walter
Well-known member
A friend gave me his amp chassis over a year ago, and I have finally got the thing rebuilt, and it ripps. He said the EL34/6L6 switch was confusing, and never knew if he was using it right, so he took out the chassis and just uses the cab for another amp. I like the way Carvin sounds, but I felt I could do better. Now I have an extra carvin PCB.
I like to mount the pots and tubesockets to the chassis. I wasn't too happy with the existing layout, but I didn't want to do any extensive metalwork. It is a free chassis, but I think building from scratch yields better results. the pre-amp tubes are so close to the pots I had to put the circuitboard right up in there, and the output transformer is next to the input.
I used the Carvin back jack assembly, it was easy to connect. Still have the 4,8,16 ohm switch, speaker jack, line out jack, and the 50% power switch. you can flip the EL34/6L6 switch all day long, it's not connected to anything. Now I need a faceplate. I can get a trophy plaque shop to make one for about $20. and a cab, I'm trying to get the two-twelve this thing came out of, there's also another two-twelve cab that can sit on to get four twelves in two easier to move cabs.
I just frankensteined parts together from existing scematics. Didn't really do any math, except for some fuzzy math and trial and error for the relay power supply. I learned how to build amps before I learned electronic math, and I'm slowly applying the theory to the practical. I still have a long way to go.
There was a tap from the power transformer that I thought was a bias supply, but it has only a volt. I don't have a schematic for this, and I gutted it a year ago. I added a transformer for the bias, and was able to supply the relay as well. I like the symetry of the bias/relay supply, it's so simple. I have a relay switchable pre-amp for either a fender type, or ampeg type. On the ampeg pre, I wanted to try something with the volume. The dual pot is like two typical volume controls. One reduces the amount of signal going to the tube, the other reduces the value of the grid resistor. The thought being as the volume is increased, the bias of the tube increases. The jury's still out on that one. I'll take this beast to bandpractice today, and hear how it compares.
I like to mount the pots and tubesockets to the chassis. I wasn't too happy with the existing layout, but I didn't want to do any extensive metalwork. It is a free chassis, but I think building from scratch yields better results. the pre-amp tubes are so close to the pots I had to put the circuitboard right up in there, and the output transformer is next to the input.
I used the Carvin back jack assembly, it was easy to connect. Still have the 4,8,16 ohm switch, speaker jack, line out jack, and the 50% power switch. you can flip the EL34/6L6 switch all day long, it's not connected to anything. Now I need a faceplate. I can get a trophy plaque shop to make one for about $20. and a cab, I'm trying to get the two-twelve this thing came out of, there's also another two-twelve cab that can sit on to get four twelves in two easier to move cabs.
I just frankensteined parts together from existing scematics. Didn't really do any math, except for some fuzzy math and trial and error for the relay power supply. I learned how to build amps before I learned electronic math, and I'm slowly applying the theory to the practical. I still have a long way to go.
There was a tap from the power transformer that I thought was a bias supply, but it has only a volt. I don't have a schematic for this, and I gutted it a year ago. I added a transformer for the bias, and was able to supply the relay as well. I like the symetry of the bias/relay supply, it's so simple. I have a relay switchable pre-amp for either a fender type, or ampeg type. On the ampeg pre, I wanted to try something with the volume. The dual pot is like two typical volume controls. One reduces the amount of signal going to the tube, the other reduces the value of the grid resistor. The thought being as the volume is increased, the bias of the tube increases. The jury's still out on that one. I'll take this beast to bandpractice today, and hear how it compares.
