G-PULTEC problems, please help!

[snaper]

I've finished my GPultec last year and I love it!
But. I really could use it after my mixer as a master eq
So, I've decided to give a stereo upgrade to my actual unit.
I've found the recommended dual switches , but, csant find a 4pdt switch for bypass.
So my idead is that bypass the onboard bypass, and use a relay bypass board from diy-tubes.
(I'm using an opamp gain stage, so no tubes involved, I can totally avoid the circuit)

Using the relay bypass sounds more ok to then having a dummy switch.

Could you help me out on where to place jumpers in the board to avoid the switch?

 

[snaper]

Has anybody a drawing about the original Pultec knobs?
Ordered them from Don-Audio, still "under delivery", and I have to cut the shaft of pots / switches...

 

[PitchFork38]

Hi
Maybe it's a stupid question but If I use a mic preamp with balanced output (like the G9) before my G-pultec.
Do I need to use the optional balanced or unbalanced Input in the Pultec ?
I don't really understand the function of this optional input.
It I use the unbalanced, input transformer is useless ?
Thank's

 

[Audioman]

@frazzman can you post a picture of the installed trimmer on the pcb ?
Just to see how to install correctly the trimmer
Thank you in advance !!

Hi Jakob,

Just letting you know the 1k trimmer at the Hi cut CW position does indeed work and allow for trimming to unity gain. I now have no level difference with pultex engaged.

Good solution!

Thank you

 

[petermontg]

Curious if someone could help me shed some light.

I am reading 247 and 5.9 which are within tolerance. Before the 4.7uf I am reading a 68v. Should I have something else here?

I am passing no audio at all. Both trafos are lundahl running balanced line.

Any ideads

Edit: okay I see it should be closer to 125v

All voltages check have reading of 122v on the output.

The SRPP is driving a loss of about -80db unit is hiss and and hum free. If I tap the tube I can here it.

I read earlier in the thread it could be inductance issues. 

Could someone shed some light for me?

 

[petermontg]

Turns out I had a 470R across the 470k on input, would explain the loss.

Silly mistake.

 

[PitchFork38]

Hi !

I purchased a G-Pultec Mono Power Transformer from Don audio

https://www.don-audio.com/g-pultec-mono-power-trafo-sec-220v-9v-5V

The 3 secondaries should be :

220v    0,05A      (red)          "HT"
9v        1A            (green)      "Heater"
5V        0,5A        (blue)          "LED"

On my transformer it's :

245V          (red)
6V                  (green)
11.3V          (blue)

It's a problem because my heater voltage is too low (4V) and HT is 345V.
If I switch the green and blue secondary on the PCB, it's closer to the "real" value of the secondaries and I get a correct value for the heater voltage (6V).
But it's not the same current (green 1A and  blue 0.5A), is it a problem ?

Pierre

 

[gyraf]

Hi Pierre,

It's probably better to ask don-audio about this - it is not the standard way of building this power supply..

Jakob E.

 

[kurganyuriy1987]

Hi everyone!
Can i get somewhere gerber files for  g pultec pcb's?

 

[gyraf]

No. There are pdf drawings available for self-etching.

Jakob E.

 

[petermontg]

Finally got around to getting mine finished and in the desk.

Those amps are spectacular. Beaut of  a low end and the detail in the stereo image is fantastic.

Thanks so much for the project Jakob . Great EQ.

Best
Peter

 

[sr1200]

Weird problem today with mine (thats been working fine for years).  The inductors responsible for the 2.1 to 6.8k boost seemed to stop working. the 12 and 18k work fine.  I opened the unit looked around, checked solder points, everything is good.  I plugged it back in, problem is still there.  I tapped one of the "107C" inductors with the rubber on the back of the screw driver i had in my hand and it started working...  switched to lower freq. and its not working... tapped the little inductor and the lower freq starts working now too....  do inductors go bad like that?  (again, no cold solders).

 

[Gustav]

  I tapped one of the "107C" inductors

Dont know whats up with the inductor, but with that marking, I want to ask if you are sure you have the right value in there?

Gustav

 

[sr1200]

As far as Im aware i have the right ones in there.  When I do a sweep to show the freq. they line up pretty well with the advertised value on the front panel.

 

[petermontg]

It could be  a cold solder elsewhere apart from the filter board.

When problem solving mine.... I had a cold solder in my amp on the right side. When chasing it a tap on the inductor on the left side would knock it out. worth checking you input amps

 

[sr1200]

@petermontg - good call indeed, thats exactly what it was. (not the same spot but a completely unrelated spot)  had to find it with a magnifying glass though!  Cheers!

 

[petermontg]

@petermontg - good call indeed, thats exactly what it was. (not the same spot but a completely unrelated spot)  had to find it with a magnifying glass though!  Cheers!

Glad to help. My heart was close to breaking before I find mine. I wouldn't wish a cold solder on anyone.

 

[petermontg]

Just a thought.
Has anybody successfully added a bypass switch for the HI freq selections on the boost while still maintaining the boost section?

Id like to able to drive the inductor a little but without adding any freq selections,

Best
Peter

 

[gyraf]

Does not work that way: without the capacitor, the high- boost would be a mis-aligned low-boost starting at a very high frequency.

Jakob E.

 

[petermontg]

Does not work that way: without the capacitor, the high- boost would be a mis-aligned low-boost starting at a very high frequency.

Jakob E.

Thanks Jakob. I had forgotten that part.