Bias dropped on 410H

[Kelster3000]

Hi there quick question…

My JVM was sounding a bit ‘mah’ he other day so I randomly checked my tube bias on my 410H and both sides were still balanced but dropped by a good 10ma since I last set it about over 8-12 months ago. I did change a couple of microphones pre amp tubes about a month ago.. and wondered whether this caused the drop? I set both side back to 74ma’s I’ll of course keep an eye on it over the next week just wonder if the pre amp tube change impacted on the drop…

 

[Ken Underwood]

"Very faint sound of the electrons boiling off"
George explain please

 

[TheKman76]

Negative. If the power valves are old or if there is a change in your local supply voltages you can expect this sort of thing.

Did it sound alright after re-biasing?

 

[Kelster3000]

It sounded fine after re-biasing.. the power tubes are about 5 years old.

 

[TheKman76]

That's a long way from new, does it get some use?

 

[Kelster3000]

That's a long way from new, does it get some use?

It certainly does, rehearsal once a week at pretty high volume (we are a loud band) .. plus a few home sessions at low volume throughout the week… so certainly used… I’ll expect a power tube failure at some point then…

 

[TheKman76]

Yup, perhaps plan to replace first. Or have them ready for when they go.

 

[PelliX]

"Very faint sound of the electrons boiling off"
George explain please

Thread crossed...

 

[Ken Underwood]

Thread crossed...

This gets more confusing by the minute

 

[PelliX]

This gets more confusing by the minute

I think you intended to reply to @George B Dickens in https://www.marshallforum.com/threa...vintage-style-tube-amp-be.135369/post-2425863

Then you hear the very faint sound of the electrons boiling off ?

That bit ^. Just happened to notice this by chance. And indeed, I too would love to know what sound boiling electrons make!

 

[Ken Underwood]

I think you intended to reply to @George B Dickens in https://www.marshallforum.com/threa...vintage-style-tube-amp-be.135369/post-2425863



That bit ^. Just happened to notice this by chance. And indeed, I too would love to know what sound boiling electrons make!

Yes you are correct, i would of hoped that George would have replied

 

[StingRay85]

Technically, an electron cannot boil. It doesn't have a melting point nor boiling point. We need to be on a molecular level to have these kind of physical effects ;-)

 

[Resident 217]

I had a ? I dont know what it actually is but there is a hiss sound I case only describe as lightly inhaling through ones nose.

 

[PelliX]

Yes you are correct, i would of hoped that George would have replied

Well, you replied in a different thread and didn't tag him, either - the only reason I noticed is because of the interesting concept of 'boiling off electrons'. Well, that and the fact I seem to spend too much time here with you guys.

@StingRay85 is right though - so, for argument's sake we can say that the sound of boiling electrons would be... absolute silence!

I had a ? I dont know what it actually is but there is a hiss sound I case only describe as lightly inhaling through ones nose.

The hiss is caused by a lot of things; EMI, interference on the power lines feeding the amp, etc. Even cosmic microwave background radiation from millions of years ago hitting us...

EDIT: Here, have a listen to 'how it all started'



In case you're wondering; that radiation is a large part of the 'snow' you used to see on your tele when between channels or without an aerial.

 

[Resident 217]

That's right now you got it.

 

[Kelster3000]

Conclusion —-Thanks guys it was the output valves going… I have a spare match quad set of PM Valves that I know are good but used, plonked them in rebiased and it sounds a million times better and a much fuller sound, than the old JJ El34 2 valves… funny how am amps sound can deteriorate over time without you realising!

The 5 year valves had developed a harsh trebly sound and a definite lack of balls…

 

[Spooky88]

I had the same issue with my JVM 205 recenlty

 

[TheKman76]

plonked them in rebiased and it sounds a million times better and a much fuller sound

Good result, sir. Too many electrons boiled off those ones, eh?

 

[Marcomel79]

Well, you replied in a different thread and didn't tag him, either - the only reason I noticed is because of the interesting concept of 'boiling off electrons'. Well, that and the fact I seem to spend too much time here with you guys.

@StingRay85 is right though - so, for argument's sake we can say that the sound of boiling electrons would be... absolute silence!



The hiss is caused by a lot of things; EMI, interference on the power lines feeding the amp, etc. Even cosmic microwave background radiation from millions of years ago hitting us...

EDIT: Here, have a listen to 'how it all started'



In case you're wondering; that radiation is a large part of the 'snow' you used to see on your tele when between channels or without an aerial.

Nonsense! Electrons CAN be boiled! I just made an electron soup! It was delicious

 

[Kelster3000]

Well all soup chefs know that boiling soup impairs flavour!