Solid state amp for Pultec EQ..

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gary o

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Dec 28, 2004
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Can anyone suggest a solid state circuit to use as a make up amp for the Pultec EQ, simple would be good, ive never made anything other than tube stuff so far, im currently deciding which tube amp to make for home Pultec & now I want to make a Pultec for on stage as im a singer, the solid state is for size & weight & cost, I,was very impressed wth my unfinished Pultec on my vocals on stage ive just made the filter section so far {& some of thats missing}, I used a Art tube MP as make up gain amp in the test like i said I like now want it on my vocals all the tme.

Cheers .............Gary O.
 
I was thinking about doing one with a 2520 makeup stage. Or maybe you can may one with a green pre as a makeup stage?? Any other suggestions?
 
Coool! hail steff indeed nice work & some nice amp suggestions too, I will investigate further thanks guys

Gary O.
 
i think all of the V x72-modules by telefunken (V372), tab and like could do the job as well. i think kubi has the schematics on his homepage www.kubarth.de. maybe an interesting item to clone?!..

chris[/url]
 
> Check out Steffen's beautifull solid state pultec...

Sweet.

But I wonder if the discrete amp lower-left is really needed. It is hardly lower-noise than a 5532. The topology allows its gain make-up function to be done in the output buffer. And it needs a third power-rail, a small but not negligible "cost" in a stage-box that needs to be compact.

Steff-mod.gif


The way Steff drew it, it is possible he tried it "my" way, and then decided to add-in the discrete buffer. Might ask him how that plan came about.
 
[quote author="PRR"]...But I wonder if the discrete amp lower-left is really needed...[/quote]I'm glad you ask that, PRR. I was wondering the same thing!

BTW, there is a new Burr Brown chip, RC4560, that they recomend for audio. It can spit 20Vpp into a 400 ohm load.
 
So if I understand it right, that discrete amp (lower-left) does not add anything to the overall sound and is only used for make up gain?
 
I think it does things to the sound. You know it may be diferent if you use the 5532 for gain and buffer.

Maybe cleaner without it, but using the discreet amp for gain and the 5532 only as a unity gain buffer might make things more intersting.
 
[quote author="radiance"]So if I understand it right, that discrete amp (lower-left) does not add anything to the overall sound and is only used for make up gain?[/quote]I don?t know... Maybe it colors the sound in a pleasing way - Steff will have to answer that one. But, using a 5532 instead of a transformer to "balance" the output would eliminate the need for that extra stage.
 
First I wanted to build this solid state Pultec without the 5532's and tranformers instead. That way I only needed a 24V power supply.
Then I found these transformer's with in them a opamp buffer (does anybody know's these?) so I still need the +/- 18V part.
Maybe I should skip the discrete amp part just to keep things simple.

Only thing is I started building the damn thing and have al the parts...
 
anyway, the discreet opamp part won´t drive a 600 ohms transformer on it´s own. You need a buffer before the transformer, or use the AKM things... Fit´s perfectly here :thumb:
 
[quote author="radiance"]...Then I found these transformer's with in them a opamp buffer...Only thing is I started building the damn thing and have al the parts...[/quote]Heck, since you have that, I'd try using it for the output stage alone. Should work fine and may even sound good!
 
[quote author="rafafredd"]anyway, the discreet opamp part won´t drive a 600 ohms transformer on it´s own. You need a buffer before the transformer...[/quote]5532's data sheet reads: Peak-to-Peak Output Voltage Swing 32 V Typ With VCC± = ±18 V and RL = 600 ohms. I'd recommend some type of heat sink, tho?
 
Is the discrete makeup stage capable of driving a profile 4804? What about using an Edcor 600:600 on the input? Obviously not trying to clone a vintage pultec sound. But trying keep it to a single 24v supply also.

Oh yeah, I already built it and love the way it sounds. Except, i think i need to try a different type of capacitor on the high end boost. But being dense at times im guessing i should buffer the output? :green: :guinness:
 
@Flatpicker: I thought of puting those Haufe trannies behind the discrete opamp part.
Anyway, maybe I just try both options (with and without the discrete opamp..)

But firts i need to sort out the power supply.
Whould this work? (I've used Ssltech's power supply as a starting poit)


SSLTechEdit3.jpg
 
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