Acoustics: Real Traps Vs. Ready Traps ?

[sdelsolray]

Originally Posted by Ethan Winer

As you yourself pointed out months ago elsewhere, it's not fair or ethical to compare corner tests in different labs because of these variables.
--Ethan

So it's fair and ethical to publish these data inferring that the end user will get similar results in all the variety of rooms in which your products will be used?

Time to lower your prices Ethan.

[Ethan Winer]

> So it's fair and ethical to publish these data inferring that the end user will get similar results in all the variety of rooms in which your products will be used? <

All of the comparative data on our site was taken in the same places in the same lab. What labs measure is Sabins, and a bass trap has the same Sabins in my room as in yours. If this is not what you're asking, please clarify.

> Time to lower your prices Ethan. <

ROF,L. Actually, we've been thinking about raising them!

In this case you definitely get what you pay for. I have no problem with someone wanting to buy cheap stuff or DIY, and I'd never diss someone for buying a budget mike pre if they couldn't afford, say, an Avalon or Grace. But are you suggesting that all high-end audio companies should lower their prices because you can buy a Behringer mixer having mike pres for $100?

--Ethan

[Glenn Kuras]

Originally Posted by Ethan Winer

> So it's fair and ethical to publish these data inferring that the end user will get similar results in all the variety of rooms in which your products will be used? <

All of the comparative data on our site was taken in the same places in the same lab. What labs measure is Sabins, and a bass trap has the same Sabins in my room as in yours. If this is not what you're asking, please clarify.

> Time to lower your prices Ethan. <

ROF,L. Actually, we've been thinking about raising them!

In this case you definitely get what you pay for. I have no problem with someone wanting to buy cheap stuff or DIY, and I'd never diss someone for buying a budget mike pre if they couldn't afford, say, an Avalon or Grace. But are you suggesting that all high-end audio companies should lower their prices because you can buy a Behringer mixer having mike pres for $100?

--Ethan

Ethan let me help you out, I think the proper response would be:

As I really want everyone to have proper acoustics in there room I do understand everyone can not afford our product... It is not that we think we have overpriced our product but feel that we have years of research, solid construction, lab reports, a proven record and as you all know I can help you will your room from start to finish. We feel that is worth every dollar you spend on Real Traps.


Don't you think that sounds a little better then comparing your competitor to, say Behringer? Just thought I would try to help out. BTW you are not high priced, not like RPG!!!

Glenn

[Glenn Kuras]

Originally Posted by Brad McGowan

From talking with the designer at the show it seemed like they were in the $200-$300 range for the 2x4 ft. trap.

Brad

I found there lab numbers and had to look twice... When those are straddled those things most have some kind of bass vacuum on it!!!! ha ha ha
When I compared his "A" mount to ours and then corner mount to ours it seems to be a huge difference on the corner numbers but closer on the "A" test.. I wish they had PDF's from the lab to see how these where set up.. Not to say they are not right, but to understand it..
I sent them a email, lets see if we hear back from them..

Glenn

[biggator6]

Glenn,
are you getting your materials locally? I have an idea for killing some reflections in my living room by building traps into the top of my entertainment center (you'd have to see it) -but not sure where do get 503 or equivalent in the area.
"-)

[aintnosunshine]

Originally Posted by myfipie

BTW you are not high priced, not like RPG!!!

I don't think either of you guys are all that high priced. But I do hear people complain such quite often on other forums... i think its just a economics issue betweem the people who run a studio for a living/music is their life, vs the huge group of hobbyists out there who also complain about synthesizer plugins costing more than $100, or a pair of studio monitors for more than $300.

All the same, I'm more of a DIY kinda guy... but you can bet if somebody offered me money to build some basstraps I'd be charging an arm and a leg for my time. It's like some guy walking into a nice steakhouse and complaining that the steak in their $14.00 sirloin steak dinners only cost $3.99/lb at the grocery store. "AND I WANT IT FOR FIVE BUCKS OR I WONT BE YOUR CUSTOMER!"

