Cameron Amplification Plate Voltage

  • Thread starter Thread starter Rocker68
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Rocker68

Rocker68

Active member
Not modded Marshalls , but the ground up build .
Curious if his plate voltage was north of 500 VDC
consistently like Bogners .
Your observations ?
Any way to reduce this without affecting heater voltage ?
 
Typically, yes... 500-530v from what I've seen.

Yes, you can reduce preamp voltages and there are ways to reduce Vp on octal sockets as well. But why?
 
You just have to burn it off with high wattage flameproof resistors. It will sound and feel different though - nothing is for free.

I’d go to Mercury magnetics and ask for a small step down transformer and step it down before you rectify it. Safer than burning DC power just for the sake of doing so and you don’t touch the heater voltage.
 
What is so wrong about reduced heater voltage? You could easily use a variac to reduce it although I agree with the above…why?
 
SpiderWars said:
What is so wrong about reduced heater voltage? You could easily use a variac to reduce it although I agree with the above…why?
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Cathode poisoning. You try to strip electrons from something that’s not hot enough and you’ll take the plating off of it, causing impurity deposits all over everything degrading tube life, and reducing the vacuum at an expedited rate.
 
glpg80 said:
Cathode poisoning. You try to strip electrons from something that’s not hot enough and you’ll take the plating off of it, causing impurity deposits all over everything degrading tube life, and reducing the vacuum at an expedited rate.
Click to expand...
Yeah I’ve read that I just haven’t experienced it that I know of. My main amp at home is variac’d to 90vac and tubes seem to last a long time. It’s almost like they’re not even trying except the load box gets hot af. The amp itself just cruises along.
 
SpiderWars said:
Yeah I’ve read that I just haven’t experienced it that I know of. My main amp at home is variac’d to 90vac and tubes seem to last a long time. It’s almost like they’re not even trying except the load box gets hot af. The amp itself just cruises along.
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I have a theory that it happens due to hot and cold spots on the filaments. I think someone would have to be hard pressed to notice it sporadically playing here or there but it’s definitely possible to see a reduction from 8,000 hours to 5,000 hours.
 
glpg80 said:
I have a theory that it happens due to hot and cold spots on the filaments. I think someone would have to be hard pressed to notice it sporadically playing here or there but it’s definitely possible to see a reduction from 8,000 hours to 5,000 hours.
Click to expand...
That would make sense, a slow degradation that’s difficult to discern from ‘decay just cranking the damn thing all the time”.

I remember it being some sort of death knell on the old Music Electronics forum 25-30 years ago. But then again back then anything Jose/diodes was heresy/garbage no way it can sound good. So that’s why I just went with personal experience.
 
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