in the midbass."

His conclusion was that the Audyssey system enhanced playback but ". . . MultEQ Pro is not a panacea, but requires an already well-configured system in a reasonably good acoustic environment

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Re: How to determine what is needed - and can you have too much?

Ethan

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Re: How to determine what is needed - and can you have too much?


Quote:
But, putting little off
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Re: How to determine what is needed - and can you have too much?


Quote:
it makes a big, easily verifiable difference (not all in room acoustics) that most people are going to find very positive


I don't have time to address all of your points, and Elk summed it up nicely. Here's an easy experiment you can do if you have an equalizer: Set the EQ for a 3 dB cut at 200 Hz with a Q of 1. You'll notice that whatever music you play cleans up nicely. Or maybe try 250 Hz. Somewhere around there. Unless the tune playing is already on the thin side, this "cookie cutter" EQ will always make music sound less boomy, and make the mids and highs clearer by comparison. Has this improved the room acoustics? Of course not. But many people will think it did.


Quote:
I believe that the DSP-based FIR (Audyssey) or IIR (Anthem) filters can also compensate for arrival times


A $150 Pioneer receiver can do that.


Quote:
It
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Re: How to determine what is needed - and can you have too much?

Quote:
Here's an easy experiment you can do if you have an equalizer: Set the EQ for a 3 dB cut at 200 Hz with a Q of 1. You'll notice that whatever music you play cleans up nicely.

I do not have a parametric equalizer, and I really do not see what this proves about Audyssey, which I do have. I hope you are not suggesting it reduces peaks that are not there. We have already covered this territory ad infinitum. Whether you have a response peak or dip, whatever the cause, and Audyssey equalizes for it, it has made the sound better. Those fools who want to think it has fixed all their room acoustics, may continue to do so, but that

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Re: How to determine what is needed - and can you have too much?


Quote:
Yes, any receiver can do that to correct for distance with a single delay for that speaker channel as a whole, but not as a function of frequency.


I don't see how that would be helpful. All frequencies travel at the same speed of sound. If you insert a device that delays some frequencies more than others, the comb filtering peaks and nulls, and ringing, are still there in the same amounts.


Quote:
Even if speaker frequency response is fairly regular, the phase response is often not, especially in crossover regions.


Phase is irrelevant except as it causes peaks and nulls where waves from two drivers combine in the air.


Quote:
I still think you need a standing exhibit that any interested audiophile could visit and listen to the difference between A and B in a typical room. Connecticut would be a good location


You'd think more people would care, but apparently most don't. My company has a standing offer for visitors to see and hear our products in my living room, and we get maybe one person per year. But you are certainly welcome to visit any time for a personal demo.

--Ethan

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Re: How to determine what is needed - and can you have too much?


Quote:
You'd think more people would care, but apparently most don't. My company has a standing offer for visitors to see and hear our products in my living room, and we get maybe one person per year. But you are certainly welcome to visit any time for a personal demo.

Yes but you need an identical untreated room for direct comparison.

Kal

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Re: How to determine what is needed - and can you have too much?


Quote:
"For example, Mr. SAS in another thread here has also expressed a lot of strong opinions about small-room acoustics even though it's clear he has some pretty large holes in his knowledge. When he couldn't understand my room measurement graphs he accused me of making up the data! People who argue the most against the importance of acoustic treatment are invariably people that have never heard a well treated room."

Let's check out Ethan's comment.

1)

Quote:
People who argue the most against the importance of acoustic treatment are invariably people that have never heard a well treated room?

Better read my initial post at

http://forum.stereophile.com/forum/showf...e=0&fpart=1

I discussed and recommended in-expensive room treatment material as an "alternative to more expensive options".

I also stated at

http://forum.stereophile.com/forum/showf...part=3&vc=1


Quote:
>The treatment will be more effective (depending upon the quality of the treatment) if the electronics (and speaker) are truly accurate.


(Ethan was posting as well as me)

I also stated


Quote:
"But to get it as close to perfect as possible, the electronics had better be the most accurate to begin with. Then work with the speaker/room interactions."

I also commented on type and amount depending upon whether the room was furnished or bare like Ethan's test room.

So contrary to what Ethan posted, room treatments are certainly necessary. It is when and how it is applied.

