Screen grid muting

[Enzo]

Leaving the main reservoir caps charged at all times?

I wouldn't read too much into it. I do not worry about cathode poisoning anyway. They would poison or not whether the plate had voltage or not. With no screen voltage, the current would be zero either way.

[SoulFetish]

In those cases, it is mutting rather than muting.

Ha!

[SoulFetish]

Any thought to using a switch to AC coupling the two output grids together as a standby, and use phase cancellation to mute the signal? I suppose you would need perfect balance in the phase inverter to get the best attenuation, but I doubt if a little unbalance would be that noticeable. Its just an idea though, I've never used tried it in a build.

[uneumann]

Any thought to using a switch to AC coupling the two output grids together as a standby, and use phase cancellation to mute the signal? I suppose you would need perfect balance in the phase inverter to get the best attenuation, but I doubt if a little unbalance would be that noticeable. Its just an idea though, I've never used tried it in a build.

You'd also get phase cancellation in the OT - so PI balance should not need to be perfect. This is essentially a "MV turned to zero" implemented as a switch. Can't see why it wouldn't work as well as a post-PI MV.

[g1]

I believe someone does this as "mute" style standby, but I can't recall who.

edit: Ok, the one I was thinking of is Silvertone 1484, but there are probably others also.

[The Dude]

I believe someone does this as "mute" style standby, but I can't recall who.

edit: Ok, the one I was thinking of is Silvertone 1484, but there are probably others also.

[ATTACH=CONFIG]40026[/ATTACH]

I would have liked your post, but you made me download and rotate the schematic.

Edit: I see you fixed it. (In my best smart a$$ voice). That's better.

[g1]

Just turn your monitor.
Ok, I fixed it. I didn't like it sideways either, but the other copy I had took a long time to render so I didn't use it.

[Tom Phillips]

Just turn your monitor.
Ok, I fixed it...

[SoulFetish]

I believe someone does this as "mute" style standby, but I can't recall who.

edit: Ok, the one I was thinking of is Silvertone 1484, but there are probably others also.

[ATTACH=CONFIG]40027[/ATTACH]

Where do those BASTARDS get off stealing my idea 50 years before I have the chance to think of it!

[Gregg]

It looks like the Master in the Matchless Chieftan:

http://elektrotanya.com/PREVIEWS/634...verb.pdf_1.png

[eschertron]

Where do those BASTARDS get off stealing my idea 50 years before I have the chance to think of it!

I hadn't seen that before, so I didn't get a chance to steal it from you

But I see that crossing the two grids works just as well for fixed bias as it does for cathode bias. universally useful techniques are always good to have in the toolkit.

When I build a fixed bias PA, I'll try to remember not to ground the grids for muting

[SoulFetish]

I hadn't seen that before, so I didn't get a chance to steal it from you
:

All you have to do is wait another 50 years, and blame me for stealing it from you. That's how it works.
....If anyone gives you any shit about it, simply qualify it by following it up with a "I'm just sayin'..." and that makes it okay. Hopefully that still works in 50 years. If not, use this one: "well that's how I feel and you can't tell me my feelings are wrong". (Try and reason with that!) I learned that one from my ex wife. It's fighting dirty, but its a very effective defense when all the facts are stacked against you. You're welcome.

[octal]

When I build a fixed bias PA, I'll try to remember not to ground the grids for muting

Just re-label the mute/standby switch as "Redplating on/off."

[Gingertube]

We learn from our stuff ups.
I have a pair of HiFi monoblocks with a quad of EL34 in each.
Noticed a problem with one amp one day so had a look inside. One output tube running at 1.5mA whereas all the other were at the correct 45mA idle current.
That tubes screen connection had come off.
That tube was in standby by anyones definition.
Use screen disconnect standby with confidence regardless of if the screen just floats or has a tie to ground resistor somewhere.
Cheers
Ian

[soundmasterg]

I hadn't seen that before, so I didn't get a chance to steal it from you

But I see that crossing the two grids works just as well for fixed bias as it does for cathode bias. universally useful techniques are always good to have in the toolkit.

When I build a fixed bias PA, I'll try to remember not to ground the grids for muting

Silvertone's standby method of shorting the input grids of the power tubes together is an imperfect standby...as in when it is in standby you can sort of play....it sounds like really bad grid blocking with the sound coming and going and sounding farty.

Greg