What's a good cheap foam we can use for our rehearsal studio?

[Jeff Leites]

"Cheap Foam".... Now there's an oxymoron for you

[Dean Roddey]

Not to interrupt a good fight but...

 

After a lot of experimentation today, here is my first room measurement:

 

 

This is with just two traps still, two 6" 2x4 ones in the corners behind the speakers, and with a few bands of EQ on the Behringer xover/EQ to knock down some of the peaks. Otherwise this is just finding a good spot for the listening position and for the sub and speakers. I do have about 50% coverage of the back and side walls with 2" foam, but that's probably irrelevant at any frequencies involved here. The speaker/sub xover is 48dB/Oct at 57Hz, so the sub is just providing mostly 60Hz and down.

 

The speakers are where I think that they'll be (relative to the chair) when I finally get my new desk put together. The differences are a bit exaggerated because it's so squished up horizontally, so they look worse than they really are generally. This image represents 40Hz on the left to 300 on the right. The thin spike is me tripping over something I think.

 

I have a fairly long low cancellation at about 70Hz and up in the 120s and another up at the 250'ish mark. The one at 70Hz is the worst one. But I'm actually in pretty darned good shape for having so little sound treatment at this point. If I can get some traps in to help with those dips, I'll have pretty good response for such a small studio. It's about 16x11'ish feet, but it's open on one side in the back into a kitchen and on the other side in the back into a bathroom and bedroom. So it's an odd shape, and some of the bass obviously is going to go around into those side rooms and never make it back out, which probably helps some.

 

I can still do some knocking down of peaks. But I want to see what the traps will do first, to see what's really a peak and what just looks like a peak because right now it's somewhat cancelled out on either side. I.e. that second hump looks like a peak, but really it's not. It's just got cancellations on either side really. But anyway, I'm pretty happy so far. If I'm starting off this good, then the addition of some more well placed trappage should put me into pretty good shape. I'll find out later this week when I get the three 4" ones. I'll take another measurement and see how it compares.

[MrKnobs]

Not to interrupt a good fight but... After a lot of experimentation today, here is my first room measurement:

 

Can you explain that plot? What's the scale on the Y axis? Clearly not dB, it's far too small for a room plot. And can you get a scale on the x axis (hopefully frequency).

 

That would be interesting. Thanks.

 

 

Terry D.

 

P.S. Using an equalizer to smooth out room modes is not recommended.

[Ethan Winer]

The thin spike is me tripping over something I think.

 

:D

 

That doesn't look too bad, but it would help to also see the low frequency decay times.

 

Terry:

 

While the scale on the left is not dB, it still gives a usable idea of the relative response. This article from Electronic Musician shows a Sonar project I created to do something similar for people with no budget to buy software:

 

http://www.realtraps.com/art_small_rooms.htm

 

--Ethan

[Ethan Winer]

There is no question that Joel is behind the site, and I'll address that soon.

 

Well, it seems Joel DuBay came to his senses and removed his Ethan Sucks site, so I guess there's little point in presenting my substantial evidence that he was behind it. Unless y'all want me to do that anyway.

 

Hopefully this will be the last we see of such slimy tactics around here. And not just here, but all of the forums where I've had to put up with such crap from Joel and his partner.

 

--Ethan

[Anderton]

Unless y'all want me to do that anyway.

 

Noooo!! Let's get back to foam!!

[Dean Roddey]

Yeh, that's captured from Audacity, after exporting the WAV. It just uses that relative scale for whatever reason, though I've never looked to see if I could change it to dB or not. I'll see I can do that. But yeh, as Ethan says, it was mainly just to show the relative min/max ranges. I'll get a dB scale on it.

[Ethan Winer]

 

So the components cost $30 and the sale price is $199. Ever costed the individual components in your car and compared it to the retail price? Give me a break!!

 

 

Exactly, but I need to point out that the components for a MiniTrap cost a lot more than $30, not to mention the labor to assemble them, the labor to pack them into shipping boxes and FedEx data entry, plus the substantial cost of the large durable boxes and corner bumpers. Then add rent, heat and air conditioning, an accountant to pay the bills and figure the payroll, advertisements in a dozen monthly magazines, and all the other incidentals needed to run a real business. In truth, the profit margin on MiniTraps is small. In most industries it costs a manufacturer about 1/4 what the product sells for. I wish we had that sort of profit margin!

 

--Ethan

[Dean Roddey]

OK, I updated the image with a dB scale. It took me a while to find that option in Audacity but it is there. So it looks like my biggest ones are about 12'ish dB. The one at 70 and the one around the 120 position (the first two big dips on the left.)

[myfipie]

Hi Glenn! (Glenn is here in Atlanta and our bands have shared bills on quite a few occasions ).

 

Hey Lee,

 

Hope all is going well for you guys. I got find some time to make it out to your next show.

