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Hello,
today I will receive a Rivera Jazz Suprema 112. I hope my question does not Sound stupid, but how does the stand by Switch work? My other amp is a Fender princeton which does not have one.
What is the correct way to start the amp- when I have a break of about 20 minutes and when I m done with playing?
Thank you for your help and greetings from Germany
Fabian
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04-13-2017 04:57 AM
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Hi,
Power up the amp with the standby in the "on" position (which means you'll hear no sound). After the amp warms up for a couple of minutes, turn the standby off so you can use the amp. If you take a break, turn the standby back on again until your ready to use the amp. Standby allows the tubes to warm before full power reaches them.
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Both switches should be in the same off position when the amp is not in use. When turning the amp on, first turn on the power switch. Let the tubes warm up for about 45 seconds (that's what the standby state is for), and then turn the standby switch on too. When turning off the amp do the opposite. Turn off the standby and a few seconds later turn off the power switch.
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This! The reverse procedure when turning the amp off is meant to discharge the power filter caps.
Originally Posted by Alter
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Thank you very much!!!
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I've asked this question to a couple of respected amp builders. They both said that standby is good for cutting sound to the speakers when taking a short break or switching guitars. They both said they just leave the standby off on their amps at home and just use the power switch alone because using standby for warm up and cool down doesn't actually do anything significant to protect components. According to them that's a myth that guitar players can't let go of.
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I'm not meaning to start a controversy here, but guitar amps are the only tube devices (AFAIK) that had a standby switch.
From TV's to car radios, laboratory instruments, shipboard electronics (like RADAR), to stereo systems none had or needed "standby" and they worked fine. I haven't read the RCA book cover to cover but I never read that tubes REQUIRE the B+ to be applied an any order maybe I missed it, dunno.
I'm pretty sure the reason for the standby switch came about because amps were used in a manner that the designers thought it was a good idea to keep the amp hot but not able to feedback if left on during breaks, or stage setup and be ready to go.
Anyway, some git amps do not have standby switches like little single ended Fender models and early bassman and Gibson models.
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Standby switches weren't needed on those devices because they had tube rectifiers. With solid state rectification you definitely need to use the standby switch.
Originally Posted by GNAPPI
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I never use the standby switch of my Twin or Blues Deluxe (I switch them both on simultaneously). Tubes are in there already several years and still fine. But I use Russian 6P3S tubes, those are maybe more robust than modern Chinese production.....
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The only time I ever used the standby switch is between sets.
My Epi VJ doesn't have one. Seems to work fine ... though it's already eaten one EL-84.
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Except that standy switches existed in guitar amps before SS rectifiers did ... Originally Posted by agentsmith
John
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The standby switch allows supplying power to the tube's heaters before supplying power to the circuit that amplifies your signal. Each tube has a heater that warms up the tube and gets the electrons flowing - this is the orange glowing filament in the tube and runs at 6.3 volts. The tube's amplification circuit (cathode, anode, grids) is powered by much higher voltage, often 400 - 500 volts on the anode (where your signal exits the tube).
Using the standby switch when starting the amp will warm up the tubes before you apply power to the amplification circuit. Using the standby switch when powering down allows your tubes to cool down in a controlled manner. Using standby during a break at a gig keeps the heaters on and the tubes ready while removing the high voltage that will age the tube.
Theoretically, using the standby switch should increase tube life.Last edited by MaxTwang; 04-13-2017 at 03:59 PM.
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I recently had Jack Anderson build me a new amp head. When I saw an early picture with no standby switch I asked him this very question. Here was his response:
Hi Bob, I’d always used standby switches until a few years ago, until I bought a batch of rectifier tubes that had a few weak ones.
When the amp was warmed up on standby, and the rectifier tube was hot and ready to conduct full current, the rectifier would short out when the amps’ full current started flowing when the standby was switched on.
But if the standby switch was just always kept on, all the amps’ voltages would come up slowly, as the rectifier tube warmed up and started to conduct current. So, I sent back the bad tubes, and stopped using a standby switch.
I’ve got a big library of old electronics books, and if I would have read them better, I’d have known this at the start.
I do use standby switches on the amps that have solid state rectifiers. Those rectifiers can withstand a whole lot more current with no problem. I only use solid state ones on the bigger amps , where a tube rectifier would be too stressed. I like the high volume compression of tube rectifiers on the smaller amps.
