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I picked up this fine specimen of a 1968 Traynor YVM-1 (PA tube amp), and decided to modify it somewhat for guitar purposes.
Here's the original schematic: http://www.lynx.bc.ca/~jc/yvm-1.jpg
Here's what I've modified it to be: http://s21.postimg.org/61nz2mrn9/yvm...wtonestack.jpg
Basically I have sort of a plexi front end with a few alterations, a pre phase inverter master volume. I upped the filtering somewhat, replaced all the electrolytics, added new individual screen grid resistors, added 5.6K control grid resistors, changed diodes to new 1N4007's, added a midrange pot to the existing tone circuit which I actually really like, added a depth control, and obviously changed the power cord to a grounded type.
I still plan to change tube sockets just to make sure connections are nice and tight.
The amp absolutely screams and is just perfect.. I was originally planning to do more of a 2204 preamp and tone circuit, but I like the slightly less gainy plexi modified preamp that I went with. Just thought I'd put this out there since it's a really great amp as it is, and if anyone's got one of these, I'd highly suggest modifying it as I have. Very simple to do, and able to keep almost all original mustard caps in place.
I'm very pleased with the way it overdrives, and it keeps a lot of string definition even when the gain is cranked up. Very very happy with it. I'll post some screenshots when I get a chance.
Here's the original schematic: http://www.lynx.bc.ca/~jc/yvm-1.jpg
Here's what I've modified it to be: http://s21.postimg.org/61nz2mrn9/yvm...wtonestack.jpg
Basically I have sort of a plexi front end with a few alterations, a pre phase inverter master volume. I upped the filtering somewhat, replaced all the electrolytics, added new individual screen grid resistors, added 5.6K control grid resistors, changed diodes to new 1N4007's, added a midrange pot to the existing tone circuit which I actually really like, added a depth control, and obviously changed the power cord to a grounded type.
I still plan to change tube sockets just to make sure connections are nice and tight.
The amp absolutely screams and is just perfect.. I was originally planning to do more of a 2204 preamp and tone circuit, but I like the slightly less gainy plexi modified preamp that I went with. Just thought I'd put this out there since it's a really great amp as it is, and if anyone's got one of these, I'd highly suggest modifying it as I have. Very simple to do, and able to keep almost all original mustard caps in place.
I'm very pleased with the way it overdrives, and it keeps a lot of string definition even when the gain is cranked up. Very very happy with it. I'll post some screenshots when I get a chance.
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