7DJ8 Surprise

BlueMDPicker
BlueMDPicker Posts: 7,569
edited February 2006 in 2 Channel Audio
Well, I must report another absolutely wonderful surprise from the tubes a friend recently gifted to me (thanks again, Dennis!) I tried a pair of 7DJ8 in my EE CDP -- after trying the Amperex 7308 -- and they came in a distant second place.

Last night, I decided to pop the hood on my Counterpoint SA-100 and put the RCA branded (Siemens) 6DJ8 (that had been in my CDP) in it. It takes a pair of 6922/6DJ8 per channel, so I thought "what the heck, I should try the 7DJ8 Dennis sent as well."

First try, I placed the 7DJ8 in the gate driver positions and the RCA in the gain stages. Nothing to write home about. I reversed the positions. WHAM! A new amp emerged -- super fast and dynamic, open with amazing mid-range clarity and HF extension, pinpoint imaging, and tight, powerful bass. WOW, I'm still shaking my head this morning. This amp has been sitting idle for quite some time, as I just was not impressed with its sonic signature using the 6922/6DJ8 variants I'd tried. Now, it's impossible to turn off.

If you know any other Couterpoint owners, I'd be interested to know if they can achieve the same results.

James, you need to try this!
Post edited by BlueMDPicker on
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Comments

  • scottyf
    scottyf Posts: 129
    edited February 2006
    What kind of 7DJ8 are you using? Unfortunatly (for this experiment) my SA-100 has been completely modified by Alta Vista and uses 6SN7's, but my SA-3000 uses 6DJ8 variants.

    HOME: VPI Classic/Grado Reference Master, EVS-modified Oppo BP83, Bryston DAC, Counterpoint 3000/SA-100 modified by Alta Vista, Polk LSi15

    TRUCK: Pioneer 8600MP, Soundstream 300SX, pr of Xtant 1001i, Autotek SS490.2, Polk SR6500, Polk MMC6500, pr of Polk MM2084DVC
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  • BlueMDPicker
    BlueMDPicker Posts: 7,569
    edited February 2006
    These are NOS Tesla PCC88

    264.jpg

    My friend got them at Galen Carol Audio

    My SA-100 was scheduled for the upgrade at Alta Vista. But, Mike was well over six months between production runs so I had him install the toroidal (which I'd already paid for drop shipped to him), upgrade the PS caps and FREDs and send it back. What do you find different/improved in the NP-100?
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  • fredv
    fredv Posts: 923
    edited February 2006
    Interesting, from http://www.nj7p.org/Tube1.php?tube=7dj8
    The 7dj8 specs look somewhat different from 6DJ8/6922. In particular,
    the heater current is only 0.15A (0.3 for 6922 and 0.365A for 6DJ8),
    and the plate voltage/current is 250V/2mA vs (90V/14mA). In this case,
    was the amp running the 7dj8 in a circuit not designed for it but happened
    to give good result?

    -fredv-
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  • marvda1
    marvda1 Posts: 4,901
    edited February 2006
    is this the same tesla tube as shown at the bottom of the page at this site?
    http://www.boiaudioworks.com/index.php?cPath=22&osCsid=98432aeb969e8eff185296ad5846a561
    Amplifiers: Norma IPA 140, MasterSound Compact 845, Ayre v6xe, Consonance Cyber 800
    Preamp: deHavilland Ultraverve 3
    Dac: Sonnet Morpheus 2, Musical Paradise mp-d2 mkIII
    Transport: Jay's Audio CDT2 mk2, Lumin U1 mini
    Speakers: Rosso Fiorentino Volterra II
    Speaker Cables: Crystal Clear Magnum Opus 2, Organic Audio Organic Reference 2
    Interconnects: Crystal Clear Magnum Opus 2, Argento Organic Reference 2, Argento Organic 2
    Power Cables: Argento Organic Reference, Synergistic Research Foundation 10 and 12 ga.
    Digital cables: Crystal Clear Magnum Opus 2 bnc, Tellurium Q aes, Silnote Audio Poseidon Signature 2 bnc
    Puritan PSM156
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  • BlueMDPicker
    BlueMDPicker Posts: 7,569
    edited February 2006
    fredv wrote:
    In this case, was the amp running the 7dj8 in a circuit not designed for it but happened to give good result?
    Yes, exactly. I've had the amp for well over 15 years and have never tried anything but 6922/6DJ8 types.
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  • BlueMDPicker
    BlueMDPicker Posts: 7,569
    edited February 2006
    marvda1 wrote:
    is this the same tesla tube as shown at the bottom of the page at this site?
    http://www.boiaudioworks.com/index.php?cPath=22&osCsid=98432aeb969e8eff185296ad5846a561
    Sounds like it from the description offered.
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  • fredv
    fredv Posts: 923
    edited February 2006
    BlueMDPicker wrote:
    Yes, exactly. I've had the amp for well over 15 years and have never tried anything but 6922/6DJ8 types.
    Hee hee, I think that's the beauty of tubes. With a little change, it is like a new amp but short of a new amp's cost :p I am only in the entrance in this arena and already found quite a lot of fun.

