How do you use the stand-by switch?

Molly · Post by **Molly** » Sat Feb 18, 2017 7:18 pm

Reading the London Pro manual today and they said to use the stand-by for warm-up purposes but when it comes to switching off to just use the power switch and leave the stand-by on. Something to do with allowing it to discharge I think it said.

Letter in Guitarist this month actually called into question the whole need for the stand-by switch and suggested it could do more harm than good.

What say you chaps?

TmcB · Post by **TmcB** » Sat Feb 18, 2017 7:31 pm

Never bother with it on Cathode Bias amps, use it on fixed boas

Molly · Post by **Molly** » Sat Feb 18, 2017 7:43 pm

TmcB wrote:Never bother with it on Cathode Bias amps, use it on fixed boas

Not even for warm-up?

Lyle · Post by **Lyle** » Sat Feb 18, 2017 7:43 pm

I use it to warm up and cool down on my AC30CC2, but reading online apparently most people don't recommend using it.

H671 · Post by **H671** » Sat Feb 18, 2017 8:09 pm

Out of interest, the original valve radios never had standby switches & they went for years without any problems.
The main use is to keep the valves hot for a fast restart if you take a break from playing. In church we play for about 20 minutes then keep the amp on standby for about an hour at which stage we go straight into a final song & the amp needs to be ready.

Molly · Post by **Molly** » Sat Feb 18, 2017 8:29 pm

H671 wrote:... on standby for about an hour at which stage we go straight into a final song & the amp needs to be ready.

Y'see.... That's exactly what this seems to be saying you shouldn't do.

chur · Post by **chur** » Sat Feb 18, 2017 8:44 pm

Personally I use mine for warm up, but just turn the main off when killing the amp to discharge it. Was just the advice I got from the local amp tech here.

I did watch this a while ago which was interesting

https://youtu.be/Bcovle3cSpM

weltall89 · Post by **weltall89** » Sat Feb 18, 2017 8:53 pm

Personally I never use them on my AC30cc2s. Just switch them on, let them warm up for a while, then master volume up. Been doing that for 5 years since I learned to avoid using it. No issues (yet...)

TmcB · Post by **TmcB** » Sat Feb 18, 2017 8:56 pm

Yep, big in-rush of current to the tube rectifier in the AC30CC2's is what nukes it – simple solution is to never use it

H671 · Post by **H671** » Sat Feb 18, 2017 9:37 pm

OK, That article was interesting & I watched several videos from that link - looks like I'll doing things different from now on.

NippleWrestler · Post by **NippleWrestler** » Sat Feb 18, 2017 10:27 pm

Just FYI that none of these methods discharge the voltage in the caps. The only way to do that is to drain them via grounding them elsewhere or wait a few years.

Don't just turn it off at the mains then poke around in there.

H671 · Post by **H671** » Sun Feb 19, 2017 6:33 am

Another perspective from Carvin - http://carvinaudio.com/blogs/guitar-bas ... -to-use-it

"Your Amp's Standby Switch: What It Does and How to Use It

While longtime tube amp owners are familiar with operating the standby and power switches, the process may be slightly confusing for new guitarists or those switching over from solid state amps. Solid state amps only have a power switch that turns the amp on and off, but all of a sudden there’s another switch next to it on your new tube amp! Fortunately, the standby switch is very straightforward, yet absolutely essential. So essential, in fact, that all of Carvin Audio’s 50 Watt or more all-tube guitar amp models - such as the V3, X100B, and BELAIR come loaded with one. This article will explain what the standby switch does and how to use it.

Unlike solid state amplifiers, tube amps need time to “warm up” before they get to providing you rocking tones. In fact, tubes operate best when they are hot. It’s akin to stretching and getting your muscles ready before you go for a run. Therefore, if you turn on your tube amp, crank it up, and start playing at full throttle before letting the tubes warm up, you are risking damage to your amp, just as you would risk injury if you were to just start sprinting without stretching or jogging first.

So that’s when the standby switch comes into the picture. By turning on your amp in standby mode, you are reducing wear and tear on your amp and extending the life of your tubes. When that switch is set to standby, you are basically telling your amp to not send the full available voltage to the tubes immediately- rather, just enough to get them warmed up. A good thing to get into the habit of is to turn your amp on standby as soon as possible when you get to the rehearsal space or on the stage. This will give your amp adequate time to warm up while you set up your pedals, tune your guitar, or socialize. Ideally, you want your amp to be on standby for about one to two minutes before you start playing at any volume.

Another useful function of the standby switch is muting your amp without turning it off. If you are taking a quick break on a session or between sets, go ahead and set the switch to standby. This will prevent you from having to turn the amp off and then on again and having to warm up the tubes all over again.

V3 Tube Amp with Standby Switch

When powering-on the Carvin Audio V3, turn on the power switch with the standby switch engaged. Wait a minute or so, and then turn the standby switch to the off position and you’re ready to rock.