[Glenn Kuras]

Originally Posted by biggator6

Glenn,
are you getting your materials locally? I have an idea for killing some reflections in my living room by building traps into the top of my entertainment center (you'd have to see it) -but not sure where do get 503 or equivalent in the area.
"-)

The company that I buy from only sells in higher quanity, but send me a email and let me see what I might be able to do for you..

Glenn

[Savant]

Originally Posted by Ethan Winer

All of the comparative data on our site was taken in the same places in the same lab. What labs measure is Sabins, and a bass trap has the same Sabins in my room as in yours. If this is not what you're asking, please clarify.

Um, I'm fairly certain Ethan didn't mean that.

I've been involved in a fair bit of low frequency absorption testing with devices in lab corners at this point and I can say, conclusively, that it won't be standardized. The reason is the results vary so widely, even with the same devices in the same room, on the same day (and so on...), but in different corners. Suffice to say, the absorption of any device in a corner cannot be quantified absolutely in the contexts of a studio room. Whatever Ethan measured in a corner in terms of Sabins is most assuredly not applicable to any studio room.

That's not to say the results are useless. But the purpose of a standardized test is to get standardized results. Over the official frequency range - 100 to 5000 Hz - that is possible, regardless of the mounting used. But once you get into the low frequency range, even the big reverb chambers go modal. So, placing things in corners will never produce absolute results.

To say that because a device measured extremely well at 80 Hz in one corner configuration means it is universally useful at that frequency in all possible corner configurations is false. Especially since the studio room in which the device might be applied may not even have a problem in that range to start with!

Of course, I'm probably just putting things a different way. But the corner tests have always worried me. The research I had a hand in at Auralex was enough to make me pull all the references to corner testing off the website a while ago. It's just futile to take part in something so erratic when the point is to remove as many variables as possible.

Anyway, the other thing I would mention is that there is an ISO standard for measuring absorption at very low frequencies. The only company using it to quantify the behavior of their "traps," that I'm aware of, is RPG. There is a rather big caveat to performing the test - the construction of the room is very exact. I.e., you can't perform the test in any ol' reverb chamber. RPG's also done LF testing in a large impedance tube. This would also be an acceptable method, but much more involved than the reverb chamber method. Point is, if the companies that make "traps" are keen on quantifying their products in a manner that can be compared to other products tested other places, they might look into following in RPG's footsteps.

As it stands, if the facilities aren't available for performing the ISO or impedance tube tests, the very least all the manufacturers can do is test their products in the standard mountings - A and/or E - and publish the results over the official range of frequencies. If other mountings and/or lower frequencies are tested, I would see two choices:

1. Disclaim the poop out of the data since they aren't official. Corner mounting is not a standard mounting method and there isn't a lab out there that's been approved to provide official test results below 100 Hz.

2. Publish the results in the contexts of a research paper or something other than "official" test results.

Of course, that assumes the "traps" in question are of the panel variety. It's been pointed out that the A-mounting testing on Auralex LENRDs was errant because they are actually triangular devices that are meant to be physically placed in a corner. This does introduce a degree of complexity, but nothing that cannot be overcome. Testing devices such as those in a manner that reports Sabins/unit, but with the mounting staying true to the standard, would be one way to help make things more comparable. I would imagine that standing the devices upright, spaced appropriately in the chamber, avoiding placement that came too near a wall, corner, the mic, etc., would give more useful data than any corner test. Now, the argument then would be that none of these methods reflects real-world usage. And my response to that was that real-world usage is not what's meant to be addressed with standardized testing. If that were the case, the auto manufacturers would take their cars out on the real streets of America to obtain their MPG ratings. But they don't. There has to be a standard method that everyone can use some vehicles can be compared side-by-side without question as to how the results might have been doctored. That's what happens in this industry when manufacturers stray from the standardized absorption tests. The results may look great on paper, but what they really mean is completely unknown.

My $0.02.

[Glenn Kuras]

Originally Posted by Savant

Um, I'm fairly certain Ethan didn't mean that.

