Who has tube-rolled Audio Note amps?

Discussion in 'Audio Hardware' started by raferx, Jun 20, 2014.

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  1. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    Hi all,

    I'm demoing an Audio Note Oto SE next week, and I've read that the tubes included vary due to different stock in rotation at Audio Note UK.

    So I'm wondering who has tube-rolled their Oto or Soro – whatever! (Ongaku anyone?) – and what tubes they ended up liking the most. I've read the driver-stage tubes have the most influence on sound?

    TIA

    –R
     
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  2. Steve Hoffman

    Steve Hoffman Mastering Engineer Your Host

    Amperex Holland wherever possible.
     
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  3. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    Gracias Steve :)
     
  4. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    Wow. NOS $159 per 12AX7 (I'd need two)! The NOS Amperex EL84s are between $85 and $190.
     
  5. chervokas

    chervokas Forum Resident

    I haven't used that amps in particular, but there are lots of good used 12ax7s that well last years and year, decades even, on the market. Buy from a good seller with a good warranty and good testing regime and you can pay half or less the price of NOS for ANOS. The Amperexes are great, but so are Sylvania black plate/D-getters which are often considerably cheaper and are my favorite all-around 12ax7. Even your common Sylvania, Raytheon, GE etc gray plate halo-getter pulls, sometimes with organ labels, can sound excellent and last forever. There are even some decent sounding new production 12ax7s -- the new Sensor "Tung-Sols" and Sovtek 12ax7LPS. EL84s are another matter. New production for hifi I think the EL84M/6P14P-EV can sound great with big dynamics and great bass extension, and supposedly they can dissipate more heat than some modern EL84s, but I've had real problems with early failure with them. Other than that you're stuck with NOS, but I've made no thorough survey of vintage EL84. These days I only use 'em in one guitar amp that eats EL84s so I don't spend money on vintage tubes for that amp. Make sure that amp doesn't use the pin 1 position on the EL84s as a tie-point. Some modern EL84-based guitar amps do, for example, which works fine with modern EL-84 equivalents because the have no internal connection between pins 1 and 2. OS EL84s do have a connection between those pins and won't work with those amp configurations.
     
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  6. Steve Hoffman

    Steve Hoffman Mastering Engineer Your Host

    He asked specifically about AUDIO NOTE. I was told by the owner of the company Peter Qvortrup, that Dutch Amperex should be used.

    Just reporting the info! Feel free to tube roll the usual suspects.

    In the Audio Note "Empress" I'm using Sylvania "Silver" 6SN7's from 1946, RCA 5U4GC rectifier tubes and Peter is sending me his favorite 2A3 quartet to try in the mono blocks. Won't know what they are until they arrive but he wants them back so they really must be his favorite..

     
  7. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    Yep. Get ready to pay. I've put into tubes half of what I paid for my amp, but the results are worth it, and I factored that into the cost before purchase.
     
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  8. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    I don't mind paying for beautiful sound, (that's how I got to where I am!) I was just surprised at how high prices could go for single tubes, before I started to research particular tubes this weekend I figured most would be in the $100 range for matched pairs... which brings me to another question I hope someone here can help with: when I get to the point (in six months or so I imagine) where I want to look at tube-rolling my Oto SE Line, Audio Note UK states the amp has "4 x ECC83 4 x EL84" valves in it, but I only see seven in this shot below of the interior of an Oto SE Line/Phono. Am I missing something? And if I do roll the tubes, should the ECC83's (12AX7's?) and the EL84's be bought in quads that are as closely matched as possible? TIA!!!

    Photo used on AN UK site for Oto SE Line/Phono... the Line wouldn't have the phono board on the lower left of the photo:
    [​IMG]
     
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  9. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    Thanks again for the info Steve, nice to get valve recommendations from Peter himself through you. Cheers my friend.
     
  10. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    The two aluminum dampers at the bottom left, centered between the lovely caps, will twist off to reveal the valves. These dampers, obviously, are used to keep them from vibrating. Or, the metal straps on the sides may release. They look like a custom variant of dampers I have seen in older military applications. Old valve amps also have them sometimes.

    The one center bottom might be for a balanced in, or could be a rectifier valve. IDK

    [​IMG]

    Also, check out the computer ribbon cable taking the signal from the pre-in. In my experience, after you get your valves and interconnect/speaker wire sorted, consider building a new ribbon cable out of better cable. It can be a major upgrade, I have found. FWIW.

    [​IMG]

    Mouser has some—Temp Flex. I do not know if the gauge and strand spacing is right. I believe Bell Hellicopter developed this for military application, but it was not available for many years. Highly recommended.
     
