Risen to a level where caution is warranted - Mullard Reissue 12AX7

mfsoa · « **on:** 6 Apr 2009, 02:06 am »

Hi everyone,

I thought I'd share my experience w/ these tubes so far.

Bought a pr from Jim McShane. Both stopped working properly after a few days. Jim took them back no problem and confirmed that one of the sections was out on each tube. He sent out two more - One just went, after about a week of pretty solid use.

So, given a failure rate of 3 out of 4 over a 1 month period (in my VAC preamp) I thought I'd make mention here.

Maybe my pre is over-voltaging them or something? I don't know.

Maybe I'll try the new Tung-Sols? or does someone else have a good reccomendation?

Thanks

-Mike

markC · « **Reply #1 on:** 6 Apr 2009, 02:14 am »

Forgive me if this is a question that is moot, but, have you used other brand tubes succesfully in the pre for extended lengths of time?

mfsoa · « **Reply #2 on:** 6 Apr 2009, 02:21 am »

Good question -

No, these are the first tubes I've rolled in.

Jim also sold me a pr of Radiotechnique NOS 12AU7s at the same time for the same pre and they have been working fine for a month.

The original VAC 12AX7s work fine when I switch them out for the Mullards which keep failing

-Mike

markC · « **Reply #3 on:** 6 Apr 2009, 02:30 am »

I take it that the pre uses both ax's and au's. I'd have to say that if other tube brands work fine for extended periods, that either the Mullards are bad or your pre runs them out of their max. operating range. The latter doesn't seem likely though. I'd try and find the specs for the Mullards and the others and compare.

mjosef · « **Reply #4 on:** 6 Apr 2009, 04:05 am »

I had been using those reissues Mullards, bought from Jim also, for several months in my Response Audio 3205(Jolida 302/502) without any problems.

After changing/tweeking a few things in my system I felt my sound became too "soft", so I rolled in the new reissue TungSols and thought they brought the right amount of "punch" back to the sound. Several months ago when I had first tried them(Tungsols) I thought they were too "hard/sterile", and had preferred the Mullards which sounded much warmer. Funny how time changes perspectives. aa
YMWV

mfsoa · « **Reply #5 on:** 6 Apr 2009, 02:10 pm »

Fourth one went this morning

HT cOz · « **Reply #6 on:** 6 Apr 2009, 02:27 pm »

I would think Jim has a good feel for how the tubes are performing and if it is your amp/tube combination or a problem with the tubes themselves. It is a little strange that it is hit or miss.

twitch54 · « **Reply #7 on:** 6 Apr 2009, 05:55 pm »

Quote from: mfsoa on 6 Apr 2009, 02:21 am

Jim also sold me a pr of Radiotechnique NOS 12AU7s at the same time for the same pre and they have been working fine for a month.

great tube Mike, I've been enjoying them in my Cary 303/300 CDP for over a year now.

Nels Ferre · « **Reply #8 on:** 6 Apr 2009, 05:56 pm »

My guess is that your preamp is running these tubes near their limit, as previously mentioned. I am running a pair in my Response Audio/Bella Extreme 3205 amp as well, with no issues at all.

I recommend you not try a Sovtek 12AX7LPS, as I believe it is the exact same tube as the new Mullard.

mfsoa · « **Reply #9 on:** 13 Apr 2009, 07:55 pm »

Thanks to all for your replies-

Nels - I was thinking that I actually would try the Sovteks, since they are cheap and Jim has them in stock. I almost don't care about the sound much (gasp) but am more curious just to see if they work! I figure I'll try some relatively inexpensive tubes first before trying some $$$ ones, if my pre is eating them.

Ian - As far as I knew Jim does a good job of testing but I don't know all he does nor am I competant to say if what he does is adequate. Appreciate the 12AX7 rec.

For now I'm just slumming it w/ my old (original) VAC 12AX7s.

And during all this, I lost another Genalex Reissue KT-88 (2nd one gone out of 4 in a year). And it took out my $$ fuse too

.

Making solid state look better and better...

-Mike

Freo-1 · « **Reply #10 on:** 13 Apr 2009, 09:34 pm »

Quote from: mfsoa on 13 Apr 2009, 07:55 pm

Thanks to all for your replies-

Nels - I was thinking that I actually would try the Sovteks, since they are cheap and Jim has them in stock. I almost don't care about the sound much (gasp) but am more curious just to see if they work! I figure I'll try some relatively inexpensive tubes first before trying some $$$ ones, if my pre is eating them.

Ian - As far as I knew Jim does a good job of testing but I don't know all he does nor am I competant to say if what he does is adequate. Appreciate the 12AX7 rec.

For now I'm just slumming it w/ my old (original) VAC 12AX7s.

And during all this, I lost another Genalex Reissue KT-88 (2nd one gone out of 4 in a year). And it took out my $$ fuse too .

Making solid state look better and better...