I've been involved in a fair bit of low frequency absorption testing with devices in lab corners at this point and I can say, conclusively, that it won't be standardized. The reason is the results vary so widely, even with the same devices in the same room, on the same day (and so on...), but in different corners. Suffice to say, the absorption of any device in a corner cannot be quantified absolutely in the contexts of a studio room. Whatever Ethan measured in a corner in terms of Sabins is most assuredly not applicable to any studio room.

That's not to say the results are useless. But the purpose of a standardized test is to get standardized results. Over the official frequency range - 100 to 5000 Hz - that is possible, regardless of the mounting used. But once you get into the low frequency range, even the big reverb chambers go modal. So, placing things in corners will never produce absolute results.

To say that because a device measured extremely well at 80 Hz in one corner configuration means it is universally useful at that frequency in all possible corner configurations is false. Especially since the studio room in which the device might be applied may not even have a problem in that range to start with!

Of course, I'm probably just putting things a different way. But the corner tests have always worried me. The research I had a hand in at Auralex was enough to make me pull all the references to corner testing off the website a while ago. It's just futile to take part in something so erratic when the point is to remove as many variables as possible.

Anyway, the other thing I would mention is that there is an ISO standard for measuring absorption at very low frequencies. The only company using it to quantify the behavior of their "traps," that I'm aware of, is RPG. There is a rather big caveat to performing the test - the construction of the room is very exact. I.e., you can't perform the test in any ol' reverb chamber. RPG's also done LF testing in a large impedance tube. This would also be an acceptable method, but much more involved than the reverb chamber method. Point is, if the companies that make "traps" are keen on quantifying their products in a manner that can be compared to other products tested other places, they might look into following in RPG's footsteps.

As it stands, if the facilities aren't available for performing the ISO or impedance tube tests, the very least all the manufacturers can do is test their products in the standard mountings - A and/or E - and publish the results over the official range of frequencies. If other mountings and/or lower frequencies are tested, I would see two choices:

1. Disclaim the poop out of the data since they aren't official. Corner mounting is not a standard mounting method and there isn't a lab out there that's been approved to provide official test results below 100 Hz.

2. Publish the results in the contexts of a research paper or something other than "official" test results.

Of course, that assumes the "traps" in question are of the panel variety. It's been pointed out that the A-mounting testing on Auralex LENRDs was errant because they are actually triangular devices that are meant to be physically placed in a corner. This does introduce a degree of complexity, but nothing that cannot be overcome. Testing devices such as those in a manner that reports Sabins/unit, but with the mounting staying true to the standard, would be one way to help make things more comparable. I would imagine that standing the devices upright, spaced appropriately in the chamber, avoiding placement that came too near a wall, corner, the mic, etc., would give more useful data than any corner test. Now, the argument then would be that none of these methods reflects real-world usage. And my response to that was that real-world usage is not what's meant to be addressed with standardized testing. If that were the case, the auto manufacturers would take their cars out on the real streets of America to obtain their MPG ratings. But they don't. There has to be a standard method that everyone can use some vehicles can be compared side-by-side without question as to how the results might have been doctored. That's what happens in this industry when manufacturers stray from the standardized absorption tests. The results may look great on paper, but what they really mean is completely unknown.

My $0.02.

Jeff,

that is a darn good point about RPG's testing... Do you have any info on labs other companies could use??

Also it is great to see you are still sticking with the forums to help out people.. We need true acoustic experts around..

[ddageek]

Okay here we have 3 very bright people who ubderstand the devices and the problems , Why don't the 3 of you get togather and writ a stanard for say the AES?
than at least while its being debated and refined we have something others can use?

