[Boatanchors] Fwd: 'Ruggedized" 12AX7's ??

Thu Dec 30 21:24:32 EST 2010

-----Original Message-----
From: jcoward5452 <jcoward5452 at aol.com>
To: k6xyz <k6xyz at sbcglobal.net>
Sent: Thu, Dec 30, 2010 2:38 pm
Subject: Re: [Boatanchors] 'Ruggedized" 12AX7's ??

I would guess that this applies to home tube audio gear as well. I have a nice set of McIntosh MC-30's and a MX-110 FM tuner/preamp.The 12AX7's have always been a problem.Back in the "day" McIntosh had a once a year tune up clinic at their distributers and I faithfully took my equipment in for a tune up.I had a pair of C-10 preamps back then and invariably the 12AX7's and 12AT7's were replaced.As I recall, they preferred RCA over any other brand.(Though sometims I got Sylvania).
 My $.02,
              Jay

-----Original Message-----
From: Dave Harmon <k6xyz at sbcglobal.net>
To: 'Philip (KO6BB)' <ko6bb at sbcglobal.net>; 'Boatanchor List' <boatanchors at mailman.qth.net>
Sent: Thu, Dec 30, 2010 2:20 pm
Subject: Re: [Boatanchors] 'Ruggedized" 12AX7's ??

Phil....I changed to the JJ line of tubes for my Fenders.
hey made a heckova improvement!
he GT (Groove Tubes)...some of them are made in China, and Europe.
hese and all other tubes sold for use in amps are 'graded' by how well the
eproduce certain audio frequencies.
his makes a huge improvement in the sound you get over the exact same tube
hat passes all mfgrs tests but have not been tested for audio response.
o....to directly answer your question....forget the military or other
uggedized tubes for better sound.
orget the warrantee....buy the JJ's.

ave Harmon
6XYZ[at]sbcglobal[dot]net
perry, Ok.

----Original Message-----
rom: boatanchors-bounces at mailman.qth.net
mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of Philip (KO6BB)
ent: Thursday, December 30, 2010 3:53 PM
o: Boatanchor List
ubject: [Boatanchors] 'Ruggedized" 12AX7's ??
Hi,
orry if this is considered OT, but at least it's not CFL's, AND we are 
alking about real vacuum tubes ;-)
I have a one month old Fender Super Champ XD guitar amplifier I 
urchased to use at the church.  MUCH smaller than I'm used to playing 
hrough, but I have a mic on it and it only needs to provide enough 
olume to sound good on stage.  With only 15 Watts I can push the output 
ubes pretty hard for good sound without being excessively loud (unlike 
he larger amps I traditionally use).
This amplifier uses 1/2 of a 12AX7 as a voltage amplifier, the other 
alf is a Phase Inverter for the PP 6V6 tubes running Class A, 15 Watts 
o a single 10" speaker. All the pre-amp and DSP circuitry is SS.
Problem is, the 12AX7 has already started to get a little microphonic.  
ot really bad, but it puts a sort of 'haze' over the sound while 
laying (the tubes are only a few inches behind the 10" speaker cone), 
long with the occasional "crackle".  I dug around in my junkbox and 
ound a "no-name" 12AX7 in a generic box, plugged it in and it sounds 
ery good now, actually better than when the amp was first brought 
ome.  I have no idea if the tube is a NOS American one or what. . .
Anyway, I could send the amplifier in for service under warranty (5 
ears, except for tubes, 90 days), but chances are, they'd put in 
nother Fender 12AX7 that might not hold up.  I understand Fender goes 
o the cheapest source for their tubes. There are premium tubes sold for 
uitarists under the "Groove Tube" name, among others.  But I've read 
here these are basically Chinese tubes that have been tested and 
atched where need be (outputs etc).  Needless to say, these tubes take 
 beating in the typical combo guitar amplifier, even though I don't 
lay rock or drive my amps into heavy distortion etc.  I play a lot of 
clean" single note lead, rhythm only when accompanying my own singing.
QUESTION:  At one time there were a lot of "Military nomenclatured" 
ubes that were supposed to be ruggedized. They typically had a 4 digit 
umber instead of number/letter/number.   Are there any such for the 
2AX7, and if so, are they likely to be still available at the usual 
ube suppliers (Antique Electronics, RF Parts etc)?   And in this case, 
ould 'ruggedized" mean freedom from microphonics, noise, etc?
-- 
3 de Phil,  KO6BB
ttp://www.qsl.net/ko6bb/   (Web Page)
ttp://ko6bb1.multiply.com/ (My OTR Blog)
ttp://cbsmysterytheater.multiply.com/ (My CBS
adio Mystery Theater Blog)
RADIOS:
aesu FT-2000 Xceiver for "hamming" and LF Beacons.
ational NC-183 16 Tube Receiver (circa 1949)
enith "American" Royal-7000 Transoceanic. (circa 1970)
enith "Taiwan made" 7000-2 Transoceanic. (Circa 1971)
ealistic DX-380 Digital Portable.
ANTENNAS:
8' Long balanced dipole.
Mini-Whip" (active antennas) for LF.
Merced, Central California, 37.3N 120.48W  CM97sh
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