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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?

funcrusha


funcrusha
verdantaudio's avatar
verdantaudio
1,469 posts
 
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.  

https://artaudio.us/products/sophia-electric-12ax7-tubes-ecc-83

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

https://artaudio.us/products/sophia-electric-el34-st


audition__audio
1,347 posts
 
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.


itsikhefez
63 posts
 
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

buellrider97
369 posts
 
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 .
fleschler
1,923 posts
 
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.
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