[Freo-1]

Well, I've been tube rolling 12AX7's in a Fisher KX-200, and it's been a lot of fun.

So far, here's what I tried:

1) Telefunken Smooth Plates:  VERY seductive, a bit recessed, but in the right way.  Excellent treble, great with vocals, good bass, good 3D stage, quiet.

2) Raytheon Black Plate D getter: Excellent tonal balance, a bit more forward sounding than the Telefunken, slightly less 3D soundstage, tight bass, very good vocals (not quite as magic as Telefunken), quiet

3) GE 17MM D getter: Does everything well, does not call attention to any area of the audio spectrum, good 3D soundstage, deep bass, quiet (a best buy at it's price point)

4) RCA Black Plate D getter:  WOW! Extremely lush, great vocals deepest bass in this rig, big, wide, deep soundstage. A winner!

5) Tung Sol D getter: Another outstanding performer.  Outstanding HF response, great vocals, deep bass, excellent 3D soundstage,  another best buy. A bit brighter than the Telefunken or RCA.

6) Sylvania Black Plate D getter:  A nice tube, but not as good as the others in this post.  A bit more noise (still low), slightly recessed midrange, bass not as deep (but tight), clear HF.


There are HEAPS of 12AX7's out there, to classify them all is impossible.  I also reckon that they will sound different from one application to the next, so just wanted to share what my experience is with this amp.

So, post your 12AX7 recommendations.  It would be helpful to state the application as well.

[toobluvr]

I direct your attention here:

http://www.audiocircle.com/index.php?topic=20251.msg180018;topicseen#msg180018

I still recommend the same ones.

In my Air Tight ATC-1 preamp, I am using a pair of Tungsram 12ax7 in the line section, and in the phono section, a single RCA "Command Series" 5751 in the middle position, flanked by a pair of Raytheon (labelled Westinghouse) 5751.

The sound with both digital and vinyl sources is devastatingly good at the moment.   So much so that I have no inclination to touch anything.....and being a hopelessly addicted roller, that says something!
 

Things on the vinyl side really started to gel and get interesting when I inserted the RCA Command 5751.  I agree with your comments # (4).  It replaced a single Telefunken 12ax7.  Despite the acclaim, I have never been a fan of that tube.   I don't find them seductive at all.  No matter where I use it, it always sounds dry and sterile.  Clean yes, but lacking in harmonics, texture, palpability and tonality.  No musical "pull".

I also highly recommend Baldwin 12ax7 "organ pulls".  They give a rich, dense, sweet and always musical sound.  Might be too much chocolate for some.

All RCA's, particularly 5751, are warm and rich with wonderful tonal density and harmonics, but some can sound slightly veiled and dirty.

My impressions and preferences are consistently the same when using these same tubes in my JuicyMusic Blueberry Xtreme phono section.

Just my 2 cents.

Enjoy!

John

[mark funk]

Most of my stuff uses 12AT7s but I do have a few that use 12AX7s and I run Telefunken in all my stuff. I do have a number two in the 12AX7s, RWN Newhaus ECC83. I like the German tubes best.

                                                            

[Freo-1]

I direct your attention here:

http://www.audiocircle.com/index.php?topic=20251.msg180018;topicseen#msg180018

I still recommend the same ones.

In my Air Tight ATC-1 preamp, I am using a pair of Tungsram 12ax7 in the line section, and in the phono section, a single RCA "Command Series" 5751 in the middle position, flanked by a pair of Raytheon (labelled Westinghouse) 5751.

The sound with both digital and vinyl sources is devastatingly good at the moment.   So much so that I have no inclination to touch anything.....and being a hopelessly addicted roller, that says something!
 

Things really started to gel and get interesting when I inserted the RCA Command 5751.  I agree with your comments # (4).  It replaced a single Telefunken 12ax7.  Despite the acclaim, I have never been a fan of that tube.   I don't find them seductive at all.  No matter where I use it, it always sounds dry and sterile.  Clean yes, but lacking in harmonics, texture, palpability and tonality.  No musical "pull".

I also highly recommend Baldwin 12ax7 "organ pulls".  They give a rich, dense, sweet and always musical sound.  Might be too much chocolate for some.

All RCA's, particularly 5751, are warm and rich with wonderful tonal density and harmonics, but some can sound slightly veiled and dirty.

Just my 2 cents.

Enjoy!

John

Interesting post, thanks John.

Funny you should mention the organ pulls.  The Raytheons and the GE's in my post are in fact organ pulls.  I think these were screened before installation in the organs.

Your comments on the Telefunkens are not the first time I've herd that.  I think it's the application that can make or break that tube.  The Fisher KX-200 came with the Telefunkens as standard issue.  They match up wonderfully in the Fisher with the 7591 and the output iron.  I've heard them in other gear where that clearly was not the case.  

FWIW's, my guitar buddies tube of choice in their rig is NOS Mullard.

[toobluvr]

Yes....I believe the Baldwin organ pulls I have are also made by Raytheon.

The Mullard CV4004 box plates are considered by many to be the finest 12ax7 ever made.
Or is it the Long plate??       Forgive the senior moment.   

In any event, I'm a big fan of Mullard tubes in general, every type.

[Jon L]

In any event, I'm a big fan of Mullard tubes in general, every type.

I'm usually not a big Mullard guy, but Mullard 7025 (12AX7A) is an excellent tube.  Loveliest most musical sound I could get out of any 5751/12AX7/12AX7A so far. 