 

 

Folks,

I had the (dis)pleasure to view that Ethan page and must say this should go down in history as the most retarded thing ever made. I got a chance to finally meet Ethan at the AES show and we talked for quite some time. Ethan is about as upstanding as they come.

Ethan, anyone that would read that page and not think the writer is :freak: would not be able to tell a bass trap from a bass guitar.

 

Glenn

[Ethan Winer]

Thanks Glenn, you're a true friend.

 

--Ethan

[Lee Flier]

Yep, Ethan and Glenn are the real deal. The real shame too is that Ethan has always offered DIY bass trap plans on his web site and has always been happy to help folks who want to roll their own. For those who either don't want to do it themselves or want something highly portable, they can pay a little more and buy MiniTraps, or Glenn's traps. It's not like these guys are trying to keep it a secret how their products are made. Quite the opposite; they are very open about it and confident that quite a few people will prefer to buy something pre-made anyway. Which they (we) do.

[MrKnobs]

I had the (dis)pleasure to view that Ethan page and must say this should go down in history as the most retarded thing ever made.

 

The problem with that page is that it was (mostly) a personal attack. If the author has some issues with Ethan's products (clearly he does) then he should (a) identify himself, and (b) address the technical issues only, presenting his data and arguments, and © leave the personal stuff out of it. Then Ethan could respond, and perhaps after a few iterations the rest of us might attain some consensus and enlightenment about the subject.

 

This is how science is done.

 

It's interesting for me to read this today because I just received an email from one of the participants in our recent "noise rodeo" where crews from all over the region came to record and measure pavement noise levels at the tire/pavement interface. The idea was for all of us to measure the same pavements at the same speed and see how our results compare.

 

Well, guess what: one crew using a different system than ours got very different results on two out of three of the test pavements. VERY different results, more than 3dBA which corresponds to a doubling of the sound energy, and therefore corresponding to a hypothetical doubling of the number of the vehicles on the roadway.

 

My first reaction to reading that email this morning was to think, "Their results are absurd! Our measurements are right! They must have done something careless or their equipment isn't properly designed or calibrated!"

 

But you know what? None of us know which (if any) of the measurements are right. So I will go out again on the test sections with handheld meters (actually we'll use tripods) and measure the actual roadside noise levels the vehicle mounted systems are designed to predict.

 

If we are wrong and they are right, we'll say so and work on figuring out why. In this way, all of us will learn something and we'll have worked together to advance our understanding of how traffic noise is produced and how to mitigate it. In other words, it's all good.

 

I would have to laugh until my sides split if our colleagues who got the high numbers were to suggest we must be "atheists" (as on the Ethan bashing website) or that perhaps their PhDs are more appropriate to the study than ours are. In the latter case, I'd simply reply that if they're so much better educated in this area than we are, it should be a simple matter for them to prove us wrong and show us the errors in our thinking.

 

But they won't do that, because they're professionals too.

 

To summarize, I sometimes defend foam on these forums because I've tested it extensively and I'm happy to share my data and methodology with anyone who is interested in why I've come to the conclusions that I have. I don't really care who makes the foam and who makes the panel absorbers, I don't work for either company.

 

That's the approach that everyone needs to take; just be honest and present your facts while leaving the personalities out of it.

 

Speaking of which, I will upload a chart showing the aborptivity of 10" of Auralex acoustic foam as measured by me using a calibrated impedance tube. Have to do that from home, if I want to use the IMG tag here.

 

Terry D.

[G Geezer]

Sorry, but this really begs for a Parody

What's a good cheap forum we can use for rehearsal?

 

Sorry, back to the previous seriousness.....

[Ethan Winer]

Terry,

 

if our colleagues who got the high numbers were to suggest we must be "atheists" (as on the Ethan bashing website) or that perhaps their PhDs are more appropriate to the study than ours are.

 

No kidding. What's so pathetic is I have been right on the science all along! I made my Balloon Party video Joel ridiculed because his friends denied the existence of quarter wavelength nulls at predictable distances from the rear wall. But now everyone understands and accepts that these nulls occur exactly as I stated years ago.

 

Likewise, his pals called me incompetent (and worse) for suggesting that standing waves and resonances are not the same thing, yet THIS thread at John Sayers site shows I wasn't so incompetent after all.

 

Then there's the hypocrisy. That web site criticized me for using ETF in a small room to show the effectiveness of bass traps, yet the Ready site uses a similar graph showing how the response in a small room improves as bass traps are added.

 

But wait, there's more. I was also criticized for my Numbers Game explanation of the Edge Effect being mostly responsible for absorption coefficients greater than 1.0, and now that too has been proven correct.

