12at7 and 12ax7 are not common subs, but some circuits do allow that in certain positions. The Herron VTPH-2A is one such example - using 4 of 12ax7 and a single 12at7 yields another 5 -6dB or so of gain over 2 of 12ax7 and 3 of 12at7. The 2 slots allowing the sub may be mu followers? 12ax7 are not usually used in follower positions, though I guess some phono stages do that. In that case a 12at7 should be a fine sub.
Definitely don't swap them unless you know it's an OK choice for that slot. |
12at7 and 12ax7 are compatible?
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Thanks to all for a compendium of great advice and resources.
I'm very happy with the way my tube-phono stage and upgraded stylus sounds..to the extent that I'm going through my vinyl collection, enjoying the adventure of hearing new, better details and color in acoustic instruments and voices. When this blissful stage has run it's course, trying a different set of tubes or two will be a fun way to tweak the sound without breaking the bank.
Without your great suggestions I wouldn't have had a clue where to start.
Sincerely,
Mark |
OP; I concur with the above comment about critical listening. During a listening session, even if you have high frequency hearing loss, you can discern the differences between tubes. Some are very obvious such as Telefunken (wide open transparent image, very dynamic) vs. Mullard grey plates (warm with a rolled off top-end).
I love tube rolling and now own an all tube system; amp, pre, and dac. I can hear the difference between each tube swap so I'm sure you'll be able to hear the difference in a single component.
My recommendation is to try NOS tubes which have extended highs and cast a wide soundstage. Get as much high-end information as possible from the tube since your hearing is causing a high frequency roll off.
Sylvania tubes have high-end energy, good detail and a transparency that is very revealing. RCA blackplates have lush sonics with a wide, deep soundstage.
IME, you will not hear drastic differences between the new production tubes made in Russia. They don't have the different flavours as NOS do.
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I am about your age and a relatively recent tube-a-holic! I think I love them because some are older than I or at least the correct generation. I found the following write up / review to be very helpful although I do not agree in any way with his blanket indictment of 12AX7 tubes...having run them all I have some favorites. I also found Brent Jesse's website to be a great wealth of information. Have fun and enjoy the journey!
https://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html
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+1 for Brent Jessee http://www.audiotubes.com or Kevin Deal at Upscale Audio. Brent Jessee has a good description of the general characteristics of various tubes that I found helpful |
Your 65 year old ears will be able to hear the difference if you're a critical listener. I'm 63 and have significant hearing loss (so I listen at an elevated volume) and I am able to hear things I would never have believed, and it's because I'm a critical listener. When I listen, I sit in the sweet spot in a dark listening room so I'm not distracted by anything. My attention is focused on the music, i.e., there are never any other thoughts running around in my mind, I'm totally fixated on the music. My listening pleasure comes from, as an example, hearing every nuanced expression in Etta James' voice (in my opinion that woman's vocal chords are connected directly to her heart). During one listening session, I heard something change in her voice and became worried there was something wrong with my audio gear. (FYI: IF I had been listening to the music as "background" music I never would have noticed a change in her voice.) I put on a CD designed to "break in" audio gear and selected the track with a frequency sweep form 20Hz to 20kHz. As the pitch began to climb I heard a very slight "rattle" coming from behind my speakers at around 400Hz. I walked back there to find I had placed the steel top plates of my mono bloc amps (which I had removed for additional cooling) leaning against the wall on top of each other. As the frequency swept through 400Hz they began to softly rattle and then stopped as the pitch continued to climb. I laid them flat on the carpet, put Etta James back on and was totally relieved when her reproduced voice was back to normal. I'll give you an example of what critical listening is for me. A friend asks you (or me) to take a ride with them in their car to help them identify a noise they hear. After driving around for 20 minutes listening to your friend say "it's kind of like a chirping sound coming from the front right tire", you finally hear it. Now you're trained to hear it, and each and every time you get in your friends car you hear the sound without effort. So how is that like critical listening? The by-product of sitting in the sweet spot and listening to every nuance of the music is that the "training" happens naturally. Once you're used to listening to the detailed expressions of a female vocalist (for example) it comes without effort each time you sit down to listen. My point in all this is that the "training" I'm referring to happens even if there is significant hearing loss, as in my case. Are there things I can't hear? Undoubtedly, but I can easily hear the difference between audio electronics, and, if you're a critical listener, you'll be able to as well.
