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Rolled some 12ax7's recently...

Hi All,
I went through my supply of 12ax7's recently and found some goodies.
I recently compared Bugle Boys to Telefunkens in the phono stage of my pre-amp. Interesting (to me, at least). I found the Telefunkens to be nice sounding; very clean and clear, very nice detail, over all a very nice sounding tube. The Bugle Boys, however, were magical! WOW! Timbre was so much more apparent. The soundstage depth and width increased; especially the depth. The music seemed to come alive and glow. It was much more captivating.
I found such a dramatic difference between two high quality tubes very interesting.
I have yet to try 10m's, and 70's Mullards that I found. I will report when I do...
By the way, NOS Sylvania's sound nice in the line-level stage. All tubes reported are vintage NOS. I match them with my tube tester. And, I do not change the volume setting between tube brands tested.
Any comments are more than welcomed! I appreciate any information on your experiences with 12ax7's. The price of some of these NOS is incredible; I am glad to have these nice examples in my collection!
Cheers.
bicycle_man
nsgarch's avatar
nsgarch
2,524 posts
 
Abucktwoeighty -- I can't say for sure about your CDP application, but let's just say don't count on less output because you're running 5751's ;-)

If you compare performance (tube) curves between a 12AX7 and 5751, you'll note that the curves are essentially the same until the upper limit of operation where the 5751 drops of some. HOWEVER, I don't think any circuit designer would use either tube where it would be driven to the limit -- there would be other tubes to choose from.

Also, keep in mind that the 5751 was originally developed as a 'ruggedized' tube for the military - so it would have to perform the same as any 12AX7 it would replace.
bicycle_man OP
100 posts
 
Just finished listening to 10Ms compared to Bugle Boys.

Mmm...

They are both detailed, clean, open, great with male and female vocals, lots of air, great timbre, dynamic, and involving. I would give a slight edge to the 10Ms overall for slightly more dynamics and slightly better presence, perhaps wider and more depth to the soundstage, too.

However, in light of the current price differential (BB $145/matched pair vs. 10M $350/pair), I would go with the Bugle Boys. Since the performance of these tubes is so damned close, I do not consider the 10Ms worth more than twice the price of the Bugle Boys. I wouldn't consider them to be worth 10% more than the Bugle Boys.

It really was close! I went back and forth for 3 hours being enthralled by both tubes! Honestly. I found it hard to decide. I played a lot of music including Stairway to Heaven, Rickie Lee Jones, Paganiniana - Water Lily Acoustics, Madman Across the Water, some from Goodbye Yellow Brick Road, Mozart's Requiem - Harmonia Mundi, some from Timbre and Solera - Opus 3, September 15 (from As Falls Witchita...) and Lonely Woman (with Charlie Hayden and Billy Higgins) -- Pat Metheny, Diamond Dogs and Ziggy Stardust -- David Bowie.

Again, I appreciate any feedback or comments -- it is very interesting to me; especially anyone with experience with both tubes.
Cheers!
magnumpi205
504 posts
 
Prefer the Orange Amperex's to the Bugle Boy's. Maybe because they hold up really well.
In 35 years of using 12ax7's, Amperexs seem to hold up better. Some of the commercial derivatives are tougher but just don't have the magic.
Just because they are of military contruction doesn't mean that they will sound better, but will hold up better in a military environement.
Just hope we don't have to test that application.
nsgarch's avatar
nsgarch
2,524 posts
 
Magnum, the reason audio people like the 5751 (or European 'CV' military) version of the 12AX7 is because they have been 'ruggedized' for military use -- which (as a byproduct) makes them free of detectable microphonics, especially the ones with the 3-mica construction. This is more or less important in audio depending on the application -- phono and microphone preamps being the most critical.

The fact that 5751's (generally) have a smoother presentation is just icing on the cake.
.
fishboat
245 posts
 
Abuck,

If you're looking for THE 5751 to put in your JD100 look for Raytheon 5751's...if you can find them. They won't be cheap, but I found them to be better than the GE blackplates and many of the other common 5751s.

Actually Amperex orange globes sound very nice the the JD100..the globes will be a reasonable-bit cheaper that BB and they sound the same to me. Make sure the Amperex tubes are made in Holland.

Never messed with TF's. I read something a while back that there were lots of fake TF's out there...or at least some made in West Germany vs East Germany & the East versions (TONS of them around) were sub-par vs those from the west...? Can't remember.
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