Amps and Preamps has standby, but should I turn them completely off?

I had a 1960 Fender Deluxe guitar amp that had caps that only lasted 45 years…damn…replaced them after noting some leakage (sounded fine with the leaky caps) and afterwards the amp sounded exactly the same. Lesson learned.

Damn Wolf, cream Tolex with Oxblood grill cloth? Great, great guitar amp.

The reason electrolytics need to be brought up slowly after a long sleep is because they will exhibit leakage current which multiplied by whatever voltage will produce some watts of heat. I dont think ESR is the main factor in caps exploding. It is best to form caps with a constant current which is sized to the cap. You can then watch a 350 volt cap charge rapidly to 200, slow down and grow to 350 in several minutes and then past its rated voltage to its surge voltage where things stop. Good caps can have this top voltage be 20-50% higher than the rated voltage. What voltage a cap was made to is not always what is on the label. I talked to an old timer at P R Mallory and got the good scoop on all this. Its the water in the caps that turns to steam that causes them to explode. Its also this water that dries over time and increases ESR. But even is ESR doubles I would not think that is a big contributor to heat. 

When you form a cap you are actually rebuilding the aluminum oxide layer to its original level. BTW this is why high voltage caps cost more because they need more plating time in the bath when being made. The plating process slows and cuts itself off at about 600 volts. That's why you dont see higher voltage caps. The surge has to be about 20-30% higher than the operating voltage for several reasons. 

I use a current of about 1 mA per 100 uf. depending on the physical size and the voltage I am going to. My examples are higher voltage because I make tube amps. 

Brown tolex and knobs, and weirdly somewhat underpowered not quite matching the supposed output rating…I've seen this exact thing in other Deluxes of that model, consequently it made a great recording or harmonica amp (miked of course), but even with an efficient speaker (like a JBL or Altec) you couldn't use it with a drummer unless it was pointed right at your head.  A real grease fest with great tremolo.

The Deluxe was suppose to produce 28 watts, but at what percent distortion? The cream and brown tolex Deluxe had somewhat different circuitry than the later black tolex (but still blackface control panel) version, with more overdrive/tube distortion at the same volume. It’s loud enough with the "right" drummer---like me ;-). I worked with a couple of guys who wouldn’t play out of anything but a Deluxe, Evan Johns being one (playing a Tele). The Deluxe Reverb had a tube tank, but the stand-alone Fender Reverb unit was better. They’re worth a lotta money now. I played with a guy whose set-up was a reverb tank into a brown Tolex Pro, halfway between the Deluxe and Twin, an amp I really dislike. Too loud, very piercing. And I have the tinnitus to prove it!