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I know I have been tough on 12ax7 but.......

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Posted on January 27, 2011 at 08:08:08
Mendel
Audiophile

Posts: 684
Location: GTA
Joined: January 17, 2009
I have finally found 3 that I really like and are competitive with the best 5751's:
1) Mullard short plate with 45 degree tilted halo getter. This tube is quite different from the other Mullards that I have (1950' long plate double getter holder and 1960's short-plate). I have only found 3 of these in my searches (2 marked Bogen and one GE). I believe they are a latter production British tube--maybe one of the last runs before production ceased in England. These are so different sounding from the standard Mullard short plate of the 1960's and the long plate of the 1950's it is really amazing. Those tubes have a very warm, round, rich, thick sound that is appealing for jazz or small-scale music, but which drags more upscale music down into the quagmire. These tilted getter tubes have the midrange magic of the others, with a faster, livelier,more focused sound. They are also bass masters--bettering even the 5751's in this regard. Treble is good, but not quite as extended as the best. But sweet and airy. The best 12ax7 I have heard.
2)Matsushita 12ax7 45 degree tilted getter. Don't know what it is about these tilted getter tubes--maybe the getter structure is more rigid leading to less micro phonics. This Japanese tube looks similar to the Mullard above and may be based on the same tooling. Very fast and clean, the midrange a little less rich than the Mullard but treble even more extended and airy. But less bass (unfortunately). A great tube.
3)Raytheon 17mm long black-plate halo getter. This is the tube right after the black-plate square getter and was produced in the early 1960's.I do not have the Raytheon square getter to compare to, but I do have the RCA back plate square getter. The Raytheon is more focused, with a very rich sound that manages not to slow up the music like the regular Mullards. Highs are slightly laid-back but still have a nice shimmer. Bass is good but not equal to the Mullard above.
The above tubes have bettered all the Mullard, Telefunken,Amperex, RCA, EI, Sylvania, Brimar, et all 12ax7 tubes I have tried in my amp. When using 6L6/KT66 output tubes I still prefer the best 5751's, but when using KT88 and EL34, the above 12ax7 tubes are very enjoyable. If you can find them (good luck with the Mullard) grab them.

 

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RE: I know I have been tough on 12ax7 but......., posted on January 27, 2011 at 10:23:03
Escobar
Audiophile

Posts: 119
Location: Colombia / Miami, FL
Joined: August 1, 2010
About the matsushita, yes i have found it to have such a great sound, especially on the midrange. My scott 222d has 3 telefunkens on it and i was feelin i needed a better midrange presence. I put a matsushita 45 degres getter and there you go! Punchier midrange! Great! So i ended havig the extension of the teles plus the midrange of the matsushita.
I guess the nickname 'mullard on the cheap' is quite valid
Scott 222D
Yamaha YP-D71 TT
Martin Logan Motion 4 Speakers
Hopefully growing!

 

RE: I know I have been tough on 12ax7 but......., posted on January 27, 2011 at 11:38:31
Neff


 
I used all three in many types of equipment- not bad tubes. A step up is Mullard long plate & Brimar CV4004 12AX7s.

 

RE: I know I have been tough on 12ax7 but......., posted on January 27, 2011 at 13:23:58
tvr2500m
Audiophile

Posts: 1553
Location: Boston
Joined: February 2, 2003
Does that Mullard have a code on it. I believe that it's not Blackburn or Mitcham tube, and that the only Philips shop that made this tube was Valvo Hamburg. Does this tube has "D" code on it anywhere?

- SJ

 

RE: I know I have been tough on 12ax7 but......., posted on January 27, 2011 at 14:05:30
Mendel
Audiophile

Posts: 684
Location: GTA
Joined: January 17, 2009
The labels are pretty well gone on the tubes. There is no visable date code except on one of the Bogen it has the number 1022-210, and all say MADE IN GT. BRITAIN in small letters across the top of the tube.Two visable seems on the top of the tube and all 3 flash brightly when put into the tube tester.The tube glass, plate stucture, bottom wiring and getter are identcal to a BOGEN Mullard I have with a B2A1 code--the only difference is the tilt of the getter.And the sound of course.That is why I figured they were Mullards.
Neff I must disagree. I have a perfect pair of long-plate mullard with the double getter holder(B8L and B8J codes)and the Brimar CV4004 12ax7 and in my amp the Mullards I am describing smoke them.I like the Brimar and the long plate Mullard--just don't love them I guess. As allways in tubeland, different tubes suite different amps and different tasks. I use these as input tubes for a Rogue Stereo 90 power amp. In a pre-amp or phono-stage, the ranking of tubes could be different. However, a good tube is a good tube. Just might not be the BEST tube for a given application.

