[Vintage-Audio] 12AX7 and other Tube questions

[Phil Lefever]

You are right to stay away from the "magic" audiophile tubes.
These are simply tubes branded to take advantage of those
that buy silly things like $500 power cords  ;)

For 12ZX7 and 12AT7 the Sovtek are likely as good as you will find.
Some will argue the advantages of NOS tubes but they are likely
not worth the price, especially in a guitar amplifier. Guitar amplifiers
are often very hard on tubes both electrically and mechanically so
killing expensive rare tubes is best avoided.

I have had excellent luck with Groove Tubes. These are a bit higher
priced but they are usually very rugged mechanically. They have been
less likely to go microphonic in my Marshall 2204 amplifier.

As for the 6L6GC tubes I'd buy only Svetlana. These tubes have
worked well in every amplifier I have used them in. I have yet to get
a bad one. The Groove Tubes 6L6GC is likely fine too but the price
is likely a lot higher. Whichever power tubes you get be sure they
are biased right. High idling current kills tubes, output transformers
and power supply components!

73

Phil, KB0NES


At 08:00 PM 6/11/02 +0000, you wrote:
>Hello
>I'm new to the list so please forgive me if this has been covered before.
>
>I got my Peavey Triumph 60 guitar amp fixed and working.  (channel select
>relay like I suspected).  It plays and sounds quite good with just a very
>slight occasional crackle,  which I suspect is probably one of the 12AX7
>pre-amp tubes.
>
>Couple questions.
>1.  Which brands of 12AX7, 12AT7 & 6L6GC are good for use in a high
>vibration enviornment. (Like a "cranked" 60Watt 112 combo amp).  Reason I
>asked was back in the early 80's I went through about 3 changes of a couple
>of the pre-amp tubes in my Fender "twin" (blackface with 2 JBL's) before I
>got a set that didn't go microphonic right away.  When I finally got it
>right I never had another problem, but don't remember the brand.
>
>2.  Are the Sovtek tubes any good (this amp has one in the first stage that
>'seems' quiet).  I can't see paying for special "golden eared audiophile
>tubes".   Ditto for 12AT7 tubes (of which I have one NOS RCA tube)
>
>3.  All the rest of the 12AX7's are apparently original, Peavey brand "made
>in the DRG".  WHERE in the world is the DRG?  Interesting thing is both the
>Peavey and the Sovtek have the same style black printing of the
>numbers/name.
>
>4.  While on the subject of tubes for guitar amps.  Although I don't need
>them right now, what are good 6L6GC tubes for this enviornment?  Are the
>Russian brands any good?  I definitely want to stay away from any Chinese
>tubes.  And with a slim wallet premium NOS American tubes  would make said
>wallet even slimmer very quickly.  BUT, I understand that some 6L6's are
>prone to "short out" in guitar amplifiers.  I had that happen to me while
>playing on the platform at church once.   That poor little 50 Watt Combo
>sounded like a BOMB went off in it.  This Peavey is the first Tube amp I've
>had since!
>
>73 de Phil  KO6BB
>
>REAL Radio is heard on Boatanchor Receivers.
>REAL Music is played through  'Valve' Guitar amps!
>k06bb@elite.net
>Merced, Central California
>
>
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--
Phil Lefever - KB=D8NES			Twin Cities Repeater Club
kb0nes@tcrc.org			Tech Team Co-Chairman
Burnsville,MN                  		http://www.tcrc.org  147.21 224.54 444.30