Is 460v too high for the plates of JJ 6v6's in PP, cathode biased with a shared cathode resistor?
I don't want to swap the PT if its worth a try...
6v6 maximum safe plate and screen voltage
Moderators: pompeiisneaks, Colossal
-
statorvane
- Posts: 568
- Joined: Thu May 11, 2006 3:28 pm
- Location: Upstate New York
Re: 6v6 maximum safe plate and screen voltage
Plates should be good up to 500 Volts; screens to 450 volts. If you are running triode, 450 volts for both.
There is a link to the JJ data sheet on this page: https://www.tubedepot.com/products/jj-6 ... acuum-tube
There is a link to the JJ data sheet on this page: https://www.tubedepot.com/products/jj-6 ... acuum-tube
-
Stevem
- Posts: 5144
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: 6v6 maximum safe plate and screen voltage
With cathode bias the tube is only seing the difference between the plate voltage and the cathode voltage, so if for example you have the tube idling with 460 on the plate and 22 volts on the cathode the tube is then running at 438 volts.
JJ 6v6s will take that no problem!
JJ 6v6s will take that no problem!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: 6v6 maximum safe plate and screen voltage
Thanks for the advice
Re: 6v6 maximum safe plate and screen voltage
Give it a try out by all means, but be aware that cathode bias tend to doesn't work well with a high HT voltage, ie significantly higher than those typically suggested in the manufacturer's info
Note that all successful / popular cathode bias designs bias at, or more usually close to, class A.
Reason being that it's undesirable for cathode voltage to rise much from idle to max clean output, eg 25%. As even with that, when overdriven, cathode voltage may still near double its idle level. That, together with regular bias shift at the grids when overdriven, results in the high signal effective operating point being somewhat colder than the idle operating point.
If, as is usually necessitated by a high HT voltage, the idle bias point must be moved away from class A, the cathode voltage rise with signal will increase, and the high signal waveform and tonal quality may be perceived to worsen.
Hence fixed bias is almost universally used with a high HT voltage.
Note that all successful / popular cathode bias designs bias at, or more usually close to, class A.
Reason being that it's undesirable for cathode voltage to rise much from idle to max clean output, eg 25%. As even with that, when overdriven, cathode voltage may still near double its idle level. That, together with regular bias shift at the grids when overdriven, results in the high signal effective operating point being somewhat colder than the idle operating point.
If, as is usually necessitated by a high HT voltage, the idle bias point must be moved away from class A, the cathode voltage rise with signal will increase, and the high signal waveform and tonal quality may be perceived to worsen.
Hence fixed bias is almost universally used with a high HT voltage.
https://www.justgiving.com/page/5-in-5-for-charlie This is my step son and his family. He is running 5 marathons in 5 days to support the research into STXBP1, the genetic condition my grandson Charlie has. Please consider supporting him!
Re: 6v6 maximum safe plate and screen voltage
THIs is a very old thread but I have a similr question.
I want to run 6v6s in a super Reverb. Ias going to buy JJs but THe poeple at the retailler's told me the Gold Lions ( current prod ) were just as tough.
I can bias them to around 21ma but then I have a plate voltage of 462V
Are they going to explode ?
Thanks
I want to run 6v6s in a super Reverb. Ias going to buy JJs but THe poeple at the retailler's told me the Gold Lions ( current prod ) were just as tough.
I can bias them to around 21ma but then I have a plate voltage of 462V
Are they going to explode ?
Thanks
-
Stevem
- Posts: 5144
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: 6v6 maximum safe plate and screen voltage
What’s your reason for running 6V6s in that amp?
You always seem to want to run different tubes in an amp then what it designed to run, why is that?
Why don’t you just get a amp made for the tubes that you want?
You always seem to want to run different tubes in an amp then what it designed to run, why is that?
Why don’t you just get a amp made for the tubes that you want?
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: 6v6 maximum safe plate and screen voltage
If you are looking to reduce the power output of a Super Reverb, disconnect two of the speakers or change all of them to 16 Ohm. Then you won't be changing the 6V6s every other month.
-
hebaton
- Posts: 317
- Joined: Sat Jun 26, 2021 5:50 pm
- Location: Saint Paulin Canada
1 others liked this
Re: 6v6 maximum safe plate and screen voltage
I actually got it going with 6v6s this mornig, I put a 5U4 instead of a Gz34 for lower voltage. But I didn't like what it did for the feel and response of the amp...
Re: 6v6 maximum safe plate and screen voltage
I have run JJ 6v6 at 450 volts but to my ears it didn't sound as good as when run at 350 volts.
Mike
Mike