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!
I have also tried many and found the Amperex Bugle Boy "France" to be the best NOS 12ax7 I have tried..New production ,I like the Cryo version EI 12ax7..Great new prod.12ax7 ( for me anyway )
Did you ever read this:
My own ranking of 12AX7's (and 5751's) is slightly different than Joe's, but one thing I totally agree with, is that even the best 12AX7's are kind of grainy compared to the best 5751's -- to the point that I don't even bother with 12AX7's anymore.

And when it comes to phonostages, 5751's are definitely the way to go (for low noise and great detail.) It's true that 5751's are spec'd at 70-80% the gain of 12AX7's (driven at full bore!) but no one has ever reported a problem on that score, not even in phonostages where gain is so important.
Try the Shuguang G-9s.They have,unfortunately been discontinued.As for the Mullards,I prefered the military CV-4004s-more "sparkle/life" in the upper octaves.
Wonder if types of Telefunken make a difference.Heard this before and some even like Mazda over either.To given godlike status of Telefunken again wondering if type makes difference.
Philips 12ax7wa ECG floats my boat, a fantastic tube will lots of air and weight in bass.
thanks Nsgarch a hellofa read!
I agree, Nsgarch, that's a vey interesting article. I have often wondered about 5751's. I will keep my eyes open for some and try them.
I was a bit surprised that I was not all that impressed by the Telefunkens, given their reputation. Oh well...
~~~~Tried various 12ax7, 5751, 5751wa in my modded jolida jd100 cdp. GE 5751WA (1958) gives the best overall sound performance. YMMV

Just The Facts
FBI: A lot of folks really like the GE 3-mica blackplates. Is that what you have in your Jolida?

Phil and Bicycle:
The TFK 12AX7's were the first tubes I replaced in my new McIntosh MC275 -- and boy! did they make a night and day difference. (McIntosh used to use TFK's as OEM tubes back in the day ;-(( They are good tubes, but waaay overpriced these days IMO. I guess my favorite AX7 was the RCA 17mm long blackplate.
~~~~Nsgarch, You are correct. They have deeeep natural bass, wonderful presence, and extended highs. Now if I could get them to wash the car, walk the dog, and cut the grass...Now were talkin!

Just The Facts
Fbi, Nsgarch, I have Svetlana 12AX7's in my modded Jolida JD100 CDP, and am now thinking of trying the 5751's. Nsgarch, you mentioned the 5751'a are spec'd at 70%-80% the gain of the 12AX7's. I'm presently using a set of Rothwell 10db attenuators with the Jolida to help with the gain. Sounds like the 5751's will help a little more in that respect.
Best 12AX7 I have tried is the very rare and expensive CBS/Raytheon D-getter 7729. I also have a pair of O-getters that are close, but avoid the later CBS/Raytheon with the O-getter and 7729 etched in the glass. These last ones were actually made by GE and sound rather ordinary. Once I heard these I sold my Telefunken ECC803S, a nice tube but thin and lean tonally in comparison.
Two best 5751 I have tried is Ge 5751 3 mica Black plate and the RCA 5751 3 mica black plate..The Ge is more neutral,but the RCA has more body and weight..Both Great tubes..Each will work great with proper system synergy....
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.
Just finished listening to 10Ms compared to Bugle Boys.


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.
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.
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.

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.
Thanks Fishboat. I just purchased a pair of Sylvania JHS 5751 WA black plate triple mica's to try. These weren't inexpensive either!
abuck...yah..I have some of those. They get good reviews in various places on the web & they are good. Whether they are better than the others I mentioned depends on how each sounds in your system. Every setup is unique in many respects.
Ruggedized means stronger not better. All tubes should be checked for microphonics on an individual basis.
That would be like saying Queen Latifah is a better singer than Beyonce because she outways her by 100lbs.
Rugged makes a Marine not an opera singer.
Magnum, I do think stronger is better for the reasons I already detailed. I believe what you're saying is that stronger doesn't necessarily mean better SOUNDING, and except for the 3-mica 5751's near total lack of microphonics, I wouldn't argue with you.

I also mentioned (and this is admittedly my own experience) the fact that for reasons beyond my understanding, the 5751's (generally) have a smoother presentation than the 12AX7's I've heard (which in my case includes most of them.) "Smoother" being my own term for a less grainy or maybe more liquid(?) sound. YMMV
I just spun two new records (both 180g vinyl) -- Rickie Lee Jones, Rickie Lee Jones and Pop Pop. Interesting result when I swapped out Bugle Boy and JJ 12ax7's.