[Bang]

Slate studios acoustic designer Teale Haley has perfected some traps made of rigid fiberglass with air gaps built into the frames so that they don't have to have them as far off the walls which to me always looked a bit strange. He can also do custom sizes and just about any color you can imagine, just ask. He's installed them into a lot of studios here in LA and everyone has been ecstatic. They are not expensive either.. See pics here:
http://www.slatestudios.com/sales4.html

[Glenn Kuras]

Originally Posted by Bang

Slate studios acoustic designer Teale Haley has perfected some traps made of rigid fiberglass with air gaps built into the frames so that they don't have to have them as far off the walls which to me always looked a bit strange. He can also do custom sizes and just about any color you can imagine, just ask. He's installed them into a lot of studios here in LA and everyone has been ecstatic. They are not expensive either.. See pics here:
http://www.slatestudios.com/sales4.html

hey welcome to the world of wacky acoustics world!! Ours also have the air gap on the back, but you still want to space it off the wall to let sound in from the sides.. Take a look at your data reports, "A" mount is flat on the wall with the spacer on the back.. It may look a little odd to you to have the space between the panel and the wall but it has to be there.. As found out in a lab..

[Ethan Winer]

Jeff,

As always, thanks for clarifying. Note that what I said about getting the same Sabins in all rooms was aside from how panels are tested. Whatever a panel absorbs in one room it absorbs in another, regardless of how it's measured. Assuming similar temperature and humidity.

> Disclaim the poop out of the data since they aren't official. <

Yes, that would be my choice too.

--Ethan

[Bang]

Originally Posted by myfipie

hey welcome to the world of wacky acoustics world!! Ours also have the air gap on the back, but you still want to space it off the wall to let sound in from the sides.. Take a look at your data reports, "A" mount is flat on the wall with the spacer on the back.. It may look a little odd to you to have the space between the panel and the wall but it has to be there.. As found out in a lab..

It was good talking to you Glenn. We are in agreement about spacing off walls. To clarify my prior post, if you have an inch or two of gap behind the fiberglass built INTO the frame, you only have to have the trap another two inches off the wall via spacers, rather then 4 inches off the wall had you not had an air gap in the frame. BUT, as I was saying, every room is different, and what a lot of people don't hear from guys who sell acoustic products (and this is no reference to anyone on this thread) is that it is not uncommon to go TOO FAR with absorption.

When a room is completely isolated and built "soundproof", it will need a lot more bass absorption then if you build a studio in a room that is not built for isolation. Teal just installed some bass trapping in the corners of a room here in LA that was not built as an isolated room. After doing listening tests, we both decided that there was no need to "stuff" R13 behind the bass traps which audibley increased low end absorption. But the studio owner couldn't believe that we opted for less absorption, so he stuffed the corner gaps with a lot of R13, and lo and behold, it sucked up too much bass and the quick mix he did was way bass heavy in the 100-200Hz area, which is an awful area to be heavy in.

So I guess what I'm trying to say is that the really key in acoustics is to listen at every stage of installation. Each room has different needs and some will require more acoustic treatment then others. Diffusion is also very important in a room and thats why Teale is almost done with a rig that will be able to mass produce quadratic diffusors for pretty cheap.

[mhartman]

Originally Posted by biggator6

Glenn,
are you getting your materials locally? I have an idea for killing some reflections in my living room by building traps into the top of my entertainment center (you'd have to see it) -but not sure where do get 503 or equivalent in the area.
"-)

In the Atlanta area, try Specialty Products & Insulation Co. (www.spi-co.com). I bought a bunch of OC 703 there a while back for my studio at a pretty good price (around $10/panel I think). They carry a good variety of acoustic stuff (OC 703, rockwool, etc.) If I remember correctly, there was no minimum purchase, but I may be wrong -- I bought 15 2x4 panels of the 703. Kevin Vetter was the salesman that I worked with, he is a good guy. You can call over there at 770-454-9643. They are located near the 285/85 junction.

Good luck,

Mike

[Glenn Kuras]

Great talking to you too,

>Teal just installed some bass trapping in the corners of a room here in LA that was not built as an isolated room. After doing listening tests, we both decided that there was no need to "stuff" R13 behind the bass traps which audibley increased low end absorption.<

did you test the room?? If so how did you test it..
I have never seen a room get to much bass trapping, but I will say that I have seen people build a bunch of traps and end up killing the high end.. That is where a membrane can help.. Hits the low end but keeps the life in the room.. Maybe that is what you guys are hearing if you are only listening and not testing..
Just a thought..

