Gyraf Pultec Insertion loss question.
« 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.


CJ

Gyraf Pultec Insertion loss question.
« Reply #1 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.
If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

gyraf

Gyraf Pultec Insertion loss question.
« Reply #2 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.
..note to self: don't let Harman run your company..

Gyraf Pultec Insertion loss question.
« Reply #3 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:

soundguy

Gyraf Pultec Insertion loss question.
« Reply #4 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

chips are good with dip...


 

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