Background: I recently won a Denessen Soundtracktor on ebay and decided to align my cartridge with it. I had used the Alphason protractor that came with my HRS-100, originally. I was using some new JJ 12ax7's that I got for cheap and noticed they didn't sound half-bad after breaking in. When I aligned my cartridge with the Denessen, I noticed that voices opened up, there was more air, and the soundstage generally cleaned up, but the bass was so thin that I really thought I had better start researching good sub-woofers.

Tonight when I received these two records and spun them I thought I would put the Bugle Boys back in the pre-amp. Of course I listened with the JJ's in at first.

Well, with the Bugle Boys I immediately realized that I don't need a sub-woofer in my current set-up and room. It was such an amazing contrast! Truly immediate and night-and-day. I know that JJ's are basicaly run of the mill 12ax7's, but I never would have guessed nor imagined that the difference would have been so dramatic. I am truly glad that I have 3 matched pair of the Bugle Boys! It will be a long time before I need to use the JJ's.

Besides the incredible difference in bass, I also noticed timbral, soundstage depth and width, mid-range, and high frequency improvements that were significant. On the high end, I noticed a raspiness or edge with the JJ's that disappeared with the Bugle Boys. I thought that the records, being re-mastered were perhaps badly pressed. The edge and rasp disappeared with the Bugle Boys.

My conclusion is that when I look for replacement tubes, it is worthwhile to seriously consider NOS tubes rather than current production ones. I have not listened to re-issues, that is why I say, "consider."

I am really interested to hear from anyone who has experience with re-issues compared to NOS tubes. That might be an interesting tube-roll. Certainly my conclusion so far is that NOS 12ax7's are much, much better than current production JJ 12ax7's. It's a pity to think that good current production 12ax7's are so lame -- what to do when it is time to buy new tubes? Another question I have is, is there such a dramatic difference between current El34's, or other power output tubes, and NOS El34's?
Here's the only new production 12AX7 worth thinking about, if you are able to appreciate the differences/improvements in sonics that the right NOS tubes provide(and it's obvious you do): ( With regards to EL34s: It's been quite a while since I've used that particular output tube, and had Svetlanas last(the original company was still in business). I've found the Winged 'C' 6550 to be an excellent replacement(sonics and reliability) for the NOS outputs that I used to be able to afford in my present amps. Matched octets of anything worth considering in NOS outputs are virtually impossible to find now. If Siemens made a 6550, I'd have to try them. Consider these, or the Winged 'C'(St Petersburg plant), for your EL34 needs: ( (
I've found the inexpensive new production / re-issue tubes to be very dissapointing (Mullard & Sovtek). As far as NOS 12AX7's go, Mullard CV4004's are more lively, but less neutral than the mega expensive Mullard 10M gold pins, however, I still give the edge to the less expensive CV4004's.

Telefunken ECC803S are fine tubes IME. Neutral and somewhat lean sounding in comparison to the Mullard CV4004's... I like the Tele ECC803S as much as the CV4004's, it's just a different sound.

I'd be inerested to know who fellow audiogoners go to to get good, authentic tubes at a reasonable price.

I've used the following:
- Vintage Tube Services (very knowledgeable, good selection... but slow service)
- Tube World (knowledgeable & good service)
- Various offerings from fellow Audiogoners & Ebay (inexpensive, but I question the tube authenticity & quality)

I once foolishly paid $800 for a pair of Mullard 10M gold pins, expecting them to be he cats meow, but found them to be somewhat dull sounding... hence leading me to question their authenticity.

Should I resign myself to accepting that buying NOS tubes is akin to buying older used cars... or are there dependable dealers with reasonable prices that I'm not aware of?
I've dealt with this eBay seller(from Bavaria) numerous times, and found him to be an educated, honest and reliable source for Teles and Siemens:( He used to have his own website, but discontinued it.
I had to laugh at Rodman's recommendation of the EAT 12AX7 as the only acceptable current production 12AX7. Oh, I'm sure it's an excellent sounding tube (haven't heard one myself) but what made me laugh was the fact that it costs $225!! So much for saving money by buying current tubes! (I was also amused that Music Direct thinks it best to hide the inside of the tube in their web photo;-) I actually did audition some (used) EAT KT-88's and they were terrible!

If you want a great pair of ANOS (almost new old stock;-) 12AX7's I have at least 1 pair (maybe 2) of RCA 17mm long blackplates I'd sell for half of a single EAT, and I bet you'd like them better than the EAT or any of the usual NOS suspects, BUT it really depends on where you're using 12AX7/5751's which I don't think you mentioned?

