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12AX7 tube suggestions for phono preamp?
- Thread starter Mr. Lin
- Start date
markd51
Nyuk Nyuk
Mr Lin,
I think you have started at a good place, first trying the Sovtek 12AX7LPS, and the GE.
At this point, you'll have three pair of Tubes to test, and of course, let "your" ears be the judge.
The Sovtek is said to be a good tube, and a neutral Tube. Listen for clarity, coherence, good bass response, and quietness of sound.
About construction, many of the old Tubes were made with very good materials.
NOS Tubes can reap you real improvements, but of course, just how much are you willing to fork over to find out? As for Telefunkens, I've already seen NOS sample running up towards $500 a pair.
Same with Tubes like the Sylvania 5751 Triple Mica Blackplates with D getter. I'd bet a sweet Tube, but I sure don't wish to fork over close to $300 a pair for NOS.
Another Tube which has gotten both good, and bad press, is the Groove Tubes 12AX7M Mullard Re-Issue.
I'm currently running a matched pair of these in my CAL Alpha DAC,
I bought a matched pair from Kevin Deal from Upscale Audio, and have been very pleased with both thier sound, and thier build. They've been in this Unit close to 8 months now with no problems.
A entire run was previously returned to China, but there were some good batches, and evidently Kevin culls through his batches. He also stands behind the tubes he sells with a guarantee.
Another Tube which I bought from him, which are even slightly better that the GT12AX7M, was a matched pair of 50's NOS RCA 5751 Triple Mica Blackplates. These I'm keeping on ice, as they were the best in my Alpha, but the GT 12AX7M was a close second.
Let us know how all turns out. mark
I think you have started at a good place, first trying the Sovtek 12AX7LPS, and the GE.
At this point, you'll have three pair of Tubes to test, and of course, let "your" ears be the judge.
The Sovtek is said to be a good tube, and a neutral Tube. Listen for clarity, coherence, good bass response, and quietness of sound.
About construction, many of the old Tubes were made with very good materials.
NOS Tubes can reap you real improvements, but of course, just how much are you willing to fork over to find out? As for Telefunkens, I've already seen NOS sample running up towards $500 a pair.
Same with Tubes like the Sylvania 5751 Triple Mica Blackplates with D getter. I'd bet a sweet Tube, but I sure don't wish to fork over close to $300 a pair for NOS.
Another Tube which has gotten both good, and bad press, is the Groove Tubes 12AX7M Mullard Re-Issue.
I'm currently running a matched pair of these in my CAL Alpha DAC,
I bought a matched pair from Kevin Deal from Upscale Audio, and have been very pleased with both thier sound, and thier build. They've been in this Unit close to 8 months now with no problems.
A entire run was previously returned to China, but there were some good batches, and evidently Kevin culls through his batches. He also stands behind the tubes he sells with a guarantee.
Another Tube which I bought from him, which are even slightly better that the GT12AX7M, was a matched pair of 50's NOS RCA 5751 Triple Mica Blackplates. These I'm keeping on ice, as they were the best in my Alpha, but the GT 12AX7M was a close second.
Let us know how all turns out. mark
Mr. Lin
Lunatic Member
Very interesting information Mark. Actually, make that four pair of tubes to test (if you're counting the stock pair), because tonight I ordered a pair of NOS Sylvania 12AX7s (forget the exact model, will find out) from Virginia Tube Audio.
So I have a variety of tubes coming from a variety of places, and the anticipation is, well, distracting me at least. I intend to start a thread wherein I will break down all the new tubes and briefly describe what I hear, but that will take a little time as I have to wait for them, then go through each one. If one pair really does it for me I might be stuck on that for a while
markd51
Nyuk Nyuk
Very interesting information Mark. Actually, make that four pair of tubes to test (if you're counting the stock pair), because tonight I ordered a pair of NOS Sylvania 12AX7s (forget the exact model, will find out) from Virginia Tube Audio.
