Mic Kaczmarczik's TubeInformation - The Blue Guitar
Mic Kaczmarczik's TubeInformation - The Blue Guitar
Mic Kaczmarczik's TubeInformation - The Blue Guitar
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From postmaster@triodeel.com Sat Oct 2 13:55:38 CDT 1999<br />
Article: 205949 of alt.guitar.amps<br />
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From: Ned Carlson<br />
Newsgroups: alt.guitar.amps<br />
Subject: Re: Stand-By Switches and Tubes <strong>The</strong>ory<br />
Date: 2 Oct 1999 01:08:06 -0500<br />
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Kent Pearson wrote:<br />
><br />
> I've heard that it's best for the amp and/or the tubes to allow the tubes to<br />
> warm up for a minute or two on stand-by before switching to play mode.<br />
This isn't a bad idea...since you've got a standby switch, why not use it.<br />
But lots of tube amps were made that had no standby at all. AAMOF, I've got<br />
a couple Bogen MO-100 tube PA amps here, diodes and no standby.<br />
Since Bogens were typically used in places like hospitals and<br />
schools, one can figure they were either run 24/7 or<br />
got hit with a turnon surge every morning.<br />
Directly heated rectifiers like 5U4 and 5Y3 are not a slow<br />
warmup device, despite rumors to the contrary.<br />
A simple voltmeter check will verify this.<br />
Fortunately for most tube amp owners, nearly all<br />
tube amps used in audio frequency service (which includes<br />
guitar amps), either apply a negative voltage to the grid<br />
of the output tubes at the time the power is applied,<br />
or have a cathode resistor to limit current.<br />
Also,<br />
> I've heard that it's best to put the amp on standby for a minute or two before<br />
> powering down. My understanding is that this practice will help to get the<br />
> most life out of your tubes. Can someone elaborate on that a bit? Why is<br />
> that? To Stand-by, or not to Stand-by . . what goes on? That is the<br />
> question!<br />
I would do exactly the opposite, turn off the power then LATER turn off<br />
the standby, so as to drain off the charge in the power supply<br />
capacitors.<br />
I've recieved some lengthy missives from certain folks regarding<br />
cathode stripping and possible damage from too fast warmup in tube amps.<br />
>From these I have determined the following:<br />
1.If you've got a tube regulated radar power supply on your B52-B bomber,<br />
you'd better use a tube rectifier, as using diode replacements that<br />
slap B+ voltage on cold 6336B tubes can destroy them.<br />
List price on 6336B is $141.00, which ain't chopped liver, especially<br />
if you have to replace them on taxpayer's money. So if you are<br />
a 3rd world dictator with some used B52-B's that need retubing,<br />
call us and get some 5R4-WGB tube rectifiers before you send your<br />
bomber fleet to carpet bomb suspected terrorist sites.<br />
2.if you've got an Wurlitzer bubble-tube jukebox, it uses<br />
a fast warmup circuit that jacks the filament voltage to<br />
over 9 volts when someone hits the selection button.