My favorite 5751 BTW is also the RCA TMBP (after endless A-
B with the Sylvania TMBP.)
To quote Bicycle man, "It's a pity to think that good current production 12ax7's are so lame -- what to do when it is time to buy new tubes?", which is what I was responding to. Where in that post was "saving money" mentioned again? FYI: The EAT comes with the cooler/damper attached, and you'll ALWAYS see them advertised/pictured that way. To quote Ivor Tiefenbrun(founder of Linn Products), "If you gaven't heard it, you have no opinion."
To quote Ivor Tiefenbrun(founder of Linn Products), "If you gaven't heard it, you have no opinion."
Right! And good luck getting anyone to send you a demo tube so you can form an 'opinion'!

I'm more interested in how these TechTubes will sound. They should be ready (finally) to release them this month:
The have a new (for 9-pins) internal structure that uses CRT technology. And at $30 a pop (or so) I'd be willing to try a couple ;-)
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.

Happy listening!
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.

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.
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 ;-)
Then you disagree, not with me, but the specifications of the tube itself: ( ( paragraph 5 of this page:( ( ( compare the plate dissipation/transconductance/plate resistance of the 12AX7 and 5751. They are different because the 5751 in not a 12AX7, and has less gain as a result of it's design.
I appreciate the input guys.

So it sounds like the 5751s wouldn't really be necessary for me then? I am just trying to figure out what tubes I should try in my Fisher. I am really curious to experiment and see if I can get a better sound than the JJs are making right now.

I am using a Fisher 400 pre-amp now with Bugle Boy 12ax7's now and am very, very happy with them. This is the pre-amp I was using when I exchanged the JJ's for the BB's recently. With the JJ's I honestly thought I needed a sub-woofer, and when I changed to BB's I realized I didn't. The sound stayed crystal clear, the highs lost the edginess that I heard with the JJ's, the mid-range blossomed into sweetness, and the bass filled out the missing void.

I would recommend Bugle Boy's. The Orange Globe labeled Amperex tubes sound tempting to me. Telefunken's are definitely a step up from JJ's, but I prefer the BB's. The Tele's are very good at everything but miss the magic of the BB's.

For less money, I bet almost all NOS 12ax7's will beat out current production jobs. I have been satisfied with RCA and Sylvania NOS 12ax7's over the JJ's.

Give the tubes time to break-in before jumping to a conclusion. The JJ's became sweeter over time, but in my opinion could not stand up to the NOS tubes that I have.

Happy listening after your search!
Rodman, when did I ever say they were the same tube? Anyway, if you're talking about the (little used) "amplification factor" curve, yes there is a slight difference, but if you look at the transconductance curves (Gm), the standard measure of gain, the two are almost identical, in fact the 5751 shown in the curves I saw was actually a little higher. Anyway, no (tube) circuit designer in his/her right mind would drive a given tube into that portion of its operating range in the first place.

Having said that, it's well-known that ARC drives their (power) tubes quite hard while McIntosh is quite easy on tubes; which is why you've yet to see a Mac tube amp with mechanical ventilation ;-)
Mr N- Since you mentioned 6201's: I bought four for an amp I was building a few years back, but never used them. I sent two to an AudiogoNer to try, and he bought them. I've still got the other pair, if anyone wants to try them out(free-no strings). Gold pins, triple mica, but I don't know who actually made them(They're labeled Tele ECC801S, but they're not- no diamond).
Bicycle Man,

Thanks for your insight. I know exactly what you mean about the highs. They have a definite edge to them in my setup right now. The bass has been fine for me, I think mostly in part due to my Forte II speakers.

What positions do you have the BB in? Also, I forget, did you end up trying any 5751s?

Rodman, I danced around with various 6201's after trying some 'normal' TFK and RCA 12AT7's (which weren't bad actually) and also a quad of Mullard CV4024's (which for some reason I didn't really like; which surprised me after all the good things I'd heard), anyway, I liked the Sylvania 6201's a lot (the 2-mica BP gold pins) but the ones I like best (they're not 6201's) are the GEC A2900 (or CV6091 military designation.) These are amazing tubes; really powerful, but smooth as silk, like Gold Lion KT-88's! I was going to try and put together a spare quad but I think the word has got out (damn!) I got my first pair for $85 six months ago, and now they're over $200!! Check the mutual conductance values on these babies, and you'll see what I mean by 'powerful'!
Sounds like me. I should have stocked up on TungSol 6SN7GT/VT-231 Round Plates($50.00 ea, when I fell in love with them) while I had the chance. I was going to use three 6201's as phase splitter/drivers, but gave up on that amp after getting burned by the transformer builder(paid for, never received). Nothing I own now uses 6201's, so- I've never even heard these.
R -- I know, don't ya just hate when that happens! ;-)
Every time(you'd think I'd learn!). =8^(
Hi Clipper,
I have the BB 12ax7's in the phono stage, a BB 12at7 nearest the transformer, 2 Sylvania 12at7's near the can caps, and an unknown old stock 7025 in between (near the 6v4 rectifier).

