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Another 12AU7 / ECC82 Tube recomendation needed

Discussion in 'Audio Hardware' started by PJC68, Apr 26, 2021.

  1. PJC68

    PJC68 Forum Resident Thread Starter

    Location:
    Liverpool UK
    Hi folks
    Just bought a secondhand Unison research Unico hybrid amp, this is the first version that takes 2 x 12AU7 / ECC82 valves (6 moons product of the year 2002)
    I was surprised when i opened it up it had a pair of NOS Mullard CV4003 tubes in it, these had been cyro treated by Watford valves here in the UK, these are £150 each inc VAT :eek: and theres no way im paying that again when the ones in the amp finally give in
    ECC82/CV4003-MULLARD-CRYO
    I had it on for 48 hours and it sounds great, i noticed there is a slight roll off in the treble and although the bass is deep it can sound unrefined on a few recordings, the midrange is great though (mullard sound)
    I am going to leave it on for a few weeks as the tubes might not have burned in yet
    I like a clear balaned sound and very musical, plenty of P R A T, i can hear the cry,s of "are you out of your mind changing the Mullards" but i prefer a different sound
    The tubes i have considered are

    Radiotecnique france with the square getter, these are the ones from the 1950,s (upscale audio does them for $95), i was thinking of the 1960,s version with the green writing on them but the above sounds better (aparently)

    Brimar CV4003, there are 2 models of this, a T14B and a T7B

    Brimar 13D5 , these seem to get a good write up

    Anyone using unison research amps would probably be giving me the best info but im open to suggestions
    I know it,s system dependant etc
    Thanks in advance
     
  2. allied333

    allied333 Audiophile

    Location:
    MI
    Just two tubes sound good in the rather poor sounding and non-linear 12AU7. Brimar 13D5 long plate and CBS Hytron 5814. The 5814 was a redesign by RCA when Collins complained about the new RCA 12Au7 distortion and poor linearity.
     
  3. John Moschella

    John Moschella Senior Member

    Location:
    Christiansburg, VA
    What do you want to be different?
    If you think the sound is too smooth/liquid and want something a little sharper then I would suggest Telefunken. I just made this change in a different Unison product (S6) for that very reason. Did the trick.
     
  4. PJC68

    PJC68 Forum Resident Thread Starter

    Location:
    Liverpool UK
    Thanks for the replies guys
    I like the sound, after coming from solid state arcam amps the bass does not sound as sharp
    I have heard the RT france ones are better all round for balanced sound, it,s a minefield this tube rolling game :help:
    Im going to leave the amp turned on for a few weeks playing music as i am burning in new kimber speaker links
     
  5. Ilusndweller

    Ilusndweller S.H.M.F.=>Reely kewl.

    Location:
    Columbus, Ohio
    I have used "Genalex Gold Lion ECC82/B749" (that is what the package says, though they are 12AU7 tubes, from Upscale Audio) and RCA "clear tops" (from Brent Jesse) in a Rogue Sphinx V2 (tube pre/class D amp section integrated amp). Both are solid. The Gold Lions are smoother sounding while the clear tops are more detailed sounding. Both sound great and are reasonably priced, I prefer the Genalex.

    As far as my thoughts on cryo?

    Cryo shmryo...Ive noticed the places that tend to offer this also tend to have "cable cookers"...where they spend about 40 cents on electricity and charge you $100 to "burn in" your cables. I dont buy that crizzola either...
     
    Last edited: Apr 26, 2021
    Salparadise and Spin Doctor like this.
  6. PJC68

    PJC68 Forum Resident Thread Starter

    Location:
    Liverpool UK
    The sound seems to have opened up a bit since i have had the amp on for 5 days now, the bass and treble have improved also
    Im thinking about buying a nos pair of Brimar CV4003 12AU7WA,s, they are a lot cheaper than the mullard version, i can get a pair of NOS siemens 12au7,s for £120
    Some of the prices for valves is just plain crazy, surely new production valves cant be that bad can they
    As for cyro treated valves i wouldnt buy myself, they were in tha amp when i bought it, and i burn my own equipment in instead of paying for someone to do it
     
  7. hogwylde09

    hogwylde09 Well-Known Member

    Location:
    Jasper Texas
    If you want to try some not so pricey tubes in your Simply Italy. I’ve have rolled quite a few Mullards, Amperex, Bugle Boys & orange globes. I have finally found the green label 60’s Sylvania 6189 actually give me the best overall SQ. You can find Platinum matched pairs for around $50.00. Very good tubes.
     
  8. PJC68

    PJC68 Forum Resident Thread Starter

    Location:
    Liverpool UK
    Thanks for the reply, it is a Unico amp i have, the first one that takes 2 x 12au7 / ecc82 valves
    Are these the ones you refer to
    6189 12AU7 ECC82 JAN SYLVANIA NOS - Langrex
     
  9. hogwylde09

    hogwylde09 Well-Known Member

    Location:
    Jasper Texas
  10. PJC68

    PJC68 Forum Resident Thread Starter

    Location:
    Liverpool UK
  11. BrentB

    BrentB Urban Angler

    Location:
    Midwestern US
    Please...
     
