Poor Man's Pultec EQP1-A

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mrclunk said:
Ian, i started out down the post office and then realised the ones i have are 1pole 12pos not 2pole 6pos...
sorry.

Hi Paul,

1 pole 12 way arrived in the post this morning. Many thanks. It looks to be of substantial construction - better than I had anticipated. Just one query, it is supposed to be 12 ways but  when I rotate the switch it appears to have only eleven positions.

Cheers

Ian
 
ppa said:
this the board quasi-finished

Interested...

I have 4 Triad hs56V's which I'm going to use. I think I'll keep one connected as output but will make the input one switch able.
This should all be possible with this board right?...maybe some fiddling around.

This should be great. Options to switch between an original solid state pultec topology and a modern opamp input variation and what not...
 
and this is the in-out board finished for pulteq eq (with inductor and inductorless).

it has trasformerless input only, usable with a IC opamps or a DOAs,

the ouptstage can use IC opamps or DOA's and can be used with or without trasformer  

you can use many IC opamps and DOA's in these stages as NE5534, OPA134, OPA602, OPA604, OPA606, OPA627.....and many others and APP opamps , API2520's , FT992, MM99, JE990, JLM and others.

if you want use a bipolar DOA (or IC opamp) on out stage you can use the fet buffer onboard to avoid the noise for the input noise current of the bipolar DOA's and IC opamps.


it's 173 x 102 mm

 

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radiance said:
ppa said:
this the board quasi-finished

Interested...

I have 4 Triad hs56V's which I'm going to use. I think I'll keep one connected as output but will make the input one switch able.
This should all be possible with this board right?...maybe some fiddling around.

This should be great. Options to switch between an original solid state pultec topology and a modern opamp input variation and what not...

yes, it's possible with an external switch using the tube section or the solid state section in a pultec eq as in a MM eq, using this board plus a tube board.

 
ppa said:
radiance said:
ppa said:
this the board quasi-finished

Interested...

I have 4 Triad hs56V's which I'm going to use. I think I'll keep one connected as output but will make the input one switch able.
This should all be possible with this board right?...maybe some fiddling around.

This should be great. Options to switch between an original solid state pultec topology and a modern opamp input variation and what not...

yes, it's possible with an external switch using the tube section or the solid state section in a pultec eq as in a MM eq.

I'm not going to use tubes. I'll switch between transformer or opamp input and maybe the same for output.
To have an original tube pultec I would have needed the notorious peerless 217 transformer which I don't.
I do have 4 triad HS56V's though...which, together with an API 2520 opamp, would be good for two original solid state pultecs, or a stereo version in my case....
 
radiance said:
I'm not going to use tubes. I'll switch between transformer or opamp input and maybe the same for output.
To have an original tube pultec I would have needed the notorious peerless 217 transformer which I don't.
I do have 4 triad HS56V's though...which, together with an API 2520 opamp, would be good for two original solid state pultecs, or a stereo version in my case....


it's possible use an external switch on out to use or not the out trasformers
 
strangeandbouncy said:
Hi Radience,

   think you need a 10k - 10k input, not 600 - 600

   Kindest regards,

     ANdyP

There's no reason you could not use a 600 - 600 input transformer with the poor man's EQP1A if you wanted. You just need to strap a 620 ohm resistor across the secondary instead of the current 12K.

Cheers

Ian
 
Just a thought, would anyone be interested in a poor man's tube gain make up stage for the poor man's EQP1A if I can come up with one?

Cheers

Ian
 
ruffrecords said:
Just a thought, would anyone be interested in a poor man's tube gain make up stage for the poor man's EQP1A if I can come up with one?

Great Ian! That's what I have been searching for!

I bet there will be 20++ sets ordered at least.
 
Just a thought, would anyone be interested in a poor man's tube gain make up stage for the poor man's EQP1A if I can come up with one?

Absolutely!


I already have a couple amps I'm planning on using but would like to see what you have in mind.  I like having about 10 or 15db beyond unity gain on the makeup amp so I've chose amps that will allow for that.

Nearly always sweeter with tubes.  :)
 
I think yes, but first I would like a group buy if there are enough people that want them,
My target is a group buy for at least 50 PCB's, with 50 PCB's ordered I can make a very good price per board, but with 100 is much better. I think with a group buy for 50 pcs I could do 11 euros per board,  and  with a group buy for 100 pcs 9 euros per boardThe problem is that the dimensions are 173 x 102 mm and for these dimensions the prices can not to be cheaper, even if however the project is cheap.

The good thing is that several sound engineers prefer having the double section: solid state and tube section in the same chassis.

 
BTW, I think that having a tube make up section (Ian's mu follower) and a germanium make up section (APP2050GE) together
in a pulteq eq is good thing 8)
 
However, before I go ordering 100 GBPs worth of PCBs it would be nice to have a little insurance. Someone mentioned making their own PCB so I would be happy to provide the gerber files to anyone who wants to make their own in exchange for confirmations that the rotary switch fits OK.

I'm a little late but Still need someone to test this out? Maybe i can help let me know.
 
ruffrecords said:
strangeandbouncy said:
Hi Radience,

   think you need a 10k - 10k input, not 600 - 600

   Kindest regards,

     ANdyP

There's no reason you could not use a 600 - 600 input transformer with the poor man's EQP1A if you wanted. You just need to strap a 620 ohm resistor across the secondary instead of the current 12K.

Cheers

Ian

Great!  I have a large selection of 600:600 transformers and only a few 10k:10K so this will be excellent.  What about using a non 1:1 transformer though?  I have quite a few 600:1200 tx that would be nice to use and though I could use them as output could I use them as input as well?  if so what should the strapping resistor be?


ruffrecords said:
Just a thought, would anyone be interested in a poor man's tube gain make up stage for the poor man's EQP1A if I can come up with one?

Cheers

Ian

Um, now let me see... yes?

Thanks again for doing all the leg work on this project.
 

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