 

It should be , posted on January 27, 2011 at 15:05:27
unclestu
Dealer

Posts: 4623
Joined: April 13, 2010
pointed out that the Brimar CV 4004 is a very different animal from the Mullard version: The Brimar is quite bright in tonal balance, while the Mullard is very dark, relatively speaking.

Also It should be pointed out that I have seen three different versions of Mullard Long plate 12AX7. The earliest I have is the mC1, then comes the f91 and f92, although I have seen 91's with 92 construction. A true 91 has a tiny wire attached to a metal staple on the top mica which touches the cathode. The 92 eliminates that little wire ( looks like a piece of filament wire).

All three have very different sonic characteristics. I find the f91 to be the most open with a slight upper midrange emphasis. The 92 sounds significantly flatter in the soundstage, and the mC1 has greatest amount of bass although a tad too warm for my taste.

Stu

 

RE: Exact sonics depends upon the amp & speakers, posted on January 27, 2011 at 15:50:54
Neff


 
The Brimar is neutral, uncolored and crystal clear. It is also bright with a lot of detail. I like this tube.

The Mullard 12AX7 (F91) long plate is warmer & musical. The Mullard is definately darker as described. I find the F91 betters the Brimar per my tastes. Wish I had some NOS just to own the tubes. I would guess a NOS pair if found would be at least $500 per pair.

The original posters tubes are ok, but do not cut it for me. Kind of like listening to a $500 vs $4000 amp. Hard to go back to the $500 model.

 

RE: I know I have been tough on 12ax7 but......., posted on January 27, 2011 at 17:03:54
Anacrusis
Audiophile

Posts: 190
Location: Southern California
Joined: September 18, 2006
I'm starting to be of the opinion that 5751s are less dynamic than their 12AX7 counterparts. That the 5751 perception of focus comes from the fact that every musical element is highlighted whereas the 12AX7s are more natural sounding with greater depth and dynamics.

The real beauty of music lies in the ambience of the venue.

 

Agreed., posted on January 27, 2011 at 17:32:16
Diode
Audiophile

Posts: 511
Location: SE Wis
Joined: September 11, 2005
To my ears 5751's sound brighter and a touch harder than 12ax7's, which would be a good thing in a lower resolving system, but is a bit too much of a good thing in a higher resolving rig.

 

RE: Exact sonics depends upon the amp & speakers, posted on January 27, 2011 at 17:34:01
Mendel
Audiophile

Posts: 684
Location: GTA
Joined: January 17, 2009
Ha Ha. Neff, you are a laugh a minute! Thank the Lord we have you to tell us what is good. You should become a member!

 

RE: I know I have been tough on 12ax7 but......., posted on January 27, 2011 at 17:47:20
Mendel
Audiophile

Posts: 684
Location: GTA
Joined: January 17, 2009
There may be some truth in that Anacrusis.My favoured 12ax7's do seem to have greater dynamic swing to them.But a windmill 5751 has great dynamics too. Depends on the tube combinations. Most of the time I find most 12ax7 too hazy and unfocused to be reminiscent of the real thing. But if you find the right one with the right combo of driver and output tubes, they can sound very good.
Diode, I never find 5751 bright in my system. Now, something like Neff's favoured Brimar or a Tele ribbed plate--that can sound bright with the wrong combo of tubes or in the wrong gear.
I guess its all a matter of balance with different tube sets in different gear. I guess 12ax7's have their place. In general I still think the 5751 is the better tube.

 

RE: I know I have been tough on 12ax7 but......., posted on January 27, 2011 at 21:24:35
Bilbar
Audiophile

Posts: 69
Location: Van Isle, BC
Joined: August 7, 2009
tvr2500m is right. The "Mullard" short plate with inclined halo getter is most likely an I60 from the Valvo plant in Hamburg. Quite often a good light and a magnifying glass will reveal the etched production codes, near the base of the tube.

