12ax7 Tung Sol(new) Problem

[hal]

Hi,

I have 12ax7 Tung Sol-in the phono stage they suond good but in the power amp(cj mv55)they sound very weak almost no sound.
I have another tubes that sound great in the cj(mullard,tungsram,sovtek).
Are the tubes are no good?can i use them in the phono stage?

In situation like this-are the tubes will bring their full potential in the phono stage?

Cheers.

[6267]

Maybe only one section is weak, the other is normal?

[tubeswell]

Taking a look at the MV55 I see they are wired for either ultralinear and triode configurations, both which differ in power output.

The ones on this page have 2 x 12AX7, 2 x 6SN7 and 4 x EL34

http://www.conradjohnson.com/It_just...ht/a-mv55.html

When you say you put the 12AX7s in the 'power amp', which socket(s) did you put them in?

[6267]

umm...the 12ax7 in that lineup is the only 9-pin tube. It will not physically fit in the other sockets. Second, 12ax7s are dual triodes, and thus cannot be 'ultralinear' or anything else other than triodes or diodes. Ultralinear operation or 'triode mode' (note mode) are generally used to refer to power tubes with pentode or tetrode internals. I still suspect either one tube section (ie. one triode out of the two in the bottle) is short or crappy, or there's something else wrong with the quieter amp.

[tubeswell]

umm...the 12ax7 in that lineup is the only 9-pin tube. It will not physically fit in the other sockets. Second, 12ax7s are dual triodes, and thus cannot be 'ultralinear' or anything else other than triodes or diodes.

Those were my exact inital thoughts, and what I put in my post before I edited it, but I changed my mind when I saw the ad on the MV55 site and got confused.

[J Martin]

I don't know if this is relevant or not, but the Sovtek 12AX7 LPS works very well in phono stages. I just built a RIAA phono stage in a friends pre RIAA flea market find 2x EL84 SE amplifier and it sounds great. Except for a CD player, I don't own any solid state audio gear.

[6267]

I haven't tried the sovteks yet, but I've heard good things for quite a while. I don't really find myself replacing preamp tubes except for entertainment...I did once sadly lose an RCA 12ax7 because it had been in a series heater amp with some wiring problems for a while and the filament died. Unfortunately I didn't catch the problem soon enough.