Roy Allison bass method

[zigzagflux]

Hello:

I have two ScanSpeak 10" 25W/8565's in sealed boxes. They are currently connected as a stereo pair through a Behringer DCX2496 processor. I would like to pursue the Roy Allison method of placing the woofers either at the room edges or corners, and EQ'ing as needed.

I have found a few threads that speak of it, but have not been able to track down the original article, or at least a detailed method of where to place the boxes for optimal room loading. Any one able to help?

Thanks.

[bear]

Get a copy of Vance Dickason's loudspeaker cookbook.
This is just room boundary loading.

Allison used just the rear wall boundary, not the corner.
The corner is what Klipsh used in the corner horns.

Doubtless the Roy Allison papers are in the JAES Journal or Anthology.

Have you searched online for Roy Allison? Probably info there.

If I have my "pi" right, this is pi/4 loading, fyi.

_-_-bear

[SY]

Allison published a nice article about this in Audio, sometime in the late '70s. The technique works, and very, very well.

[richie00boy]

I think there is a mention of it in Colloms book High Performance Loudspeakers. If you do get some more info, please let us (me!) know. Thanks

[zigzagflux]

Well, I do have the Loudspeaker Design Cookbook, and haven't found any information in there regarding room boundary loading, other than try it out and see if it sounds good.

I've done extensive searching on the internet, and can only seem to find references to the work, but not the work itself. Do I have to become an AES member ?

[SY]

It wouldn't hurt.

If I can dig up the Audio article, I'll scan it and post it. Basically, it looks at the effects on frequency response with different multiple boundary interactions. The basic technique was to place the woofer close to at least two of the boundaries to minimize the notches, then cross over to the midrange at a relatively high frequency. His suggestion was placing the mr at about ear height, woofer near floor and back wall, then using about a 300-400Hz crossover at third order.

Once you get rid of the boundary-induced notches, the bass sounds MUCH more natural.

[zigzagflux]

Cool, that confirms what I've read, that you get good bass well over the traditional 80Hz point. My system is most satisfying from 400Hz and up, and it's very easy to turn up the sub amp to get strong sub-80Hz. Things have been weak in what I call the midbass region (the part of the snare drum you can feel, or makes your eyes blink).

I'm really hoping this method works out to get that extra snap to the system. I would think having the DCX2496 to tweak the bass is ideal coupled with this method.

I'll pursue a membership, but any other info provided is much appreciated.

[bear]

You are suffering from floor bounce probably.

Anyhow, there are problems with loading your walls and bouncing your sound off a wall...

If it was a really good solution, a whole lot of others would have adopted it quickly.

In the dickason book he discusses loading a driver into pi, pi/2, pi/4 and pi/8. Look for that.

_-_-bear