    Last edited: Jun 29, 2014
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  11. Steve Hoffman

    Steve Hoffman Mastering Engineer Your Host

    What's wrong with the tubes that are in there now?
     
  12. TONEPUB

    TONEPUB Forum Resident

    Location:
    Portland, Oregon
    One suggestion I'd make, if you are going to roll tubes and go to the trouble of getting them matched, buy two extras. That way if a random tube fails, you won't lose the sound you worked so hard to get in the first place.
     
  13. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    Nothing.
    I haven't got the amp yet.
    I'm trying to learn more about tubes and how the different tubes affect the sound of a valve amplifier.
    I figure after having the amp for six months or so, and being intimate with it's sonic signature, I might want to experiment with tube rolling.
    Right now I know very little and I'm trying to educate myself.
     
    Last edited: Jun 29, 2014
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  14. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    How important is matching really? So many seem to emphasize it's importance.
     
  15. Radiotron

    Radiotron Tube Designer

    Location:
    Montreal, Canada
    The amp was voiced with these tubes. Wasn't this the set-up that made your jaw drop? Let them settle in and enjoy.

    Later on, if money is available, start with the preamp tubes.
     
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  16. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    Talk with Brent Jessie. There are several variables that can be measured on valves—some more important in particular applications. If, for example, a L and a R valve spec differently, the circuit will compensate for that difference in a different way. Like matching caps or transistors, you want to keep each channel signal path ideal so each channel is doing the same thing and each transformer is working the same way. If you have individual bias pots for the power tubes, you can use non-matched tubes, however, you will probably find matched give better stereo imaging. In a sense, the amp will fix the problem if the tubes don't match, but why make it do that work?
     
  17. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    I
    I think the two valves in dampers on the lower left are the phono stage? No? I don't think the line stage has them... only eight valves total in the line, 10 in the phono version. Here's another pic I found that is supposed to be the SE Line model, but I don't know how old it is, again – seven valves that I see. Just curious!

    [​IMG]
     
  18. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    Yes it was.
    And did it ever :)
    I'm in no rush to tube roll at all, just curious. I like to know how things work, and how the different valves would influence the sound.
    Just on Thursday I had a friend come over and listen to the Sugden A21SE demo in my system at the moment. He brought a higher-end DH Labs interconnect with Eichmann plugs on it... the improvement in the sound was not subtle – it really smoothed out some "tizz" on the highs we had noticed on a few LPs and definitely opened the sound.
    My point?
    The better the system gets, the more you can tailor the sound to it's optimum with minor adjustments, but unless you understand how these (what some would call "ludicrous") tweaks affect performance, you don't really know what's going on with your system.
     
  19. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    Interesting. Note, no ribbon cable! Looking at photos, I can’t tell. Here is this though, which may indicate two valves per-channel in the pre? Maybe an older model? Someone with real knowledge can comment.

    Oto Line SE version

    10 watt Class A single-ended EL84 line only integrated amplifier, 4 inputs & tape loop, 4 x ECC83 4 x EL84.


    Oto Phono SE version

    The MM Phono version adds 1 x ECC83 and 1 x 6DJ8 to the valve compliment

    ?

    [​IMG]
     
    Last edited: Jun 29, 2014
  20. triple

    triple Forum Resident

    Location:
    Zagreb, Croatia
    Interesting amp. Signal caps seem to be placed under PCB's. I don't think I have seen that before. Parts quality is so-so. No tantalum resistors and the caps are probably Jensen alu foils, not the copper foils like in that phono stage.
     
  21. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    So there must be some confusion, then, in which valves. This is the push/pull version.

    [​IMG]
     
  22. vinylkid58

    vinylkid58 Forum Resident

    Location:
    Victoria, B.C.
    AFAIK, they aren't "dampers", but shields to protect the phono tubes from stray hum and RF. Very common in older gear.

    The OTO Phono SE manual lists an extra 12AU7. http://www.audionote.co.uk/downloads/manuals/oto_phono_se_manual.pdf

    According to the manual, there's only 2 (two) 12AX7's in your amp. http://www.audionote.co.uk/downloads/manuals/OTO Line SE Manual smaller.pdf

    jeff
     
    Last edited: Jun 29, 2014
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  23. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    Thanks. That conforms to the photo. Seems there is some confused info out there with the versions of the amps.

     
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  24. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    Man, every photo of that amp's internals is different... as are the schematics and what the manual states, I'll have a look-see inside when I get it I guess.
     
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  25. raferx

    raferx Forum Resident Thread Starter

    Location:
    Vancouver, Canada
    I emailed Auido Note :cool:
     
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