If a 6L6G is running at 415VDC on the plate, is a 470 ohm grid resistor adequate?
If a 6L6G is running at 415VDC on the plate, is a 470 ohm grid resistor adequate?
if it keeps the screen a few volts lower than the plate it's fine. i don't recall what's in my hoffman/bassman ri,,,but i think 470 is correct, and it runs much higher plate voltage @470...the screens run just a couple of volts lower.
they can kill ya, but they can't eat ya.
A 6L6G shouldn't see 415 on the plates. You'll toast it.
http://www.mif.pg.gda.pl/homepages/f...127/6/6L6G.pdf
Several guitars in different colors
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I know its beyond specs, but I've heard that they'll handle 420VDC no sweat even though the original design specification was only 360 volts.
There are only so many left of those coke bottles. I'd swap it with somebody with a TV front amp, or something, and get GB or GC rated tube.Originally Posted by ragtweed
Several guitars in different colors
Things to make them fuzzy
Things to make them louder
orange picks
i've been running this pair of rca blackplates for 2 years, no problem at all. here's some spec sheet data
6l6gc specs
they can kill ya, but they can't eat ya.
I like the Kap'n wouldn't risk cooking an old coke bottle 6L6G. GC's are a different story.
6L6G specs:
no arguement. g's and gc's are way different. i wouldn't use wgb's instead of gc's either.
they can kill ya, but they can't eat ya.
Exactly!
i don't see all the posts anymore. :rl
they can kill ya, but they can't eat ya.
Doesn't the 6L6GB have the same specs as the 6L6G? Just a different bottle methinks. The 6L6WGB has a higher dissipation rating, but less than a 6L6GC. I suppose I could run 5881's or even 5932's, but I was hoping that I could run the "coke bottles". Yathinks that 54ma (two tubes) at 413VDC is gonna fry 'em?
Max plate voltage on a 6L6GC is 500 vdc. On a 6L6G it's 360.
You're listing a combined mA rating.
If so, you need to subtract the Vk (voltage at the cathode) from the plate voltage.
- Is this a cathode biased amp?
- Is that the plate voltage?
For example, if you've got a 250kohm cathode resistor, and are running 54mA across it, you've got 13.5V between the cathodes and ground. Not a lot, but it puts the potential difference between cathode and plate to less than 400V. That, while still over spec, I might risk.
Several guitars in different colors
Things to make them fuzzy
Things to make them louder
orange picks
Nope, its a grid biased (fixed) amp. If that's too much juice then I won't bother with the coke bottles.
The screen resistors are fine, and the plate voltage is fine.
A lot of people see the specs and assume they are absolute maximum ratings. They are not. They are design centered ratings. The tubes will be fine.
The reason Fender increased the plate voltage (and it's only by 50V BTW), was to maximize clean headroom.
Now if the plate voltage was pushing 500+ then we might use a different tube, but it's not so much that the tube is on the edge of destruction. A lot of vintage American products, including vacuum tubes, not only met their ratings but exceeded them.
On the other hand, with most newer production tubes it's best to stay with the ratings.
Justin
Justin
"Music without emotion is noise."
Thanks Justin. I was looking at a schematic for a Bandmaster circuit and it showed 410VDC on the plates of 6L6G's with no screen grid resistors. I'm gonna try a pair of "coke bottles" for a while and see how they hold up.
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