If you’ve read on the internet about standby switches and tube warmup, there’s about a thousand different explanations of what’s best. I’m sticking with this way of doing it ; I think it’s the best way , with the slow warmup rectifier tubes that I use.
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In a twin if it has 6x 1N4007 the source current it can supply over 2 amps. Figure out the plste currents in a Twin and get back to us. Originally Posted by agentsmith
Last edited by GNAPPI; 04-13-2017 at 09:53 PM.
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read this and get back to us but frankly, you saying that an amp with a solid state rectifier doesn't need a standby disqualifies you from any commentary about vacuum tube guitar amps. Originally Posted by GNAPPI
Standby Switches
Anyway, no need to make a sarcastic reply. You're now in my ignore list.Last edited by agentsmith; 04-13-2017 at 09:53 PM.
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Jeez dude take a breath
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For those not familiar with the terminology: a "rectifier" is the component/circuit in our amps that converts AC to DC. Vintage amps use a tube rectifier and modern use solid state (silicon diodes). Preamp tubes and power amp tubes are powered with DC.
Tube rectifiers take time to warm up which causes the amp's DC voltage to slowly increase when you turn on your amp, solid state rectifiers supply full power immediately. Solid state rectifiers are more efficient and provide more consistent power making an amp feel like it responds quicker. Tube rectifiers are much less efficient and often don't keep up with the power demands when an amp is cranked - this makes the amp feel spongy and is known as 'sag' as the power supplied by the rectifier decreases, or sags, as the demand increases which leads to natural compression of your signal - the harder you play the more the power to the tubes sags causing your signal to squish.
rectifiers are before the standby switch and power up when the amp is turned on. The standby switch cuts DC to the preamp & power amp tubes.Last edited by MaxTwang; 04-14-2017 at 02:50 AM.
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That's because standby switches are also useful for silencing the amp during breaks. Originally Posted by John A.
Last edited by KirkP; 04-14-2017 at 03:22 AM.
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That's true, and that may actually be the reason Fender first installed them. But I was responding to the claim that they're necessary for SS rectified amps. Googling the subject, I see completely contradictory technical explanations for why standby's are needed, why they are not needed, why companies install them, and why companies don't. I've had many tube amps, some with standby's, some without. I don't think anybody really knows why some guitar amps have standby's. Don't tell anyone, but I always turned both off and on at the same time. Nobody died. No tubes went up in flames. I've also rarely used the standby for muting. It's easier just to turn the volume down. Originally Posted by KirkP
John
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How does the link you provided justify standby switches in SS-rectified amps? I read it and all it seems to say is that standby switches are a mistake made by Fender and perpetrated by imitation. Is there another article on that site explaining the value in SS-rectified amps? Originally Posted by agentsmith
John
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As a general rule: if the person who designed your amp thought it should have a standby switch, then it should be considered safe to use it.
Dumble, Randall Smith (Mesa Boogie), Ken Fisher (Trainwreck) and Jim Kelley amps have standby switches, who am I to argue with the masters.
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This is a bit puzzling. The article you quote doesn't say anything about SS vs tube rectifiers, concludes the danger of cathode stripping in guitar amps is insignificant, and finishes by saying " The safest standby switch - bypass the standby switch so it does nothing". I agree Kevin O'Connor is a respected authority and builder, and he is saying that no guitar amp needs a standby switch, but if you have one, leave it on all the time. Originally Posted by agentsmith
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I started to write a post about the importance of a standby switch due to the phenomenon of cathode stripping of the tubes when they are slammed with full b+ voltage prior to the heater elements fully heating up and stabilizing. Then, I reconsidered because I know that this has been essentially disproved.
FWIW, I would baby NOS, expensive tubes and let the new tubes rock and roll. When I put $200 into a vintage rectifier tube, etc., it's going to get the benefit--real or not--of the standby switch.
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For anyone still following this discussion, the soft-start idea described here works pretty well. Simple and cheap.
The Valve Wizard
$200 for a rectifier tube?
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I candidly admit the technical discussion is over my head. Electronic considerations aside - in four+ decades of performances and sessions, primarily with tube amps large and small, I have found standby switches to come in mighty handy for any brief-ish interruptions in work flow. Onstage amp settings are crucial to a good mix and I prefer not to turn things up or down unless really necessary. That goes triple for studio work - once it is dialed in, I don't touch it until time to pack up. The standby switch assures repeatable tones, take after take, as needed. My personal experience and long-standing policy. YMMV.
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