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Its been quite a while sense I have used a Tube amp. I do rember that playing thru it while warming it up helped to achieve the the sound I wanted out of it. It would take mabie 3 min could have been less.
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06-19-2019 03:23 PM
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ruger9,
I agree that with tube-rectified amps the rectifier tube(s) serve some of the function of the standby switch. Until the rectifier starts flowing, i.e., until its heater produces a thermionic effect at its cathode, the preamp and power amp tubes won't be hit with high plate voltages.
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This is very close to what I've read in Fender and Mesa Boogie Owner Manuals.
Originally Posted by Greentone
Oddly enough, there typically are no Standby Switches in Fender low wattage amps (Champ, Princeton, Blues Jr., or '80's Super Champ, and Princeton Reverb II). I included the latter 80's Fender Rivera era amps since they also have solid state rectification.
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Electronically ridiculous. Originally Posted by AlsoRan
But psychologically, if it makes him happy, who am I to judge?
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Sounds like something out of the Golden Ear set. These are the guys who literally pay thousands of dollars for an audiophile-grade ac power cord (more transparent... the soundstage just opened up to me...).
The audiophile market must have been created by a P. T. Barnum descendant
Cheers!
Sent from my iPhone using Tapatalk
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I recall reading the recommendation to let the amp warm up on standby -- in the Mesa Boogie manual. For the reason Greentone stated.
I hadn't heard the thing about solid state rectification, although I can see the logic. Standby might be better, because it would totally, not partially, protect the tube while it's warming.
That said, I had the original tubes in my Ampeg Reverberocket for decades. Solid state rectifier in that amp and no standby switch.
It might be true that it matters, but it may not matter all that much.
Meanwhile, I've decided to carry my cables in a 12 foot long case designed for one piece cane fly rods. This way, the electrons won't have to bend their way around crimps. Have to order them that way from the manufacturer to avoid getting a cable that has already been completely compromised before it has ever been sold.
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Alright here’s my take on it. And this is just what I’ve been told and what I personally like to do. I’ll let my head warm up for about 10 mins. I can understand letting it warm up that long if you’re going on stage and playing full volume out of the gate, then sure, let it warm up a good 10-15 mins. 30 mins? I feel like that is unneeded. I’ll let mine warm up while i plug in pedals, tune my guitar, and that’s it.
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Cathodes need a few seconds to come up to temperature. One minute is plenty. A standby switch cuts the high voltage to the anodes, leaving the (generally 6.3v) voltage to warm up the cathodes.
If your standby switch is downstream from the rectifier, you will hit the anodes with full voltage when take it off standby. If it is upstream, the rectifier will take some time to produce full voltage. Unless it’s a GZ34/5AR4 type, which comes up quickly, or a solid state rectifier, which comes up immediately.
Cathode stripping is controversial and is now largely a religious question.
If you have bad solder joints in your amp, increasing heat will affect those. Maybe better, maybe worse. A half hour would cover that.
Home radio receivers never used them, but then, many radio companies were tube manufacturers (RCA, etc.) and someone who sees conspiracies everywhere would assume they wanted to sell more tubes.
It would be interesting to know if radio transmitters use standby switches. I’ll bet not. Or if they were used in B52 bombers when they still used countless tubes.
In my own amps, I use a mute switch which shorts signal to ground - before the PI in PP amps, and before the power tube grid in SE.
Anyway, 30 minutes for better tone sounds like a load of hooey to me. But then, regardless which end of the cable I use, I don’t hear a tonal difference, so maybe I have tin ears.
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The bass resonant frequency of some loudspeakers is temperature dependent to a degree because of the damping material painted on the cone surround. That might cause some combo tube amps to show a slight change in response as the temperature inside the box rises. Tube amps do tend to have higher output impedances that make the speaker resonance more noticeable. Maybe this could happen on cold days. Pure speculation, of course.
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Stand by is a bad thing Originally Posted by Greentone
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Interesting info:
Radar System's thermionic valves (tubes) ran continuously for three months before being routinely changed.
Lots of these 'used' Radar System thermionic valves (tubes) were sold 'second hand' in the UK, they were good in guitar amps.
