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Old 18th April 2009, 06:04 PM   #1
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Default Patrick Snyder's Bass Reflex Equalizer

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

TIA
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Old 21st April 2009, 04:38 AM   #2
djk is offline djk
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It's just a 2nd order filter with a Q=2 and an input buffer.
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Old 21st April 2009, 11:55 AM   #3
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Default Patrick Snyder's Bass Reflex Equalizer

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

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Old 21st April 2009, 01:25 PM   #4
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Click the image to open in full size.

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.
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Old 21st April 2009, 05:58 PM   #5
freddi is offline freddi  United States
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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

Click the image to open in full size.


heres the page with parts list
Click the image to open in full size.
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Old 22nd April 2009, 01:03 AM   #6
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Default Patrick Snyder's Bass Reflex Equalizer

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
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Old 30th April 2009, 08:39 AM   #7
dangus is offline dangus  Canada
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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
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