Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => PC Express and JSchem - Schematics and Layout diagrams => Topic started by: tubenit on May 15, 2011, 05:29:30 pm
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I haven't built this but sure would like to. I think this amp would sound really good.
CHECK for errors and compare the schematic with the layout.
The idea came from a blend of Mat's 86 Special and the using the cathode follower on my Tweed Overdrive amp after the 5879. The CF smoothed out the 5879 tone quite a bit.
With respect, Tubenit
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If it's okay I made a couple of simple possible changes or suggestions mainly being to use a lesser value vol pot w/ no gain stage preserving a bit more high end, especially w/ the high value 220k grid resistor feeding the power tube. Then in keeping the gain stage's output more similar to the setting w/out it (and being able to turn it up all of the way for a more useful range), a divider when throwing the switch between the two settings. The 100pf treble bleed would not be needed on the OD vol pot when the tone setting is slightly more than halfway up - they then would both be in parallel otherwise.
I like the idea T :)
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I am not sure how to draw the mosfet on the layout board so if you use this layout, please note you may need to redo that section?
Check for errors and compare the schematic with the layout.
The schematic and layout marked 6-23-11 are the most current one. I moved the passive effects loop location. The result was that it has a more transparent (less colored) tone between V1a and V1b with NO volume drop. Having the passive effects after the clean/od prior to the 6BM8 pentode gave it a volume drop and the tone was somewhat colored and not nearly as clear & transparent.
With respect, Tubenit
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I have not built this yet. It's a mini-TOS with a 6V6 and a mosfet CF following the 5879 pentode.
CHECK for errors!
Compare schematic and layout.
With respect, Tubenit
GEEZER: The TOS dual clean is what I was suggesting that might be worth considering? Tubenit
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I like this in that the clean side doesn't go through the mosfet but wonder about the high value 22k grid stopper before the 6v6? anything up to 10k and higher seems to affect high end. Maybe that's what you're trying for though?
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This was drawn by HoneyDip on the Amp Garage.
This is a proven amp design with a great tone.
CHECK for ERRORS!
B+ is reportedly around 240v.
With respect, Tubenit
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I have not built this yet. It's a mini-TOS with a 6V6 and a mosfet CF following the 5879 pentode.
Tubenit,
I plan to put one tube reverb stage instead of effects loop into the circuit with 6V6 SE .
Could you advice me how to rebuild the whole schematic?
Thank you in advance.
Regards,
Adam
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Adam,
I don't have any experience in putting a reverb into a single ended amp.
with respect, Tubenit
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Tubenit,
I plan to put one tube reverb stage instead of effects loop into the circuit with 6V6 SE .
Could you advice me how to rebuild the whole schematic?
You are asking for a lot there my friend with no compensation for time spent doing something for somebody else right out of the wild blue yonder. This is a 6 year old thread on top of it all. I will say that at least you asked nice and politely, and that's the way to approach it.
If it were me I'd go searching a few of T's one tube reverb schematics from the past and put it in there. Plan for a gain stage after the recovery stage a la the AB763 idea and mix it right back into the dry signal. You will likely have to improvise a bit on a thing or two but that's the fun of this stuff. Planning for the unplanable. This is the type of stuff that makes a person grow and attain building skillz. Good luck!