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One thought is his bleeder resistor(s) are failing and increase resistance after about 30 min getting hot. Thus raising the B+ to where it sounds louder. Louder = better in most phychoacoustic tests.
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I have experienced with both solid state and tube amps that after playing them for a while I start to like them more.
To me the obvious explanation is that it is my perception of the sound that has changed, rather than that the sound has changed.
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"Tube amp" is a big category. Wattage, circuit, etc, are going to be variables influencing performance. I've witnessed it many times, the amp noticeably getting warmer and having a more singing/sustaining quality. But other times, I've also noticed it NOT happen. The way it's being used makes a big difference, also.
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The filament in the tube that emits the required electrons needs to reach a minimum temperature to do this and that is a fast process. Why does a filament light bulb switch on immediately? In practice, turn on your amp and then get your guitar; that small amount of time is more than sufficient!
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My ex-FIL had an audiophile system with an Eagle 7-A amp plus Levinson preamp, Watkins speakers. He claimed if it was turned off one had to warm up the stereo for at least 24 hours before it would sound appropriate. Originally Posted by Ljgrinnell
Sounds like something out of the Golden Ear set. These are the guys who literally pay thousands of dollars for an audiophile-grade ac power cord (more transparent... the soundstage just opened up to me...).
The audiophile market must have been created by a P. T. Barnum descendant
Cheers!
Sent from my iPhone using Tapatalk
He later gave it to us when he got a new system. When I plugged the 7-A in, the lights on that side of the house would dim. Weighed about 100#.
I kept it for about a year then traded it to Dave Rogers for some guitar equipment. I never had a listening space big enough to accommodate such a stereo.
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Transistor amps are ready to play immediately after power on, but their operation changes slightly over the time it takes for them to reach thermal equilibrium with respect to their heat sink assembly. This may take ten minutes and may be unnoticeable for class B, however class A operation may take a bit longer to stabilize, still may not be noticed.
Tube amps use output transformers to match impedance to their speaker load, and transformers do take a while to warm up in class B operation because the only thing passing through the transformer is signal. With class A, the B+ voltage (hundreds of volts) is passed as DC through the primary coil of the transformer and the signal is added as a variation of that high DC voltage (the transformer's secondary coil that connects to the speaker is only responding to changes in the primary coil, in both cases, but in class A the transformer will need a while while to get up to temperature. Maybe thirty minutes, and this may or may not be noticed.
Old radios used to have small tubes in the tuning circuit powered up when the cord was plugged into the wall even when the "On" switch was in the off position. This was to maintain the tuning circuit tube temperature so they did not drift after power up. The wait time for tuning drift to settle down could be over 30 minutes. I just mention this as evidence that things with tubes do need some time to settle into operating temperature, and some things (like tuning drift) are easy to notice, whereas some things (like tone quality) are easily confounded with other effects.
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Observations from fifty odd years of using and abusing valve amplifiers;
A minute or so of warm up, and you are good to go.
After playing at volume for maybe half an hour, yes, they do tend to sound slightly better. No big deal.
The standby switch is a rabbit hole for internet conspiracy theories.
I have never run into any kind of problem using my standby switch on Fender, Mesa, Music Man, Peavey amps of varying wattage and age.
The only exception was a Vox AC30, Korg reissue. On this amp the standby was wired in some strange fashion, with the result that the amp could fail. Apparently a manufacturing error. The fix was to not use the standby.
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I see this topic -Amp warm up- always coming back up. In other forums mainly.
Those conversations then centre around the standby switch use (or origin), or part of it focuses then on warmup needed for only the valves and delicate harmonic frequencies surviving in the cold vacuum……
Rarely do they touch on the whole amp. Pauln just touched on it. I have no science to cite but everything responds consistently at consistent temperatures. Whether you can hear the inconsistency of different temperatures is probably a function of amp design& component choices and the listeners ears. And I guess the context the listener is hearing the amp.
I myself had a valve amp that sounded better after 30 odd minutes. It was a class A designed ef86 circuit with el84s. That thing was biased very hot. The valves are not what changed sound for me. The background noise and hum is what changed. The transformers on that design- the power supply in particular would roast.