    Lowrider75 likes this.
  12. allied333

    allied333 Audiophile

    Location:
    MI
    In 1947 Collins Radio stated to RCA the new at time 12AU7 was very non-linear and anyone can see the poor plate curves. Collins Radio was first to use the new tube. RCA immediately built the 5814 to replace the 12AU7 and Collins never used the 12AU7 again. I guess Collins and I plus the poor plate curves are wrong per your 'expert' statement.

    I see you use a Silvertone preamp, RCA amplifier and $200 Cerwin Vega 311P and $200 Altec 3 speakers. Hum.......
     
    Last edited: May 1, 2021
  13. hogwylde09

    hogwylde09 Well-Known Member

    Location:
    Jasper Texas
    No, I could have, but opted for a couple of 1965 gf2 Mullards NOS.
    I had in my stash of tubed at least good pairs of green label 5814, 5963 and the JHS 6189.
    I listened to the 5814 & 5963. Didn’t know if the extra little heater current has any effect on SQ, but they were just too bright and a bit extreme in the highs. Same with the RCA clear tops.
    Completely satisfied with the 6189’s.
    Now in the Fisher 400 which I completely went through, all the suggested mods with the exception of NFBtm, it prefers Telefunken throughout the small signal tubes. My McIntosh MC30’s and MC75’s doesn’t seem to be so sensitive to tube rolling. However the C20 likes Mullard or Telefunken as well. Especially in the phone stage.
    But back to the Unison Research Simply Italy. I have found pure synergy with its current lineup. The Klipsch CF4 are very revealing to put it mildly.
    I may try some Westinghouse long black plates I have around yet though, as well.
     
  14. Mad shadows

    Mad shadows Forum Resident

    Location:
    Karlskrona- Sweden
    That's material for another thread.
     
  15. Funky54

    Funky54 Coat Hangers do not sound good

    I am completely confused... I have two different pairs of NOS 12 Au7 Mullards and Four pairs of Brimar 4003 tubes. I also have some RCA and Sulvania’s it’s basically “you can’t win” it’s always a compromise. I think the Mullards yield the widest, deepest, tallest sound stage. I think the RCA are the quietest, the Brimar are probably the best mix and the least expensive but don’t excel as much..... It gets to the point were you just enjoy whatever is decent for a while and switch it out for the sake of change.
     
    rischa and mds like this.
  16. allied333

    allied333 Audiophile

    Location:
    MI
    Do you have the Brimar long plates?
     
  17. BrentB

    BrentB Urban Angler

    Location:
    Midwestern US
    I am not claiming to be an 'expert", but it seems strange that a such a poor tube would be used in countless applications over the next 70 years. And still in many to this day...
    I mean if one went by specs and "readings" tube gear would have died LONG ago. And LPs for that matter. Hmm...
     
  18. allied333

    allied333 Audiophile

    Location:
    MI
    Your right, Collins, I and the poor plate curves is wrong.
     
    BrentB likes this.
  19. allied333

    allied333 Audiophile

    Location:
    MI
    These are true USA made RCA 12AU7 clear tops that are superior to Mexico made clear tops. The made in Mexico have curved cutouts on top mica. The USA made have straight mica cutouts.

    2 NOS NIB RCA 12AU7A Clear Top Tubes USA 1960's | eBay
     
  20. Ilusndweller

    Ilusndweller S.H.M.F.=>Reely kewl.

    Location:
    Columbus, Ohio
    Matched pairs of RCA cleartops (side getter) can also be found for $69/matched pair here (Brent Jessee).

    12AU7 Tubes in Stock . (scroll down)

    "New Old Stock Original Box and White Box. A great tube that rivals West Europe types, making it a great buy at this price. Some say the side getter contributes to the low microphonics of this tube. Wonderfully balanced airy highs, midrange warmth, and accurate bass. These pairs have been carefully hand selected for close dynamic mutual conductance on a Hickok 539A. I have sold dozens of pairs of these, and clients agree this tube is an incredible bargain among NOS tubes. Stock up now, this tube is vanishing from the market just like the Telefunken smoothplates!"
     
  21. allied333

    allied333 Audiophile

    Location:
    MI
    But, Brent does not state if USA or Mexican made. Only USA made are good. This seller will look for the RCA 12AU7 USA made clear top and his tubes in NOS that cost $6.50 each.
    Bob Dobush's Find A Tube – Vacuum tubes and vintage radio parts for sale at FindATube.com (wordpress.com)
     
  22. Ilusndweller

    Ilusndweller S.H.M.F.=>Reely kewl.

    Location:
    Columbus, Ohio
    They are stamped "U.S.A.", I just checked.

    That does not necessarily mean all the stock are U.S.A. but one could call or email and ask.
     
  23. Never tried US or mexican RCA cleartops but I have a pair of made in brazil RCA cleartop, side getter and they are not good, so beware the country before you buy.
     
  24. Ilusndweller

    Ilusndweller S.H.M.F.=>Reely kewl.

    Location:
    Columbus, Ohio
    I prefer the Genalex Gold Lion over RCA clear top in pre section of Rogue Sphinx v2.

    Right now I am powering Carver Amazing Silver MK4 with it. Plays loud enough. :)
     
  25. PJC68

    PJC68 Forum Resident Thread Starter

    Location:
    Liverpool UK
    The two Brimar CV4003 came yesterday but i have not had a chance to open the packet, theses will be going in the amp in a few weeks
    Looking at the comments here and elsewhere, there does not seem to be a "do it all" valve
    Your ears/equipment/room will all play a part
     

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