Will this stress my rectifier tube?

[Tonegeek]

I tried asking this at 18watt.com but now something is broken over there and my login is rejected.

Can I move my first filter cap to the hot side of the standby switch? This is to simplifiy my wiring as I am adding a VVR. see pix:

[Phil_S]

It is common practice to charge the first filter cap with the standby switch. I have several amps built like this. Go ahead. IMO, this is better than puttiing it on the cold side of the s/b switch.

[paulster]

It'll actually stress your rectifier less as the inrush current will be lower.

The first cap will charge gradually as the voltage comes up as the rectifier heats and then the ones after the standby switch will be current-limited by the 1K5 resistor.

Bear in mind that your bleeder resistor is going to be on only one side of the standby switch and you'll have caps on both sides, though. It's not a problem technically, but you could be in for a surprise when you open the chassis if you don't think about it.

[Phil_S]

Good one Paulster. Yes, remember to close (set to on) the standby switch so the bleed resistor is in the circuit and make sure the amp is unplugged from the line supply.

[Tonegeek]

Bear in mind that your bleeder resistor is going to be on only one side of the standby switch and you'll have caps on both sides, though. It's not a problem technically, but you could be in for a surprise when you open the chassis if you don't think about it.

I actually thought of that and was going to add a high value resistor to ground on the cold side of the S/B switch after the mod for safety. Thanks guys, this is what I needed. I had seen the first filter caps on the hot side of S/B on amps with SS rectifiers, but had not seen it done with a tube recto. This is my first build of a tube rectified amp so I don't want to assume anything.

[Sonny ReVerb]

I had seen the first filter caps on the hot side of S/B on amps with SS rectifiers, but had not seen it done with a tube recto.

It was good enough for Leo (in a classic circuit, no less - AB763):

http://www.schematicheaven.com/fenderam ... _schem.pdf

[Structo]

The only problem with having the cap(s) on the hot side is that you will get a thump through the speakers when you throw the standby switch.

[Structo]

You could borrow from the D'Lite power supply and place a 150K to 220K resistor across the last filter cap to ground in the chain.

[Tonegeek]

You could borrow from the D'Lite power supply and place a 150K to 220K resistor across the last filter cap to ground in the chain.

That is an idea although I think the Dlite did that more to simulate the load of the FET cicuit in the real Dumbles.
I may have to play with my dropping string anyway since I am having to move the preamp filter closer to the rectifier to accomodate the VVR (only scaling the PA at this point). I suspect I will have too high a voltage at the pre's so strapping a resistor to ground at the end may actually help bring my voltages back in line and bleed off HV.

[Structo]

Correct about the FET simulator but as you mentioned you can also adjust the preamp voltage with it and as a bonus it acts as a bleeder.