I have a modded 100-watt Marshall here that sounds pretty wicked. It has five tube gain stages and some other cool features, like switchable cathode on one of the stages. I understand most of it, but there's something puzzling going on with the gain control. It has a bunch of resistors, caps, and diodes hanging off it. I did my best to draw it correctly in the schematic but I just don't know what to make of it. Any takers? I can't identify the diodes. They are too small to read any writing. But they kind of look like zeners. They're a shiny orange/bronze color with a black stripe on one end like most diodes. And I don't believe they're providing any clipping like a typical Jose mod.
I think the 430K resistor is there to limit the gain control's sweep? Measuring with a meter, the pot maxes out at 450K.
What's Going On With This Preamp?
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FourT6and2
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What's Going On With This Preamp?
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FourT6and2
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Re: What's Going On With This Preamp?
Actually, seems like it's a make-shift noise gate?
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Reeltarded
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Re: What's Going On With This Preamp?
Peavey VTX compression circuit. It's diode clipping in it's mildest form. Those will be 20v Zeners.
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Reeltarded
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Re: What's Going On With This Preamp?
Peavey VTX compression circuit. It's diode clipping in it's mildest form. Those will be 20v Zeners.
omg
omg
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FourT6and2
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Re: What's Going On With This Preamp?
I don't think that's correct. They are not set up like diode clipping (the amp also has a Jose mod, which is diode clipping, later on down the line). This is a make-shift noise gate someone added after the fact to tame the amp a bit.Reeltarded wrote: ↑Sun Oct 20, 2024 11:22 pm Peavey VTX compression circuit. It's diode clipping in it's mildest form. Those will be 20v Zeners.
Re: What's Going On With This Preamp?
Some Peavey amps have the same kind of noise gate circuit.
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FourT6and2
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dorrisant
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Re: What's Going On With This Preamp?
It's a Mile stone...Reeltarded wrote: ↑Sun Oct 20, 2024 11:25 pm Peavey VTX compression circuit. It's diode clipping in it's mildest form. Those will be 20v Zeners.
omg
IMG_3470.jpeg
https://youtu.be/cphNpqKpKc4?si=KWylh5JzEYRSBgLD
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Reeltarded
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Re: What's Going On With This Preamp?
hah
Ok, now I can see the whole image too. Is this place safe to post on 10,000 times?
Ok, now I can see the whole image too. Is this place safe to post on 10,000 times?
Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.
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Reeltarded
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Re: What's Going On With This Preamp?
Yeah, before when I clicked on the image it showed in my mobile browser as just the area around the diodes.FourT6and2 wrote: ↑Mon Oct 21, 2024 3:10 amI don't think that's correct. They are not set up like diode clipping (the amp also has a Jose mod, which is diode clipping, later on down the line). This is a make-shift noise gate someone added after the fact to tame the amp a bit.Reeltarded wrote: ↑Sun Oct 20, 2024 11:22 pm Peavey VTX compression circuit. It's diode clipping in it's mildest form. Those will be 20v Zeners.
You are correct.Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.