[MaxCast]

We have some good threads dealing with room treatment, product design, product shootouts and reviews.  Buying a better sounding source, amp or speakers will not get us to our systems potential if we have huge humps or valleys in our in-room frequency response.  I would like this thread to deal with equipment, uses and experiences using rt analysis.

In reading about QSC's product used in the mensa/dio thread, Wayne1 brought to my attention QSC's rt analyser.  The NC dac shoot out told me about Brad's "preamp" that has room correction in it.  All of the listeners talked about how better the music was with these devises in place.

I guess we're talking about fully adjustable, high quality parametric eq's that may redigitise the signal (another break in the signal).  It is apparently worth it.

First question is, what is needed to do a full analysis of our rooms?

Second, and for more discussion, what are some of the products (and cost) available for analysis and correction?

[Dan Banquer]

What a great question!
Typically what is used is a pink noise generator and a Real Time Analyzer connected to a calibrated microphone. The pink noise generator is connected to a pre amp input. The microphone is placed at the listening position, and the response is displayed on the Real Time Analyzer. Set your initial level at approximately 80db spl.
There is some controversy as to what is an ideal response. If your a mix down engineer in a studio you are going to be looking for something as flat as possible. If your like the rest of us you are looking something close to that. Most people will see a higher response below 100 hz which is due to the room gain (coupling of the speaker) to the surrounding walls. (that's if you have some decent size woofers with the speakers close to a wall) The response should flatten out after that. Two important things to look for. Spikes and dips. Attempt to flatten these out by use of acoustic room treatment if you can. It's cheaper than equalizers and the assorted "active" room correction devices.

[Rob Babcock]

BTW, if I read the post correctly, the QSC is only being used for the bass; therefore I don't believe the entire signal is being digitized, just the low pass.

I'm a firm believer in the value of parametric eq for the bass end of the spectrum.  I don't have an RTA or calibrated mic, had to do it the old fashioned way (ie many passes thru test tones w/SPL meter-a little tedious, but effective).  I've made a few changes to my room/system since I last eq'd the subs, so I really should tweak the settings a bit.

I recently read a review that claims that properly set up, the Behringer 8024 is transparent enough for full range use.  His assertion is that claims to the contrary are mostly the result of people being too lazy to learn how to set it up correctly and ignorance/bias towards the benefits of digital eq.  I will admit to some scepticism, but I won't rule out trying it, as that model isn't too expensive.  One could always use it as a sub eq.

[JohnR]

I'm gonna sell my 8024 if anybody wants to try it...

[hairofthedawg]

I was going to mention the 8024.  I have it connected to a preamp input.  I've only used it to input pink and white noise, but it's supposed to be able to generate sine waves.  It definitely shows some humps and dips, but after reading some things on the audioperfectionist site, I agree with the writer who said that a mike doesn't hear the way a brain does.  there's going to be a lot missing.  That said it's a nice toy and kind of fun to watch during a song.  I'm keeping mine to see if it shows the differences I may or may not hear after treating my room.

cheers,

Dick

[MaxCast]

I read a mike has a lot to do with it also.  I never would have believed it if it wasn't for SP test cd #3 having the naration done with different mikes.  What a difference the mike can make on how a voice sounds. Apply a different mike to nathanm's music and maybe we could make out a word or two

But still,  I think RTing one system can show us where some big problems are and address them as best we can.  If you get some of the little ones on the way then all the better.  Hopefully one wouldn't have to run the whole frequency spectrum thru the thing, as Rob points out.  But don't room correction products run the whole signal thru?

John, what does the 8024 do?  I will look it up, but maybe you could "rent it out."

[hairofthedawg]

http://www.behringer.com/02_products/prodindex.cfm?id=DSP8024&lang=eng

Not sure if this link will work, it gives this browser gibberish, but it's a link to the product.

cheers,

Dick

[nathanm]

Remember this one?
Ye olde Harmonic Discord topic with plenty 'o Behringer 8024 posts scattered throughout

A cool product, but ultimately frustrating IMHO.  Those notch filters might be nice on the sub though...

[Wayne1]

The Behringer  ECM 8000 Measurement mike is an inexpensive, fairly flat responce mike designed for room correction applications.

http://www.behringer.com/02_products/prodindex.cfm?id=ECM8000&lang=eng

This mike can usually be found for $40.00 or less.

It does need a mike pre-amp with a phantom power supply.

The M-Audio DMP-3 is a very good choice for this application and it can be found for less than $200.00

http://www.m-audio.com/products/m-audio/dmp3.php

TrueRTA is an incredible program for room analysis

http://www.trueaudio.com/rta_abt1.htm

The first level of the program is a free download.

We were using the $100.00 version using the 1/24 octave RTA.

So, for under $350.00, these three pieces make finding out what is going on in your room almost foolproof

[Mike Dzurko]

I agree with Wayne, TrueRTA is an exceptional piece of software. I run it on a laptop which makes it very handy. Another winner is ETF
http://www.etfacoustic.com/
I have ETF installed on the same laptop. Between the two programs I can get very good measurements.
More info on rooms and measurements at:

http://www.subwoofers.org/acoustics.htm