Alot of 12AX7's about

[richwalters]

There's alot of 12AX7's about with huge price differences from NOS to new edition Tung-sol and Mullard versions by the same reflektor plant.
Putting these new edition versions against the (pricy!) NOS Mullard and others, they often out-perform the golden oldies. Agree ??

When I get my digital camera sorted out I will submit some thd pics with my standard feedback cascade circuit.. There are large differences of the thd signature despite the microphonics being generally low.. anyone else noticed ??

Who's using "which" favourite ?

richj

[Brett]

AX7's are crap. Sell then to the foolish and buy decent tubes.

[Tweeker]

Is there a better dual triode with a three figure mu?

[richwalters]

Thanks Brett....à bit more....despite the choas regarding the JJ ECC803S clones, this tube is about the worst I've ever got my hands on.
The ECC83S is marginally better.
But help, the Mullard ones are fetching absurd prices! Which ones are you using ?

richj

[ray_moth]

I seem to remember seeing recommendations for Sovtek 12AX7s. However, I'm not 'into' these tubes personally, so what do I know?

[Brett]

Originally posted by richwalters
Which ones are you using ?

Me? None. Not even in guitar amps which is where they belong.

[kstagger]

I use 12AX7s in vintage restoration - though I have also built a simple phono stage using them.

If you want to get into the 'character' of 12AX7s. the Tubes Asylum on 'Audio Asylum' is a good place to start. Having said that, I've had good luck with tested/matched sections of the Shuguang 12AX7C9. Sounds an awful lot like a real oldie Mullard. The 12AX7LPS is good too. I haven't heard the new Mullard 're-issue' yet - and I probably won't bother since I also have a small stash of Telefunkens and EIs that I can use with my old Dynaco PAS (second system).

[gingertube]

I use selected JJ ECC803S and ElectroHarmonix. The EH consistently match well side to side - the JJ's don't. Oh - I also use some NOS Philips for the "special" projects.

Since Brett is a fellow Aussie I'll take him to task (without risking an international incident) as being a representative of a sub culture here. Its the "12AX7 is a guitar amp tube and is therefore crap for HiFi" subculture.

Rubbish, 12AX7 is like any other tube, it performs well in a properly designed circuit and performs badly in a badly designed circuit. Too many give it a caning, and probably without ever listening critically to it. Either that, or they quite correctly say (for example), that as a phase splitter / driver it won't properly drive that quad of output tubes. Don't blame the tube - blame the idiot who incorrectly specified the use of a 12AX7 ifor that duty.

Why do you think its used in 99% of tube guitar amps? Well the mu of 100 helps but its mostly because its so easy to tailor its sound by abusing it in various ways.

On the other hand, it is just as easy to get lovely sound from it by using appropriate operating points and circuit duty.

My latest "Baby Huey" uses a 12AX7 in the front end diff amp. I've done A/B listening betwen that amp and some very expensive 300B Push Pull Monoblocks., and 845 SET etc. and all that expensive stuff came off second best. 12AX7 can and does sound great when used properly.

Appologies to all for the "vent" - I've wanted to "have a go" at the "anti 12AX7 crowd" for a while now, consdier it done and "off my chest/spleen/liver (or whatever)".

Cheers,
Ian

[AKSA]

Nice post, Ginger.

One of the Japanese greats (Komura?) once said:

'You do not know a tube until you find it's address and telephone
number'.

I can relate to that, it took me about two months to find the best operating point for a 6SL7, but it was worth it.....

The downside of the 12AX7 is its microphonics, and it's very high plate impedance (62K) which makes any realistic load a bit tough to pull. And in guitar amps it's often teamed up with a 100K plate resistor, which at only 1.6 times the rp is a fairly distortive loading.

Cheers,

Hugh

[HollowState]

Originally posted by gingertube

Rubbish, 12AX7 is like any other tube, it performs well in a properly designed circuit and performs badly in a badly designed circuit. Too many give it a caning, and probably without ever listening critically to it. Either that, or they quite correctly say (for example), that as a phase splitter / driver it won't properly drive that quad of output tubes. Don't blame the tube - blame the idiot who incorrectly specified the use of a 12AX7 ifor that duty.

Amen to that Ian. The 12AX7 is a perennial that has earned a place of honor in audio history with more then half a century of excellent and reliable service in almost every conceivable piece of sound equipment both professional and consumer. The ramifications of this are very far reaching when one stops to consider the hundreds of brand name items that are sought after both for their collectablity and their sonics. It would seem to me that perhaps it's just a group of audio elitist's that find this tube currently unfashionable because if it's minor limitations.
(Haha, that'll ruffle a few feathers)

Victor