determining room gain

[valhallax]

building cabs by software programs is extremely intruiging, however, how does one determine room gain and factor it into the equation? everytime i build a new set of speakers do i subtract the cab volume from the ever dwindling room volume? does it have anything to do with how many drivers your running in the room? for example, pressurizing a room with a large amount of altecs would effect a single cab how? kinda generalizing here i guess but just some basic starter info may lead me down the right path

[Todd W. White]

As a degreed musician (brag, brag), I do think it is possible to saturate, yea over saturate a room acoustically.

I have heard this in concert halls in which I have played in orchestra's and symphonic bands. Once you reach saturation point, or, as my long-time friend Don Davis might say, once you've excited the reverberant field to excess, everything else becomes just noise.

A good example of a room where the acoustician did an EXCELLENT job of handling this problem is the Meyerson Symphony Center in Dallas. That room can handle LOTS of acoustic power! It also has very uniform RT60's at all frequencies, and will hold the sound until just before the pitch begins to decay, then it drops off like a stone.

WHAT A ROOM TO PLAY IN!

Or listen in!

Therefore, it would follow that you can overload a listening room at home, and do it more easily than you can a larger room, given the right set of circumstances...

[bfish]

Nice post Todd! And a pleasant diversion from disscussion of the eBay "geeb du jour" too.

I've not yet become familiar with the function, but TrueRTA now offers room gain simulation features in a versatile and affordable package. A brief overview of the principles involved is in their tech library.

Since I've been a renter to date, and know my system(s) are likely to be in other rooms someday, I've never gone to the trouble to design in the parameters for a particular room, but it might be a worthy consideration for a more permanent installation. Instead, I just measure the in-room response, and try to obtain the desired result with either room treatment or EQ.

Pressure modes are a whole different story, and are encountered often in car stereo apps, but seldom in a home or venue. (Note; pressure modes can easily cause permanent hearing loss!) TrueAudio also offers a brief disscussion on that topic.

[gamalot]

I will always be a believer there is such a thing as too much speaker for a given room.

Someone here says "Loud is beautiful as long as it is clean"!

In my living room I can get loud and beautiful and then I can get a bit louder and it is no longer clean.
I always associated this with sound waves bouncing around the room and then getting re played by the speakers until it sounds like junk.

I can appreciate how many love their music loud and how SPLs do it for them but there is a point where it becomes wasted.

Gary

[bfish]

Todd's mention of Don Davis reminded me of some of his thoughts on the subject. Altec's old methods offer some good insight (I'm not implying that I understand it all though) ;

Calculating and using Critical Distance

New ways to look at needed and potential acoustic gain

[Todd W. White]

My friend, the late Dr. John K. Hilliard, designed his then new home with an Altec system built into the walls on either side of the fireplace. I believe I may have the actual article from AUDIO magazine...if I do, I'll try to find time to scan it and put it on the website.

The last time I talked with John, he had pulled out the horns and was messing with 288's, trying to use them as direct radiators for the HF - he hadn't decided if he liked it or not yet, as I recall, and he died soon thereafter, so I never knew his final thoughts on the matter...

[bfish]

No need to scan, it's already at hifi-museum;

[Todd W. White]

The entire article has floorplans of John's living room - no parallel walls at all. Pretty neat!

I'll see if I can find the whole thing...

Thanks Brad!

P.S.: I'll try to look you up the next time I'm in NWA - when it cools off, I'm going to come over there in my un-airconditioned '65 Chevy pickup...

<font color="#FFFFFF" size="1">[ September 01, 2007 10:38 PM: Message edited by: Todd W. White ]</font>

[bfish]

Originally posted by Todd W. White:
...messing with 288's, trying to use them as direct radiators for the HF...

<font size="2" face="Verdana, Helvetica, sans-serif">Do you mean flipped around with esposed domes?

[bfish]

I've been waiting for cooler temps too...so I can head off some of the catfish being washed by after your flooding before they make the Big Muddy....prob'ly as soon as the tourists go home, like Tuesday.