I suspected the laminations had loosened up from thermal cycling over time and it was not until the whole chassis had heated up the hum would reduce.
I have heard power filtering capacitors performed differently at room temp vs 60+ degC, I have heard voice coils and speaker magnets change behaviour or efficiencies, and even paper cones drying out any absorbed moisture thereby changing the speakers tone, response and breakup points. These all sound like diminishing returns to me. Or perhaps only theoretical physics at best.
Either way, there is probably something to it, the sum of parts equaling the whole. How big a deal is up to the individual and their equipment. Personally, the consistency of my pick angle probably changes consistency of my tone more and that is the bit I will be focusing on for now.
Cheers
EMike
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A regarded amp builder once told me that the standby switch could be put to "run" almost immdiatly after the "on". And warm up was a question of seconds before playing.
"Standby is only there when taking a break and prevent the tubes from getting from warm to cold, and warm again, which fragilizes them in the long run.."
When we tested an amp, he dimed the thing, plugged his guitar and played a few chords at full volume (it was a Tweed 8 watt amp) before taming the storm with the volume pot on the guitar "that's how you warm up a tube amp, and use your volume, on the geetar"
He was a funny guy.
He also told me preamp tubes wear faster than power tubes. I'm still a bit skeptical about that one, but WT... he's the tech after all
One thing I've noticed is that if a tube amp is well built in the first place, then it's very reliable and sturdy, and that tubes can last very long, and take quite a (reasonnable) beating as long as you don't move the amp brutaly.
Problems I have encoutered with tube amps where the ones that where mass produced, low cost units, and most of the time it happened very quickly after purchase, dare I say immediatly.
The good ones are very sturdy.
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And other regarded folk say one shouldn't use the stand during intervals. All these regarded guys have differing views and seem to have plausible explanations for them. Originally Posted by Jx30510
A regarded amp builder once told me that the standby switch could be put to "run" almost immdiatly after the "on". And warm up was a question of seconds before playing.
"Standby is only there when taking a break and prevent the tubes from getting from warm to cold, and warm again, which fragilizes them in the long run.."
When we tested an amp, he dimed the thing, plugged his guitar and played a few chords at full volume (it was a Tweed 8 watt amp) before taming the storm with the volume pot on the guitar "that's how you warm up a tube amp, and use your volume, on the geetar"
He was a funny guy.
He also told me preamp tubes wear faster than power tubes. I'm still a bit skeptical about that one, but WT... he's the tech after all
One thing I've noticed is that if a tube amp is well built in the first place, then it's very reliable and sturdy, and that tubes can last very long, and take quite a (reasonnable) beating as long as you don't move the amp brutaly.
Problems I have encoutered with tube amps where the ones that where mass produced, low cost units, and most of the time it happened very quickly after purchase, dare I say immediatly.
The good ones are very sturdy.
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A few minutes to get a good sound. At least 10 years to sound good.
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Warming up the tubes for 30 minutes seems like a great way to kill off your tubes in half the time. I'm playing my TM Twin a lot these days but on the Mark IV I usually just give it a minute or two. The Mark always sounded fine with that amount of time.
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This thread is so old some of the posters have passed on and some have passed away.
rip citizenk74
ps previous advice re just put it on standby 5 minutes before use should be fine. Provided all the other components besides the tubes are up to snuff you likely won't hear a difference unless you're a dog, and maybe not even Fido will hear it.
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Im a old tube guy, when a tube amp gets hot the whole amp gets hot. As many know you can actually warm a room with a tube amp. So that means everything in the amp is hot, caps resistors wires etc so its possible what people are hearing is a change in "conductivity" of the other components not to mention transformers and has nothing to do with the tube. Just a theory but credible audio engineers have expressed hearing a small difference between a cold and warmed up tube amp. Not so much with guitar amps but with old audio amps of high wattage. I have a nice selection of both tube and ss hifi and guitar amps where my guitar amps are concerned Im warming up while they are so that explains that phenomena. Where HiFi is concerned your listening experience will be directly proportional to the small fortune you paid for that tube amp sound (after it warms up). Just ask your dentist...
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