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




----- 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/






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