All tube amps, standby switch, and load

[baxter_x]

I'm the proud owner of a full tube Sadowsky SA200.
As it's my first full tube amps, I have a several questions about this topology.
First is about the standby switch. I've read it shouldn't be used as a mute button. In case of a long break, it's better to switch the amp off or set the volume to zero.

About the load, I'm fully aware a tube amp MUST "see" a load on it's power section. However, I also read a load is actually not mandatory as long as the standby is on. Is that true?

As it's my first tube amp, I'm totally opened to further advices.

 

[Crater]

However, I also read a load is actually not mandatory as long as the standby is on. Is that true?

That's true, it will not hurt the output transformer if the amp is on standby, but it's not good practice to power on your amp without a speaker load connected. Just make it a habit to always connect the cab to the amp before turning the amp head on.

First is about the standby switch. I've read it shouldn't be used as a mute button.

Not sure what this person meant...of course you can use it as a 'mute button' to avoid things like the pops and glitches when plugging an instrument cable into your bass and amp. The standby switch turns off the B+ power supply to the power tubes, so it allows you to quickly resume playing after a break without waiting for your tubes to warm up.

 

[beans-on-toast]

Always leave a speaker cab connected when the amp is on. It's common sense. The standby can be switched by anyone. An important point is that not all standby switches put the amp in full standby. Some amps have a resistor and or cap across the standby switch. In these cases the high voltage is always partially on. If you don'y know how the amp's standby is designed, assume that you always need a cab connected when the power is on.

Use the standby as a mute if you wish, it isn't a big deal if you do or don't. Purists argue that switching in and out of standby can damage the tubes. Don't worry about things like this.

Do whatever the manual recommends.

[Invalid or Expired Link Removed]

 

[Guitalia]

Why is it that most all-tube guitar and bass amplifiers are equipped with standby switches but almost no other tube audio amplifiers are? The only answer that seems to make sense is that guitarists and bassists need a convenient and safe way to mute their amps between sets or while switching instruments.

 

[Sid the Kid]

Congratulations on finding one of those, I've never had the pleas of hearing one in person but all sound clips have been dreamy.

There are more sophisticated ways to mute an amp than the standby switch. I would certainly try to figure out a new method as to not inadvertently damage your extremely rare and valuable amp.

I would also always run a load. My tube amp has a silent record feature where it will operate with no load, though the manual says to still run a load just to be safe. I think safe is better than sorry with these expensive and soon irreplaceable amps. I have 3 small children so I run through a routine before I even fire my amp up. First thing on the agenda, is the cab plugged in?

 

[beans-on-toast]

Why a standby switch?

Some of it is marketing. Players are conditioned to seeing a standby switch. If a product doesn't have one, they think that a feature is missing. Some amps do not need a standby switch other than to mute. Some tube amps are designed to require a standby switch. It depends when the bias supply is applied to the power tubes in a fixed bias amp.

 

[coreyfyfe]

I think a lot of the standby debate comes from readers of Merlin Blencowe's books/the valvewizard website. There certainly are amps which don't utilize a standby, and some that shouldn't, but I agree unlikely that you'd cause any long term harm using it.

I wouldn't power up the amp without a cab, even if there's no HT applied while in standby you're just setting yourself up to forget.

 

[oberkampf]

Maybe this explains a bit better: The Great Standby Switch Myth | Sweetwater[URL='https://www.sweetwater.com/sweetcare/articles/great-standby-switch-myth/']The Great Standby Switch Myth | Sweetwater[/URL]

 

[baxter_x]

Maybe this explains a bit better: The Great Standby Switch Myth | SweetwaterThe Great Standby Switch Myth | Sweetwater

Thats was my source actually. And they sey: "Don't use it as a "beer break" switch."

 

[dbsfgyd1]

Maybe this explains a bit better: The Great Standby Switch Myth | SweetwaterThe Great Standby Switch Myth | Sweetwater

Hey, thanks for the link. Very informative.

I've owned 4 tube amps in my life. A 60's Ampeg Reverbrocket (no standby switch), a SVT, a Hiwatt, and now an Eden WT-300v all with standby switches.

I had heard from my authorized Ampeg repair tech back in the 70s that put in to layman's term, "just to let the tubes warm up". I'm pretty sure he knew about the stress on the caps, but I guess he figured I would I wouldn't understand the details, and he was probably right.

As for using standby as a mute switch, guilty as charged.

 

[Engle]

Hey, thanks for the link. Very informative.

