Valve emitting hi freq sound

[farflungstar]

One of the driver 6sl7g valves in my Cary's has started to emit a very high pitched whining sound - like the old tone (but higher in frequency) when a TV channel went off the air. It rises then stops, then starts then stops after a while then starts again - whining away - I'm assuming it's f*cked?

Adey

In perpetual pursuit.

[anthonyTD]

Does sound like it!
As they age, their parameters change, and they go noisy, some make rumbling noises, some rustling, and some, well like yours!
Make sure though that its not picking up something thats near it, or plugged into the same circuit etc.
One of the driver 6sl7g valves in my Cary's has started to emit a very high pitched whining sound - like the old tone (but higher in frequency) when a TV channel went off the air. It rises then stops, then starts then stops after a while then starts again - whining away - I'm assuming it's f*cked?

Adey

In perpetual pursuit.

[farflungstar]

Well they're less than a year old, Shuguang Black Treasure series. If you shake it gently it rattles whereas the good one doesn't - put in my trusty old Phillips (hardly audiophile) but the whining has gone. One of them is a little noisy though, a slight hum and picking up a bit of RF. Typical just sold my RCA red base lol.
Adey

In perpetual pursuit.

[Jimbo]

Gone microphonic ?

[Arkless Electronics]

Presuming the sound is being physically generated by the valve itself and is not present through the speakers then a very rare case of the 6.3V AC heater supply causing audible resonance due to microphonics is the likely cause. If your amp uses DC for heaters then it's plain bizarre!

[agk]

I actually spent time looking for a mouse in a Rogers Cadet III due to rustling valves.

[farflungstar]

The sound was also coming from that monoblocks speaker tweeter and at first i assumed it was some weird interference and was checking cables like an idiot and scanning for taxis outside the house. but I realised i could also hear it in my other ear as I was listening to the tweeter and when the tweeter stopped I could still hear it in my other ear - the monoblock is very close and I followed the sound back to the Shuguang driver tube which was whistling happily away like a high pitched kettle, ebbing then rising in volume - the sound then coming back through the tweeter.

I've been realigning my new cart and the amps had been on for hours, mostly silent.

I removed the tube and replaced with an old Phillips tube. Silence. Gently shaking the Shuguang you can hear what sounds like when you shake an old filament style bulb that's broken. The other tube doesn't rattle or make any sound. I've replaced them both.

It's not microphonic.

In perpetual pursuit.

[anthonyTD]

Hi Adrian,
AS I said in the earlier post, valves can make all sorts of noises after they have been used a while, And I stick by what I said in the earlier post, their parameters change,ie; the internal structures can move slightly, tiny bits of the getter fall off the glass and get stuck between things, also; the gain with signal can change, making them more sensitive, and therefore more prone to self oscillation, etc, etc.
And if you can hear a rattle while shaking it, most of the time, its the bonding material they use to stick the valve base to the valve glass, sometimes bits fall off inside the base, hence the rattle.
Either way; you seem to have sorted it, and that's all that matters.
A...
The sound was also coming from that monoblocks speaker tweeter and at first i assumed it was some weird interference and was checking cables like an idiot and scanning for taxis outside the house. but I realised i could also hear it in my other ear as I was listening to the tweeter and when the tweeter stopped I could still hear it in my other ear - the monoblock is very close and I followed the sound back to the Shuguang driver tube which was whistling happily away like a high pitched kettle, ebbing then rising in volume - the sound then coming back through the tweeter.

I've been realigning my new cart and the amps had been on for hours, mostly silent.

I removed the tube and replaced with an old Phillips tube. Silence. Gently shaking the Shuguang you can hear what sounds like when you shake an old filament style bulb that's broken. The other tube doesn't rattle or make any sound. I've replaced them both.

It's not microphonic.

In perpetual pursuit.

[farflungstar]

The problem is I miss their sound! Kind of spoilt now. Not sure I want to shell out another €200 on a pair only for one to go bad in a year but their sound is the best I've heard of any 6SL7.

Adey

In perpetual pursuit.

[anthonyTD]

Speak with Marco, he has had a lot of experience with diffrent 6SL7's, and can hopefuly point you in the right direction.
A...
The problem is I miss their sound! Kind of spoilt now. Not sure I want to shell out another €200 on a pair only for one to go bad in a year but their sound is the best I've heard of any 6SL7.

Adey

In perpetual pursuit.