 

RE: I know I have been tough on 12ax7 but......., posted on January 28, 2011 at 06:26:54
Mendel
Audiophile

Posts: 684
Location: GTA
Joined: January 17, 2009
Hi Bilbar:
I did look along the bottom of the tube with a flashlight and could not find a code. But you and tvr2500 could be right. I have never heard a Mullard sound like this! Just for grins I put the Mullard long plates back in last night and guess what? They kinda suck! Either they ain't that great, or they are just a bad match for my gear. So thick and rich the music sounded as if it was drowning in molasses.Not my cup of tea thank you!

 

RE: I know I have been tough on 12ax7 but......., posted on January 28, 2011 at 08:14:07
JNS
I agree with you on the long plate Mullards. To me they are dull and thick. Now long plate Amperex are a different story. You should try some Tung Sol 12AX7s if you can find them at a reasonable price.

 

RE: I know I have been tough on 12ax7 but......., posted on January 28, 2011 at 11:23:15
unclestu
Dealer

Posts: 4623
Joined: April 13, 2010
Again it should be noted that 5751's have a slightly lower amplification factor in comparison to a 12AX7. Not surprising you lose a little in dynamics. IIRC 5751's were developed in order to compete with the European ECC83 which had better control of the signal.


Stu

 

Out of curiosity, posted on January 28, 2011 at 11:24:40
unclestu
Dealer

Posts: 4623
Joined: April 13, 2010
Which version of the Mullard long plates do you have?

Stu

 

RE: Out of curiosity, posted on January 28, 2011 at 12:23:51
Mendel
Audiophile

Posts: 684
Location: GTA
Joined: January 17, 2009
Hi Stu:
They are the ones with the D shaped getter with a double getter holder The Labels are pretty much gone, but one says MADE IN GREAT BRITAIN on it and the other has the faint remains of a Mullard logo with ECC83 marked below it and BVA in a circle below that.
The codes I see on the bottom of the tubes are B8J(or possibly BBJ)and B8L (or BBL).
They are obviously not NOS, but they test about 80%-85% on my Stark 12-22 tester (Canadian Hickock), and the 4 sections on the two tubes match very well.They test well, I'll give them that.
A very famous,much sought after tube. Wonder what they are worth? To bad they sound like shht in my application. In a pre-amp, they could be awesome. But I kinda doubt it.

 

RE: Out of curiosity, posted on January 28, 2011 at 12:57:31
unclestu
Dealer

Posts: 4623
Joined: April 13, 2010
They seem to be a late mC1 with the D getters, all the later long plates are halo style getters although I have seen one f91 with a D getter. The mC1 or f91/92 appellation should be located right above the date codes. If it is infact the mC1 they are quite valuable as are all Mullard long plates, but I find them excessively warm as I stated elsewhere. The f91 series is a totally different animal, significantly more open and airy sounding.

The f91's can be distinguished by the unusual construction on the top mica opposite each plate structure. There is a metal staple with a little coated wire extending from the outboard staple to the cathode.


Stu

 

RE: Out of curiosity, posted on January 28, 2011 at 13:59:34
becketma@yahoo.com
Audiophile

Posts: 1344
Location: Sunny Tucson AZ
Joined: May 21, 2007
For me, it's always great news when some one finds a tube or tubes they love.

With Brimar grey half plates CV4004 there are two models, large O getter and small o getter. The grey half plates, which are identical to the CV4004, but installed as mirror images, also have large O and small o getters.

I haven't purchased any of the Brimar 12AX7 long grey plates with square getters. There might be half plate versions with square getters?

Enjoy your new found tubes.
Bob
"He (R.M. Nixon) was a foul caricature of himself, a man with no soul, no inner convictions, with the integrity of a hyena, and the style of a poison toad." H. S. Thompson

 

RE: Out of curiosity, posted on January 28, 2011 at 14:00:26
Mendel
Audiophile

Posts: 684
Location: GTA
Joined: January 17, 2009
Ha--learn something new every day. It appears they are not a perfect pair. One (B8J) has the staple with a small white wire running from it. The other has a slightly raised section on the top mica--no wires. Both actually have halo getter's supported by a "bridge" getter holder that cuts across the circle getter, making it look like a D getter. Wait--I found another one. This one has the Mullard shield logo code B7A--the same long grey plates and a bent square getter with "bridge" double getter holder.
Given that they are not a perfect pair my judgement of these tubes may be harsh (but I doubt it). Hopefully soon I will find a match to one of these three a try them again.

