comparing Gyraf pultec schematic to real one...

[radiance]

Apart from cap & inductor values there is another difference that strikes me.
In the original schematic the low cut frequency selector wiper (the pole from the rotary switch) is located AFTER the 10K summing resistor.
In the Gyraf schematic it's located BEFORE the 10K summing resistor.
Steffen's schematic has this as well.

Question is what does this to the sound? Or maybe, is this to compensate for the different cap values in the low cut section?

Attached the original schematic. Next post the Gyraf schematic.

 

[radiance]

Gyraf schematic....

 

[radiance]

No interest?

 

[okgb]

Has anyone EVER seen a real one ?
the above looks more like the tube tech , which maybe close

the only Official looking ones I've seen show only a box that says " Filter network "
or something like that .There was a member here who was collecting " Mojo parts "
and owned real ones , I think he may have been prepping for a business of some sort .

So the debates continues , about most critical parts to getting Max mojo of the original Pultecs
I have a Tubetech , never used a real pultec but I'm fairly satisfied

 

[gyraf]

and yes, my schematic is from a Tubetec - they rev'ed a real one for their version, so I consider them accurate. As for the other schematic, I don't know it's origin - but drawing style is very different from pultec schematics (looking more recent).

Maybe try mocking up both versions to see if you get a difference in behavior? After all it's a pretty simple circuit...

Jakob E.

 

[radiance]

The original schematic does indeed look like it's recently made...at least not at the time the original Pultecs were sold.
However, this circuit has been added as an addendum to a pultec manual you'll find online.
Might be misleading, I know...so maybe I should not have called it THE real schematic.


And yes, I'll definitely try both scenarios...let you know my findings...maybe post audio...

 

[Joechris]

Hmm,are you shure. The only difference I see is that the 1K is outside the low cut pot/cap loop in the gyraf, and inside in the old one..
Im proberly blind

 

[radiance]

Hmm,are you shure. The only difference I see is that the 1K is outside the low cut pot/cap loop in the gyraf, and inside in the old one..
Im proberly blind

You're right...so I must be blind...