Tube Amp Archive

Think I got it. Thank you!

I've also heard some folks were using a 5k 5watt resistor in place of the 4.7k dropping resistor?

Ok cool. So the 1M is actually 10M. But shouldn't I be able to measure resistances between the pot and the 10m resistor and between the pot and the 56k resistor? Looks like it should be 3.5k between the 1pm and 6.8 k between the 56k and the pot? Am I confusing something? Is this a measurement I shou...

Couple of other questions: Regarding PI 10k pot Does anyone here have any experience adjusting the 10k PI pot? How did you take resistance measurements...between the lugs of the pot and the resistor each lug is attached to(besides the wiper)? I assume you have to do this with the amp on...is this sa...

I ordered a 350v pt from mercury to be safe

I know...here's the spec sheet for it. Tell me what you think.
https://imgur.com/gallery/0zNrBFB

Totally. My only question was should I try to find a 350v pt (mercury makes one) to have ready as a backup just in case.

This is only 75ma. Yours is 150ma? The one im talking about is the MOJO756EXLV ...has a CT and 330v/75ma on each red tap.

Anyone think there would be a problem using the mojotone lower voltage (330v) PT for a tweedle dee 5e3?

"Probably. Note Fender's '57 Twin schematic shows 460V on the first filter cap"

Do you think that's 460v with tubes in or unloaded?

This is the choke I used:

Choke weber wo14684 (5-8H @ 200ma, 125 ohms)

I measured tube current first off of 1 ohm resistors off of pin 8, then using a bias probe.

Ok...ordered a set of 7581a tubes and first will try subbing in a 3.3k for the 2.2k and see that leaves me with biasing capacity. You guys are awesome.

Was wondering what anyone thought in terms of safely using either 5r4gyb/a rectifiers in place of 5u4gbs in a 5e8a low power twin. Would that change the character of the amp much? Reason for doing this is my plate voltages came out a little high (480 unloaded) and was hoping to drop them a bit. I th...

I agree...went with Leo's scheme. Sorry to be a pain in the ass.
Any thoughts on this bias layout? Obviously haven't put in bias tap yet.
5e8a bias3 https://imgur.com/gallery/Sq9VeWH
5e8a bias2 https://imgur.com/gallery/xkq8LSq
5e8a bias 1 https://imgur.com/gallery/PveYpfC

Gotcha. Appreciate all the thoughts. I like the idea of running 1-3 together.