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Topic: Tube amp question |
Matt Steindl
From:
New Orleans, LA, USA
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Posted 6 Sep 2002 8:08 am |
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My Fender Princeton Reverb tube combo does not have a standby switch. Does it hurt the life of the tubes or the amp to leave it on and unplayed for extended periods of time(2 hours). Ot does it only suck life out of the tubes/amp when sound is running through it?
Thanks,
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Mattman in "The Big Sleazy"-:
S-10 Dekley, Suitcase Fender Rhodes, B-bender Les Paul
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Joe Smith
From:
Charlotte, NC, USA
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Posted 6 Sep 2002 8:49 am
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| Matt, it won't hurt the tubes to leave the amp on. Turning the amp on and off a lot will hurt the tubes more than just leaving it on. |
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Bob Metzger
From:
Waltham (Boston), MA, USA
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Posted 14 Sep 2002 9:53 am
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Having a standy switch will help to reduce cathode stripping and will extend tube life. I use standby switches on both of my Princeton Reverb amps. You may not want to drill into the chassis to add this feature as it will devalue your amp alot. The hot ticket is to get the local amp hotshot to remove the present on/off switch and install a 3 way switch that will track: 1) off, 2) standby, 3) play.
Bob M. |
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ajm
From:
Los Angeles
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Posted 14 Sep 2002 10:50 am
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Bob;
The Princeton Reverb has a tube rectifier. I seem to recall reading somewhere that amps with TRecs do not need a standby switch due to the time it takes the TRec to warm up. Is this a true assumption?
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Stephen Gambrell
From:
Over there
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Posted 14 Sep 2002 2:17 pm
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The whole purpose of a standby switch on a tube amp, is to turn off the plate(high) voltage to the tubes, while leaving the filaments fired up. This extends the life of the tube in two ways; first, it eliminates "cathode bleed-off," the tube turning on when an unnecessary, or unwanted signal comes in. Also, since the filament is always on, it's less likely to burn out, exactly like a light bulb. I don't think rectifier tubes HAVE filaments.
In short, it ain't a good idea to leave your amp on full blast, but I would rather leave the amp on all night, than turn it off and on every set. Your call, but I think a tube will be lost due to a burnt-out filament, than by high voltage being left on 4-5 hrs. a night. |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 14 Sep 2002 5:25 pm
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Yes...rectifier tubes do have filaments!  |
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Stephen Gambrell
From:
Over there
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Posted 15 Sep 2002 11:30 am
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Donny, weren't there some old gas-fired rectifier tubes(I can't remember the numbers) that didn't fire(light up)until the input voltage reached a high enough level to turn it on? Or what am I thinking about?
I'm old, it's raining... |
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Rob Hamilton
From:
Acton, MA, USA
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Posted 15 Sep 2002 6:58 pm
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You're thinking of voltage regulator tubes, which do not have filaments. They are used in tube power supplies, but I've never seen one in a guitar amplifier.
Using the standby switch cuts B+ voltage to the power amplifier tubes (6L6, KT66, EL34, 6550, whatever), and the preamp and driver tubes (12AX7 etc.), saving their lives some. It does not turn off the rectifier tube (5AR4, 5U4G, etc.)
If you do not have a standby switch, you should turn off the amplifier if you're not going to use it for an hour or two. Avoid turning it on and off more than a few times per day. That is, don't leave it on ALL the time, but don't be turning it on and off and on and off all day either.
And, yes, I agree with Stephen's advice above -- if you're playing a gig, turn the amp on and leave it on for the duration of the gig, rather than shutting down between sets.
--Rob Hamilton
'62 Vibrolux
[This message was edited by Rob Hamilton on 15 September 2002 at 08:04 PM.] |
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Stephen Gambrell
From:
Over there
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Posted 16 Sep 2002 12:59 pm
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| Thanks, Rob. I'm not as smart as I thought I used to be, but, then again, I probably never was.(Apologies to Bill Hankey) |
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Bill Leff
From:
Santa Cruz, CA, USA
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Posted 17 Sep 2002 7:40 am
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My guitar tech is an older guy that worked at Fender during the '60s. He told me that there was no need to use the standby switch on my Deluxe Reverb because of the tube rectifier.
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Bob Metzger
From:
Waltham (Boston), MA, USA
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Posted 25 Sep 2002 12:46 pm
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I know this is an old post but some more should be said about this standby thing.
Of the commonly used rectifier tubes in MI amps, there are two operational types: Directly heated cathode rectifier tubes and indirectly heated cathode rectifier tubes. Indirectly heated cathodes provide a slow warmup and don't apply B+ immediatedly to the power tubes. Amps without standby switches are best served by indirectly heated cathode rectifier tubes, however, many smaller amps that weren't originally intended as professional amplifiers don't have standbys nor an indirectly heated cathode rectifier tube either. This was probably to keep costs down on smaller, lower priced units. Also, as it applies to older units, power tubes cost alot less 30 years ago than nowadays and tube replacement wasn't such a widely discussed activity as it is today.
There is one thing that has been glossed over and should be said, regardless of rectifier type. Heat is the enemy of all electronic components: resistors, capacitors, diodes, transformers, switches , tube sockets, ect. Amps exposed to less heat will sound better, longer. It's your amp and up to you, but I wouldn't use (in heavy rotation) an amp without one (Nor would I deface a classic old amp without one.)
Bob M. |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 25 Sep 2002 2:30 pm
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| Stephen, you're quite right. As I recall, there was one rectifier tube (OZ4?) that didn't have a filament, but it was an old metal low-power job, and I don't think it was used in musical instrument amps. You will find it in some old console radios, though. |
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