Pultec with a 2520 make up gain questions

Coldsnow

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HI all,
There is a schematic posted by Drpat at this address on the 5th post down.  I don't know if anyone has ever built it so anyone know if it looks correct? 
Also, anyone know if there should be a cap going from the powers supply to ground before the opamp and a regulator?
And, Does the 1mfd cap take the place of the 220n cap and 100k resister going from + to - take the place of the 470K resister on Gyraf's pultec?

http://www.groupdiy.com/index.php?topic=16390
 

Coldsnow

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Also should I add a cap going to go along with the 20K resister going between the  - on the 2520and the output?
 

MikeClev

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Hello!

I have also been looking at the solid state 'Pultec' idea, and have found a few morsels of information you may find useful. For a start, and to state the obvious, the Passive EQ Meta thread is full of good stuff.
http://www.groupdiy.com/index.php?topic=16761.0

More specifically, heres a thread titled "Solid state amp for Pultec EQ"
http://www.groupdiy.com/index.php?topic=6501

Within that thread, you will find references to Steffen's solid state pultec, using a 'BA283' amplifier card clone and 5532 opamps for output. Take note especially of PRRs comment which highlights the possibilty of removing the BA283 and simply using the 5532s for makeup gain. Of course, if you can use a 5532 or 5534, you can use a 2520!
The link to Steffen's schematic in that thread does not work, but Steffen has a webpage for his EQ complete with schematic here:
http://www.diygallery.de/DIYsites/stpultec.html

I'm currently building 2 stereo EQs based on this design. One will use NE5534s and the second will use 2520 opamps and Jensen output transformers. Hopefully this will give me a useful choice of flavours. Delightful!

(Edited - wrong Solid State EQ thread linked to - now points to correct thread)
 

Coldsnow

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Any problem with leaving out the 1K resister and light that goes between the + and - current?
 

Coldsnow

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Thank you very much for all your help.
Just to make sure, there is not a interstage transformer at the end of the filter section is there?
Also, would it hurt to place a 1:1 600 ohm transformer in between the two stages for extra color?
 

Coldsnow

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Do I use the 220 n and 470k at the end of the filter section from Gyraf's circuit or not?
Thanks,
 

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