7025/12AX7A's I've tried so far have all been at least great, including Raytheon, Sylvania, RCA, Mullard, etc.  The RCA 7025, in particular, is sensational, and I prefer it over the 1950's RCA 12AX7 blackplates. 

5751's have really gotten way too overpriced IMO, but the usual suspects from Sylvania, RCA, TungSol all have their own charms and can be especially useful if lower-gain, lower-noise of 5751 is needed in the system (i.e. headphone system).

[BillB]

My favorite 12ax7 is a 12at7.

[iGrant]

My favorite 12ax7 is a 12at7.

Agreed, if your gear is using 12AX7's, do try some 12AT7's, 30% less gain, but not really noticable in my my gear (pre-amp stage), more relaxed sound, more space in the soundstage.

Cheers,
Ian

[toobluvr]

Hmmm........

I know that 5751 can safely be dropped in for 12ax7 and offer about 30% less gain....but 12at7?!!

Is it safe to do this?

 


I've been rolling tubes, and reading audio boards for a long long time, and I've never come across this!

Hope it's true...I have a decent stash of NOS 12at7.

[doug s.]

my fave is the matsushita 12ax7.  why?  cuz it's pretty-much the same tube as the mullard 12ax7, (mullard sent its mf'g equipment to japan for matsushita to make them), and it's usually cheaper than new production tubes.  i am not so obsessed to try tube rolling a lot of different tubes when these are so cheap.  i do have a some tele's which i got before i discovered the matsushita's; also nice; i can't say one is better or worse than the other.  i don't have a lot of tube rolling experience; all i know is that either of these are much better than cheap chinese or sovtek 12ax7's that come w/a lot of gear, and i am happy to leave it at that...

ymmv,

doug s.

[iGrant]

Hmmm........

I know that 5751 can safely be dropped in for 12ax7 and offer about 30% less gain....but 12at7?!!

Is it safe to do this?

 


I've been rolling tubes, and reading audio boards for a long long time, and I've never come across this!

Hope it's true...I have a decent stash of NOS 12at7.

I can't of course make a blanket statement that all is cool rolling in a 12AT7 for a 12AX7 circuit, but I've done it to all of my gear (pre-amp stages, CDP output stages) at one point or another with no ill effects at all and used to do it on guitar amps in the studio for a more refined tone. Was a suggestion a long time ago from a tube guru. Not suggested to go the other way on a roll (12AX7 in a 12AT7) circuit though.

Cheers,
Ian

[BillB]

Technically the at7 is about 60% of the ax7 but if you actually get a decibel difference it would be shocking.

Looking at the two sheets:

AT7 can handle more current but has half the cathode to heater capability so that would need to be checked prior to subbing.

Also the AT7 has a waaaay lower plate resistance.

The 5751 has lower plate resistance too (about 60%) but not as low as the at7 (15% or so).

It would probably work in most circuits but not in all.

[toobluvr]

It would probably work in most circuits but not in all.

If 12at7 doesn't "work" in a 12ax7 circuit, does that mean:

(a)  it just doesn't sound right

or

(b) something might get damaged

        

[ted_b]

Most claim that the AT7 is ok to substitute for an AX7....if you have any qualms check with your mfg

here's a nice table
http://thetubestore.com/gainfactor.html

[BillB]

Dunno...never had one "not work"

What could the much less plate resistance do? probably change voltages and current right?

Current shouldn't be an issue but you could run into a voltage problem...

I think the checking with Mfr. is a good idea...or plug it in and run. 

[Frihed91]

I have a bunch of 1950s RCAs and Sylvanias + a couple pairs of Raytheons + 1 pr TF smooth plates and 2 prs Siemens 3MBP + some 70s Teslas, all good NOS tubes.  I also have a bunch of 60s grey plate Sylvanias pulled from Baldwin Organs.  They all have slightly different characteristics, but sound great as driver tubes in my Quick Silver mini-mites.

I really don't care for any of the new production models.

[Lizard_King]

I use 1960's short plate Mullard 12AX7s in my ARC preamp and they are great.

[ginger]

Freo,
One of the best 12AX7's ever were the ones made in The Philips Hendon factory here in Adelaide. All those old 3 in 1 console jobs were fitted with them and you still occasionally find NOS. Worth keeping an eye out for them.
Cheers,
Ian

[Freo-1]

Freo,
One of the best 12AX7's ever were the ones made in The Philips Hendon factory here in Adelaide. All those old 3 in 1 console jobs were fitted with them and you still occasionally find NOS. Worth keeping an eye out for them.
Cheers,
Ian

Cheers, Mate!

I'll keep an eye out for them.  Perhaps I can find them in your area next time I have to visit ASC.

[dangerbird]

I have a bunch of 1950s RCAs and Sylvanias + a couple pairs of Raytheons + 1 pr TF smooth plates and 2 prs Siemens 3MBP + some 70s Teslas, all good NOS tubes.  I also have a bunch of 60s grey plate Sylvanias pulled from Baldwin Organs.  They all have slightly different characteristics, but sound great as driver tubes in my Quick Silver mini-mites.

I really don't care for any of the new production models.

If you had to pick 3 tubes for your quickies, what would they be.I ask because in the past 6 months I have aquired a pair of M-80's and a GLA (for my vintage) Polk SDA rig. I've been buying the output tubes from Mike @ quicksilver,,NOS Tesla El-34,and I would like to roll some input tubes in the GLA,,uses a AX7 and 6DJ8, any suggestions  based on experience would be appreciated. NOS please.
Thanks