[SteveFord]

I had some today to fool around with a box of 12AX7s in a Jolida JD9 phono stage.
It came with Tung Sols which were okay but bass heavy, Electro Harmonix (unexciting presentation), Sovtek LPS' which sound good from top to bottom, some old RCAs which sound really distant (kind of like your grandparent's Magnavox console) and the winner:
JJ Tesla ECC 803S
by a wide margin.
Inexpensive and really, really good with great dynamics, great top end and an even balance from top to bottom.
The 803S has more gain than the other tubes so be prepared to make some adjustments. 
I really wanted the RCAs to be top dog but oh well, back into the box uh spares they go.

[Ericus Rex]

Good to know!  Thanks for the info.  BTW, this is the new production version of this tube, yes?  Gold or steel pin version?

Thanks!

[SteveFord]

Yes, current production tubes from an eBay seller and I chintzed out and got the regular old steel pin.  I believe that the whole gold plating thing is for corrosion resistance and I use either a little dielectric grease or WD40 (AVNerdguy's tip) so that's not a concern.
I haven't heard the Genelux Gold Lions so don't know how these compare to the Genelux. 
I forgot to mention the JJ Tesla 12AX7s are real good, too.  I found that they gave a wider and deeper soundstage than the Sovtek LPS but these ECC 803S are better than the JJ 12AX7s.

[medium jim]

Most of the current production 12AX7 tubes are being made for guitar amplification.  This is not a bad thing as most tube guitar amps are high gain and this caused better or lower Microphonics.

For home stereo I like the EI's that were in production in the early 2000's.  Nice gain, they typically spec'd at or near 1.1ma and are a neutral sounding tube.  I roll them into my preamp now and then in lieu of my smooth plate telefunken's which may be one of the best hi-fi tubes ever.

Surprisingly, Chinese 12AX7's are a very nice tube. Gold pins used to mean something and typically were reserved for the PQ or SQ designated tubes or for the industrial numbered equivalent tubes, such as the 803S. As Steve said, it was more of a anti-corrosive thing.  The most important thing is the guts of a tube and the inert gases.



Jim

[BPoletti]

Every circuit is different.  A tube that sounds great on one circuit might sound mediocre in another.  My suggestion is to buy a lot of different ones and see which sound best.  Sell the others.

[medium jim]

Every circuit is different.  A tube that sounds great on one circuit might sound mediocre in another.  My suggestion is to buy a lot of different ones and see which sound best.  Sell the others.

Some truth to your post, nevertheless, a good or great tube will sound good regardless of the topography/circuit.  Much is personal preference in the end.

Jim

[BPoletti]

Some truth to your post, nevertheless, a good or great tube will sound good regardless of the topography/circuit.  Much is personal preference in the end.

Jim

Hardly!!  And good luck with that!  Some tubes will just sound bad in hifi applications.  Because of loading, voltage variations, and resonances, tubes that perform well in some circuits don't necessarily perform well in others.  Though there is personal preference involved, that does not overcome the obvious performance differences between circuits and the interaction with tubes.

Though I am personally strongly opinionated on this topic, YMMV based on your personal preferences and pride of ownership.

[roscoeiii]

I have really liked the Psvane 12AX7s in my MiniWatt N3 amp. A Rogue 90 is on its way and I will try them in it shortly.

[galyons]

Some truth to your post, nevertheless, a good or great tube will sound good regardless of the topography/circuit.  Much is personal preference in the end.

Jim

There are just too many variables in circuits to make such a gross generalization.  As an example, the plate voltage can vary significantly in various 12AX7 topologies and have a dramatic impact on sound.

Why would anyone want to take a "great tube" and make it sound just "good"?

Cheers,
Geary

[medium jim]

While there can differences in circuits and topologies, the 12AX7 is designed to be a 100mu gain tube and one would design their amp or preamp as such. While there will be variances, a quality tube will usually rise to the occasion.

And yes, I can safely generalize.

Jim

[SteveFord]

These are my findings using my crud, YMMV.