I've owned 4 tube amps in my life. A 60's Ampeg Reverbrocket (no standby switch), a SVT, a Hiwatt, and now an Eden WT-300v all with standby switches.

I had heard from my authorized Ampeg repair tech back in the 70s that put in to layman's term, "just to let the tubes warm up". I'm pretty sure he knew about the stress on the caps, but I guess he figured I would I wouldn't understand the details, and he was probably right.

As for using standby as a mute switch, guilty as charged.

Same here. Between sets it seems logical to put the amp in Standby mode.
On my PF50T, I sometimes forget to switch it to Standby before turning it off. Good to know that isn't doing any harm.

 

[6thplanet]

So for clarification, presuming that ya don't have a tuner or anything to mute the input, you should shut the amp off to swap bass/guitar as apposed to just flipping the stand by switch?

 

[Old Fart]

....Use the standby as a mute if you wish, it isn't a big deal if you do or don't. Purists argue that switching in and out of standby can damage the tubes. Don't worry about things like this.....

This ^^^

Standby generally just turns off the B+ voltage to the tube plates. Tube heaters remain on, keeping the tubes warm and ready for action. B+ is the "action." In my view, there is no danger in using Standby. As a mute or whatever. Heck....what else would it be for? Why do Standby switches exist except to mute?

 

[Old Fart]

No. Use Standby rather than shutting the amp off. I have some tube-rectified hifi amps that cannot be powered up immediately after being shut off. They must rest a bit in between to avoid GZ34 tube flashover.

Use Standby as a mute, and find something else to worry about.

 

[6thplanet]

Exactly

 

[tekhedd]

Standby is perfect for set breaks, that's practically what it was designed for. The point of a standby switch is that it stops wear on the tubes when you're not playing, while keeping the tubes at constant temperature so they're ready to use. Turning the amp off and on *does* reduce the lifespan of tubes a little through thermal cycling, although not as much as some people will tell you. I know one audiophile who never turns his power amp off, 24x7 on standby to increase the lifespan of expensive tubes. (Not sure how much this costs him in electricity but I guess if it makes him happy lol.)

 

[Lostgallifreyan]

I did repairs and maintenance for a guy in Bristol who ran a sound system that used a Hiwatt DR405 and four 1x18 cabs. If the standby switch was used, the resulting punch of sound was like being slapped in the chest by a heavy hand. I advised against its use, though apparently the previous person who worked on it had apparently said otherwise.

Eventually the caps did wear out, and I replaced them all with Kemet 500V types with a high temperature rating and a slight increase in capacitance because of limits on what was available. The originals had been 450VDC rated. When I did this the surge at mains switch-on warranted a change from slow blow 5A to fast 7.5A but this will likely revert to normal as the new caps begin to age, and that uprating of cap parameters could easily give more than 50 years of renewed lifetime. Even the old ones got that far, just barely.

The owner was well pleased with my choice when we compared the cost of new caps, to new valves. That standby switch is now left firmly in its 'on' position at all times. This protects the speakers too, and those also cost a lot more than the caps. This repair was over ten years ago now, and the amp is doing extremely well. It has outlived its owner but his family still use it often.

 

[Deleted member 389437]

No. Use Standby rather than shutting the amp off. I have some tube-rectified hifi amps that cannot be powered up immediately after being shut off. They must rest a bit in between to avoid GZ34 tube flashover.

Use Standby as a mute, and find something else to worry about.

They were originally placed on old Fender guitar amps as a handy tool when servicing, but they are a great way to mute/ "Standby" your amp. Im sure Fender had that in mind too. After that, everyone just copied them, and after so long of seeing standby switches on amps, people freak out when they dont have one. All its doing it just cutting the signal being fed to the tubes. And no you cant harm your amp if you dont use the standby when powering on and off

 

[Old Fart]

All its doing it just cutting the signal being fed to the tubes.

A signal may still be going to the output tubes on Standby, but the tubes would not be able to amplify that signal because the B+ voltage is missing from the plates. Standby typically eliminates the B+ voltage. This is typically a few hundred volts DC.

no you cant harm your amp if you dont use the standby when powering on and off.

I always power my tube amps on with the amp in standby, for reasons of safety. I might power the amp off when not in Standby, and I might be sending a signal through the amp at that moment. Sometimes. But then I put the amp on Standby after it is powered off.

 

[coy garcia]

I'm no expert but I've been using mostly tube amps for over 30yrs. When the tubes warm up the tone changes (gets grittier). I use the standby to warm up the tubes, then I soundcheck, then I leave in standby so my tone doesn't change when I hit the stage....same for breaks if doing multiple sets.