nacho459

Gyraf Pultec EQ curve
« on: July 28, 2004, 05:40:24 AM »
OK, I ghetto rigged the passive section of the pultec together, point to point style on my bench, and ran it through my X-Y plotter. Here's the results.

The scale on the chart is off. Where it says +5 it's actually +10. -5 is actually -10 etc...

http://www.459audio.com/Pultecres.jpg

I used the same values as the Gyraf schematic. Someone that's built one before let me know what you think. There's this weird dip around 4k in some of the low cut curves, anyone have any idea why? Everything else looks relatively ok.


Steffen

Gyraf Pultec EQ curve
« Reply #1 on: July 28, 2004, 07:24:44 AM »
yepp that dip looks strange....

steff

matthias

Gyraf Pultec EQ curve
« Reply #2 on: July 28, 2004, 10:32:49 AM »
I always thought the lowcut of my Gyraf Pultec sounds a little bit "strange"

maybe there's an error in the schematics or on the pcbs ??

CJ

Gyraf Pultec EQ curve
« Reply #3 on: July 28, 2004, 04:50:55 PM »
Cool graphing software!
Which is it?
You might have had the high cut turned on slightly, or there might be a little interaction from one filter section to the next.
   I put a groung lift on mine also, which is cool, as you can go 1/4 inch cable. balanced or unbalanced.
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

nacho459

Gyraf Pultec EQ curve
« Reply #4 on: July 28, 2004, 06:07:01 PM »
Quote
Cool graphing software!
Which is it?


Software!? it's an old UREI X-Y plotter!


CJ

Gyraf Pultec EQ curve
« Reply #5 on: July 28, 2004, 06:11:37 PM »
Way cool!
I think I'll do a tube version of that!
 :grin:
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

nacho459

Gyraf Pultec EQ curve
« Reply #6 on: July 29, 2004, 12:32:37 AM »
Quote from: "cjenrick"
I think I'll do a tube version of that!


HAHAHAHA :grin:  :guinness:  :guinness:

gyraf

Gyraf Pultec EQ curve
« Reply #7 on: July 29, 2004, 06:28:47 AM »
Kev's GroupDIY-page once had a couple of plots of the frequency response of the pultec clone. But I can't find them now..

Somewhere i have the complete set of plots from the original pultec manual. I'll see if I can find them for you.

I don't think the bump in low-cut is an error.

Jakob E.
..note to self: don't let Harman run your company..

Michael Krusch

Gyraf Pultec EQ curve
« Reply #8 on: July 29, 2004, 09:44:39 AM »

Steffen

Gyraf Pultec EQ curve
« Reply #9 on: July 29, 2004, 10:42:11 AM »
hmmm, the  eqp has a low mid dip when bass boosting and cutting the same time. but the dip on graph looks  too hi, frequencywise...

steff


cayocosta

Gyraf Pultec EQ curve
« Reply #10 on: July 29, 2004, 11:12:16 AM »
Here's the original manual with curves:

http://www.purpleaudio.com/pdflib/PultecEQP.pdf


 

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