So I have a variety of tubes coming from a variety of places, and the anticipation is, well, distracting me at least. I intend to start a thread wherein I will break down all the new tubes and briefly describe what I hear, but that will take a little time as I have to wait for them, then go through each one. If one pair really does it for me I might be stuck on that for a while
Sounds like a good plan Mr. Lin
What I've personally noticed with Tube swapping in my CAL Alpha, was when I first got it used, it came with NOS JAN (Joint Army Navy) Phillips 5751 Tubes, and the sound from the DAC was so shrill, and glassy, it was unlistenable, and horrible.
A friend gave me a pair of NOS Mullard CV-4004 (a 12AX7) Tubes to try that were originally bought from Kevin Deal, and this did tame the shrillness, but tamed it too much. The sound was lackluster, and dull.
Onto some unbranded Shuguang C-9 production Tubes from ebay for a cheap price, and these sounded much better, but not for long. After 10 hours of play time, the sound turned horrible, with graininess, and harshness to the sound, so a temporary pair of Sovtek 12AX7WB (Fender Branded) Tubes from the local music shop went in.
When I got the three pairs of Tubes from Upscale Audio-Kevin Deal, which were all platinum graded, and matched, the NOS JAN-GE 5751, the GT12AX7M, and the 50's NOS RCA 5751, all sounded just great, with the JAN-GE sounding the most forward of the bunch, in that the singer sounded like he stepped up closer to the Mic. The RCA triple mica blackplate 5751 sounded the very best, and the GT Mullard 12AX7M re-issue was found to also be a great smooth, even keeled performer. All three pairs were a considerable improvement in sound over any other tube in this particular CAL DAC.
As other's have mentioned, you mileage may vary, and it is sometimes hard to predict how a tube will perform within a certain piece of equipment.
What I said earlier, to use "your ears" to test is important, but sometimes, it is also wise to have a friend over, and see if they note the exact same characteristics as you do. It's a fun way to spend the afternoon. Mark
analog addict
Glory or Death!
It's a gain issue....
The 12AX7's are rated at a gain of 100, while the 12AU7's are IIRC, a gain of 20. The 5751's are 80 I believe, with the 12AT7, 12AY7, and 12AV7 all intermediary between the X's and the U's....
One of the experts can clarify or correct me, but typically one could consider a swap for a tube with less gain, but you're asking for trouble swapping in a tube of higher gain for the intended application. Now for guitar amps, where you're looking for distortion, and the amp is designed to handle it, that's another story. As with all things tube, there are no guarantees because of the variations in circuit design, but sometimes there's only one way to find out....:scratch2:
YMMV...
PS it's amazing that I actually sound like I know what I'm talking about, more or less....
It's a testament to the fountain of knowledge that AK is that I've learned so much in such a short time....
The 12AX7's are rated at a gain of 100, while the 12AU7's are IIRC, a gain of 20. The 5751's are 80 I believe, with the 12AT7, 12AY7, and 12AV7 all intermediary between the X's and the U's....
One of the experts can clarify or correct me, but typically one could consider a swap for a tube with less gain, but you're asking for trouble swapping in a tube of higher gain for the intended application. Now for guitar amps, where you're looking for distortion, and the amp is designed to handle it, that's another story. As with all things tube, there are no guarantees because of the variations in circuit design, but sometimes there's only one way to find out....:scratch2:
YMMV...
PS it's amazing that I actually sound like I know what I'm talking about, more or less....
It's a testament to the fountain of knowledge that AK is that I've learned so much in such a short time....
Mr. Lin
Lunatic Member
Sure, I'm hoping that at least some of these will give good results with the preamp. As I've said a couple times in this thread, I'm more interested in changing the sound than just improving it, ie. I want to hear more detail, or warmer bass, etc. from one tube to the next.
