Power Tube Question

[Simba]

Hello everyone,

I just purchased the new Groove Tubes 6l6GE's for my 2X12 Hot Rod Deville.

Does anyone know what the proper biasing level for these tubes are. They are currently running at 30.8 which is the max my amp will adjust to. Is this too hot for these tubes.

Also, does anyone have any opinion on the Fender Vibrolux compared to my HOt Rod.

Thanks

 

[Simba]

Re: Power Tube Question

Anyone have an answer.

Thanks

 

[Curly]

Re: Power Tube Question

I run some tubes at 30 ma in my Bassman

I tried looking for basic tube biasing parameters, but didn't find it

they should be OK at that bias, but I'd prefer to check first

it surprises me that 30 ma is the high end of what you can bias to, though

 

[Simba]

Re: Power Tube Question

Thanks Curly,

I'm also noticing that these tube break up at a very low volume (around 2) on my deville. Does that sound right?

 

[texasguitarslinger]

Re: Power Tube Question

This is quoted from the Unofficial Fender Hot Rod Deluxe User's Guide:

"Q: The highest I can bias is (a very low number). What's wrong?
A: You could have weak tubes, but usually the problem is bad screen resistors (R61, R62) which aren't allowing your tubes to draw enough current. Always check the tubes first! This seems to be fairly common. Bad screen resistors are usually a sign of bad tubes, so be prepared to change your tubes within the next month. I replace bad screen resistors with 5W/500V 1K flame-proof types. These are heavily over-engineered for high reliability. These resistors can take on a bad tube short and the entire supply voltage where normal screen resistors would be toasted. You'll occasionally hear of Hot Rod owners complaining about a nasty distortion and a dramatic "loss of volume." This is sometimes their problem. Resistors that fit on the PCB board can be found at Mouser, part # 283-1.0K. I ordered some heavy duty 5W 750V power resistors that were supposed to fit, but ended up being absolute huge! With a little creativity I was about to solder them into place. You can also find these same resistors at Mouser, part # 286-1.0K. (These are the ones that Randall Aiken recommends using on his website.)"