Gyraf Pultec Insertion loss question.

MikoKensington

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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.
 

CJ

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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.
 

gyraf

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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.
 

MikoKensington

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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:
 

soundguy

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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
 

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