As an update about my grandfather checking to see if he has any 12AX7 tubes lying around -- he called today and said that after spending a while on the phone he managed to find one place in Arizona that sells that type of tube. This is what happens when you don't use the internet, but of course I didn't have the heart to tell him that they're actually rather widely available. He said a pair of 12AX7s are on the way to NJ for me, which made me feel slightly guilty because I think he misunderstood me and thought I just needed to replace the tubes in my preamp but couldn't find any. In any event now I have four pair on the way
Mr. Lin
Lunatic Member
Then does 12AX7A mean anything in particular? That's what it says in the specs for my Pro-Ject Tube Box II, and I hope that the tubes I've ordered will still [theoretically] work in my preamp.
gogofast
Addicted Member
Sovtek's are ok as substitutes or to fill the sockets, but when you need one tube for phono preamp, go for the NOS or better older tubes.
used telefunken's, amperex's, and mullard's are readily available at decent price ($20-30 ea.). same tubes with different companies' labels make it little cheaper. anyways, sound difference is amazingly clear for even tubie nubies like me. i personally had very bad experiences with Sovtek's and EH's, and i wouldn't recommend them unless you want to hear the difference between good and bad tubes in order to appreciate good ones.
analog addict
Glory or Death!
A lot of times tubes will have "A" or "B" or "C" designations indicating a newer design. Some tubes will have an additional letter, for example a "W", indicating IIRC, that they were built to military specs. Lots of 12AX7WA tubes out there. What you need to determine is if the amp design takes advantage of some of the improvements that might have been made to a tube design.
For example, I have an old amp that lists 6L6 output tubes, but the comment was made here that 6L6GC tubes would work, and take advantage of higher plate voltage. The plate voltage is one of the determining factors in the amount of power an amp can generate.
What you can do is to visit some of the tube data sites, like...
http://tdsl.duncanamps.com/tubesearch.php
and get the spec sheets for each of your tube types, and compare them. You can also do a google search for "tube substitution", and have additional sites pop up. Lastly, failing to come to an educated decision. I would post a specific thread describing the amp, and the tube question, but it is always considered good form to do your homework first.....
Good Luck!
Mr Lin,
Since we are almost neighbors, give me a shout when you start playing with your tubes. I'm sure I have pairs of 1950's vintage RCA 12ax7, 12au7, and possibly some 12au7a and 12ax7a as well. If I can dig them up, it will give you a chance to see how the different tubes from a single supplier can change the sound. Hopefully I'll have some decent tube testing equipment soon so the pairs can be reasonably matched.
Since we are almost neighbors, give me a shout when you start playing with your tubes. I'm sure I have pairs of 1950's vintage RCA 12ax7, 12au7, and possibly some 12au7a and 12ax7a as well. If I can dig them up, it will give you a chance to see how the different tubes from a single supplier can change the sound. Hopefully I'll have some decent tube testing equipment soon so the pairs can be reasonably matched.
Mr. Lin
Lunatic Member
Mr. Lin
Lunatic Member
Ok, I see from the tube data site that 12AX7A can in theory be substituted with an array of 12AX7 tubes, but there is something I don't quite understand. It lists ECC83 as a substitute, but I thought ECC83 was exactly the same thing since that's what it says in the specs for my preamp(12AX7A/ECC83). This isn't particularly important, just something I noticed. So apparently the variety of 12AX7 tubes I ordered will probably work in my preamp, of course the results are up in the air.
From the audioasylum thread I now understand that the A was a letter often (but not always) on the tube signifying a twisted filament design to reduce hum, and that many tubes of this design are still labeled simply 12AX7 or something else.
goldear
Certifiable Audio Junkie
Not the best advice for a phono stage, unless you truly don't care about the accuracy of your RIAA equalization. But I do agree that 5751s can sound great inside of line stages as a 12AX7 substitute.
dividebytube
Well-Known Member
the Shuguang 12AX7C is not a bad tube at all... a 'carmel' Mullard-ish sound. Some people really like the Sovtek 12AX7LPS, so you may want to try those too. Bang for the buck I like Matsushita and Hitachi 12AX7s. They are very quiet and consistent.
