Tube Amp - Standby Switch Position

[Whoops]

Let's just forget the switch itself for now, because I can buy a proper AC or DC switch in case it's needed.

Operation wise it's better to have the standby at position 1 on the AC side before the solid state rectifier,
or on the DC side after the Rectifier and C1 and C2, similar to the Fender standby?

Thanks

 

[PRR]

Do it Fender style.

Before the main filter caps is HUGE charging surge.

Some amps simply short the two power grids to each other. The amp goes silent, which is typically all you need. "Tube life" is NOT extended by killing B+ 20 minutes each hour.

 

[Whoops]

Do it Fender style.

Before the main filter caps is HUGE charging surge.

Some amps simply short the two power grids to each other. The amp goes silent, which is typically all you need. "Tube life" is NOT extended by killing B+ 20 minutes each hour.

Thank you

 

[CJ]

here is a hi-tek solution, used on a Laney that just came in,
running 485 DC thru a relay rated at 30 VDC at 16 amp, go figure...

has a time delay also

 

[CJ]

relay shown next to the Laney logo,

nice chrome chassis,

 

[trobbins]

The Omron relay contact is effectively in an AC circuit, as the current drops to zero between each conduction pulse.

That relay contact actually has a 440VAC max switching rating, in addition to a 250VAC 10A continuous rating, so its not too bad a choice.

Perhaps an NTC thermistor in series with the contact would alleviate contact degradation over time, especially from contact bounce.

PS. changing the relay coil suppression diode from a 1N4007 to including a series 12V zener or similar will also help in two ways - it makes the 'contact opening' a faster operation, and alleviates any contact sticking that may have arisen during the 'contact closing' action.

 

[lordraptor1]

Do it Fender style.

Before the main filter caps is HUGE charging surge.

Some amps simply short the two power grids to each other. The amp goes silent, which is typically all you need. "Tube life" is NOT extended by killing B+ 20 minutes each hour.

i need to clarify something to all of you on this even though it is an old post and that is the schematic in the op is the schematic from 1980 and already shows the standby switch ala fender AB763 9 look a little urther right at point 7 to find your oem standby switch position, and note the other end of switch goes to ct of opt same as the fender AB763. so, i dont know why anyone would need to mod the standby switch considering it worked for on fender amps for decades on a number of their amps. the only reason i would mod anything with the standby switch is if it was not as shown in the 1980 schematic. to be honest unless you are gigging there is no reason to even use the standby switch just leave it on, and if you are a gigging musician i suspect you would only use the standby while n breaks correct? if that is the case then we are talking what 10-15 minute breaks? if that is the case the way it is done in the 1980 schematic is fine and no need to be modded, however if you are a gigging musician and are taking extended break 9 say 30 minutes then just turn the amp off and come back a little early from your break to turn the amp back on and let it warm back up.

i was researching this exact topic and was finding multiple sources citing to "do it like fender did it" while schematics for fender AB763 schematics were used as reference only to look at the bolt 60 schematic (dated 1980) to find the standby switch already showing as same to fender in that one side standby connected at point

 

[Estomagado]

Ok guys, it's 2021 and we're still talking about stand-by switches. Why?

Here's the almost famous Valve Wizard article about how they are useless, dangerous and harm your valves:
http://www.valvewizard.co.uk/standby.html

 

[grid_stopper]

Ok guys, it's 2021 and we're still talking about stand-by switches. Why?

Because they are a useful tool when servicing the amp, plus if you ever try to sell an amp most people want/expect a standby switch regardless of the truth of the matter and removing the standby switch would no doubt hurt resale value. Seems like an oddly combative first post to make on a forum where sharing information and discussion methodology is the primary aim...

 

[Tubetec]

An improperly used standby may well be a waste of time ,but no standby and applying full unloaded HT volts to cold valves damages the cathodes , Ive seen many examples of this over the course of nearly 30 years repairing tube amps , I cant be arsed arguing or trying convince anyone otherwise ,believe what you like .

 

[groovyloop]

"Tube life" is NOT extended by killing B+ 20 minutes each hour.

but STAND BY switch burn on DC side... go to the AC side...

 

[Whoops]

This thread was already solved in 2016

 

[okgb]

Was this conclusive? Is it a placebo ? then what harm ? can it be harmful?
Tubes seem a lot crappier these days [ and more expensive ] It makes me question whether I should even turn my tube amps on or just use something else if it doesn't matter.

 

[groovyloop]

This thread was already solved in 2016

as you could see no

 

[groovyloop]

Was this conclusive? Is it a placebo ? then what harm ? can it be harmful?
Tubes seem a lot crappier these days [ and more expensive ] It makes me question whether I should even turn my tube amps on or just use something else if it doesn't matter.

Some amps(combos) disconnect the EARTH!!!! (Peavey Classic-50 etc.)So when you need to repair it - you might be killed by the high voltage... So, please, place STAND BY switch on AC side and you will never need to replace the switch

 

[Estomagado]

Seems like an oddly combative first post to make on a forum where sharing information and discussion methodology is the primary aim...

I'm sorry that was not my intention, and you are right about users' expectations. But, still, standby switches do more harm than good. I am always baffled that people still regard them as necessary.

Amp makers should implement a mute switch on the front panel, and hide the standby switch inside the chassis for maintenance purposes only. And use marketing to spread the new gospel.

Anyway, I'm awfully sorry if I offended anyone. Again, that was not what I intended.

 

[JohnRoberts]

Some amps(combos) disconnect the EARTH!!!! (Peavey Classic-50 etc.)So when you need to repair it - you might be killed by the high voltage... So, please, place STAND BY switch on AC side and you will never need to replace the switch

I am pretty sure the Peavey amps are UL approved so chassis would be bonded to earth or safety ground (at least for the last several decades).

I recall one musician last century who was killed while playing a Peavey guitar amp that was plugged into a mis-wired (reverse polarity bootleg ground) outlet that energized the safety ground and amp chassis. That amp was UL approved and they defended the design in court.

JR

 

[groovyloop]

I am pretty sure the Peavey amps are UL approved so chassis would be bonded to earth or safety ground (at least for the last several decades).

I recall one musician last century who was killed while playing a Peavey guitar amp that was plugged into a mis-wired (reverse polarity bootleg ground) outlet that energized the safety ground and amp chassis. That amp was UL approved and they defended the design in court.

JR

I replace the power caps this summer on Classic-50 and its STANDby switch still disconnect the ground from power tubes but leave the high voltage on anodes inside the chassis. I do not know why they did that...

 

[JohnRoberts]

I am not the tube guy here but in general I'd suggest, do not poke around inside a tube amp while it is plugged into mains power.

JR

 

[xazrules]

I’ve taken 350 to 450v multiple times with a 60’s amp without earth connection and the death cap, I think I’ve loose a fair amount of neurons because of that. So bypass switch on ac side and chassis ground first. Case closed!