Standby switches

G

GuitarDoc

Bacteriaolgoist
Why do amps have a separate standby switch? Why not a 3 position power switch that goes from "off" to "standby" to "on"?
 
Standby switches are mostly decorative . . . so probably the answer is that they've always been like that.

A better question is 'why do amps have a standby switch at all when they're not necessary at all for a tube amp to work properly, you can just turn them on and play fine after 15-30 seconds without the useless switch.'

:P
 
Are modern amps with a standby switch designed that way for a specific reason? Is 'tradition' the only reason? It seems silly that companies would spend the money to include a useless switch in an amp just because it has always been that way. I really never thought about it much, but it is a weird thing that people still believe in and companies still put into designs.
 
The real question is why does sound still come out the amp when the standby switch is on?
 
My guess would be the removal of the high voltage function is at a different place in the circuit from the main power on, so putting all that on one switch overcomplicates things. I'd have to peruse a schematic to confirm.
 
Mincer said:
Are modern amps with a standby switch designed that way for a specific reason?
Click to expand...

Nope.

Mincer said:
Is 'tradition' the only reason?
Click to expand...

Yep.

Mincer said:
It seems silly that companies would spend the money to include a useless switch in an amp just because it has always been that way. I really never thought about it much, but it is a weird thing that people still believe in and companies still put into designs.
Click to expand...

Yep. It is silly. But guitar players hate change, so it's easier to put the switch in then try to explain that it's not necessary.
 
Last edited:
GuitarDoc said:
Why do amps have a separate standby switch? Why not a 3 position power switch that goes from "off" to "standby" to "on"?
Click to expand...

Bogners do. Couple others. Standby allows the heaters in the tubes to warm the tubes before zapping them with 470 vdc and damage the tube potentially. Also comes in handy during cold weather.
Don't want it / dont use it.
 
Mincer said:
Is 'tradition' the only reason?
Click to expand...

I would say yep!


The actual reason for standby switches. It’s all about the capacitors!

As the public asked for louder amplifiers, Leo Fender began to build amplifiers with higher power supply voltages. When first turning on the amplifier and before the tubes are warm, tubes do not conduct high voltage, so there is no “load” on the power supply. This phenomenon would allow voltage to rise above the maximum voltage rating for the large capacitors used in the circuit, putting them at risk of shorting out from the stress. This was especially true when Fender started to use solid state rectifier diodes that provided power supply voltage instantly when the mains power was turned on.

While the tubes are warming up, the standby switch removed the high voltage from the circuit until the tubes filaments were warmed up to operating temperature and the power supply voltage would be loaded down by the tubes to the nominal safe operating voltage for the capacitors.

Sure, Leo could have installed much higher voltage rated capacitors that could safely handle the voltage rise, but these were very expensive back in his day. His company’s goal was to produce high quality, but lower cost amplifiers (and guitars), so keeping the price down was important to him. Therefore, the standby switch was a cost-saving design feature much cheaper than the alternative very expensive capacitors.

It’s as simple as that. Why else would you use something that often pops loudly in the audio when used (remember I mentioned it cuts off the high voltage)? By the way, other brands did not use standby switches until Marshall copied Fender’s Bassman amplifier design and after the two biggest makers used these standby switches, everyone assumed you always had one on a guitar amp. Often, designers put these on amplifiers only because the public asks for them, not that they are needed. This is due to the power of the myth! These days we have other devices available to protect the capacitors and in general capacitors are much cheaper now and can be made to run at higher voltages without great cost.

https://www.sweetwater.com/sweetcare/articles/great-standby-switch-myth/
Click to expand...
 
When Fender was making amps in that era, he was known for running higher voltages and using caps that were just capable of handling those voltages. When caps are run at or very near their rated voltage, their life is rated in minutes as opposed to hours. go over that voltage and if it doesn't go boom you are lucky.

I think for him it sped up maintenance and set-up time. You shouldn't be hot-swapping tubes, but with the standby switch it gives you this false sense of security that you can. The only truly positive thing I think it can do is allow you to swap the speaker cab out while you still have the amp on. But if that is your only real reason for it, then whats the point?

There are certain designs that do benefit from a standby switch, but you can emulate a standby switch using parts and labor that cost less than it does to install a standby switch, and or eliminate the need for it altogether. The standby switch is such a thing of ubiquity that companies utilize one simply because of that fact alone. The amps that

I made a video on it recently: https://www.youtube.com/watch?v=GXvZIHpIEuU
 
Actually come to think of it, I only really use a standby switch so that I can rearrange my pedals or unplug/plug guitars that don't have silent plugs.

That popping noise otherwise is awful.
 
Mincer said:
Are modern amps with a standby switch designed that way for a specific reason? Is 'tradition' the only reason? It seems silly that companies would spend the money to include a useless switch in an amp just because it has always been that way. I really never thought about it much, but it is a weird thing that people still believe in and companies still put into designs.
Click to expand...

They are 100% unneccesary.

However as to not including it as someone who builds amps I can tell you from first hand experienc people get very uneasy and dont really buy amps when they don't have a standby switch.

I wire mine as an actual mute switch. Another reason to not have a standby switch is how theyre typically wired theres 450-500vdc across the switch while switching. The switches used are only rated to 125-250vdc and some dont even have a DC rating at all.
 
I thought they were more useful on SS rectifiers since you get a fast power up. The tube rectifier gives you a slower HV ramp up.

But I was shocked (lol) when I realized that no, they aren’t really needed.
 
I was playing the Fender Excelsior yesterday, and I really didn't notice or care before, but there is no standby switch on it. It is only 13w, and it is supposed to emulate a 50's amp in sound. looks and function. As I recently found out standby switches did not gain widespread popularity until the 60's.
 
Might as well discover master volumes and pentode/triode switches are useless while you're at it.
 
You must log in or register to reply here.
Back
Top