2)Ethan states


Quote:
it's clear he has some pretty large holes in his knowledge. When he couldn't understand my room measurement graphs he accused me of making up the data!

Interesting since Ethan has yet to refute any evidence in my initial post concerning his graphs. In fact, read below and see him sidestep any meaningful response, not once but at least twice.

at

http://forum.stereophile.com/forum/showf...e=0&fpart=1

I stated


Quote:
>Anybody can make a generalized, off the cuff response.
>Do you have some specific technical information you would care to pass on concerning my observations in my initial post?

Ethan's reply


Quote:
If you'd like to list a half dozen points or questions I can address, I'll be glad to do so. But please be concise.

On page 2, I state


Quote:
Ethan has not been able to refute any evidence or points I presented in my initial post. For those new, one can clearly see this in his previous posts.

Ethan's reply on page 2


Quote:
Your entire premise in this thread is fatally flawed, and based on fantasy and misinformation.

So although Ethan claims he understands my initial post, he cannot refute any evidence I presented. Instead just generic responses anyone could write because he cannot offer any more.

Ethan has also attempted to provide misleading information pertaining to the number of speakers and type of mic used after my initial post.

So on all counts, it appears to me that Ethan was manipulative in his comments in order to deceive others.

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Re: How to determine what is needed - and can you have too much?


Quote:
Yes but you need an identical untreated room for direct comparison.


Of course, but it's still totally obvious that the sound in my living room is extremely clear and articulate. One of the demos I like to play is the Diana Krall: Live in Paris DVD. I point out to visitors how articulate the string bass is, and how all notes have more or less the same weight to them.

Also, room treatment is not like speaker cables, where you have to convince yourself there's really a difference. As soon as you walk into my living room from the kitchen the effect of the acoustic treatment is immediately obvious to everyone.

--Ethan

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Re: How to determine what is needed - and can you have too much?


Quote:
So on all counts, it appears to me that Ethan was manipulative in his comments in order to deceive others.


Just to be clear, I am not ducking anything. Rather, I'm ignoring you because you are a troll. If anyone (including sas) has direct questions about my graphs, and would like to discuss the science of audio and small-room acoustics, I'm glad to answer. But this nonsense is just stoopid and I won't dignify it with a reply.

--Ethan

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Re: How to determine what is needed - and can you have too much?


Quote:
As soon as you walk into my living room from the kitchen the effect of the acoustic treatment is immediately obvious to everyone.


What is fascinating is that one can hear the immediate difference even if there is no music playing. The a treated room's ambiance is entirely different. Even talking is more clear.

ethanwiner
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Re: How to determine what is needed - and can you have too much?

Yes, and talking even while music plays is clearer too. A few months ago one of the guys who works at my factory came over with a DVD of a loud action movie to hear it on my system. Even with loud explosions and circling helicopters at full blast, we could talk at the same time and hear each other clearly without screaming into each other's ears.

--Ethan

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Re: How to determine what is needed - and can you have too much?


Quote:

Quote:
So on all counts, it appears to me that Ethan was manipulative in his comments in order to deceive others.


Just to be clear, I am not ducking anything. Rather, I'm ignoring you because you are a troll. If anyone (including sas) has direct questions about my graphs, and would like to discuss the science of audio and small-room acoustics, I'm glad to answer. But this nonsense is just stoopid and I won't dignify it with a reply.

--Ethan

You just ducked again. You can't seem to refute the evidence, even though you claim to be an expert.

The evidence I presented at
http://forum.stereophile.com/forum/showflat.php?Cat=0&Number=43995&an=0&page=0#Post43995

explains that one can mimick the measurements/graphs that Ethan posted by simply rotating the speakers off axis and reversing the polarity of one speaker. Plus some other points.

I suggest one read the string to learn more about this guy.

Buddha
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Re: How to determine what is needed - and can you have too much?

Holy cow, I'm having terrible "Thread Deja Vu" right now.

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Re: How to determine what is needed - and can you have too much?


Quote:
Holy cow, I'm having terrible "Thread Deja Vu" right now.

Hi Buddha,

I understand. I was fast asleep and snoring in Entry Level and was woke up by Ethan's antics and deceptions again. posted some deceitful comments about me on page 3. Just responding.

I went to sleep and was snoring in Entry Level, but was awakened by Ethan with his antics and deceptive behaviour.

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