Patrick Snyder's Bass Reflex Equalizer

[bwhitejr]

Does anyone have a copy of Patrick Snyder's (SpeakerLab fame) Bass Reflex Equalizer paper, where it shows the schematic of the equalizer?

TIA
bwhitejr

[djk]

It's just a 2nd order filter with a Q=2 and an input buffer.

[bwhitejr]

Thanks for the response. Would anyone happen to have the schematic or the paper itself? I would appreciate it very much.

bwhitejr

[djk]

http://sound.westhost.com/software/esp-lr13.exe

Check 12dB, check High Pass, enter cap value, enter frequency.

This gives the resistor value for a Q=0.5 (LR)

For a Q=2 (6dB boost):

Take resistor value times 4 for the resistor going to ground.

Take the resistor value and divide by 4 for the feedback resistor.

Example:

32hz
100nF
49.74K (Q=0.5)
*4=198.96K (Q=2)
/4=12.435K (Q=2)

For the higher value resistor, pick the next highest standard value.
For the lower value resistor, pick the next lowest standard value.

The square-root of the product of the higher and lower value resistors should be equal to the original Q=0.5 calculated value.

[freddi]

I don't have the orginal paper anymore (or its buried) here's the scheme from Weems - not sure how well the adjustable feature works - seems like DJK commented




heres the page with parts list

[bwhitejr]

Freddi,
Thank you very much. That is exactly what I needed. I have the paper somewhere, but couldn't find it. Every now and then the old stuff is valuable.

Again many thanks.

bwhitejr

[dangus]

I sort of remember an article in Audio magazine with a similar circuit. Probably the same as:
"W. M. Leach, Jr., "A Generalized Active Equalizer for Closed-Box Loudspeaker Systems," Journal of the Audio Engineering Society, vol. 38, no. 3, March 1990."

Here's a sub project with a similar equalizer, including layouts:
http://home20.inet.tele.dk/audio/mini-sub/mini-sub.htm