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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
bicycle_man OP
100 posts
 
Thanks Rodman! I have read good things about the Winged C el34's. The National el34's look nice, too. Great information!

I use the 12ax7's in the pre-amp phono stage.

Cheers!
rodman99999
6,130 posts
 
Happy listening!
theclipper
26 posts
 
I am trying to find some tubes to replace the six JJ 12AX7s in my Fisher 400. I am wondering if you guys have any suggestions? They way everyone is talking I might be wise to try some 5751s in there. Any input would be greatly appreciated.

Thanks,
-Clipper
rodman99999
6,130 posts
 
Clipper- You'll have to turn your volume control up a bit to get the same SPLs with the 5751, as they have about 30% less gain than 12AX7s. Their "tone" is also a bit more laid back(richer/smoother/warmer-more 2nd order harmonics) than most 12AX7s, if that's what you're looking for.
nsgarch's avatar
nsgarch
2,524 posts
 
I disagree that you'll need to compensate for the 5751's slightly less gain; because that difference doesn't really occur until past the normal operating range on the two tubes' curves. Most people can't hear any difference, and the military (who originally requested a 'ruggedized' 12AX7) wouldn't have traded that requirement for a loss in performance when they replaced their 12AX7's.

As for tone, that really depends on the specific tube and to a (lesser) degree on the make of amp. I specify 'amp' because that's where the tube produces the most gain and so the tonal qualities are most obvious. In a preamp, what you are looking for is low noise -- especially in tube phonostages where a 5751 might be a plus.

I don't have tube preamp/phonostages, but the majority of my friends with McIntosh tube preamps (with tube phonostages) seem to have settled with Telefunken AX's and AT's over the stock Chinese tubes, and haven't ventured much beyond that. People with hissy tube phonostages who can't find a quiet 12AX7 and/or 12AT7 should definitely try 3-mica 5751's and/or 6201's (and tell us what happens please ;-)
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