5F11 Tweed Vibrolux build with standby switch - risky?

[gkaada]

Hi all,

I am building a 5F11 Tweed Virbolux and I was thinking to add a standby switch using a Carling 110-63 SPST toggle switch.
I know this is commonly used as a standby switch, but looking at the rating stamped on the switch I am not sure if it can handle the voltage.
It says 250V @ 3A. I am using a Mercury Magnetics PT and the B+ will be more than 400 VDC (not sure of the current from the PT).
But wouldn't that be a bit risky? https://el34world.com/Forum/Smileys/default/dontknow.gif

Maybe cancel the standby and use the switch to toggle negative feedback on/off instead, any thoughts?
The hole for the switch is already in the chassis, so I would like to use it for something.

I was playing around with the DIYLC software and here is my layout diagram.

Would appreciate your advice and comments,

Thanks,
Geir


 

[sluckey]

Fender did not use a standby switch on the original. Why do you need one?

[Colas LeGrippa]

Just plug the hole with a metal cap made for that purpose. Some people think high voltage can t be applied to cold tubes. In case of an amp with a rectifier tube, by the time the rectifier warms up and yield full voltage, the other tubes are warm too. You can use the switch you re talking about to ground the firstbpreamp grid. It will mute your amp.


Jack

[PRR]

1) You do not need a standby switch

2) The Carling has served severe switch duty in Fenders and vacuum cleaners for 70 years. It will last a lot-lot longer than your current cell-phone or car (even my 2002). While it is not RATED for such use, that's just because it was not designed for large stress, it "just happened" from the size of the parts they used.

[gkaada]

Thanks a lot for the replies!

I have decided to cancel the standby switch and instead install an NFB control pot which I believe will be more useful to me.
Compared with other tweed amps, the 5F11 has an NFB loop and I would like to reduce some or all of this feedback on various occasions, but still keep the possibility for the stock 56K NFB resistor value and cleaner tone in other occasions.

Could someone kindly take a look at the attached layout and check if I got this right?
In general, I would appreciate any comment or advice on the circuit.

Many thanks,
Geir

[shooter]

looks like it'll not smoke anything
since 100k is bigger than 56k, I'd think you could just use the pot to dial your happy, including the original 56k

have you read this thread, might set off some lightbulbs, or give you knowledge
http://el34world.com/Forum/index.php?topic=25683.0;topicseen

[gkaada]

Thanks for the reply Shooter,

I had a look at the thread you recommended and see that it is related to presence control.
What I am trying to include is a variable control that will roll off the entire NFB signal, not only the high frequencies like a presence control.

However, I found a few other threads with good information and also a couple of weblinks and videos on Youtube.

Uncle Doug made a similar control in a 5F1, but he wired the pot differently as a range between 10k and 60k and changed the NFB resistor value, which is a way to go.

Here is a link to a page describing exactly what I am trying to achieve with a similar setup and wiring and I would prefer to do it this way. A 500k pot in addition to the 56k resistor should be more than sufficient to choke the NFB signal to near "OFF", just like a switch would do. But maybe a 250k or even a 100k pot will do the same trick and give a better range. I will test and see which value will work best.
https://guitar.com/guides/diy-workshop/diy-workshop-rift-amp-mod-part-2/

Thanks again,

Cheers,
Geir