One of the common complaints about owning a tube amp is maintenance of the tubes (and maybe the increased weight!) However, using your tube amp’s standby mode properly can go a long way and keep your tone sounding sweet for years.
TAGS: Guitar Amps, Tube Amps"

sizzlingbadger · Post by **sizzlingbadger** » Sun Feb 19, 2017 7:54 am

I haven't read the articles above so apologies if I'm repeating anything. Firstly forget what you read in the amp user manuals about the standby switch as its usually nonsense.

There were no standby switches in valve amps until Fender put one on its Bassman. Marshall copied the design along with the switch. Many other amp manufactures followed suit later on. No other valve amplifier equipment at the time had standby switches and you won't see them mentioned in valve audio design books from the 40's - 60's

Amps (more so silicon rectified ) will have an HT "spike" when they are first switched on. This is the "no load" HT voltage, this happens because the valve heaters are not warm at first "power on" so the valves are effectively 'open circuit' i.e. not drawing any current form the HT supply. With no current being drawn through the HT 'drop down' resistors we get the full rectified HT voltage present at the valves anode and across the HT smoothing capacitors.

The higher voltage is not an issue for the valves. It could stress the smoothing capacitors if they are not rated at a high enough voltage but this is very unlikely with modern amps and caps and is why you should use caps rated above the no load voltage when designing an amp.

So why did Fender add a standby switch ?

Some say because the capacitors of the era were expensive and fragile and Fender were trying to protect them from the no load voltages. Earlier Fender amps didn't have them but the new Bassman was quite complex and expensive for the day and the schematics do show high "off load" voltages in excess of the capacitors ratings. There was no need for everyone else to copy this design flaw of course

Modern guitar amps (cathode or fixed biased) do not require a standby switch. They do not prolong the life of the valves, that is complete bullshit.

As for discharging the HT caps most modern amps have bleed resistors so that the caps are discharged when the amp is powered off. Some rely on the HT circuit to bleed the voltage so will only discharge when the standby switch is in the on position. Bottom line is you never take it for granted and always check before putting your fingers in there.

TmcB · Post by **TmcB** » Sun Feb 19, 2017 8:05 am

NippleWrestler wrote:Just FYI that none of these methods discharge the voltage in the caps. The only way to do that is to drain them via grounding them elsewhere or wait a few years.

Don't just turn it off at the mains then poke around in there.

Disagree - turning it off without engaging standby will discharge the caps as the tubes pull out anything left over.

https://m.youtube.com/watch?v=sw9KnSFy3 ... e=youtu.be

But then afterwards I do ensure they're discharged by measuring, and still use a 10w resistor on a cable clipped to ground to discharge anything and keep a cable clipped between p1 on tube 1 and ground.

willow13 · Post by **willow13** » Sun Feb 19, 2017 8:06 am

sizzlingbadger wrote:I haven't read the articles above so apologies if I'm repeating anything. Firstly forget what you read in the amp user manuals about the standby switch as its usually nonsense.

There were no standby switches in valve amps until Fender put one on its Bassman. Marshall copied the design along with the switch. Many other amp manufactures followed suit later on. No other valve amplifier equipment at the time had standby switches and you won't see them mentioned in valve audio design books from the 40's - 60's

Amps (more so silicon rectified ) will have an HT "spike" when they are first switched on. This is the "no load" HT voltage, this happens because the valve heaters are not warm at first "power on" so the valves are effectively 'open circuit' i.e. not drawing any current form the HT supply. With no current being drawn through the HT 'drop down' resistors we get the full rectified HT voltage present at the valves anode and across the HT smoothing capacitors.

The higher voltage is not an issue for the valves. It could stress the smoothing capacitors if they are not rated at a high enough voltage but this is very unlikely with modern amps and caps and is why you should use caps rated above the no load voltage when designing an amp.

So why did Fender add a standby switch ?

Some say because the capacitors of the era were expensive and fragile and Fender were trying to protect them from the no load voltages. Earlier Fender amps didn't have them but the new Bassman was quite complex and expensive for the day and the schematics do show high "off load" voltages in excess of the capacitors ratings. There was no need for everyone else to copy this design flaw of course

Modern guitar amps (cathode or fixed biased) do not require a standby switch. They do not prolong the life of the valves, that is complete bullshit.

As for discharging the HT caps most modern amps have bleed resistors so that the caps are discharged when the amp is powered off. Some rely on the HT circuit to bleed the voltage so will only discharge when the standby switch is in the on position. Bottom line is you never take it for granted and always check before putting your fingers in there.

that all sounds like it makes sense (not that I understand any of it hehe) so can you explain why modern day amp makers still use them? surely if they are of no use then I would have thought builders would have ditched them by now

NZGuitars.com : Filling you with GAS since 2003

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