Fet version of Marshall Superlead Plexi

[phatt]

Thanks for the crarification,   Tis all good then, :tu:.
Phil.

[KMG]

Perhaps can you post some sample sound of it?

At this point still only reamping samples
Clean 9.9M
http://milas.spb.ru/~kmg/files/projects/slp/reamp/Clean.mp3
Clean wih DRE AL3201 (hardwood studio effect) 10.0M
http://milas.spb.ru/~kmg/files/projects/slp/reamp/CleanR.mp3
Drive 12.6M
http://milas.spb.ru/~kmg/files/projects/slp/reamp/Drive.mp3

[polo16mi]

Yes!!!! I like it!!!  Very cool sound!!!  :tu: :tu: :tu:

Maybe i´ll copy and paste!!!!

[joecool85]

Excellent tones coming from that circuit.  Who needs tubes anyway?

[J M Fahey]

Excellent tones coming from that circuit.  Who needs tubes anyway?

Amen.
Besides, that's the Forum's idea, isn't it? :tu: :tu:

[rowdy_riemer]

Wow, I like the sound samples.

[joecool85]

Excellent tones coming from that circuit.  Who needs tubes anyway?

Amen.
Besides, that's the Forum's idea, isn't it? :tu: :tu:

It wasn't originally, but it is a wonderful outcome that has just started and hopefully continues to thrive.  No point is using inefficient (lots of watts go to the heater and not the speaker) tubes that are getting harder and harder to come by since they aren't being manufactured by many places when you can have a much more efficient and great sounding FET device.  I love it!

[KMG]

Two short samples with tube screamer in front (at first part of each file TS is bypassed for reference)
Neck
http://milas.spb.ru/~kmg/files/projects/slp/reamp/BoostNeck.mp3
Bridge
http://milas.spb.ru/~kmg/files/projects/slp/reamp/BoostBridge.mp3

[joecool85]

Two short samples with tube screamer in front (at first part of each file TS is bypassed for reference)
Neck
http://milas.spb.ru/~kmg/files/projects/slp/reamp/BoostNeck.mp3
Bridge
http://milas.spb.ru/~kmg/files/projects/slp/reamp/BoostBridge.mp3

I can't believe the metal tone coming out of it on the bridge pickup with the TS on!  That seriously rocks!

[THChrist]

Sounds amazing! The schemo OTOH looks like a mace...

[J M Fahey]

Maze?
No pain no gain 

[THChrist]

s#it! i always confuse those. which one is where you put mice in?

[J M Fahey]

Maze: labyrinth
Mace: something to break walls, stone, or your head. Also "tear gas"

[THChrist]

Maze: labyrinth
Mace: something to break walls, stone, or your head. Also "tear gas"

Well, that schemo broke my head...

I was used to the typical 2k7/680n, 820/680n, stuff like that. Now I don't see any of these values anywhere (same thing goes for the JCM800. What if I want to add an extra cap? Like a 680n in parallel with 820r before the tonestack? I'm lost.

[KMG]

Each stage of preamplifiers was designed with the help of this "test equipment".

Right part is the tube version of the stage with input and output interstage circuits.
At the FET part, I first set up the gain below the cathode circuit cutoff frequency of the tube stage by adjusting the resistor at the FET source (adjusting biasing voltage at the same time to keep operating point).
After this I added a correcting RC circuit at the FET source to adjust gain above  the cathode circuit cutoff frequency of the tube stage. R define gain, RC define cutoff frequency.
Frequency response i checked by "RightMark Audio Analyzer".
Thats why you don`t see original values of components in source networks.
The last thing I adjusted the parameters of the "scalable diode" part to provide adequate "grid" limitation.