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Having recently acquired a Pro Ject Tube Box S2 phono stage,
I'm liking what I hear
and am wanting to learn more about tubes.
No no no, it's a bottomless well, stick with whatever you already like, sleep like a newborn baby. |
I moved from NAD PP2 to the ProJect Tube Box DS. I would imagine the sound is similar to your model. That move was dramatic in my system. I have Audio Research amps and preamp so later upgraded to the PH5 which was another wonderful leap in sound. It seems we are similar that we simply love what the tubes offer...in general. I have had minimal experience with tube rolling and have not been able to distinguish or see any appreciable differences. You have options for a minimal investment so I would encourage you to look at a different mfg tube. You get into the NOS realm and you can easily spend more on a pair of tubes than you did on the preamp. I feel it would be a better investment to upgrade the component to whatever brand preamp speaks to you. Shop the used market and you can always resell if you don't like it. |
+1 Tomcy6.....great answer! |
Not long ago I bought a quad each of Upscale Audio’s Platinum Grade for the following Russian re-issue tubes: Mullard, Tung-Sol gold pins, Gold Lion. For use in my VAC Renaissance phono stage. All of them sound really good! But yes I slightly prefer the long plates (Mullard, Gold Lion) to short (Tung-Sol). The Gold Lions are particularly nice. The Mullards are great for systems that need help taming an aggressive treble response.
I also tested these in my MaxPreamp2 tester, and yes both long plate types show notably higher transconductance than the short plate Tung-Sol (+10% - 15%). The Tung-Sols weren’t weak, though - in fact they’re still a good deal stronger than most of the vintage/NOS 12ax7 in my large collection.
That said, even though they measure a lot lower in transconductance, my favorite vintage 12ax7- the 1960’s Mazda chrome plates - still whip all 3 of the the new tubes in detail. I’m currently using a mix of Mazdas and the tall plate Russians, since too much Mazdas causes too much top-end energy. |
I have a ProJect Tube Box DS2 which came with JJ ECC 803 tubes. Sounds quite decent with stock tubes. Its construction is different from your Tube Box S2 - the tubes are sunk inside, and on order to replace them with NOS tubes, I would have to open the top cover, remove the stock tubes together with heat dampers glued to them and install vintage tubes. I could not cope with this simple task as I could find a suitable tool.
Re long vs short plates: It is rumored that tubes with long plates (such as Mullard tubes) have higher value and sound better, but I would say it depends on the application. |
First, you need to decide what is lacking in your music and how you want to change it. For example, if you want more detail or more extension in the bass, or if you want a warmer presentation, you can select tubes with the appropriate characteristics or timbre.
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Given your system I would go with RCA or Mullard NOS. Telefunken and Siemens are said by many to be better but possibly out of your price range. I don't know your phono stage but if it has 2 or more tubes be sure to get matched pairs. |
@lewm
First, in my experience mediocre sounding gear does not become wonderful sounding gear via tube rolling. Beware, the corollary is also true - a bad tube can make a great amp sound average. |
AAAAAHHH Tubes :-) They are like little bottles of electronic wonder and joy. However, being new to tubes in 2020 is to embrace the term "made in Europe or Asia" Of course anyone with an old warehouse and a tube tester is now on the tube bandwagon and is a expert. My point is that there are many crappy pedestrian sounding brand new tubes out there so it pays to do as much research as you can by yourself and take the time to learn why tubes work and what they do. I agree with lewm that tube rolling is better with better sounding gear, so dont worry about buying a $180 tube to put in a $150-$300 unit. Stock tubes are fine with these products. Where Andy At Vintage tubes comes in is when you have a special sounding unit and your looking for "real new old stock tubes from the 50's 60's 70's" to really bring out the best. That is special.
Matt M
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To avoid a lot of disappointment and frustration: just follow tomcy6's advice. |
I suggest trying some 6FQ7s with good paint. Conrad Johnson used them back when they were in production. Matched pairs $25-$50.
RCA sounds better than Sylvania to me.
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Caveats, in relation to "tube rolling". First, in my experience mediocre sounding gear does not become wonderful sounding gear via tube rolling. If you don't like the sound of your preamplifier, don't expect to transform it by buying expensive "rare" tubes. Maybe that which is already "good" can be made a little better, at best. However, with some understanding of circuit design, sometimes changing a capacitor or the basic topology, here or there, can make a big and permanent difference. Second, keep an open mind. Sometimes you will be surprised by a Chinese or Russian made tube compared to an NOS Euro or US made tube. Also, in some rare cases, you can substitute one TYPE for another which can be a big step up, but you need to know that the replacement tube will be connected to the circuit the same as the discarded tube. Any time you can get rid of a 12AU7 or ECC82 in favor of a 6FQ7 or 6CG7, you will be happy, but in some cases you will need to do some soldering. (6FQ7 and 6CG7 are electrically like a 12AU7 but filament current and voltage and connections need to be considered.)