Glenn

[Bang]

Glenn, I've spoken with some of the top acousticians on the planet and the idea of too much bass trapping not only happens, its common. And Teale zaps rooms with MLS noise, but I don't give a shit about MLS noise, I play music through the speakers and listen! Then I'll have the guy do a quick mix. Too much bass trapping often finds a drop starting at 250Hz. The positioning of speakers and mix position in the room can alter this as well. Finding a good spot in the room is the hardest thing to do imo. And I agree about the high end.. although rigid fiberglass and mineral wool are less dampening on the highs then foam, too much can lead to a dull sound coming from your monitors. However, the dampening of high end due to over absorption would not lead to the sense of less lows, but more lows actually.

[Ethan Winer]

Steve,

> if you have an inch or two of gap behind the fiberglass built INTO the frame, you only have to have the trap another two inches off the wall via spacers <

I think you're missing Glenn's point about mid and high frequency absorption. Most panels based on rigid fiberglass can absorb through the rear surface as well as the front. But in order for sound to get to the rear the edges must not be blocked. That is, more total sound is absorbed with a panel spaced 4 inches off the wall, when compared to a panel having sides 2 inches deeper than the panel thickness and spaced 2 inches.

I also agree with Glenn that it's not possible to have too much absorption at bass frequencies. No matter how many bass traps you have, the room will still not be flat and there will still be low frequency ringing. So the best you can aim for is as much bass trapping as possible, then you accept the results. I do agree with you about listening, but more to "tune" the appropriate amount of mid/high frequency absorption.

--Ethan

[Ethan Winer]

Steve,

> I've spoken with some of the top acousticians on the planet and the idea of too much bass trapping not only happens, its common. <

Yes, I've heard some people say this, but they're wrong. Regardless of how "top" they may be.

> Too much bass trapping often finds a drop starting at 250Hz <

As you add more and more bass trapping the response becomes progressively flatter and the ringing progressively shorter. Peaks continue to come down in level, and nulls continue to come up. By the time you have 100 percent surface coverage the response is finally flat. Of course, by then there's too much absorption at mid and high frequencies. Again, it's the balance between absorption at low frequencies and everywhere else that can be "tuned." But it's not possible to have too much absorption below about 300 Hz. Unless you prefer a skewed LF response with a little ringing thrown in for good measure.

--Ethan

[KrisAnderson]

I have been reading this forum for the past week or so, and it just hit me now. The traps i have in my room are actually GIK's. I knew Glenn's name sounded familiar. My studio is in my bedroom, which means there is a lot of potential for the sound to suck. Let me tell all, F**k all this nerdy spec talk, his traps did wonders in my room. Granted, my room still isn't at where i want it to be at compared to other studios i have worked, but it definetly improved everything a hundred fold. Clients are real happy with there mixes AGAIN. I used to live in a 3flat apt. building on the second floor. My studio was in the dining room. I somehow did the best mixes of my life there, ironically, without any acoustical treatment at all. Even better than mixes i have done in a real professional studio(old chicago trax, old slang music studios). My point being, once i put the GIK's up in my bedroom, where my studio now currently resides at, my mixes are back to there old self. Thanks glenn.

Here is something worth tossing around. How come noone has ever tried to make traps with dirt or adobe? I heard that dirt (earth) has no resonace. Dirt is the cheapest thing you can get. Go outside, dig a whole, voila, dirt. Granted it isn't as clean as fiberglass , but why not? If it was built rite, maybe. Something to think about.

