The amp that wouldn't stop singing

[Justinginn]

So how weird is this:
A few minutes ago I was playing my guitar and put my amp on standby but kept noodling for a few seconds and I thought I heard some distortion on my playing, even though the amp was on standby. Sure enough, when I put my head right up next to it, I heard it playing extremely softly, but still playing. An amp that plays even in standby? 
So does anyone know what's up? It's probably been doing this for a while and I'm not very concerned because my amp's sounding better and more consistent than ever but if it's something I should be concerned with, I thought I might as well ask. Thanks for yall's help, guys.

 

[Mor Paul]

What amp?

 

[mayfly]

Depending on how the standby is implemented, I would not worry about it.

 

[erogenousjones17]

My Peavey does the same thing. It's probably not a big deal, though it is a little odd at first.

 

[Justinginn]

Traynor YCV50. A bit like a JCM800, I hear, though probably gained down a little. Best dang amp I'VE ever heard and that's saying a lot because we're talking $650 here. If you need an amp, buy one soon because they're going out of production.


Yeah I'm sure it's fine but I though I'd check here/share my (obviously not so unique) story.  ccasion14:

 

[Cagey]

Putting a tube amp on standby generally just opens the center tap on the primary of the output transformer, which takes the high voltage supply off the plates of the power tubes. Depending on the amp, the preamp's plate supplies may or may not be interrupted as well. If not, then you might hear the tubes singing a bit in response to any input that comes in. It just doesn't make through to the output.

It doesn't hurt anything, and isn't anything to worry about. It's just a side effect of some amp designs.

 

[mayfly]

Traynor YCV50. A bit like a JCM800, I hear, though probably gained down a little. Best dang amp I'VE ever heard and that's saying a lot because we're talking $650 here. If you need an amp, buy one soon because they're going out of production.


Yeah I'm sure it's fine but I though I'd check here/share my (obviously not so unique) story.   ccasion14:

I Checked the schematic - I could see it happening.

Nothing to worry about.

 

[fdesalvo]

Putting a tube amp on standby generally just opens the center tap on the primary of the output transformer, which takes the high voltage supply off the plates of the power tubes.

It actually creates an open in the high voltage supply feeding the filter capacitors.  These switches are usually placed immediately after the rectifier tube/diode arrangement, which is why the rectifier still sees full power even while on standby.  Besides from that, the only other places you should expect to see voltage while your amp is on standby would be on your tubes' heaters.  

 

[Cagey]

Putting a tube amp on standby generally just opens the center tap on the primary of the output transformer, which takes the high voltage supply off the plates of the power tubes.

It actually creates an open in the high voltage supply feeding the filter capacitors.  These switches are usually placed immediately after the rectifier tube/diode arrangement, which is why the rectifier still sees full power even while on standby.  Besides from that, the only other places you should expect to see voltage while your amp is on standby would be on your tubes' heaters.  

That would work, and I'm sure some amps do it, but I've not seen it. I suspect it's hard on the filter capacitors.

 

[fdesalvo]

I haven't seen it any other way.  I'm familiar with Fender, Marshall, and Mesa topologies.  All of my homebrews are set up like this. To my knowledge nothing short of AC is really hard on those caps.  Here's an example- the rectifier board is on the lower right hand side of the chassis.  You can see the secondary taps of the PT ffeding it and from there, it goesto the standby switch and off to the first filter cap.  Sorry for the poor pic quality and this is a prototype used for testing diff preamp/poweramp topologies.

Im perplexed as to how the amp is still passing a signal.  The heaters are boiling electrons from the plates and maybe there is a small amount of input signal passing? 

 

[Cagey]

You're right. I went through a bunch of schematics from Marshall and Fender, and they're wired the way you say. I don't know what I was thinking about. So, that's an "awshit" for me, which wipes out all the attaboys I've collected to date <grin>

 

[fdesalvo]

lol get outta here with that.  I have awshite moments everyday!  ccasion14:

You're right. I went through a bunch of schematics from Marshall and Fender, and they're wired the way you say. I don't know what I was thinking about. So, that's an "awshite" for me, which wipes out all the attaboys I've collected to date <grin>