 

I was also criticized for my wood panel bass traps design, and Joel's "expert" pals said if you put them on a wall they'll reduce isolation by creating a triple-leaf effect. I don't know if you saw the big thread about a year ago at Sayers' site, but I convinced Brian Ravnaas (Green Glue guy) to test that in a lab, which he did, and I was proven right. Here is the thread:

 

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=7053&highlight=triple

 

Bryan Pape's final post on the last page sums it up: "There had been concern that using these types of absorbers could *significantly* decrease TL. Yes - they did what was expected but the idea that it was going to be a large problem, in this particular situation, was disproven."

 

So yet again I was right and the Ethan-bashers were wrong.

 

I have even more instances of me being right on the science and "them" being wrong, but I'll stop here lest ya'll fall asleep.

 

--Ethan

[Dean Roddey]

Something I was wondering about is how things like hanging slat blinds affect bass response. It would see that, if they are closed, that they would act alomst like a very bendable wall, and give slightly with the pressure wave, effectively reducing the reflections off of the glass window or door behind it. Would this be the case?

 

In my room, the wall behind me (about 10' back) is a double sliding glass door. So I can't mount bass traps there. But I have fairly heavy curtains with a fairly heavy blackout type of cloth on the back, and the heavy hanging slat blinds behind that.

 

I have a very small apartment, so basically it's the usual thing of an elongated rectangle, with some dividers sticking out of one wall to create 'rooms', though they are really more big cubicles since the whole back (except for the bedroom at the end) remains an open hall. Kind of a trailer without the wheels. So any energy coming out of the speakers would go out into these the two spaces on either side (kitching/bathroom/bedroom.)

 

I was thinking maybe I'd hang a couple of traps from the ceiling behind my to create a kind of 'pseudo room' for the studio. So it would kind of wall off the studio from hall type space. That would be basically like mounting them on the back wall, just that they would be maybe 4' from the back wall. So they would be hung from their tops and hanging down the the long dimension. Would that be worth it, say relative to putting them on the door and wall on either side of the sliding glass doors?

[myfipie]

Something I was wondering about is how things like hanging slat blinds affect bass response. It would see that, if they are closed, that they would act alomst like a very bendable wall, and give slightly with the pressure wave, effectively reducing the reflections off of the glass window or door behind it. Would this be the case?

 

Bass will go right through the blinds so it will not help at all. In fact I would think they would hurt by scattering upper HF unevenly. Here is a little link on diffusion if you would like to learn more http://www.gikacoustics.com/education_diffusion.html

 

In my room, the wall behind me (about 10' back) is a double sliding glass door. So I can't mount bass traps there. But I have fairly heavy curtains with a fairly heavy blackout type of cloth on the back, and the heavy hanging slat blinds behind that.

 

Why not put panels on stands?

 

Glenn

[Lee Flier]

Why not put panels on stands?

 

Yeah, I have several mounted on mic stands. Not only does this allow me to move them around to places that normally wouldn't be blocked, like windows or doors, but I can create an "instant vocal booth" out of them for a tight vocal sound, etc. Works really well and gives me maximum flexibility.

[Dean Roddey]

I'd probably just hang them as I was mentioning above. These are pretty heavy, so they couldn't really be hung on a mic stand very easily, and the stand legs would get in the way. So I'd probably just hang them to create a 'rear wall' for the studio. When tracking vocals, I could just flip around and put the mic right in front of one of them.

 

 

 

In fact I would think they would hurt by scattering upper HF unevenly. Here is a little link on diffusion if you would like to learn more

 

 

As I mentioned, there are fairly heavy curtains with blackout backing, sitting in front of the blinds, so I doubt much HF ever even reaches them.

[UstadKhanAli]

 

 

How to make a Bass Trap Acoustic Panel (Tutorial)

 

I just came across this YouTube video, and thought people might be interested in seeing this. We're thinking about going this DIY route and doing something similar to this / what Ethan suggests on his website.

[Anderton]

Ethan would have a lot more credibility were it not for the well-known fact that he personally faked the moon landing photographs. He slept with John F. Kennedy, too. Also, he admits to playing cello -- an instrument large enough to contain contraband!!

 

We tolerate him on this forum only because of the cute kitty in his avatar.

[Dean Roddey]

 

Ethan would have a lot more credibility were it not for the well-known fact that he personally faked the moon landing photographs. He slept with John F. Kennedy, too

 

 

That's perfectly legal... well, as long as you don't do them at the same time.

[Ethan Winer]

Also, he admits to playing cello -- an instrument large enough to contain contraband!!

 

Mmmmm ... contraband.

 

--Ethan

[Ethan Winer]

 

How to make a Bass Trap Acoustic Panel (Tutorial)

 

 

That video was posted by a lamer.

 

Here's the real deal for DIY'ers:

 

http://www.ethanwiner.com/acoustics.html

 

--Ethan

[myfipie]

Ethan,

 

Watch out Ethan someone is making some killer videos about room acoustics. Damn:p

http://www.expertvillage.com/videos/recording-studio-sound-isolation.htm

http://www.expertvillage.com/videos/recording-studio-outro.htm