Enhanced Pultec DIY

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Postby sangeet » Tue Oct 25, 2011 3:42 pm

I gave up on Version 1.6 boards. I even had a high boost of some dB with all pots turned down :roll:

Now I am back to Version 1.4 boards.
Unity gain in bypass mode is possible: I changed the 18k resistor on the gainboard for a 39k.
High boost and cut are working fine.
But:
Lowboost is only around 9-10dB, Lowcut around 25dB.
I wonder if somebody elese who builded this version 1.4 has same results in the low band.
Modifications were done like this:
http://img.photobucket.com/albums/v426/brio/Pultec15wiringcorrected.gif
which i found here:
http://www.groupdiy.com/index.php?topic=37324.40
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Re: Enhanced Pultec DIY

Postby sangeet » Wed Oct 26, 2011 3:16 pm

I got the low cut to work proper (cuts now around 15dB instead of 25dB) cause I changed the pot from 100k to 20k.

So everything works fine exept the low boost which is with 9db too low :(
The trick with changing value of the pot to a higher one didn´t work here....
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Re: Enhanced Pultec DIY

Postby 9T9R » Sat Oct 29, 2011 9:21 am

Hallo Frank
nice eq project
is the pcb 100% ok ?
(sorry for question i checked all pages but
it's not more clear (for me ) if it's ok or not )
thanks
9t9r

nrgrecording wrote:ENHANCED PULTEC DIY

Here is the Thread about the Enhanced Pultec DIY Project.

Component Placement and PCB Layout.
http://www.nrgrecording.de/temporary/PultecV15.pdf
Wiring Layout.
http://www.nrgrecording.de/temporary/Pultec15wiring.pdf



FAQ:

Q: What is it?
A: Its an inductor based Equalizer. Based on the Pulse Technology Pultec EQP1A - but with more frequencies. The frequencies are the same as EveAnna's Manley Enhanced Pultec.

Q: Where can I get pcbs?
A: From Gustav at the prodigy forum
http://www.prodigy-pro.com/diy/index.php?topic=10776.0 18€ for gainstage and filter pcb
I heard that Gustav doesn't sell these pcbse anymore... back to the roots... here is the self-etch-file:
http://www.nrgrecording.de/temporary/Enhanced%20Pultec%20_PCBlayout.pdf

Q: Whats the value of the inductor?
A: 26mH, 39mH, 78mH, 155mH, 312mH
Here is a shop for knobs and the inductor... http://don-audio.com/Startseite

Q: Can I make a tube pultec out of it?
A: Abselutely. You could use Gyraf's nice SRPP Tube Gainstage instead of the Opamp/PSU Gainstage.

Q: I can't find a capacitor with the value X or Y... What can I do?
A: You could wire some capacitors in parallel to get the value you're looking for. Ther are already some paralleled capacitors on the pcb because its easier to find these values in the electronic shops. If you don't have enough space you could solder capacitors to the bottom of the pcb - and don't tell anyone. :wink:

Q: Is there a frontpanel template?
A: Yo.

http://www.nrgrecording.de/temporary/Pultec_Program_EQ%203.fpd
http://www.nrgrecording.de/temporary/Mann%20ey%20Pultec.fpd :lol:

Q: Is it active or passive?
A: There are two pcbs... one is the passive filter (so you could use it with other gainstages like Neve, tube, Gyraf SRPP, whatever) and there is a second, smaller pcb which has a simple opamp gain circuit and a power supply onboard.

Info: I will delete old postings and if there is some important information I will automatically add it to the the first posting.
:cry: :cry: :shock: :roll: :roll:
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Re: Enhanced Pultec DIY

Postby nrgrecording » Sat Oct 29, 2011 6:20 pm

9T9R wrote:is the pcb 100% ok ?


I never built the filter myselfs. Thats why there is "untested" written in the pdf file. I only built the first version years ago and it worked fine. If it's not working it's probably quiet easy to fix. You can seperate the filters to see where an error is.

I just had a look at the pcb layout and found a wrong connection between the inductor tappings 0 and 26mH of the alternative inductor connection.

@ ivan and sangeet: Please cut one connection shown on this pdf and let me know:
http://www.nrgrecording.de/temporary/errata%201.6.pdf

My first audio diy project I'd ever built didn't worked, too. It was gyraf's G1176. All signal transistors had the wrong wiring. :D (because he changed the transistors from US to EU versions but he forgot to change the pinouts on the pcb). Building a project is one thing - but the interesting thing begins when something doesn't work like expected.
Frank Röllen. www.energyrecording.de [FORUM · DIY WEBSITE · TONSTUDIO]°°°° www.frontpanels.de [cnc gefertigte Frontplatten]°°°°
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Re: Enhanced Pultec DIY

Postby sangeet » Tue Nov 01, 2011 10:34 am

Frank, thanks for your help, but it seems that the cut is not necessary on version 1.4 boards. These are the boards I am currently working on.

EVERYTHING IS WORKING NOW :D (with the excellent help from a friend)
The resistor at the LF CUT had to be changed from 1k to 10k. After that the low gain and cut worked as they should.

UNITY GAIN:

Is possible with some resistor mods on the gainboard:
Inputs resistors (located after the 2,2uF caps) changed to 5,1k.
18k resistor I exchanged to 139k.

http://dl.dropbox.com/u/163999/Web%20Bi ... rected.gif

http://dl.dropbox.com/u/163999/Web%20Bi ... 20gain.pdf
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Re: Enhanced Pultec DIY

Postby nrgrecording » Tue Nov 01, 2011 5:57 pm

sangeet wrote:Is possible with some resistor mods on the gainboard:
Inputs resistors (located after the 2,2uF caps) changed to 5,1k.
18k resistor I exchanged to 139k.


You could also use a small mutli turn trimpot to set the gain. Iam not sure, but I think there is already a footprint for a trimmer on the V1.4.

The simulated loss of the filter is 20,907dB (with spice simation software)

Frank.
Frank Röllen. www.energyrecording.de [FORUM · DIY WEBSITE · TONSTUDIO]°°°° www.frontpanels.de [cnc gefertigte Frontplatten]°°°°
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Postby frans » Fri Feb 22, 2013 1:53 pm

Danke an alle, die hier ihr Wissen und ihre Erfahrungen einbringen - ich hab grad diesen Pultec Klon (1.4) fertig gebaut und alles läuft bestens. Hab nen JLM Dingo für's Gain genommen weil der ziemlich idiotensicher ist, außerdem hatte ich +/-24v an Bord, das geht ja mit den JLM DOAs, dazu ne Don Audio Spule.
Sangeet - Hut ab und Danke nach Berlin.
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Postby jensenmann » Fri Feb 22, 2013 2:00 pm

Supi, zeig uns doch mal ein paar Fotos hier: http://www.nrgrecording.de//nrg/viewtopic.php?t=1932
Jens
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Re: Enhanced Pultec DIY

Postby 9T9R » Fri Jan 16, 2015 1:49 pm

New Super Website ? :shock:
Supergut ! :p :bounce:
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Re: Enhanced Pultec DIY

Postby 0point0 » Tue Aug 25, 2015 1:51 am

I heard from different people that the circuits worked fine for them.
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Re: Enhanced Pultec DIY

Postby frans » Thu Aug 04, 2016 6:43 pm

Mine worked fine with the mod Sangeet posted a few posts back.
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