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

[Pete Lancashire]

12AX7WA and 6681

I don't have my tube specs on me but maybe just more physically rugged

-pete

On Thu, Dec 30, 2010 at 1:52 PM, Philip (KO6BB) <ko6bb at sbcglobal.net> wrote:
> Hi,
> Sorry if this is considered OT, but at least it's not CFL's, AND we are
> talking about real vacuum tubes ;-)
>
> I have a one month old Fender Super Champ XD guitar amplifier I
> purchased to use at the church.  MUCH smaller than I'm used to playing
> through, but I have a mic on it and it only needs to provide enough
> volume to sound good on stage.  With only 15 Watts I can push the output
> tubes pretty hard for good sound without being excessively loud (unlike
> the larger amps I traditionally use).
>
> This amplifier uses 1/2 of a 12AX7 as a voltage amplifier, the other
> half is a Phase Inverter for the PP 6V6 tubes running Class A, 15 Watts
> to 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.
> Not really bad, but it puts a sort of 'haze' over the sound while
> playing (the tubes are only a few inches behind the 10" speaker cone),
> along with the occasional "crackle".  I dug around in my junkbox and
> found a "no-name" 12AX7 in a generic box, plugged it in and it sounds
> very good now, actually better than when the amp was first brought
> home.  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
> years, except for tubes, 90 days), but chances are, they'd put in
> another Fender 12AX7 that might not hold up.  I understand Fender goes
> to the cheapest source for their tubes. There are premium tubes sold for
> guitarists under the "Groove Tube" name, among others.  But I've read
> where these are basically Chinese tubes that have been tested and
> matched where need be (outputs etc).  Needless to say, these tubes take
> a beating in the typical combo guitar amplifier, even though I don't
> play 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"
> tubes that were supposed to be ruggedized. They typically had a 4 digit
> number instead of number/letter/number.   Are there any such for the
> 12AX7, and if so, are they likely to be still available at the usual
> tube suppliers (Antique Electronics, RF Parts etc)?   And in this case,
> would 'ruggedized" mean freedom from microphonics, noise, etc?
>
> --
> 73 de Phil,  KO6BB
> http://www.qsl.net/ko6bb/   (Web Page)
> http://ko6bb1.multiply.com/ (My OTR Blog)
> http://cbsmysterytheater.multiply.com/ (My CBS
> Radio Mystery Theater Blog)
>
> RADIOS:
> Yaesu FT-2000 Xceiver for "hamming" and LF Beacons.
> National NC-183 16 Tube Receiver (circa 1949)
> Zenith "American" Royal-7000 Transoceanic. (circa 1970)
> Zenith "Taiwan made" 7000-2 Transoceanic. (Circa 1971)
> Realistic DX-380 Digital Portable.
>
> ANTENNAS:
> 88' Long balanced dipole.
> "Mini-Whip" (active antennas) for LF.
>
> Merced, Central California, 37.3N 120.48W  CM97sh
>
> ______________________________________________________________
> Boatanchors mailing list
> Home: http://mailman.qth.net/mailman/listinfo/boatanchors
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Boatanchors at mailman.qth.net
>
> List Administrator: Duane Fischer, W8DBF
> ** For Assistance: dfischer at usol.com **
>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>