[medium jim]

More to the point, the 12AX7 is a "Preamp" tube and plate voltage for the most part is a non sequitur.  Agreed, there will be different voicings within different circuits and matching said tube to said circuit is paramount, you need to know what you are seeking.

Jim

[BPoletti]

More to the point, the 12AX7 is a "Preamp" tube and plate voltage for the most part is a non sequitur. 

Jim

If I agree with you then we'd both be wrong.  Vary the plate voltage and hear the gross changes in performance. 

[galyons]

More to the point, the 12AX7 is a "Preamp" tube and plate voltage for the most part is a non sequitur.  Agreed, there will be different voicings within different circuits and matching said tube to said circuit is paramount, you need to know what you are seeking.

Jim

Really?  Plate voltage is a non sequitur to a "preamp " tube?  Well guess that works, it is always most illuminating to defend a generalization with a generalization.  Good to know. Gotta go toss all my tube data sheets..especially those confusing graphs!!!

So how do I match "said tube" to "said circuit"? # of pins...bottle length...color of logo?

Talk about non sequiturs, here we have a classic example.

Life can be so simple....

Cheers,
Geary

[BPoletti]

Really?  Plate voltage is a non sequitur to a "preamp " tube?  Well guess that works, it is always most illuminating to defend a generalization with a generalization.  Good to know. Gotta go toss all my tube data sheets..especially those confusing graphs!!!

So how do I match "said tube" to "said circuit"? # of pins...bottle length...color of logo?

Talk about non sequiturs, here we have a classic example.

Life can be so simple....

Cheers,
Geary

     +5

[Freo-1]

My fav 12AX7 are the Raytheon Black Plates.  Wonderful sound from those.

[SteveFord]

I'll have to hunt up a set of the Raytheons and the Psvanes and give them a shot.
I've got some GEs which I liked better than the RCAs but they're nothing to write home about.
A DAC here has JJ Tesla 12AX7s which I'll use as a guinea pig.  I can hear the differences in that but I don't know if they'll be as dramatic as in that phono stage.  Guess I'll find out.
P.S.
BPoletti, you gave me a laugh with the pride of ownership comment as it made me picture somebody getting all puffed up over a tube that cost $13.95 on eBay.

[medium jim]

I have to laugh at some of the responses.  First off one matches a preamp tube from each half of the tube (assuming it has two sides) for output, then for mutual conductance.

Power pentodes (output tubes) are different and plate voltages come into play, especially amps that have say 450 plate volts as lesser tubes will fail.

Back to preamp tubes, a matched preamp tube is more important if it is to be used as the phase inverter tube.

I suppose if one has inferior equipment then there can be wide variances (design flaws) that come into play.  With tried and true circuits just the opposite

Jim

[BPoletti]

P.S.
BPoletti, you gave me a laugh with the pride of ownership comment as it made me picture somebody getting all puffed up over a tube that cost $13.95 on eBay.

I know people that swear some awful sounding piece of equipment or recording they own is just the most wonderful in the world.  Why?  Because THEY own it.        

I have to admit to a bit of that myself.  But that was before I got the best set-up on the planet.       (just kidding)

[tfpic mode off/] 

[JoshK]

While there can differences in circuits and topologies, the 12AX7 is designed to be a 100mu gain tube and one would design their amp or preamp as such. While there will be variances, a quality tube will usually rise to the occasion.

And yes, I can safely generalize.

Jim

I would tend to agree with both of you.  Circuit can easily trump the tube, as circuit variations are huge.   Many 12AX7 types are not mu=100 they are mu=70, only some are mu=100.  I forget the details on that because I don't like this tube type in designing my own gear and given their expense and mediocre characteristics, I opt for other better and cheap tubes.  But for commercial gear, I'd look to measurements of actual linearity.   

That is where I agree with a good tube is a good tube.   A linear tube will be better in any circuit unless one actually likes distortion or euphonic coloration.  Many commercial designs use feedback (no idea on the Jolida) so the max gain is usually better and linearity is somewhat less important, but I'd still opt for linearity uber alles.