Help with a build (6L6GC power)

[trevorus]

I am cannibalizing an old Silvertone 1483, and I will be building a 2-6L6GC powered amp, and I am wondering what the best setup would be. I'm probably going with a fixed bias, and changing the recto over to a 5AR4, to get a little more beef out of the power side. I have a Triad 50 watt OT that I am planning on using it with, so a ~40watt output section would be fine. The difference here is I am looking to create a 2 channel preamp with a gain channel that gets mean. I've been sifting through a ton of schematics, and my head is spinning with options. I'm really just a modder, but I am looking to tackle a build, finally. Does anyone have any advice on which direction to head with this thing?

[Robert M. Martinelli]

I am cannibalizing an old Silvertone 1483, and I will be building a 2-6L6GC powered amp, and I am wondering what the best setup would be. I'm probably going with a fixed bias, and changing the recto over to a 5AR4, to get a little more beef out of the power side.

Hi Trev,
if with "beef" you mean "dynamic" the first thing I would advise you to do is to use silicon rectifiers ( 1N4007s ) instead of a tube rectifier ( 5AR4/GZ34 ) and to complement the PS section with big ( value ) filter caps to provide an " energy reservoir" during loud transients ( picking attack ). This way the amp won't sag ( at least not due to the PS section ) and the notes' attack will be reproduced more faithfully, improving the amp's dynamic response.
HTH
Best regards
Bob

[txstrat]

After I had my last build (double channel amp - 2 6L6) troubleshooted enough - it played well in each channel and was quiet as a mouse - I figured I want something else.
By listening to sound clips, changing the amp I was woking on and reading about amps and their tone a lot, I came to the conclusion, that I like the brown vibrolux for clean and the brown deluxe for distortion.
That's what I did to my build. These amps share the same values LTP inverter.
I changed one channel to 6G11 specs and the other to 6G3 specs. Switchable via relay. The 6G3 channel has a pre PI master volume (1 Meg log) to adjust the channels volume to each other. The amp had a reverb anyway and I left it there. But that's not a must.
What do you mean with a "mean" gain? High gain or just dirty for "bad blues"?
The 6G3 is the dirtiest circuit I know - great distortion but not mushy at all. Also not singing (like boogies), though. Just right.
Oh, and it has a diode recto like Bob proposed.

Keep on soldering

[trevorus]

Well, the PT I am going to be using is set up for the tube recto, so I suppose if I set up a full wave DC filament network with that winding, it ought to bring the voltage up a tiny bit from the 5 volts it's at now. That could be used to run some beefier power tubes like a set of EL34's, with their higher draw heaters, and separate the preamp section from the power amp section. I'll also have to tap off of the HT winding for my bias supply, but that shouldn't be too much of an issue.

[Robert M. Martinelli]

Well, the PT I am going to be using is set up for the tube recto, so I suppose if I set up a full wave DC filament network with that winding, it ought to bring the voltage up a tiny bit from the 5 volts it's at now. That could be used to run some beefier power tubes like a set of EL34's, with their higher draw heaters, and separate the preamp section from the power amp section. I'll also have to tap off of the HT winding for my bias supply, but that shouldn't be too much of an issue.

If you are planning to use the 5VAC sec ( originally intended for the tube rectifier ) to supply the output tubes heaters with DC, the bridge plus filter capacitors arrangement will bring the 5VAC to some 7VDC, and maybe that's a little too much.

Supplying the output tubes' heaters with DC is usually not necessary on push-pulls anyway, because they're hum-canceling by design, so, if you're planning to run "separate" supplies for the heaters, it would be worth to supply the preamp tubes' heaters with DC instead IMHO.

HTH

Best regards

Bob

[trevorus]

If you are planning to use the 5VAC sec ( originally intended for the tube rectifier ) to supply the output tubes heaters with DC, the bridge plus filter capacitors arrangement will bring the 5VAC to some 7VDC, and maybe that's a little too much.

Supplying the output tubes' heaters with DC is usually not necessary on push-pulls anyway, because they're hum-canceling by design, so, if you're planning to run "separate" supplies for the heaters, it would be worth to supply the preamp tubes' heaters with DC instead IMHO.

HTH

Best regards

Bob

I was wondering about his soon after I typed it. It probably would be easier to use the DC on the pre side and knock down the voltage a bit to get it within range and use the regular heater winding on the power tubes, yielding a bit more versatility in that I can run EL34's or 6L6's depending on my configuration. I'd like to be able to do both, really. I want the pre to be a higher gain setup, possibly two channel, and I would love to be able to experiment with the two types of tubes.

Basically, I am just in the planning stages and conceptualizing at the moment. I'll have to buy electronic parts and turret boards and such when I figure out what I actually want to do. I'm trying to nail down what will work and what won't in order to make this build as smooth as possible. Like I said, I'm a modder, but not yet a builder. I'm still getting this tube stuff down.