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What type of amp should I make with this? Schematic help also needed

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jmilch

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Joined 2009
#1
Greetings

I recently picked up an old General Electric L916 console radio that support many bands that no longer exist today 😀

The caps were all bad, and the resistors were out of tolerance, but the tubes and sockets were still mint, and could be reused.

I removed everything from the chassis except the tube socked and the PT. I am wondering if anyone can give me some direction on a schematic I can follow to put together a decent low wattage P-P guitar amp, something for use in the den.

This chassis has the following tubes:
(2) 6V6 Output tubes
5Y3G rectifier
6SG7 (RF amplifier?)
6SA7 (Oscilator?)
6SK7 (IF amplifier?)
6SQ7 (Detector for 1st audio, according to the manual)
6J5GT Phase Inverter

It has a decent sized PT for its rated 6-9 watts (in the default configuration).

I was thinking adding (2) stages of 12AX7 pre amp tubes and running the 6V6's in P-P. The only thing is, I need some tips on where to find a schematic.

Thanks in advance for any suggestions or links
 
#4
I think all those tube sockets are the large "octal" type right? So no 12ax7 possibilities since those require the small 9 pin sockets.

My friend has an old Ampeg M-12 Mercury with tremolo that uses 6SL7 tubes. I think these are fairly close to the 12ax7 but in the larger type with 8 pins. There may be others that are closer but you want tubes that are not hard to find/expensive.

I don't recommend the full schematic for the M-12 since the PI is weird to me and there is only one gain stage in each preamp channel. You deserve much more than that! 🙂 However I do recommend the tremolo setup on the M-12as it sounds very nice.

http://www.schematicheaven.com/ampegamps/m12_6v6.pdf

You have 4 sockets available for the preamp/effects/loop. Using dual triodes like this means 8 stages which is more than enough for whatever you want.

The sovtek 6SL7 tubes were humming in my friends amp but changing to NOS made in USA tubes fixed that. I think many guitar amps also used 6SN7 dual triode tubes which are not as close to 12ax7 in specs. Google reports twice as many hits for "guitar amp" with the 6SN7 than 6SL7.

Some of the earliest Fender amps used the 6SC7 tube which provides double the google hits of the 6SN7 for guitar amps.

So if you want to use the original sockets, look for guitar amp schematics with "octal preamp tubes." Here is a common site for guitar amp schematics.

Schematic Heaven. Where All Good Amp & Effect Designs Await Resurrection...
 
#6
jjman said:
I think all those tube sockets are the large "octal" type right? So no 12ax7 possibilities since those require the small 9 pin sockets.

My friend has an old Ampeg M-12 Mercury with tremolo that uses 6SL7 tubes. I think these are fairly close to the 12ax7 but in the larger type with 8 pins. There may be others that are closer but you want tubes that are not hard to find/expensive.

I don't recommend the full schematic for the M-12 since the PI is weird to me and there is only one gain stage in each preamp channel. You deserve much more than that! 🙂 However I do recommend the tremolo setup on the M-12as it sounds very nice.

http://www.schematicheaven.com/ampegamps/m12_6v6.pdf

You have 4 sockets available for the preamp/effects/loop. Using dual triodes like this means 8 stages which is more than enough for whatever you want.

The sovtek 6SL7 tubes were humming in my friends amp but changing to NOS made in USA tubes fixed that. I think many guitar amps also used 6SN7 dual triode tubes which are not as close to 12ax7 in specs. Google reports twice as many hits for "guitar amp" with the 6SN7 than 6SL7.

Some of the earliest Fender amps used the 6SC7 tube which provides double the google hits of the 6SN7 for guitar amps.

So if you want to use the original sockets, look for guitar amp schematics with "octal preamp tubes." Here is a common site for guitar amp schematics.

Schematic Heaven. Where All Good Amp & Effect Designs Await Resurrection...
Click to expand...

I had a few extra 12AX7 shielded sockets, and I am semi familiar with their preamp stages and tonal quality, so I would like to use those for the preamp is possible.

Thank you so much for the links guys, you have been a huge help!
 
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