Stand By Switch

Ted Keane

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Why doesn't every amp come with a stand by switch?I think it's mainly for tube amps.But I use it to change guitars,pedals,ect.Any ideas?
 

Steve Holt

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No idea. I do remember reading about why some amp makers chose to include them and others didn't, though I can't remember any of the guts.

And once I posted a thread about how cool I feel when I use an amp with a standby switch. It's a small pointless pleasure that I really enjoy.
 

King Fan

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A true *mute* switch is handy. The "standby" switch wasn't developed as a mute switch, and though still used by thousands of guitarists and some big amp companies who think it'll 'protect the tubes' it's actually not helpful, and possibly harmful to tubes.

To this day we see lots of threads defending its benefits -- but then we see nearly as many arguing about what those are.

Good (and authoritative) discussion here.

http://www.valvewizard.co.uk/standby.html
 

Rich_S

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The only amps that really need a standby switch are tube amps with solid state rectifiers. In these amps, the high voltage comes up as soon as the amp is powered on, and the standby switch keeps the voltage off the tubes until their filaments are warmed up. Amps with tube rectifiers don’t really need them, since the recto tube takes as long to warm up as the rest.

When I built my 18 Watter clone, I put the power switch on the back (Fender-style) to keep all the AC power in the back corner, away from the audio circuits. But I put the standby switch on the front (Marshall-style) to keep it handy for set breaks and the like.

However, I use the tuner on my pedalboard to mute the rig for guitar changes.
 

King Fan

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The only amps that really need a standby switch are tube amps with solid state rectifiers. In these amps, the high voltage comes up as soon as the amp is powered on, and the standby switch keeps the voltage off the tubes until their filaments are warmed up.
I've often heard this, I respect your idea, and I don't know enough about SS rectification to comment. OTOH, Merlin doesn't make an exception for diode rectification, and his data on the *total* absence of cathode stripping at guitar amp voltages seems to say that voltage hitting cold tubes isn't actually harmful. I'd need a factual article like Merlin's that showed the *reason* it would matter with an SS rectifier.

I do see a whole lotta folks who just *feel*, intuitively, that tubes should be warmed up before use. But if there's a reason besides the (incorrect) theory of cathode stripping, I haven't seen it. The *main* other reason cited by defenders of standby is to "protect the caps" from current inrush. But as our wise friend @Wally said somewhere, if cap damage from inrush was a thing, how come all those old directly-heated tube rectifiers didn't damage caps?

Again, I'm no expert. In a world where a huge portion of users, some amp 'gurus', and several prominent amp manufacturers tell us standby is needed, I don't criticize people for their beliefs. But the opinions I trust are the ones from experts like Merlin or Wally who cite evidence.
 

Wally

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@King Fan, I appreciate the mention. However, I am nowhere close to being on the same level as Merlin. I am a ‘shade tree mechanic’ whereas he is an electronic engineer…or so I would guess.
A standby switch can be a handy thing. It is not needed to warm tubes up since it takes 10,000 volts to cause cathode stripping. Extended standby times can cause a deterioration of the cathode through what is called cathode poisoning.
to change instruments or pedals, one need only unplug the instrument cable from the input on the amp or turn the input stage gain/volume to zero. A standby is handy for changing speakers.
 

King Fan

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@King Fan, I appreciate the mention. However, I am nowhere close to being on the same level as Merlin.
LOL Wally, you and Merlin are both people I trust, but I didn’t name you here to make you blush. :) My point was you both cite evidence and logic and *reasoning.* I recall your argument about cap current inrush in old amps as a great example of all three.
 

takauya

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I trust what techs say.


It's just a handy tool. I don't use it with my amps when I power it up, but I'd use it on others because they'd upset if I didn't.
And tbh, I wasn't following the rule; warming up tubes, blah blah, even before I learned the correct info on the net. 😅
 

Paul G.

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Since you have to reach back to your amp to engage a standby switch, why not just pull the cable halfway out of the jack? That's what I do. Works a treat, no stress on the amp.
 

Paul G.

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They were used everywhere. TVs, radios, amps, lab equipment, organs, tanks, fighter jets....no standby switches.
One of the main reasons we still have tube manufacturing in China, Russia and former Soviet states is because MIG fighter planes continued to use tubes in their radar and communications into the 1980s.

Tubes are less susceptible to EMP, and thus jamming, while powerful tube-based radar systems can burn through conditions that SS couldn't.
 

roeg

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If you love your speakers. I'm pretty convinced when i pull that 1/4" jack plug, my speaker coils are thanking me for not seeing that loud transient spike that can occur.
Voice coils are known for giving up the ghost over loud spark-like transients, from dead quiet.
My belief in the practicality of a standby switch on a loud amp.

If you say turn down the guitar volume, think again.:oops:
 

AAT65

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If you love your speakers. I'm pretty convinced when i pull that 1/4" jack plug, my speaker coils are thanking me for not seeing that loud transient spike that can occur.
Voice coils are known for giving up the ghost over loud spark-like transients, from dead quiet.
My belief in the practicality of a standby switch on a loud amp.

If you say turn down the guitar volume, think again.:oops:
That is a good reason -- for those that swap speakers live. Wally also mentioned it:
A standby is handy for changing speakers.

Not so relevant for combos though. 😕 (I know, there are extension and external speaker sockets on many combos.) Maybe they should label it a "Speaker Mute" switch and put it down by the speaker jack sockets if that's the only solid reason for using it.
 

King Fan

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Seems like a useful thread could be built around design options for a simple mute switch.

Merlin admits standby does provide a mute function: “…but you could just ground the volume pot wiper or something.”

FWIW, I *think* Merlin isn’t saying brief use (like swapping guitars) is actually harmful in terms of cathode poisoning, the real-world opposite of ‘specious' cathode stripping. He seems to say the harm occurs with longer (true standby) use. I’d especially worry if I forgot and left my amp in standby overnight or something. But none of my amps have standby, and I now swap guitars with the 'silent plug' on my cable.
 
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northernguitar

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Seems like a useful thread could be built around design options for a simple mute switch.

FWIW, I don’t *think* Merlin says brief use (like swapping guitars) is actually harmful in terms of cathode poisoning, the real-world opposite of (non-issue) cathode stripping. I think he says the harm occurs with longer (true standby) use. But heck, I now swap guitars with the 'silent plug' on my cable.
I have a 'silent pedal' (Polytune).
 




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