Mr. Lin
Lunatic Member
Now we're getting somewhere.
A short while ago I plugged in the Sovtek 12AX7LPS tubes and gave it a quick listen. Unfortunately it's late and other people are trying to watch TV through my receiver, or sleep, so I was only able to play 2 songs from records with which I am very familiar.
I could hear the difference immediately, and I was actually surprised at what an improvement it was.
During this very preliminary audition of the new tubes I noticed 4 things:
1. More powerful bass. This was the first thing that struck me. Again, I played songs I listen to a lot on my Thorens so I could easily hear the difference.
2. More clarity. Right away everything, throughout the entire range, sounded clearer, more crisp, clean.
3. More detail in the midrange. This made me very happy as it's one of the things I was really hoping to get from a pair of tubes eventually, and here it is with the first pair I tried! I heard an entire piano part in the background that I'd never noticed before, and in another song the backup acoustic guitar was much more audible and blended neatly with the rest of the instruments.
4. Probably the most significant and desirable difference was that everything sounded more real, or I suppose the proper term is neutral. Will Oldham's (Bonnie Prince Billy) voice sounded as it would if I were listening to him perform live in a bar. With both songs this change was most noticeable in the vocals; voices sounded more up front and three dimensional.
All this in less than 10 minutes of listening, of course I can't wait to get home from work tomorrow and try it out at a much higher volume. I have to say the stock Pro-Ject tubes must be pretty bad if $16 worth of tubes can make such a big difference. And NOS tubes will be better? I'm hooked.
A short while ago I plugged in the Sovtek 12AX7LPS tubes and gave it a quick listen. Unfortunately it's late and other people are trying to watch TV through my receiver, or sleep, so I was only able to play 2 songs from records with which I am very familiar.
I could hear the difference immediately, and I was actually surprised at what an improvement it was.
During this very preliminary audition of the new tubes I noticed 4 things:
1. More powerful bass. This was the first thing that struck me. Again, I played songs I listen to a lot on my Thorens so I could easily hear the difference.
2. More clarity. Right away everything, throughout the entire range, sounded clearer, more crisp, clean.
3. More detail in the midrange. This made me very happy as it's one of the things I was really hoping to get from a pair of tubes eventually, and here it is with the first pair I tried! I heard an entire piano part in the background that I'd never noticed before, and in another song the backup acoustic guitar was much more audible and blended neatly with the rest of the instruments.
4. Probably the most significant and desirable difference was that everything sounded more real, or I suppose the proper term is neutral. Will Oldham's (Bonnie Prince Billy) voice sounded as it would if I were listening to him perform live in a bar. With both songs this change was most noticeable in the vocals; voices sounded more up front and three dimensional.
All this in less than 10 minutes of listening, of course I can't wait to get home from work tomorrow and try it out at a much higher volume. I have to say the stock Pro-Ject tubes must be pretty bad if $16 worth of tubes can make such a big difference. And NOS tubes will be better? I'm hooked.
analog addict
Glory or Death!
DaLarry
The Elder Geek
Communal Wisdom
I haven't really figured that out either. The same person who suggested I try the Sovtek 12AX7LPS' suggested I try some 5751 "black plates". I haven't found any but I did whip out the plastic on some of the new Mullard 12AX7's. Can't wait to get 'em and try 'em out. I've got the Sovtek's cranking right now and they're sounding pretty good.
I haven't really figured that out either. The same person who suggested I try the Sovtek 12AX7LPS' suggested I try some 5751 "black plates". I haven't found any but I did whip out the plastic on some of the new Mullard 12AX7's. Can't wait to get 'em and try 'em out. I've got the Sovtek's cranking right now and they're sounding pretty good.