Let's roll: what pre-amp tubes should I consider next?

I am looking for some guidance from experienced vacuum tube amp users. I have a Unison Research S6 (most recent model) which runs six x EL34 power tubes and two x 12AX7 pre-amp tubes.

Having gone NOS in the pre-amp section, I've had great results over the new manufacture Tung Sol 12AX7s that come stock with this integrated. The tubes I've played with are the Philips Miniwatt 12AX7s and the Siemens 12AX7s. I like what both have to offer, but there are differences. The Miniwatts being warmer and contributing to an overall more subtle listening experience whereas the Siemens are more precise, producing a sound that has attack, excitement and thrill in abundance. However, I find the latter can be a bit too much in the upper mid/lower treble region some times. Is there another new manufacture (thinking Psvane?) or NOS (Brimar, Mullard, Mazda) that would give me the best of both worlds? Good tone and timbre while maintaining a sense of involvement through speed and attack?

What are your recommendations?


If you want to tame some of the treble maybe look at 5751 tubes which have a little lower gain that the 12ax7.
Sylvania-Baldwin green label circa 1960’s or GE from the same era are great sounding preamp tubes!
Amperex/Bugle Boy and Philips/Miniwatt tubes tend to ride a line, between the warmth/romaniticism of British tubes and the clarity/transparency of the likes of Siemens and Teles. Contact Brent Jesse, for info. Reviews/listening opinions, here: http://www.audiotubes.com/12ax7.htm
The Pvane 12AX7 tubes in my cdp are just right (for that application).Clean and clear but not harsh.
NOS Amperex are the best sounding and best made.Jump on them asap from Brent Jesse not cheap but the best by far.
12AX7 Mullard Longplate Halo Getter from Brent Jessie

Groove Tubes for your EL34s, if you are considering trying different power tubes.
new production Gold Lions are pretty impressive. I'm using the 12AU7's in my rig. top to bottom clarity, extension and speed.

Brent Jessie tubes are priced about 3 times what the market really is...only a fool would pay his prices,IMO
"3 times"?   Nonsense!    However; the confidence that I will receive actual NOS tubes, that have been comprehensively tested and will provide the performance paid for, is worth a premium(to me).   There are some other tube mongers, that provide equivalent service/product, and their prices are consistent with his.   
I do have limited experience with tubes (I’m a solid state guy). Though, I do have some comments:

I do like the PSVANE tubes very much. I would say that they are just about the highest resolution and least colored tubes that you can get. I don’t know how this will turn out in your particular system or how it will compare to your Seimens. I will say that the PSVANE are very clean and clear. If you are getting a harshness/brightness in the upper mids/highs, I would say that there is something else in your system that is contributing to this (such as silver wire, metal dome tweeters, metal cone midranges, etc.). The PSVANE could definitely reveal flaws in other sections of your system.

That being said, I will say that the true old Amperex Holland 12ax7 tubes are just excellent. They do not have the resolution and clarity or speed of attack as the PSVANE, but there is just "magic" about them that makes the music so emotionally engaging and so "live" and "naturally analog" in a sense. However, it is extremely difficult to get the "real" Amperex tubes without being screwed over with fake tubes and fake sellers. They can be very expensive (like $400-500 for a pair of 12ax7).
I'm a repeat customer of Brent Jesse , he provides quality tubes and reasonable prices
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I think the Phillips/Amperex tubes that people are recommending are tubes made in the Amperex factory at Heerlen, Holland. Phillips sold these tubes with many different labels. Phillips owned many tube factories, Amperex, Siemens, Mullard, Valvo and many more, and tubes made in one factory were often labeled with another factory’s "brand." Your Phillips Miniwatts could have been made at Heerlen.

You can tell a Heerlen, Holland tube by the left facing right triangle that is the first symbol in the bottom line of the etched tube code. You can read about these codes here:


Any tube you’re likely to come across these days would have the ’New’ Code, illustrated on page three, etched on the side of the tube. The "tube type" code for a 12AX7, the first two symbols on the top line, would be I6.

The correct spelling for Brent is Brent Jessee.
Sure as hell is!   As many times as I've been to his site, I never paid attention to his header.  Thanks for the correction, Tom.
Shuguang Treasure 12AX7LS from Grant Fidelity are the best you can buy. They beat out my Telefunkens in the phono stage. They sound good out of the box but do need 20 hours burn in and sound at their best after 100 hours. They are ultra quiet. I've posted about them here before. 
My favorite 12AX7 compatible tube is the 5751 triple mica black plate from the 1950s by RCA and GE, in that order.  There are several versions of these.  The older silver clip versions are the very best.