    -fredv-
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  • scottyf
    scottyf Posts: 129
    edited February 2006
    BlueMDPicker wrote:
    These are NOS Tesla PCC88

    264.jpg

    My friend got them at Galen Carol Audio

    My SA-100 was scheduled for the upgrade at Alta Vista. But, Mike was well over six months between production runs so I had him install the toroidal (which I'd already paid for drop shipped to him), upgrade the PS caps and FREDs and send it back. What do you find different/improved in the NP-100?

    The mods made the amp much more dynamic and imbued it with wonderful tonal shadings. Instruments sound very real (cymbals, guitars, sax), and it's easy to imagine the actual instrument in front of you. I rolled tubes to make the my system to sit just a smidge to the warm side of neutral (Ampy 7308 white labels with '52 Sylvania 6SN7s). Mike really made this stuff sing!

    Specifically, the modified amp has an incredible clarity that the unmodified amp didn't have. Call it "veils removed", or graininess taken away, I have never heard that kind of clarity in an amp before. Dynamics are also much improved. You can hear the suddeness of a stick hitting the drumhead, or the pick of the string to go with the body of the note on a guitar. Cymbals ring, not splat, and you can really hear the stick hit and the metal vibrate now. The old amp was pretty good, but nothing like what the modified amp sounds like.

    Mike has taken it to a level I didn't even know existed. Honestly, the normal bass, midrange, treble comments really don't matter. Sure, everything got tighter, cleaner and more liquid, but what really makes me giggle is how much more easily I lose myself in the music now. I find my toes tapping more often, and when the music is glorious, I just get swept up in it! I can no longer put music on when I want to read....I always end up getting drawn in.

    I wish you lived near me, I would love to let you audition the amp. I'm afraid I'm not describing how incredible this amp sounds, and would rather you heard it for yourself. I am so happy with my modded amp and preamp that I sold all my backup gear to buy tubes to last me until I'm 85. (I keep them in a safety deposit box, so don't get any ideas!) The weak link in my system now is the LSi15s, but everything sounds so right, that it's hard to seriously consider getting new speakers. At some point, I'll probably have to audition some Quads with this setup, as I have always loved them.

    Sorry I rambled. I'm liken' this amp!

    HOME: VPI Classic/Grado Reference Master, EVS-modified Oppo BP83, Bryston DAC, Counterpoint 3000/SA-100 modified by Alta Vista, Polk LSi15

    TRUCK: Pioneer 8600MP, Soundstream 300SX, pr of Xtant 1001i, Autotek SS490.2, Polk SR6500, Polk MMC6500, pr of Polk MM2084DVC
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  • scottyf
    scottyf Posts: 129
    edited February 2006
    BTW, I'm sending it back this week to have it taken from the Premium to the Premium Gold level. Basically, he's gonna put a Plitron tranformer in there and beef up the power supply a bit more. I had an extra 2k after my tax return that was earmarked for my stereo, and decided to take both my amp and preamp to the fully modified level.

    Hard to imagine, but Mike says it will sound even better when I get it back. Gives me goosebumps!

    HOME: VPI Classic/Grado Reference Master, EVS-modified Oppo BP83, Bryston DAC, Counterpoint 3000/SA-100 modified by Alta Vista, Polk LSi15

    TRUCK: Pioneer 8600MP, Soundstream 300SX, pr of Xtant 1001i, Autotek SS490.2, Polk SR6500, Polk MMC6500, pr of Polk MM2084DVC
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  • dorokusai
    dorokusai Posts: 25,577
    edited February 2006
    Don't you think a disclaimer might be neccesary beings that it's not a direct replacement to a 6DJ8, and apparently gear specific? Just wondering.
    CTC BBQ Amplifier, Sonic Frontiers Line3 Pre-Amplifier and Wadia 581 SACD player. Speakers? Always changing but for now, Mission Argonauts I picked up for $50 bucks, mint.
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  • BlueMDPicker
    BlueMDPicker Posts: 7,569
    edited February 2006
    scottyf wrote:
    Hard to imagine, but Mike says it will sound even better when I get it back. Gives me goosebumps!
    WOW! I'd love to hear your upgraded Counterpoint gear. In retrospect, perhaps I shouldn't have been so impatient -- but, SIX MONTHS?!

    I've kept my SA-100 all these years because I love the sound of it. I would have never guessed this tube roll would have such an impact.
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  • BlueMDPicker
    BlueMDPicker Posts: 7,569
    edited February 2006
    dorokusai wrote:
    Don't you think a disclaimer might be neccesary beings that it's not a direct replacement to a 6DJ8, and apparently gear specific? Just wondering.
    Not really.

    If I were suggesting subbing a 6922/6DJ8 into a circuit designed for a PCC88/7DJ8 I might offer a caution (based on operating parameters.) This sub, IMO, is no more sinister or problematic than a 7308 for a 6922/6DJ8.
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  • scottyf
    scottyf Posts: 129
    edited February 2006
    BMDP -- pm sent.

    HOME: VPI Classic/Grado Reference Master, EVS-modified Oppo BP83, Bryston DAC, Counterpoint 3000/SA-100 modified by Alta Vista, Polk LSi15

    TRUCK: Pioneer 8600MP, Soundstream 300SX, pr of Xtant 1001i, Autotek SS490.2, Polk SR6500, Polk MMC6500, pr of Polk MM2084DVC
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