Tube Amp Archive

I have an Artist 3203 in for service and I'm not sure if it even has the correct reverb tank in it. Does anyone know for sure what tank these are supposed to have? The reason for my uncertainty is threefold: 1) The tank I pulled out is a 4EB3C1B; it was upside-down to how a B should be mounted. 2) a...

I use Canare GS-4 which I buy from Redco: https://www.redco.com/Canare-Instrument-Cable/ I also buy my PTFE tubing from them: https://www.redco.com/Redco-TT250.html They're pretty quick to ship and I've been happy with them. :) Thanks for the tip. Looks good. Is it safe to assume this stuff doesn't...

I need some shielded cable like used in amps to connect the input jacks and tone controls (1 conductor + shield).
So far, Mouser has been my only hit but I don't want to buy a 100' roll.
Anybody got a good connection?

Look at the tube data sheets. For example: https://frank.pocnet.net/sheets/127/6/6L6GC.pdf For Push-pull class AB, see given plate and screen voltages, and Grid #1 bias voltages. Now, in practice, our amps usually have screen voltage much closer to plate voltage, and higher (more negative) bias vol...

It seems like you have a handle on what's going on there. It's just a matter of figuring out the jack/switching arrangement. I would add grid stop resistors. There's not a whole lot of advantage to running parallel triodes. You'll get some gain boost and less noise.

Is there a way to calculate the bias voltage required to run an output tube (or pair) at a given wattage? If someone can create a spice model for a 6L6GC it seems like I ought to be able to crunch a few numbers and come up with a range of voltages to design a bias circuit around. I've been searching...

EDIT: As the Mark 1 Boogie is a modded Fender amp. I have posted here. ...snip... There are a few resistors in the circuit that I don’t understand. There is a 100K resistor between the treble wiper and the top of the volume control this 100K resistor was in my late 70’s Boogie, there is also a 220K...

Here's another cathode switching configuration...

Seems like a 1M resistor across the switch would allow the capacitor to charge, thus eliminating the pop. Ya think? I tried that, didn't work. Even with the amp on standby it popped, hard. I found this in another thread in el34world: "The ol' switched cathode bypass cap on a preamp tube or CF stage...

I would put a 0.047uF or 0.1uF cap in series with the 470K resistor to isolate the DC voltage. Why so big? In the case of the AB165 there are no pots between stages wut? ALL the pots are between the first two preamp stages... Fender are also not too concerned about one stage affecting the DC voltag...

I was wondering about the purpose of R10 (470K) on V2.2, there seems to be a mistake in the circuit. As far as I can see it will put DC on your pots causing them to be scratchy. IMG_1363.PNG Do you suppose it's as simple as adding a series capacitor on the "cold" side of the 470K resistor? That wou...

Lots of versatility there. The creamy/crunchy switch -- I've not had any success putting this on my amp without a terrifying pop when switching. Maybe a make-before-break switch would work (I just thought of that now)? Seems like a 1M resistor across the switch would allow the capacitor to charge, ...

Lots of versatility there. The creamy/crunchy switch -- I've not had any success putting this on my amp without a terrifying pop when switching. Maybe a make-before-break switch would work (I just thought of that now)? I was wondering if that would be the case. This is exactly why I submitted this ...

The original AB165 and AA270 circuits had this resistor. It's local negative feedback which tames that stage a bit and offers some compression. Thank you for pointing out this flaw; it made more sense with the volume pot before the second gain stage. Not so much with this configuration. I'm gonna ha...

A friend brought me this ratty, old (1970) Bassman amp to resurrect. He said he wanted some mods to allow a greater variety of tones. Down the rabbit hole I went. I'm going to pretty much gut it and build new boards. I have a preliminary schematic of the pre-amp and output stages that I would like t...