-Mike

Interesting about the Genalex KT88 Re-issues. The tube vendors seem to take it personal when people point out their troubles with them. I've personally had better luck with the Penta KT88SC than the Genalex. The winged C 6550 is a solid performer (but not as nice sonically)

The reality is, any tube can give you trouble, that's part of owning tubes. Then again, I've know people who have has Fisher receivers/amps for years with little to no trouble.

carusoracer · « **Reply #11 on:** 13 Apr 2009, 09:52 pm »

Sorry to hear about the tube failures

I took out a Winged C when i first had my 302b have had no problems since.
I did not like the Sovtek tubes in any of the Amps I have tried just not my sound.

I did try the New Sensor Tung Sol re issue 12AX7's from Jim and once they settled in I really like the sound

BTW, I'm a NOS fanatic so this was a first for me buying new tubes.

jon_010101 · « **Reply #12 on:** 14 Apr 2009, 07:54 am »

Anyone know what the circuit is in the preamp? The Mullard almost certainly has a spiral filament, so I'm guessing it's an SRPP circuit but with the heater voltage referenced to ground, causing heater-to-cathode breakdown. In this case the blame is half the tube, half the preamp

mfsoa · « **Reply #13 on:** 14 Apr 2009, 05:50 pm »

I just emailed VAC to see if they can shed light on anything.

In the meantime I ordered the Sovteks - Should be interesting to see if they bite the dust soon as well

-Mike

iGrant · « **Reply #14 on:** 15 Apr 2009, 02:44 pm »

Quote from: mfsoa on 13 Apr 2009, 07:55 pm

Thanks to all for your replies-

Ian - As far as I knew Jim does a good job of testing but I don't know all he does nor am I competant to say if what he does is adequate. Appreciate the 12AX7 rec.

-Mike

Hi Mike, wasn't trying to imply that Jim isn't doing a good job matching tubes, more of a general statement that I used your post to share about section matching on dual section tubes. I wasn't aware of this myself until some guys from the Canadian arm of AudioNote started specifying what they want from us for tubes a while ago. Lots know this, lots more seem unaware.

Hope you get your situation sorted

Cheers,
Ian

mfsoa · « **Reply #15 on:** 15 Apr 2009, 09:39 pm »

I just got a reply back from Kevin @ VAC-
He says that there is nothing unusual in the operating parameters for the tube, and that failures there are rare.

I won't say much more because I don't have his permisson to quote him, but he's thinking it's a tube quality issue.

Oh well, bring on the Sovtek's (which, if they are the same tube as the Mullard) should poop out in short order.

I don't mean to make blanket statements on the quality of these tubes - My intent w/ this thread was only to say what's happening to me in my system and seek advice - I'm one data point, that's all.

Thanks all,

-Mike

mfsoa · « **Reply #16 on:** 15 Apr 2009, 09:42 pm »

Quote

Oh well, bring on the Sovtek's (which, if they are the same tube as the Mullard) should poop out in short order.

...and then Ian gets a call

mfsoa · « **Reply #17 on:** 17 Apr 2009, 11:51 pm »

OK, the Sovteks are in and playing. They sound really good out of the box, keeping my fingers crossed for longevity. They have a palpable organic feel to them that the (old) stock VAC tubes lack.

Based in Nels' feeling that the reissue Mullards are the exact same tube as the Sovtek, I looked very closely at each before I put the Sovteks in the pre - I could not see one bit of difference, except one had a "2" molded into the bottom, and one had a "3".

I forget the name of the US company that is resonsible for these tubes, but if they have simply bought the names of Tung Sol, Mullard, Amperex etc and are simply printing different names on the same tube, I gotta say that really sucks and seems very dishonest.

Does anyone know the truth about what is coming out of the old Reflektor factory now?

Are the reissue Gold Lion KT88s the same sort of deal? What happend to all the "We painstakingly recreated the exact same classic tube from years ago down to the molecular level..."

That's a far cry from "We just put 10 different names on the same crummy tube, charge different prices for them and pretend that they are something they are not".

What's the truth? Inquiring minds want to know!

Wow, I just hijacked my own thread. Can I get banned for that?

(BTW, throughout this process Jim McShane has been a pleasure to deal with)

-Mike

Les Lammers · « **Reply #18 on:** 25 Apr 2009, 07:03 pm »

"Are the reissue Gold Lion KT88s the same sort of deal? What happend to all the "We painstakingly recreated the exact same classic tube from years ago down to the molecular level..."

That's a far cry from "We just put 10 different names on the same crummy tube, charge different prices for them and pretend that they are something they are not".

What's the truth? Inquiring minds want to know!

I dunno about the molecular level but the new GL's are very good. There is a LOT of hype and myth in the world of NOS tubes. Many of the sought after ones were not originally designed for audio. Tubes were in everything and as common as light bulbs. In the Golden Age, tubes were routinely re-labeled by various manufacturers for many reasons. Most older tube gear was not as transparent as modern gear so the choice of tube 'brand' did not matter as much. Personally, *I* don't want to own any gear was voiced for tubes that are becoming unobtanium.

mfsoa · « **Reply #19 on:** 1 May 2009, 02:40 am »

Update-

The Sovteks have been playing for about two weeks now with no issues at all. This is already much longer than I got out of the Mullards.

Now that I've jinxed myself...

-Mike