Russian Compressor Build?

[markm]

Check this out guys;

http://www.sugardas.lt/~igoramps/article60.html

Looks kinda Dynacomp-ish huh?
That transistor setup with P channel Fets seems strange.
Wonder how it sounds??

[blanik]

Do It Yourselfsky !!!   

R.

[DDD]

It sounds great.
The author is a famous Russian FET guru. All of his creatures are masterpieces.
So pls don't hesitate.

[moosapotamus]

Too many components... and, if it's only a guitar compressor... well, there's already plenty of them to go around.

~ Charlie (bass player)

[markm]

I'm a bit confused about the P-Channel FETS in there + it appears in the layout the cases of the trannies have a pad for ground 

[Medved]

It sounds great. Yes, it is a bit more complex than 2 trannies.
P channel regulator is a know-how of  the author. It completely eliminates the penetration of control signal in the sound.
Any more questions?

[markm]

Sure 
What can be used as a sub....if anything?

[Jay Doyle]

That looks like an incredibly well thought out design which I bet would sound really good. Good A/D network, use of SRRP stages for gain and tone...

If I had the time, I would build it.

[markm]

Right now I have the time......just not the right parts I think 

[Seljer]

theres some soundclips at the bottom (you have to rename the extension abc to mp3) which do sound really good

[markm]

Maybe Mr. Hammer can lend a couple of ideas for parts substitutions?? (hint-hint  )

[Medved]

What can be used as a sub....if anything?

What is "sub"?

parts substitutions

T1 KP303E<--> 2N5458, 2N5459 ( VGS(OFF) = 4...5V )
T2, T3, Т4 KP303A, KP303>|< <--> J201
T6 KP103E<--> 2N5020
Silicon diodes D2,D3 1N4148
Op-amp LM324
Pt1,Pt2<--> J271, 2N5461, 2N5462, J175, J174, 2N5115
pt1,pt2 -dual p-jfet. With discrete p-JFETs some minor tuning is needed.

[markm]

You got it!
Subs =  substitutions.

I guess that when substituting this pt1,pt2 -dual p-jfet., there would perhaps be some bias issues with the P-Fets.
My unknowing guess is, when using the Pfet chip, they would be matched.
Correct?

[markm]

Searched on mouser and came up with this;

http://focus.ti.com/lit/ds/symlink/lm393.pdf

They are referring to it as a comparator.
Don't know if this is correct though as the Russian number doesn't seem to cross very well 

[Medved]

LM324, not 393.

I guess that when substituting this pt1,pt2 -dual p-jfet., there would perhaps be some bias issues with the P-Fets.
My unknowing guess is, when using the Pfet chip, they would be matched.
Correct?

Absolutely. Trannies mathing or tuning some resistors values is needed with discrete jfets.

[markm]

LM324, not 393.

No No,
The 393 would substitute the Pfet chip КР504НТ3(4).
LM324 is no problem.

[Medved]

КР504НТ3 is a dual p-channel Jfet.
pT2 -any p-channel JFET with Vcutoff=3..5v (2..6 is acceptabe but THD of regulator will increase)
pT1- any p-channel JFET with Vcutoff=1.5..5v

[markm]

The Google translator is fairly good however,
Some of the text I don't understand still but, If I figured this out correctly by the pictures, if using individual Pfets then
that would account for the trim pot in one of the illustrations.

[Medved]

"You should trim the value of Ra3 if using discrete p-jfets. The method is:
1)Set threshold to max resistance.
2)By changing the value of Ra3 set the voltage on the gate of Pt2 equal to its cut-off voltage."
That's all you need.

[markm]

Have you built this one??