The pre-amp sounds fine on tuner and both aux's, and of course, super fine on phono. I have repaired mine as many of the old Wima caps have dried out and wasted away.

I have also used the BB's in my Dynaco Pas3x and have found the same results as I previously described. The Fisher is not as forward sounding as the Dynaco, but it is, oh, so much sweeter! I was happy to see some Fishers selling on ebay for more than $450 in the last few months! As I recall, one of those was the 400-cx, which has a better following, but the other was a plain old 400-c. I have the 400-c. I like it and can't wait to get my Koetsu re-done -- should be mid-range luscious delight!
In my phonostage (Viva Fono) I've tried a number of different 12AX7 variants. The Mullards sounded a bit veiled (muddy) for my particular application. In a friend's Tron phonostage, Mullards actually sounded oddly phasey.

I liked the sound of 5751s -- neutral, reasonably detailed and open on top. I did not notice a loss of gain, but, I wasn't looking at gain because gain and noise are not issues with my phonostage.

Telefunken 12AX7/ECC83s were also very good in my phonostage -- quite detailed, extended top and good harmonic density without being muddy sounding.

The Telefunken ECC803S is a very different animal from the other 12AX7s I tried -- incredible clarity and detail and explosive transients. It sounds a bit lean (less upper bass) and perhaps clinical, but, I made other minor compensating adjustments (primarily to VTA), and it is the very best tube for my application.

However, the ECC803S is WAY more expensive than the competition. For the money, a good pair of 5751s are hard to beat.
RE what Larry just said about the premium TFK, I have a general 12AX7/5751 question/poll(?) for those familiar with both (hopefully, but not necessarily, in the same piece of equipment ;-)

In his famous "Tube Lore" article on AA, Joe asserts that he could never really find a 12AX7 he liked. He lists some preferences, but compared to his favorite 5751's, he finds all 12AX7's "grainy" (I think his word was.)

I maaaybe understand what he means. However I've rolled many different 12AX/AT7's and 5751/6201 in my McIntosh MC275, and like Larry, I've learned that to have blanket prejudices/preferences may not lead to the best choice - my love for the GEC A2900 being a perfect example (I never would have tried it if I'd decided to only go with 6201's.)

So does anyone agree with Joe's take on the issue: that 5751's are better across the board than 12AX7's? Just curious ;-)
I don't what is meant by the statement that 12AX7s are "grainy." I sometimes wonder if "grainy" is sort of the opposite of "fluid" or "smooth." Sometimes, what some others describe as smooth or fluid, I think of as being "soft" and a bit "muddy." The "muddy" quality I am talking about is a bump up in upper bass lower midrange that tends to obscure (or soften) upper frequency detail. Perhaps this detail is the "grain" being referred to; its hard to guess what these terms mean. So much is dependent on personal taste and system application, I don't think any generalizations can be made that one tube is better than another across the board. That is why, in my prior post, I emphasized the fact that my observations pertained to MY system.

One thing I forgot to mention in my prior post. For the Tron phonostage, the best alternative turned out to be Amperex Bugle Boys, at least in my friend's system (the consensus of several listeners). We did not try the ECC803S for this particular trial. I don't recall what current production tube the Tron came with, but, it is utter crap compared to the old alternatives we tried. The Tron was extremely sensitive to tube choice. I suppose this is a tribute to how revealing this phonostage can be.
Thanks Larry. Anybody else want to chime in?

I'm listening to horns today (recordings), so maybe that should be 'honk' in ;-)
Actually I found the upper frequency detail softened and veiled by the Telefunkens in my system compared to Bucgle Boys and Mullards, including the 10ms.

This is with my Fisher 400c and Dynaco Pas3x pre-amps.

I did not have muddiness with the Tele's, just not the same upper frequency and timbral magic of the BB's and Mullards. Also, the latter two brands were more open and had wider and deeper soundstaging qualities.