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Project Specific Discussions => Filters/Equalizers => Topic started by: MikoKensington on October 10, 2004, 04:59:48 PM

Title: Gyraf Pultec Insertion loss question.
Post by: MikoKensington on October 10, 2004, 04:59:48 PM
I'd like to build an EQ of my own.  I plan on using the Gyraf filter section and mating it to a Quad Eight line amp I have laying around.  I would need to set the voltage amplifcation on the line amp to an appropriate level.  15dB?  Less?  More?

Additionally, is 600:600 all I need for an input trafo?  Thanks guys.
Title: Gyraf Pultec Insertion loss question.
Post by: CJ on October 10, 2004, 06:18:07 PM
yes, 600:600.
15 db might be a tad low, better to have it a tad high and trim down me thinks.
Or use taps on the input transformer  to make it a 1:2 ratio.
Title: Gyraf Pultec Insertion loss question.
Post by: gyraf on October 11, 2004, 03:46:07 AM
But if you use a 1:2 input transformer, the input impedance can be VERY low at max. treble boost setting (down to some 18 Ohms - 75R:4). I think it would be better to find some extra make-up gain in your output stage, maybe wire the output transformer 1:2?

Jakob E.
Title: Gyraf Pultec Insertion loss question.
Post by: MikoKensington on October 11, 2004, 01:49:01 PM
My QE line amps are good for 40 db.  I am just looking for a good number to set the gain at.  I could put in a gain switch, but I'd rather keep it straight and simple.  :thumb:
Title: Gyraf Pultec Insertion loss question.
Post by: soundguy on October 11, 2004, 01:51:53 PM
no real need to be academic on this, build your box, run your program with it, wire up a pot to the QE feedback loop, dial in the makeup gain you need while looking at a meter hooked up to the output, and then either mount the pot on the front panel if you want, or replace it with the correct value resistor.

dave