[Glenn Kuras]

>Let me tell all, F**k all this nerdy spec talk, his traps did wonders in my room. <

I have to say that I have read great stuff from clients, but this one takes the cake!! Thank you sir... Oh and I agree F the nerd talk! ha ha

>Here is something worth tossing around. How come noone has ever tried to make traps with dirt or adobe? I heard that dirt (earth) has no resonace. Dirt is the cheapest thing you can get. Go outside, dig a whole, voila, dirt. Granted it isn't as clean as fiberglass <

SSSSSSSSSSH, don't tell anyone but that is what we have in the traps.. GA red clay is the best!!!!!!!!!!!!!!! Just kidding...

[Bang]

Originally Posted by Ethan Winer

Steve,

> if you have an inch or two of gap behind the fiberglass built INTO the frame, you only have to have the trap another two inches off the wall via spacers <

I think you're missing Glenn's point about mid and high frequency absorption. Most panels based on rigid fiberglass can absorb through the rear surface as well as the front. But in order for sound to get to the rear the edges must not be blocked. That is, more total sound is absorbed with a panel spaced 4 inches off the wall, when compared to a panel having sides 2 inches deeper than the panel thickness and spaced 2 inches.

I also agree with Glenn that it's not possible to have too much absorption at bass frequencies. No matter how many bass traps you have, the room will still not be flat and there will still be low frequency ringing. So the best you can aim for is as much bass trapping as possible, then you accept the results. I do agree with you about listening, but more to "tune" the appropriate amount of mid/high frequency absorption.

--Ethan

I think you are missing my point. Given there is already space behind the fiberglass, you can put it two inches off the wall and air CAN and WILL get to the fiberglass because there is nothing blocking the back of the traps. It is more aesthetically pleasing to me to have a trap 2 inches off the wall rather then 4 inches, especially if the traps are doing equal absorption.

Now about too much bass absorption, it is very real and I've heard it and measured it in more then a few rooms. A few calls to some of the top guys in LA and you'll hear them say the same thing and they are very right. You have to be very careful when piling in the absorption to carefully monitor the 100 to 300Hz area. Sometimes you're sucking too much out of this area. It really all depends, but simply throwing in a zillion fiberglass or mineral wool bass traps all over the place does not insure a flat room and not just because the dampening of the high end. Its very difficult to get an even ratio of absorption at say 80Hz and absorption at 250Hz, especially in room not built to be a studio room. Depending on many factors, its easier to suck out a lot of 250Hz and not as much 80Hz. Hence the reason why tuned absorbers are such a presence in high end studios.

Case in point, a room Teale just did had a huge 80Hz resonance due to its room dimensions. The owner of the room had made his own OC 705 traps, piling them up in each corner and stuffing behind them with more OC 703 pieces. The 80Hz resonance was down a bit, but it sucked the hell out of 200Hz a lot MORE. So we tuned a trap to 80Hz to relieve that peak FIRST, then proceeded to appropriately bass trap the rest of the room resulting in a beautiful sounding space.

[Glenn Kuras]

Hey Steve I am always up for learning so if you would post me one of these graphs of a room having the low end "sucked" out of it..

[Bang]

The first thing you should do to learn is to use ears just as much as you do graphs. However, I'm sure I can provide you the graphs as well. Its not really hard to think about, if you absorb more at a given set of frequencies then you do at others, things will be uneven. If you trap the hell out of space that has a funky curve under 300Hz, its very possible to attenuate certain resonances a LOT more then others, like my little example of 250Hz vs 80Hz.

So far I think you agree that too much absorption can attenuate the high end frequencies, but do you think that that low end frequencies are magically defensive against attenuation due to absorption? And also how can you generalize about any of this without knowing the acoustics of the room with NO abosorption?

[Youn]

So, you are saying it really becomes a balancing act at some point? Is this because 100% absorption across the low spectrum is unlikely? Do bass traps simply need to be thicker in dimension to absorb lower? Maybe they need to get denser as they approach the room, so higher freqs gradually get bounced back and not sucked in. Just a thought.

I just sorta vaguely remember these types of cases, where folks filled their small room's volume upto 30% or more. they were positive more = better and the before and after graphs were pretty convincing. Was that over in StudioTips forum?

[Bang]

Its because that and because that its very unlikely that the low spectrum is even to begin with in a given room.