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Hi,
trust a reputable dealer for NOS (brand new) tubes. ECC83 (7025, 5751, ECC803, CV4004, M8137) is a very common tube so you have plenty to choose from, Teslas, Teles, Mullards, RCA’s, CBS, Raytheon, GE....Define first what short of sound you want with the tube rolling, but all of them, short or long, ribbed or smooth plates are fine tubes. Only by trying out you'll find the ones that suit your phono stage. |
With vintage small-signal tubes, long plate variants are usually considered more desirable. Long plates and short plates are not specific to a manufacturer, but they are generally used in reference to 12ax7 or 12au7 type tubes. "Long" is generally around 19 mm, and "short" about 16 - 17 mm. In most cases, a manufacturer produced long plates in their early-year runs of that type, and then later switched to exclusively short plates (late 1950s - 60s). In general, earlier vintages from any given manufacturer contain features that are considered more desirable (but it can be hard to decouple this from the fact that earlier vintages themselves are almost ALWAYS more desirable in vintage tubes!) - other examples of this include specific kind of getters (square, "D", or double halo getters versus later single halo getters), black plates vs. grey plates, triple micas vs. double micas, pinched waists vs. straight tubes, larger and prettier getter flash patches (e.g. Sylvania "chrome dome" 6sn7), etc.
The "smooth plates" are a pretty unique feature and pretty much always refer to the Telefunken 12ax7/12au7 tubes. Those are excellent tubes. Ei (Yugolsavia) later bought the old Telefunken tooling and made smooth plate tubes for some years - these are good tubes too, but perhaps not as good as the original Teles.
With new tubes you can find tall and short plate variants of 12ax7/12au7. If I were to generalize (though probably badly badly), the tall plates tend to give a sweeter sound but the short plates could be less microphonic (less to rattle around). |
Thanks for the great information and resources!
Always fun to have a new direction for tweaking the system!
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Tube rolling is never ending quest, you’d better look and read an Tube Asylum site. You tube (ECC83 /12AX7) is slightly different from mine (ECC81 /12AT7), i ended up with NOS Sylvania Gold Brand (Gold Pins), Matsushita, military Telefunken are the most expensive... Sylvania was the best value for me. You can always look for RCA Avoid Chinese tubes, in general Russian military grade are not bad if they are very cheap, but you’d better look for NOS from the 50s 60s 70s. If (ECC81 /12AT7) are compatible for your phono pre you can ask me, i have some NOS |
NOS tubes are vintage tubes which sound better than new production which mostly come from Russia, although these tubes have been improving over the past few years. The Project website states that the Tube Box S2 phono stage uses ECC83 tubes which is the European designation for 12AX7 tubes. These are widely used in audio components. The following website provides good info on the different manufacturers and a description of how the tubes sound. Lower down on the page are the tubes for sale. There are many versions of 12AX7’s which include different plate types and internal tooling. http://www.audiotubes.com/12ax7.htm |
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There is generally not a sonic advantage to a particular plate design. Plate design can be used to differentiate a specific tube in a manufacturer’s line that some people consider superior, though.
For example, Telefunken smooth plates are thought to sound better than Telefunken ribbed plates by some. Other people think there is no difference.
To someone who wants to get into tube rolling (trying different tubes), I’d recommend talking to a couple of reputable tube dealers and telling them what you’d like to hear from a new set of tubes and then decide what you want to buy based on their recommendations. This will save you a lot of money and time because there is a lot to learn about various tubes and many pitfalls along the way. It's better to find a seller you trust and rely on his knowledge rather than try to relearn it all on your own.
When you’re buying for a phono stage, it’s important to get phono grade tubes (low noise, closely matched tubes and triodes within each tube).
Here are a few good dealers. You can google them.
Andy Bouwman at Vintage Tube Services (he can be slow but many people swear by him)
Brent Jessee
Kevin Deal at Upscale Audio (some people find his personality abrasive)
Jim McShane
I hope others will chime in with those I’ve forgotten.
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