Adventures in Room Correction

To a limited extent you can, but they have effects further up the frequency range also.

If you have a room with problems from nodes, it will almost certainly sound better with broadband traps than without as long as it does not result in too much HF absorbtion.

 

My point was you can use acoustic treatment to control nodes in a room better than digital EQ as you can achieve correct attenuation without killing the music. If you have big room nodes you cannot use broadband traps to control them properly, they may roll stuff off a bit but it isn't going to give you a flat bass response.

 

Agreed.

 

Lowest frequency = Speed Of Sound / (4 X Absorber Thickness in feet )
= 1130 / (4 * 0.5)
= 565 Hz

according to http://www.etfacoustic.com/

 

It's not quite that simple... Even an inch thick absorber will absorb at 20Hz. Just not very much. A 2 ft thick absorber will absorb much better at low frequencies.

125Hz 250Hz 500Hz 1KHz 2KHz 4KHz
VENUS Bass Traps 1.63 1.34 1.29 1.26 1.25 1.20
4" Studiofoam Wedge 0.31 0.85 1.25 1.14 1.06 1.09

 

That's what my system in my room is doing (the black line is a flat response, reflecting the 10dB/decade of pink noise). Interesting...

 

There is an interesting comparison chart of 'Corner absorbtion' on the Studio Tips forum. in the 'III. Treatment' section

I have moved from using RPG Modex corners (tuned membrane traps) to some cheap foam corners but using a single auto parametric subwoofer Eq. the overall sound is 'better' IMHO. I just didn't have the money or space to use enough of the Modex to sort my modes satisfactorally.

 

The resonators I have seen were generally very large. Made from a cavity with slats of wood across the front giving gaps of different size to target different frequencies. Some have even been built of concrete and made part of the wall spanning the entire height of the room.

It seems there is quite a bit of disagreement as too what constitutes broadband treatment amoung people. In my last post I was referring to things such as the Aruralex bass traps and especially membrane panel traps (not Auralex). The panel traps treat sound as pressure and thus can absorb way down below the thickness of them would suggest using the target frequency = Speed Of Sound / (4 X Absorber Thickness in feet ) formula.

I'm not sure how it works with resonators but with 'broadband' absorption like the membrane panel traps you can't really have too much. The more you have, the flatter your frequency response will be, and they do help out the bass a lot, right down to 40 or even 30hz.

Anyway, I think my point was I don't consider a resonator as tall as the room and a few feet deep & wide as being as 'simple and effective' as a EQ just for targeting a few strong peaks. In my experience EQ (forgetting the quality of the gear as, of course, it needs to be up to the spec of the rest of your playback equipment) doesn't take life out of the music just for flattening a few peaks, it only has a noticeable effect on the life and energy of the music if you use it across a large frequency range and/or in very large amounts.

 

Isaac, if it's any use as a comparison this is what my system is doing in my room.

I know it's not perfect but it is a very small room so I do not have much more space to improve it further.

 

here's an interesting read

http://www.soundonsound.com/sos/sep...s/realtraps.htm

 

Tenson - have you treated the room at all? What did you measure it with?

 

Those Real Traps are hideously expensive. aren't they?
There are some entertaining arguments on several forums between Ethan vs Professional acousticians and I won't be getting any Real Traps.

 

Isaac, yes the room is treated with 9 DIY'd membrane panel traps of a few different depths (this adjusts the frequency range they operate over), some Auralex diffusion and foam for absorption on the back wall as well as some foam on the front wall in the middle behind the speakers.

If I knew what I do now I would have done it slightly differently and only used the membrane panel traps for the deep bass and gone for some implementation of those 'studio tips corner chunks' to help the mid and high range. the mid and high range panel traps don't seem to do too much.

On top of that I am using the Behringer DEQ to help with a remaining hump at 60hz and a small dip at 80hz.

I am sure I could cure those last 2 humps and dips with room treatment but unfortunately I have no space on my walls in the place I believe the standing waves are occurring.

I measured it using a Behringer ECM8000 mic, playing white noise through CoolEdit and recording it back then doing a frequency analysis.


Avanzato, why not try the RealTraps and see what you think? It seems a much better way to judge a product than reading disagreements between the company founder and other acousticians on the internet. Acousticians seem to disagree quite a lot. If they bring as large an improvement as the absorption figures and reviews suggest then no, I wouldn?t consider them hugely expensive. Do you have any acoustic treatment in your room? If so, what have you found works?

 

Yes trying them would be a nice idea but, I don't like the way Mr. Winer represents himself on the forums I read and £220 per 2ftsq panel is a lot of £££'s for a peice of 'nicely' finished fibreglass. IMHO
The absorbtion graphs of course look good as they're there to sell the product but what foam was used for the 'foam corner' data? It's much, much worse than the Auralex data on their corner products, which is on the Studio tips site.
I've just got some no-name foam treatments (which will be installed properly soon) having sold my Modex Corners that mostly worked but took up a lot of space.

 

Yes but my point was resonators don't have to be that big at all.
Surely even if you only want to flatten out a few peaks you still have to pass the whole signal through the processor? It still digitizes all of it then converts it back to analogue.

 

The incoming data is digital. It sits between transport and DAC.

 

Ah sorry, I thought you chucked everything through it. So how does it correct for vinyl etc?

 

I don't have any vinyl.

If you were using it for that then yes, it would digitise the signal.

 

Yes I use it in pure digital mode, both my transport and computer go through it. If you were to use it's analogue input it is still damn good, but does degrade slightly. However you may find much larger improvements from it than you loose due to the A/D and D/A process.

Which resonators have are you talking about Anex? My common sense tells me if they are only the size you say then they wouldn't make much difference, but I could be wrong. Generally there is a strong correlation between surface area of the treatment vs total room surface area and the improvement gained.

Avanzato, let us know how you find the no name foam compared to the Modex stuff. It sounds interesting.

 

They're the resonators in the listening room at uni which conforms to the ISO standard.