Prices are all over the board on these.  I have an abundance of the GE version if you want to give them a try.
I'm a big fan of the Mazda(France) silver plate 12AX7 tubes. They have a beautiful air and sparkle to the high frequencys. They wont have the force and power of the Siemens you are using though. But the Mazda is all about elegance and finesse. 
Wow. Not 1 mention of telefunken 12ax7’s. 
Thats odd. 
@mickeyb I'll mention them again. Telefunken ECC83 (smooth plates over ribbed plates) are the best 12AX7 type after the Shuguang I listed above. The Teles are neutral and transparent. The Shuggies have better frequency balance, extended highs, and cleaner, deeper bass.
Another vote for current production Gold Lions. I like the extension they give on both top and bottom. I use them in Bob Carver VTA-120 monoblocks as well in a Manley Chinook phono stage. 
Thanks for all the responses. Lots to think about on the NOS front. I have tried Gold Lions 12ax7s, and they didn't suit my tastes. In my system, they sounded lean and a bit bright up top - though I know they have a reputation for being dead neutral.

Will seek out a pair of Psvane 12ax7s and either Sylvania or Mazda old stock.

I’ve noticed some clear differences between 6SN7GTBs that both my pre and power amp currently use, and NOS GEs are my faves for those. I continue to use 12AX7s in my guitar amps (and previously in my Jolida 502p amp also, although I no longer own that amp). I did wind up using Gold Lion 12AX7s though, as they sound great, are consistent, and are readily available.
For NOS Tubes I love the Mazda's.  Top end sparkle and a very dimensional.  I am running 12AU7s in the input stage in a power amp and love them.

NOS Mullard's are decidedly warm.  Wonderful tubes if you like that sound profile.  Not sure I would pair them with an EL34.

For current manufacturing, I would look at Sophia.  Great sounding tube with no real weaknesses.  


If you are interested in rolling your EL34s the Sophia Coke-Bottle EL34 is freaking amazing.  


A Telefunken smooth plate 12AX7 might hit a good balance between the Amperex (Philips) and Siemens.

I dont like any Mullard 12AX7. I also dont care for any U.S. made 12AX7 except perhaps for the old stock Tung-Sols.

If you can live with roughly 30% less gain, 5751s are great tubes. Best of these are: Raytheon Windmill Getter (double mica), GE and Sylvania triple mica black plates. For less money, the double mica Tung-Sol is also good.

I'm not an expert here but for my 300B I was told that the gain stage tubes may have more influence than the power tube, and that the Telefunken is the best choice and best 12AX7 produced.
I went with smooth plate as understood it is slightly more refined and less sparkle than the ribbed plate.

Whether its the best or not I can't say because I haven't compared, but the amp that uses them is the best I've ever heard

My #1 pick are Telefunken smooth plates . Also Brent Jesses Tube Sound description is spot on . Also “ Missioncoonery “ is wrong . I have for rotation RCA, Mullard , Seimens CCa , Seimens silverplate, Amperex , Phillips , Telefunken ( smooth , ribbed , black coated , Tektronix) . Out of them all , the smooth plate Telefunken is the most linear , and TO ME THE MOST ENJOYABLE IN MY SYSTEM . All the tubes I’ve tried are exactly how Brent Jesses’s site describes them . Also I’ve never  purchased tubes from them , but have paid comparable prices . Although I purchased 4 Telefunkens G73R’s for $500. I’ve found the the Seimens and the Amperex push the treble and upper mid out front in relation to the Telefunken, hence a sometimes too bright experience. But it varies with power tube and speaker rotation . So have fun , Mike .
For an EAR 864 pre-amp, Mullard 4004 (not the sweet and syrupy 12AX7).  Also, large D getter Sylvania.  For 12AU7, I prefer the clear top RCA.  As to 6SN7, I'm using late 40s Raytheon, although Ken-Rad and RCA sounded excellent as well (including RCAs from the 1970s-same tube).  The chromedome Sylvania was too forward and bright in my application; however, it should be tried in a system which is on the less detailed or warm side.  The GEs are also rans, not really good, not really terrible-they sound grainy even from the 1950s.  The 1970s-90s Russian and rebranded Russian 6SN7s just suck.
I have extensive experience with the use of tubes. My pre-amp, phono pre-amp, cd player plus 4 different power amps all use tubes, using single ended or push-pull circuits.

I have to tell you, I have been really pleased with my Telefunken and Mullard tubes. I also use Siemens, Philips, White Westinghouse, RCA, (cleartop in particular) as well as Psvane GE, Tung-Sol, Magnavox, Rogers and Sylvania.

The argument in favor of the Mullard/Telefunken tubes really gets down to better bass and inner detail. They are also extremely quiet and expensive, but the benefits outweigh the cost.

Experiment around....have fun!!!!!

+1 for NOS Amperex preamp tubes.