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Calling all EE's


Coytee

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Question... would an EE be the right person to send to?

I have an equalizer box specifically made for my EV Interface "D" speakers. It's designed to be used with them. I don't really know what it does other than reside in a tape loop!

If I wanted to have someone draw the schematic for this to whom would it be sent? An EE? A crossover guy (psst, GeanD!!) How's about the EQ fairy?

Second, once the schematic was successfully figured out (I presume it could be done WITHOUT taking the box apart?)

Anyways, once done, could that then be translated into PEQ's so that it could be bypassed and an active be used?

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The EV Sentry and Interface EQ boxes have 6dB of lift at various frequencies. For the Inteface D and Sentry III I believe the center frequency is 30hz, the Interface A is 35hz.

For a PEQ you will want to set the Q=2 on a 12dB high-pass filter at those frequencies. If you can't specify the Q for the HP filters you will need to combine a HP filter with the corner frequency as above, with a Q=2 boost of 9dB at the same frequency, this will give the required 6dB of boost.

Later vintage boxes used opamps rather than discrete transistors.

C2 (C11) control the HF boost.

If you bypass the electrolytics in the signal path with small film types the box sounds fine.

R8 and R10 (R24 and R26) control the frequency and Q of the filter, so you can use it with any of the models requiring the box.

Edited by djk
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