 

RE: I know I have been tough on 12ax7 but......., posted on January 28, 2011 at 15:12:19
Neff


 
I did have a pair of Amperex 12AX7 long plate in the phase splitter bail out a Kenwood PP E84 amp. However, I gave up on PP amps, less perhaps PP 2A3 or 45s.

 

RE: Out of curiosity, posted on January 28, 2011 at 15:40:38
unclestu
Dealer

Posts: 4623
Joined: April 13, 2010
It does sound like you have three different versions of the Mullard Long Plate!

In combining the two different Mullards (if both are in different channels), the excessive warmth of the mC1 will dominate and cloud the sound (IMHE). One of those Mullards you have, if the construction is identical to the f91 except that it has a mica piece "spring" loaded against the cathodes, would be an f92. It does not have the openness of the f91 although more extended on the top end than an mC1 which normally has a true D getter.

If you got them used, and suspect some aging on the tubes, you can rejuvenate them by doing a bake out. I place the tubes in a toaster oven at the lowest temperature setting and bake them for 30 minutes and then raise the temperature by 50 degrees every half hour to about 300 degrees, and just leave them there for as long as I feel comfortable (overnight some times). Then I simply unplug the oven to allow them to cool to room temperature slowly. Usually the sound is restored to like new conditions, although there is no guarantee how long this bake out will last.

Try the procedure on some older tubes first. It will NOT change any readings on a tube tester, but will absorb a tremendous amount of the gasses which have been purged by running the tubes ( emitted from the metal structure itself as well as the glass) and thus restore the tube closer to the original factory vacuum. I've noticed in using this procedure that that blue glow that many tubes acquire over time will disappear, particularly on power tubes.

Stu

 

RE: Out of curiosity, posted on January 28, 2011 at 16:41:49
becketma@yahoo.com
Audiophile

Posts: 1344
Location: Sunny Tucson AZ
Joined: May 21, 2007
Ahhhhhh!

The Betty Crocker tweak?

Best from Tucson
Bob
"He (R.M. Nixon) was a foul caricature of himself, a man with no soul, no inner convictions, with the integrity of a hyena, and the style of a poison toad." H. S. Thompson

 

RE: Out of curiosity, posted on January 28, 2011 at 17:08:30
Mendel
Audiophile

Posts: 684
Location: GTA
Joined: January 17, 2009
Wow--great tip Stu. I think I have heard of that one before, but never tried it.
Thats what these forums are suppose to be about! Will definitely give it a try.

 

RE: Out of curiosity, posted on February 4, 2011 at 06:55:04
david62


 
This is probably a stupid question,but are the new re-issue 12ax7 tubes any good?How about NOS Amperex 12ax7's?Thanks,
Dave

 

RE: Out of curiosity, posted on February 4, 2011 at 08:27:54
Mendel
Audiophile

Posts: 684
Location: GTA
Joined: January 17, 2009
Hi Dave:
The only new issue 12ax7 I have tried is the sovtec LPS---a pretty good tube--very quiet, good extension at both ends. But it does not have the "midrange magic" of the best NOS tubes IMO.
Amperex made many 12ax7's. They are all pretty good, the best are probably the early long plate(17mm) D getter tubes. The bugle boys are sweet and warm sounding while the orange globe tubes are good too. But as in all things tube, it depends on the equipment. In my amp the Amperex is not my favorite, the three tubes I mention in my original post and most 5751's easily best them. In another amp or pre-amp the Amperex's could be killer. You just have too spend your money and try it. That is why people end up with huge tube collections worth far more than their amp's. Collecting tubes is fun!

 

RE: I know I have been tough on 12ax7 but......., posted on February 4, 2011 at 08:42:14
Mendel
Audiophile

Posts: 684
Location: GTA
Joined: January 17, 2009
tvr and Bilbar:
Just to follow up--it appears you are right about my favorite 12ax7--the short plate with the 45 degree tilted getter. Despite the fact that they are marked made in Gt. Britain I now believe these tubes are Valvo made in the Hamburg plant in Germany. They do not "flash" like most Mullards and I do not believe Mullard ever made a tilted getter tube. A picture of the tubes I have can be seen on the tube classic website as coming from the Hamburg plant which specialized in these tilted getter tubes. An absolutely killer tube! Thanks for the assist guys.

 

RE: I know I have been tough on 12ax7 but......., posted on February 4, 2011 at 09:10:22
david62


 
Thanks for the information.How about the new re-issue Mullards?Are they any good?

 

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