Room Acoustics

Just tested my media room using the Rives test disc (pink noise) and a RS analog SPL meter.

Couple of things:
- I kneeled behind the meter, which was set on a tripod in my so-called sweet spot for two channel. Certain midrange frequencies were very sensitive to my location and movement.
- For the heck of it I put some FG acoustical treatments (4'x2') at the first reflection points. Plotted the data and found that it impacted some frequencies but appeared to create more spikes a troughs than without!

I am interested in how some of these room treatment companies can quote you a package without measurement!

I'm going to repeat the test from all seven seating locations. Expect to see some wide variation.
You may want to smooth-out the bass response in your room with bass traps and then work on the other freq. to make the job more easy. Upper freq. will be very easy to deal with unless you have a reverb-chamber for a room.

Sogood is the bass first ( and look at treating all the first order reflection points which are left, right, ceiling, floor. The purpose of the first order reflection points (using either absorption or diffusion depending on your room) is to prevent the delayed echo from reaching your ear. This will clean up the imaging in a huge way. Unfortunately the rives cd test sweap has big gaps and is useful for basic idea but you really need to use something like EFT to sweep a frequency in small increments.
Most "mild" room treatments utilizing thin layers of foam and / or "stuffed" cloth materials, etc... are actually very non-linear in their absorption of frequencies. I commented on this many, many years ago in the Agon archives and posted links to actual absorption curves for commonly used devices. I did this after someone inquired about purchasing some of these devices and told them that they would actually be creating more of a problem. In plain English, most of those types of devices are a big mess.

If you want to treat a room and end up with results that are actually better / more linear than what you started with, rather than just shifting problem areas to different frequency regions, you have to treat the room as a whole. Once again, i recommend that folks pick up and read some books by F. Alton Everest BEFORE spending money on products that you can do a better job of buildng yourself and impliment them in a manner that is more suitable to obtaining optimum results. Not all rooms are the same, nor do they require the same type and quantity of treatments. If they did, they could design speakers that worked within those constraints and did so perfectly. Sean
Sean, have you played with room correction electronics (e.g. the TacT system)? If so, how would you rate their performance over standard room treatment approaches?

Finally - to everyone - why is there such a bias against such systems?

No bias here. Room treatments that get over-all freq. response with-in even 6-8db is very good in most rooms. These room correction devices can only help even more if used correctly.

Between speaker placement, seating placement, room treatments, and some mild room correction you should be able to smooth things out to a great degree.

Another nice feature of some of the correction devices is the fact that you also get an active digital X-over with many settings.


First, cool system! Love it. Second, that's what I see: room treatment is - at best - shotgun accuracy; contrast that to what these RCS systems can do (rifle accuracy) on the linearity of the response! On paper, amazing.

I'd love to compare a spectacular system (e.g. Mike L's or Albert Porter's) before room treatments with RCS and after room treatment (or construction, in Mike's case) without the RCS.
Thanks Mprime, we have a member of the Apogee speaker user forum with Apogee Mini Grands. He has used the TacT unit to tweak his system/room with fantastic results as reported by him and other members who have listened to the before and after results.

He mentioned that before the TacT he could never fully enjoy his system because of his room.

Once you get your room bass traps and some more treatment you will find out that the sound can improved dramatically. Without the treatment of some sort of DSP like the Tact then your sytem will not sound near as good as it can. The best part is that room treatment has a very good sound improvement per dollar ratio.
Mprime: As it is right now and if properly done, treating the room acoustically provides far more benefits than doing so electronically. This is not to say that electronic correction doesn't sound good, but that i don't think it sounds "as good" overall.

As a side note, AudioXpress has been running a multi-part article about electronic room correction and the results that one can achieve. In the article, the author stated that in-room response was drastically improved using DSP, but that dynamics were compromised. I don't know if this has to do with the "slower" circuitry in some of this gear trying to compensate for on the fly corrections as needed or if it has to do with shifts in the tonal balance. As we all know, getting rid of large bass peaks can drastically effect the apparent "power" of what we hear.

My guess is that DSP will get MUCH better over time. Due to the use of more refined circuitry and the use of "audiophile grade" parts sometime in the future, i think this holds a lot of potential. There are already companies offering various formats and products for this type of device with some of them being quite sophisticated in operation. There is one in specific that i'm thinking of but can't recall the name. It is quite expensive but supposedly works VERY well.

What i've done in the past is to take a DSP unit, install it into a system and take readings of it as is. After analyzing the results and making a few changes to the system and room, we've run another series of tests. This results in a few more changes to the system and room. After doing this several times, you get to the point where the system / room is consderably more neutral in response and doesn't need all that much correction. You've now reached the point that the system and room sounds as good as possible without going "gonzo". Once we've reached a level of performance that the owner is happy with ( or we are just too tired to carry on further ), we pull the DSP out of the system and relax.

By using this approach, you can obtain truly excellent results without introducing yet another component and two sets of cables into the reproductive chain. Having said that, this type of "adventure" can be VERY time consuming and "interesting" to say the least. That's because some "changes" that "fix" one problem create a new one. On top of that, some physical changes that might be necessary to achieve optimum performance may not be possible in a given installation, so you end up compromising in both cases.

In that respect, DSP may achieve "better" or "more neutral" results than "physical correction". Depending on the quality of the DSP device being used and the level of reproduction achieved without it, sonic results can vary pretty drastically though. This is not to mention that going this route can introduce further cost and complexity to a system.

In a side by side comparison ( acoustics vs DSP ), I would bet that DSP has a MUCH higher "WAF" : ) Sean