Re: tube question

["Bob Maglinte" <bbqbob917@xxxxxxxxxxx>]

- ----- Original Message -----
From: The Bernadettes
To: harp-l@xxxxxxxxxx
Sent: Friday, December 27, 2002 4:41 PM
Subject: Re: tube question


Daniel,
    Power tubes wear out faster.  Pre-amp tubes don't have to be changed
unless they go noisy, short out, arc, or just sound plain lousy.  If you
like the sound of the amp, I'd leave the pre-amp tubes alone.  Pre-amp tubes
can last quite awhile, especially if they're the older US or Western
European manufactured NOS tubes.
    Power tubes are another story.  If they do short out, they can sometimes
take other components with them (such as the screen resistors).  Usually
you'll have some warning such as visible arcing inside the tube, weak power,
and weak frequency response.  Age has little do with wear, it's use.  Tubes
will last forever if not used so you can't judge by 5 years.  If you used
the amp regularly, (say gigging every weekend, and rehearsing once or twice
a week) for 5 years, you're probably due for a power tube change.  If the
amp hasn't seen much use in 5 years, then don't sweat it.  Also, the type of
tubes and type of amp has a lot to do with it.  Again US or WE NOS tubes
will tend to outlast the newer Russian and Chinese made tubes, 6L6 GC tubes
will outlast 6L6 WGB or GB or 5881 tubes, especially in amps with higher
plate voltages.  For instance, my silverface Super Reverb, which has high
plate voltages, went through a set of NOS 6L6 WGB's in about 6 months, but
I've had a pair of JJ 6L6 GC's in there now for over a year, still going
strong.  The JJ's are rated to withstand much higher plate voltages.  If you
have a local amp tech with a good tube tester, pull the tubes and have them
tested.
Hope this helps some,
Don D.

Hi,
Gotta agree with Don on this one BIG TIME. Of the newer production tubes
being made today, the JJ's, Svetlana's, and some EI's are the only ones
worth a damn. Most all of the newer stuff from China and Russia (with
Svetlana's the SOLE exception) I absolutely REFUSE to use.

Sincerely,
Barbeque Bob Maglinte
Boston, MA


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