How much DC leakage is acceptable?

[Randall]

How much DC leakage is acceptable in a tube amp? Specifically, on the control pots and from a fiber board? I have a Deluxe Reverb new build that has 3 - 5 mV across both volume pots and I can also measure anywhere from 100 mV to almost 4 vdc to ground depending where I probe the fiber itself. The higher V's are closer to B+, with the lower range being around the preamp side of the board.

[Leo_Gnardo]

If the DC leakage is making your pots sound scratchy, injecting noises into your audio, or upsetting the DC bias of tubes especially the outputs, then it's unacceptable.

What I do is rebuild the affected audio circuits on tie strips above the afflicted board. If you have a big budget & time, you can scrap the leaky board & build new on phenolic or glass/epoxy board.

[ToneMerc]

If you have a big budget & time, you can scrap the leaky board & build new on phenolic or glass/epoxy board.

I'm with Leo here;as much as I like the look of the fiberboard, I refuse to use it in a new build. The exact material Fender used 50 years ago caused problems and I'm not even sure if the "fiberboard" that you commonly see today has the insulation properties equal to the original material.


TM

[tubeswell]

How much DC leakage is acceptable in a tube amp?

Preferably none

[Leo_Gnardo]

I'm not even sure if the "fiberboard" that you commonly see today has the insulation properties equal to the original material.

Thanks for your support TM. I've had to "rescue" brand new kit builds that included "authentic" leaky black fiber board. As well as hundreds of aging Fender amps. It's wise to avoid the stuff entirely.

Funny thing, old Traynors used a light grey or beige fiberboard, and I've never encountered a leakage problem with them. Black boards had "carbon black" added to the paper mix. And as we know, carbon is conductive.

[Randall]

If the DC leakage is making your pots sound scratchy, injecting noises into your audio, or upsetting the DC bias of tubes especially the outputs, then it's unacceptable.

Scratchy pots is what lead me to this discovery. I put so much time and care into building this amp, the idea of ripping out and stripping the board is heart breaking. But, the idea that I can measure differing voltages pretty much everywhere on the board material really makes me uncomfortable, so it looks like it has to go.

Where does one find better board material?

[ToneMerc]

Where does one find better board material?

I've ordered G10 board from McMaster Carr before, but generally I get most of my board material from here. Ken will cut it to whatever size you desire as well

www.turretboards.com

TM

[Leo_Gnardo]

Scratchy pots is what lead me to this discovery. I put so much time and care into building this amp, the idea of ripping out and stripping the board is heart breaking. But, the idea that I can measure differing voltages pretty much everywhere on the board material really makes me uncomfortable, so it looks like it has to go.

Sorry you had to learn the hard way, but you won't make that mistake twice, for sure! Your amps will sound better and there's all that time in the future you won't have to waste trying to troubleshoot because of leaky board material. I hope others who build from scratch or kit will take notice & avoid the stuff.

Decades ago I spent many hours trying to figure out what was going on in old Fenders, then finally figured out it was the fiberboard. (Hmmm why don't Marshalls do this???)

[martin manning]

More than a few people have had trouble with black G10. Some of it is ok and some is not. No slave to fashion, I just won't take the chance...

[rdjones]

Where does one find better board material?

I saw this stuff and wondered if it might be a better choice.

http://www.ebay.com/itm/111089254951

Anyone try the grey material ?

rd

[cbass]

Where does one find better board material?

I saw this stuff and wondered if it might be a better choice.

http://www.ebay.com/itm/111089254951

Anyone try the grey material ?

rd

I have some but I havent used any of it yet.

[Milkmansound]

I have a friend who tells me that my G10 turret board amps will never sound like a real fender with its black fiber board and soldered chassis grounds.

Thats fine by me!

Forget the eyelets too - spoil yourself with some double turrets

ahh, this is why the terrorists hate us

[LeftyStrat]

Forget the eyelets too - spoil yourself with some double turrets

Heretic! We must burn him at the eyelet, umm, maybe the turret would work better for this. Anyone have a staking tool?

Just kidding, I prefer turrets too.

[Leo_Gnardo]

I have a friend who tells me that my G10 turret board amps will never sound like a real fender with its black fiber board

Yeah, your amps won't be making aardvark noises. At least due to the circus board.

I'd call that an improvement. If your friend has a problem with that, tell him to buy his own soldering iron & a sheet of black fibreboard and tell him to go at it. When it turns out noisy, "embrace the suck" or do as the OP here is about to do.

[M Fowler]

I have some of the gray paper boards darn difficult to work with, can't drill it out you need special punches or something.