Re: [Harp-L] Power Tubes shot???

["Bob Maglinte" <bbqbob917@xxxxxxxxxxx>]

----- Original Message ----- 
From: "Michael Fugazzi" <mfugazzi67@xxxxxxxxx>
To: <harp-l@xxxxxxxxxx>
Sent: Thursday, January 06, 2005 1:42 PM
Subject: [Harp-L] Power Tubes shot???


> I was between bands about 2 months and not using my
> amp.  I started with a new group and switched out to
> some lower gain preamp tubes, in hopes I could get
> louder and change my tone.  Since, feedback hasn't
> been a problem, but now I get way less volume.  I can
> crank everything and get no feedback, but very little
> volume difference from 1 to ten.
>
> I find it hard to believe the preamp tubes are the
> reason for the problem.  I just don't see them
> creating that much volume loss (I've done this before
> without an issue and the tubes are only 5751's).  I
> tried running my amp into 4x10's, but there was no
> difference in volume.  I've had the amp for about 9
> months and have never touched the power tubes.  Could
> this be the source of my problem?  I am afraid to
> spend a large chunk of change to find out it has
> nothing to do with it.
>
> The guitar player has the same amp and plays it at 2,
> whereas I was at ten last night and couldn't hear
> myself.
>
> Mike
>
> =====
> Mike Fugazzi
> Harmonica/Vocals

Hi Mike,
If you're gigging pretty steadily, power tubes will eventually wear out. 
Preamp tubes wearing out can cause this too, and signs of either are unusual 
volume changes within minutes or seconds up and down. For the power tubes, 
when you play the amp, see if the light in the tube flashes or changes in 
ANY way. Most of the new production tubes don't last as long or sound as 
good as the more highly expensive NOS tubes that were made in the USA or 
Western Europe, as most of the tubes being made today aren't made to 
military specs, as were the NOS tubes, and tubes made to those specs heavy 
heavy duty everything in their components. If  and when you change the power 
tubes, MAKE SURE that you change the preamp tube that's closest to the power 
tubes (often called driver tubes or phase inverter tubes) because without 
those, the signal from the other preamp tubes won't be strong enough to 
drive the power tubes adequately. As to how long they should last, it 
depends on how often you're gigging. If you gig at least 6-10+++ nights per 
month, with newer production power tubes, it should be 3-4 months, and 
another tell tale sign power tubes are on their way out is that the bottom 
end definition of the amp starts sound mushy and loses definition (with NOS 
power tubes, you should be getting at least 6-8 months based on gigging 6-10 
nights per month), and with preamp tubes, you should get a minimum of 1 year 
out of the newer production stuff, and a minimum of 2 years out of the NOS 
stuff. BTW, one thing to remember as a gigging musician is to ALWAYS keep a 
spare set of EVERY tube in that amp on you WITHOUT fail to avoid some of 
these problems, ESPECIALLY in regards to the power tubes as well as the 
driver tube. Having worked for 30 years using tube amps, these things are 
basic rules of thumb, and repairs on tube amps are generally a lot cheaper 
than it will be for a solid state amp, especially if you encounter a power 
surge, which would damn near permanently fry a solid state amp like a 
chicken. Hope this helps.

Sincerely,
Barbeque Bob Maglinte
Boston, MA
http://www.barbequebob.com
MP3's: http://music.mp3lizard.com/barbequebob/