99J: 6V6 vs 6L6

[nmiller]

I just won a ghost label 99J on Ebay (this cabinet); I should get it early next week. I've noticed that all the schematics on the internet show 6L6s, everybody seems to be running 6V6s. I even read somewhere that the chassis has "6V6" printed next to the sockets. Is it actually safe to run 6L6s in this amp (with proper rebiasing, of course), and does anyone have a preference tone-wise?

 

[capnjuan]

Hi Noah and congratulations on the amp.

Bias: unless the as-delivered amp is different, both the 6V6 and 6L6 versions were cathode-biased leaving only manipulating the value of the cathode resistor as a way to change idle current.

Heater current: Two 6L6s draw 1.8 amps but 6V6s only draw .9 amps. I don't know how much current the rest of the tubes draw but if the heater winding is rated for 3 amps, you might not have much margin for safety.

There's at least one thread on TGP discussing subbing 6L6s for 6V6s ... I don't have the link.

 

[nmiller]

The amp arrived today and it sounds great - all four inputs have different voices, though actually I think some of it may be due to resistors drifting over time :wink: . It has something of an Ampeg flavor, but it's definitely its own beast that combines bits of Magnatone, Marshall/Vox and Fender into its sound.

It came to me with two old Dumont 6L6s, and no writing on the chassis. Anyone know what brand(s) were originally used in Guild amps? The rest of the tubes are a mix of old RCA, new JJ and no-name Chinese glass.