Standby switches

I guess my biggest issue with standby switches is not so much that they exist, but their labelling is so ambiguous.

The power switch is labeled "Power", and can be switched to "ON" and "OFF". When it is switched to the "ON" position the "power" is on. Very intuitive/logical/obvious. The standby switch is labeled "Standby", and can be switched to "ON" or "STANDBY". When you put the standby switch in the "ON" position does that mean that the standby is on? Or when you switch it to the "STANDBY" position is the standby on? It seems to me that it should be switchable between "ON" or "OFF" like the power switch. "ON" would mean that the standby is actually on ...in the muted position. And in the "OFF" position the standby would be switched off and the amp is now playable.
 
Securb said:
Sound guys always gave me crap about that amp especially when they would watch me stack it on top of a 4x12 Ampeg V4. Studio engineers hated that amp also.
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I love amps that sound guys hate.

Sent from my SM-A115A using Tapatalk
 
Demanic said:
I love amps that sound guys hate.
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We only say things about people's gear that will make us look better ;)

The next time a sound guy says XYZ about your gear or volume, it's because he wants it to sound better, which will make them look better, which also means your sound will be better too ( likely anyway ). Might not be " Your " sound, but, it will at least be something, not you :)

There is nothing worse for a sound guy than to have a band that they have ZERO control over, where nothing they do can fix what is going on. I myself, when in that situation, tend to find the nearest barstool and duck away. I don't want anyone to know I'm associated with the mess. It is truly horrifying to have to stand there when four different girlfriends of the band members are all asking you for more, or less of someone in the band they have a vested interest in, but you can't fix it.
 
I've seen sound guys just throw their hands up and walk away due to excessive stage volume overpowering the PA out front.
 
Ewizard said:
We only say things about people's gear that will make us look better ;)

The next time a sound guy says XYZ about your gear or volume, it's because he wants it to sound better, which will make them look better, which also means your sound will be better too ( likely anyway ). Might not be " Your " sound, but, it will at least be something, not you :)

There is nothing worse for a sound guy than to have a band that they have ZERO control over, where nothing they do can fix what is going on. I myself, when in that situation, tend to find the nearest barstool and duck away. I don't want anyone to know I'm associated with the mess. It is truly horrifying to have to stand there when four different girlfriends of the band members are all asking you for more, or less of someone in the band they have a vested interest in, but you can't fix it.
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I learnd that early on. I would back off the stage volume with the master volume. I did a bit of gain staging back then so I didn't need to crank my amp to get a good tone. We learned early to tip the house sound guy before the set during load in, if going to dinner after sound check, grab him something to eat or bring him with you and get him a cold beer during the set. We always assumed the sound guy knew more about the house system and live sound than we did in our younger years.
 
Heard long ago from an amp tech that SB sw was developed (b4 Leo Fender) as a means of protecting the pwr supply by limiting the voltage draw into two stages.
 
Beer$ said:
Is it true that turning off without using the standby switch drains capacitors?
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If true, is that a bad or good thing? I have heard the same but never investigated. I guess it's good if getting ready to service the circuit.
 
dave74 said:
If true, is that a bad or good thing? I have heard the same but never investigated. I guess it's good if getting ready to service the circuit.
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If it’s not true, I know some websites that need revision before they get some poor kid killed.
 
Beer$ said:
If it’s not true, I know some websites that need revision before they get some poor kid killed.
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I wonder if it has any affect on the cap's life or performance.
Probably not if it's an amp that gets frequent use, but what if it's an amp that only gets ran a couple times a year.
Would being drained-out after usage be bad for longer term storage?
 
It is sort of true, but not exactly truthful. They will discharge for as long as the tubes and other electronics can conduct. As soon as the tubes can no longer conduct, the current draw goes away and no more discharging takes place.......In amps that don't have a bleed resistor. Most modern amps use a bleed resistor. This resistor is a controlled leak of the B+ to ground. This will discharge the caps slowly, so that after several minutes, the amp is safe to touch.

Now when I said not exactly......In amps that don't have a bleed resistor, the caps can be discharged quite a bit before the tubes no longer conduct, BUTTTTTTTT, caps have a memory, and even if discharged significantly, they can rebuild a charge to stunningly high voltages. Caps only discharge about 60% of their energy on the initial zap, if left alone, they will recharge a little and then discharge another 60% of that on the next zap, and so on and so on. This assumes no constant shorting of its leads.

This is where the bleed resistor is helpful, it constantly shorts the caps out to ground when the amp is not on. When the amp is on, the " leak " to ground is minimal and insignificant.
 
Interesting interview with Fender's Stan Cotey (Vice President, R&D):

There is a lot of debate on the origins and relevance of the standby switch on tube amplifiers. First, did Fender invent the standby switch? What was its original purpose?

Cotey: While it's been suggested that Fender invented the standby switch, I don’t know if that's true. And whether it's a "necessity" depends on how you define the word.

The myth is that the use of standby switches is to prevent cathode stripping before the tube is at operating temperatures (which is provided by the tube's filament). But I believe the reality is that cathode stripping does not occur at the plate voltages of typical tube amplifiers (between, say, 300-700 volts DC) and is something that is much more likely to occur in radio frequency (RF) transmitters, where the plate voltage can be in the thousands or even tens of thousands of volts.

In fact, I think the earliest use of standby switches was with vacuum tube radio transmitters where cathode stripping would definitely have been a factor. So Leo Fender, being a radio repairman, may have borrowed the feature for his instrument amplifiers.

Is the standby switch a necessity on amplifiers today? It has been suggested that the switch is no longer vital to amp function but has remained there because its disappearance would confuse players.

Cotey: Standby switches are still quite useful, though, for working musicians who take breaks. The reason is that the most wear and tear on a tube’s filament comes from a cold start where the resistance is lowest and the tube, therefore, draws the most current and generates the most heat.

I think it is better for the tubes to do as few cold starts as possible, so one cold start at the beginning of a gig with use of the standby switch on breaks is better than going through multiple cold starts from turning the amp on and off several times.

One other thing about standby switches: If the amplifier has a tube rectifier (like a GZ34, 5AR4, 5Y3, 5U4, etc.), then it’s better for the filter capacitors to leave the standby switch in the "on" position when first turning the amp on. Tube rectifiers don’t produce output voltage until their filaments are warm, and this provides a gradual voltage rise to the capacitors rather than a rapid surge, which can cause premature aging.

Regarding the disappearance of the switch, I think users are used to seeing it as a useful feature—and many players do believe cathode stripping does occur.
 
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