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Vintage threads from the first ten years

Re: 12AX7 shootout; Mullard or Tele?

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8/24/2000 9:20 PM
SteveG	Re: 12AX7 shootout; Mullard or Tele? I've tried all sorts of preamp valves, and actually prefer Chinese valves in high gain amps. In a particular old Marshall combo, I found using a Brimar somewhere in the chain warmed up the tone considerably. Swapping Mullards and Chinese didn't make a fat lot of difference to my ears. NOS seem to be much less prone to becoming microphonic though. Steve

8/24/2000 11:43 PM

I agree with the other posters that it really depends on the amp - and the speaker, too. I recently went through retubing a '77 Princeton Reverb (partially converted to Blackface specs and with a 0.0033uf PI coupling cap and Weber C10Q speaker), and I'll throw a curve ball in here and say that I really liked the NOS GE 12AX7s (1963 version) for the preamp and PI tubes. They sound really great in that circut with the Weber speaker - bright, sparkly, and shimmery. The point, though, is that it is the combination of ALL of those factors working together that makes the sound, and each contributes about equally. So, the question is what are the other variables you are dealing with, and what kind of sound do you want?

Tom

8/25/2000 12:32 AM

Well, I spent over a year building this amp trying out different values, ect. and I finally got it the way I want. when I finished it I tried out over 6 different speakers and I finally settled on one. now that's its finished I want to put the icing on the cake. my rectifier is an RCA 5Y3, my power tubes are RCA 6V6's. now I want to upgrade the preamp tube and the PI from the sovteks that are in there. I have always heard that the Mullards are one of the smoothest tubes out there. but I have heard lot of great things about the Teles too, and have always been curious about them. FWIW, this amp is close to a 5E3 and gets a lot of distortion from the preamp, hence, the importance of quality preamp tubes.
Ricky

8/25/2000 1:39 AM

Ricky,
FWIW, I've always found that the old RCA's with the circular logo on them sound really good in 5E3 amps. Also, Tungsol. Mullards are excellent lower gain 12AX7s for the first gain stage of most Tweeds and Marshalls if you want a slightly cleaner, but less bright sound. For new manufacture tubes, the new Sovtek LPS are a good sounding higher gain tube, and the Tesla ECC83's are good for lower gain. For some reason, many of the Teslas seem to have a very low DC voltage on the grids, which doesn't seem to be a problem, except on the first gain stage. Chinese tubes, in my experience, are only usable in super high gain amps. Amps like Tweed Deluxes and Bassmans need good tubes in the first couple of stages in order to sound good. Are Mullards worth the extra money.......not in my opinion at 45 bucks a pop or so. If you can find some resonably priced ones, buy 'em. Same goes for the old RCAs, Tungsols, Sylvania 12AX7a(NOT WA).

Peter S

8/25/2000 4:17 AM

Lately I've been concentrating on building around the 12AX7EH-LPS.
They actually sound pretty darn good when you stop fixating on previous RC components from days gone by and come up with your own RC tuning.
There's something to be said for good old generic mid 60's RCA 12AX7s too!

By the way, IMHO, you'll never get a great sounding 5E3 clone using a 12AX7 in the first stage unless you rebuild the stages for less preamp gain and and coupling, plus slightly different tone tweaking.
Preamp distortion is not what a guy normally lusts for in a 5E3!
Bruce

8/25/2000 4:52 AM
Ricky	yeah, I have "turned down" the bypass and coupling caps from the 5E3 design. If I went with a 12AT7 or a 12AY7 are you saying there would be less preamp distortion and more power amp distortion? Incedentally, do you know any NOS dealers who have any RCA 12AX7's? Ricky

8/25/2000 12:27 PM
Tom B	Ricky- Try Mike Kropotkin at Kropotkin Classic Amplification, http://users.erols.com/bluestat/. Great guy, and he's the guy who steered me to the 1963 GEs. In fact, for my application and the tone I was wanting, he actually steered me away from Mullards even though he likes them himself. Get in touch with him; he will do you right. Tom

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