Reckless Abandon
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Is it necessary?
biasing a class A amp.
- Thread starter Reckless Abandon
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Gearjoneser
Gear Ho
Re: biasing a class A amp.
Almost all EL-84 and 6V6 amps.....you simply buy tubes and put them in. It's usually Class AB EL-34 and 6L6 amps that include a bias pot.
Almost all EL-84 and 6V6 amps.....you simply buy tubes and put them in. It's usually Class AB EL-34 and 6L6 amps that include a bias pot.
Re: biasing a class A amp.
class of operation doesnt have much to do with it. bias type does. cathode biased doesnt need to be adjusted although some tubes will sound better than others. fixed bias (adjustable bias) need to be set properly to get the best tone and to make sure that you are roasting your tubes.
el84 amps tend to be cathode biased alot since there isnt much improvement by going fixed (fixed requires more parts & work to build, so cathode is cheaper). but lots of 6V6 amps (like fender deluxe) and even some el84 amps (fender blues jr) are fixed biased
class of operation doesnt have much to do with it. bias type does. cathode biased doesnt need to be adjusted although some tubes will sound better than others. fixed bias (adjustable bias) need to be set properly to get the best tone and to make sure that you are roasting your tubes.
el84 amps tend to be cathode biased alot since there isnt much improvement by going fixed (fixed requires more parts & work to build, so cathode is cheaper). but lots of 6V6 amps (like fender deluxe) and even some el84 amps (fender blues jr) are fixed biased
Fresh_Start
New member
Re: biasing a class A amp.
+1 on bias method, not class of operation, being the key point. However, "roasting" your power tubes is not recommended for longer life
Cathode bias is sometimes called "self adjusting" because that's essentially what the tube does using a capacitor/resistor network.
Fixed bias means that a negative DC voltage is applied to the input grid of the power tubes, and some amps provide the ability to adjust that negative voltage. Unfortunately, the Blues Jr. is fixed bias without an adjustment and probably IS roasting your output tubes...
Hope this helps more than it confuses,
Chip
+1 on bias method, not class of operation, being the key point. However, "roasting" your power tubes is not recommended for longer life
Cathode bias is sometimes called "self adjusting" because that's essentially what the tube does using a capacitor/resistor network.
Fixed bias means that a negative DC voltage is applied to the input grid of the power tubes, and some amps provide the ability to adjust that negative voltage. Unfortunately, the Blues Jr. is fixed bias without an adjustment and probably IS roasting your output tubes...
Hope this helps more than it confuses,
Chip
Reckless Abandon
New member
Re: biasing a class A amp.
lol.
It is a blackheart. The manual does not say cathode or fixed bias.
lol.
It is a blackheart. The manual does not say cathode or fixed bias.
Reckless Abandon
New member
Re: biasing a class A amp.
thanks
thanks
Kosh Naranek
New member
Re: biasing a class A amp.
I looked under the hood and I'll be darned if I can see anyplace to adjust the bias for my Crate Palomino V32H.
I looked under the hood and I'll be darned if I can see anyplace to adjust the bias for my Crate Palomino V32H.
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Kosh Naranek
New member
Re: biasing a class A amp.
I replaced the stock Sovtek power tubes with a quartet of Ruby EL84's. I'm not the most discriminiating and fussy-eared person but I think it sounds punchier with the Ruby tubes. It didn't improve the tone so much as the dynamics. The tone is great too.
Oh. That's cool.
I replaced the stock Sovtek power tubes with a quartet of Ruby EL84's. I'm not the most discriminiating and fussy-eared person but I think it sounds punchier with the Ruby tubes. It didn't improve the tone so much as the dynamics. The tone is great too.
Reckless Abandon
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