Hello friends! I have a schematic that a computer science professor designed for me (he doesn't know much about audio, he only works with computers). It is a system that goes between a Class D module and the output of an electric bass preamp, specifically an Ampeg SVP Pro, it has a volume and a control that mixes the output of both triodes.
The design sounds very good connected to a Class D Ice Power 125 ASX module, the triode used is a 6sn7 with modifiable filament voltage adjustment to be able to use 12sn7 as well. Unfortunately, the Professor is no longer with us (RIP) so I cannot ask him for help.
The problem with the design is that it distorts when an external Bass Preamp is connected to it, when there is too much signal, the whole distorts, not too much, but if the idea is to keep it as far away as possible, the important thing is a clean sound.
I am not an expert, but I do know how to read electronic schematics and draw them (although I still have a lot to learn)
Thank you very much. 🙂
The design sounds very good connected to a Class D Ice Power 125 ASX module, the triode used is a 6sn7 with modifiable filament voltage adjustment to be able to use 12sn7 as well. Unfortunately, the Professor is no longer with us (RIP) so I cannot ask him for help.
The problem with the design is that it distorts when an external Bass Preamp is connected to it, when there is too much signal, the whole distorts, not too much, but if the idea is to keep it as far away as possible, the important thing is a clean sound.
I am not an expert, but I do know how to read electronic schematics and draw them (although I still have a lot to learn)
Thank you very much. 🙂
1) The design is fine.
It uses somewhat lower than usual resistors forppate and cathode, soit runs at somewhat higher current than usual, but it should still work.
FWIW, Forum member PRR kindly posted:
which is datasheet recommendations, but again,yours should still work fine, those are not outrageous values.
2) everything distorts if driven hard enough.
3) your design starts with a loud signal, SVT3 preamp out, easily 1 V RMS, and then further amplifies it 15X so some 15V RMS 😱 ... what did you expect?
Tube preamp might not clip by itself butICE power module certainly will.
What is to be expected.
There is nothing wrong or broken in your circuit, it´s only doing what it´s expacted to.
PS: you are NOT showing the blend circuit.
Don´t write "oh, it´s just a blending pot", draw it.
Thanks for the quick reply. 😉1) The design is fine.
It uses somewhat lower than usual resistors forppate and cathode, soit runs at somewhat higher current than usual, but it should still work.
FWIW, Forum member PRR kindly posted:
which is datasheet recommendations, but again,yours should still work fine, those are not outrageous values.
2) everything distorts if driven hard enough.
3) your design starts with a loud signal, SVT3 preamp out, easily 1 V RMS, and then further amplifies it 15X so some 15V RMS 😱 ... what did you expect?
Tube preamp might not clip by itself butICE power module certainly will.
What is to be expected.
There is nothing wrong or broken in your circuit, it´s only doing what it´s expacted to.
PS: you are NOT showing the blend circuit.
Don´t write "oh, it´s just a blending pot", draw it.
The Blend control is to make only one triode sound, and turn the potentiometer until the 2 triodes sound, it has no more secret, it is the same as a Fender Jazz Bass where you can mix the sound of a single pickup, or that of 2 at the same time.
Regarding the gain established in the configuration of the triodes, I think it is quite low, we have tried it with other configurations, but it sounds a little "dull".
What do you think of the 2 zener diodes? do they have something to do with limiting signal peaks? Would it be good to increase the value of the volume potentiometer? Would it prevent the set from distorting a little less? And finally, the issue of impedance (which confused me a lot) would it have something to do with everything?
1) no, Zeners ar at the input, before Tube amplification, they will clip with 5V peaks, so about 3.5V RMS.
While SVT preamp output is presumed 1V RMS or less, and to boot you have an input volume control before it, so ....
2)
Self-quoting:
D-R-A-W it.
3)
SVT preamp can easily drive ICE module into clipping.
All you are adding is the unbalanced to balanced circuit ... which is Op Amp based.
6SN7 adds desired "Tube Flavour", ... a.k.a. "Distortion"
If you like it, fine ... if not, forget the tube and just use the balanced out section.
Please reread my answer until it clicks.
While SVT preamp output is presumed 1V RMS or less, and to boot you have an input volume control before it, so ....
2)
Self-quoting:
D-R-A-W it.
3)
Anything above 1X is already high, go figure.
SVT preamp can easily drive ICE module into clipping.
All you are adding is the unbalanced to balanced circuit ... which is Op Amp based.
6SN7 adds desired "Tube Flavour", ... a.k.a. "Distortion"
If you like it, fine ... if not, forget the tube and just use the balanced out section.
Please reread my answer until it clicks.
