Newbie tube amp question(s)

[Grinderman]

When shutting down it makes no difference if you go straight to switch off without first switching to standby. I think most people, including me, have just got into the habit of using standby when switching in both directions (or or off).

Likewise, pulling the IEC plug out before switching off won't harm the amp and some people claim that's actually a good idea because it is said to bleed the large power supply capacitors more quickly. I dunno about that. It seems to me that could be useful if one were planning on poking around inside the amp but otherwise it's probably irrelevant.

It a good habit to help be sure the amp is in standby before powering it up again next time/later.

I've always also had a habit with tube Ampegs I've owned to switch to standby, pause for at least a moment, if not a minute or two, then power off.

Being in rush to go somewhere else or do something else and playing bass, especially with a big tube amp, don't typically or naturally go hand in hand. If I'm that busy with other tasks I'm probably not also juggling noodling on a bass between things.

Playing out, same.

 

[FronTowardEnemy]

I have a Fender Super Bassman and and Ashdown Little Bastard. The SB has a standby, the Little Bastard doesn’t. I hit the standby first on the SB and then the power switch. With the little bastard, I just flip the power switch off.

Guess it depends on what amp you are using.

 

[mike buzzetti]

The Great Standby Switch Myth - SweetCare
Interesting read FYI

 

[KenD]

The Great Standby Switch Myth - SweetCare
Interesting read FYI

Mostly true but I still think it's not a bad idea to allow the tubes to warm up before hitting them with full B+ (the article, in fact, alludes to that).

 

[agedhorse]

There are multiple pluses and minuses, and there are standby switches that do additional things as well (including ramping up/down the high voltages over time).

 

[darkwasthenight]

Ashdown CTM-30 Little Stubby. I’m guessing the low wattage didn’t require a standby because even the CTM-100 has a Preheat switch. Although Ampeg’s PF-20t has one…

I had a Fender Musicmaster which was similarly low wattage and no standby. Suspect that was just a way of keeping the price low at the time though!

 

[Old Garage-Bander]

So.... when shutting down my new Prodigy, do I need to let it cool off
in standby before shutting down the power or do I go straight to the on/off switch?
Also, when/if I remove the instrument cord from the front, do I need to be in standby or mute or just turn down the volume to "off". thanks!

Doesn't matter for shutdown.
All work for pulling the plug.

 

[stevensivak]

and to think that I thought this was a noob question!

 

[Old Garage-Bander]

I hit the standby first on the SB and then the power switch.

If you turn the standby switch on first, isn't that like not having a standby switch at all, other than wearing out the standby switch for no additional benefit to you or the amp? The standby switch controls high voltage applied to the tubes. If the power switch is off there is no high voltage to control with the standby switch.

The intended use of standby switches in transmitters, where all this noise seems to have started, was to turn on power so the filaments could warm up, then take the transmitter out of standby to apply the high voltage.
Power first, standby second.

 

[FronTowardEnemy]

If you turn the standby switch on first, isn't that like not having a standby switch at all, other than wearing out the standby switch for no additional benefit to you or the amp? The standby switch controls high voltage applied to the tubes. If the power switch is off there is no high voltage to control with the standby switch.

The intended use of standby switches in transmitters, where all this noise seems to have started, was to turn on power so the filaments could warm up, then take the transmitter out of standby to apply the high voltage.
Power first, standby second.

With the Suoer Bassman the standby switch needs to be “on” in order for the auto bias to function. Once you take it off standby the auto bias kicks in, then your good to go.

While powering down, I just hit the standby switch and shortly after kill power. I thought that is how it works.

As for the LB-30, no standby at all.

 

[Old Garage-Bander]

With the Suoer Bassman the standby switch needs to be “on” in order for the auto bias to function. Once you take it off standby the auto bias kicks in, then your good to go.

While powering down, I just hit the standby switch and shortly after kill power. I thought that is how it works.

As for the LB-30, no standby at all.

Well yes. You can't measure bias without high voltage being applied to the tubes.
The primary function of the standby switch is to apply high voltage to the plates of the tubes so that the auto-bias circuits have something to measure.

Did Ashdown thumb their nose at Leo, RE a standby switch?
Or did they save a couple of bucks by not putting in something that wasn't needed?

But in the interest of following the manual, you should always do that regardless of what you read on the internet.
If I understand the consequences of varying from the instructions and am willing to accept the cost$ of doing so, then that's on me. YMMV.

 

[mike buzzetti]

I seem to remember >>>??? that one amp I had or built used the heater on/off for standby ??

 

[Patrice B]

So.... when shutting down my new Prodigy, do I need to let it cool off
in standby before shutting down the power or do I go straight to the on/off switch?
Also, when/if I remove the instrument cord from the front, do I need to be in standby or mute or just turn down the volume to "off". thanks!

Do like me and let it in standby for all the week-end Did it by mistake last fall with my tube amp in my music classroom. I hope the Board is well insured No harm but four EL34’s with only heater power is kind of « hot » three days later!

 

[stevensivak]

No thanks!

 

[agedhorse]

Do like me and let it in standby for all the week-end Did it by mistake last fall with my tube amp in my music classroom. I hope the Board is well insured No harm but four EL34’s with only heater power is kind of « hot » three days later!

Not nearly as hot as with the plate supply connected.

 

[stevensivak]

Thus?

 

[agedhorse]

Thus what?

 

[Wasnex]

Did Ashdown thumb their nose at Leo, RE a standby switch?

No. Only the smaller tube amps like LB30, CTM 30, Little Stubby etc lack the standby. Perhaps it's because they are cathode biased.

The bigger Ashdown tube amps have standbys.

 

[Patrice B]

Not nearly as hot as with the plate supply connected.

No but not too safe neither Fortunately, all electrolytics were replaced… An old electrolytic spewing its gut inside and burning is… interesting. Happened to me twice (I guess there are still a bit of current inside the e caps even in standby?):

- with a Voice of Music 6AQ5 amp I’ve started, then received a long phone call, to witness a beautiful smoke and liquid spill…

- with a « new » no name cheap electrolytic in one of my amps. There were sparks and fumes and could had started a fire but I was there.

 

[agedhorse]

No but not too safe neither Fortunately, all electrolytics were replaced… An old electrolytic spewing its gut inside and burning is… interesting. Happened to me twice (I guess there are still a bit of current inside the e caps even in standby?):

- with a Voice of Music 6AQ5 amp I’ve started, then received a long phone call, to witness a beautiful smoke and liquid spill…

- with a « new » no name cheap electrolytic in one of my amps. There were sparks and fumes and could had started a fire but I was there.

Sure it's safe if the amp's properly designed and in operating condition. There's nothing inherently unsafe about it.

With many designs, the filter caps remain energized while in standby.

Too bad you had such experiences, the ones I have seen like this relate to either defective components or poorly specified components for the application.