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Thread: Little bear tube Preamp T7 real tube amp or IC amp with glowing tubes for visual

  1. #1
    Join Date: Aug 2016

    Location: Kent UK

    Posts: 121
    I'm Paul.

    Default Little bear tube Preamp T7 real tube amp or IC amp with glowing tubes for visual

    Hi all

    Just taken delivery of a Little Bear T7 Tube Preamp

    One of the questions I had was is it a true tube amp or one of those low end chinese tube amps that are really IC amps and just use the tubes for visual effect.

    The price from Douk was low enough for me to take a punt and see whats inside, the seller posted a picture of the populated circuit board that appeared to show that there where no IC's present so it should be a true tube amp, but is it

    Pictures below

    How it looks in all its splendor



    Picture of the top of the PCB showing no IC's



    But wait, whats this underneath



    The 8 leg IC is a JRC2068 which is some form of OpAmp

    http://www.datasheetcafe.com/jrc2068-datasheet-pdf/

    So the question for those in the know, is is it a true tube amp or is that OpAmp really doing the amplification.

    Thanks for any feedback

    Paul
    Current setup Thorens TD-160 Mk1 with Denon DL-110 MC Cartridge, Pioneer A-70 Amp, Yamaha AX-592 Amp, Yamaha CDX-710 CD Player, Pioneer PD-4300 CD Player, Monitor Audio Bronze 5 speakers, Van-Damme Cables throughout.

  2. #2
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 3,252
    I'm Alan.

    Default

    With a quick search it looks like the op-amp is the phono amplifier stage and the tubes are the 'valve buffer' stage after and for the AUX function.


  3. #3
    Join Date: Oct 2016

    Location: Bolton, England

    Posts: 311
    I'm Andrew.

    Default

    Quote Originally Posted by Paul-H View Post
    So the question for those in the know, is is it a true tube amp or is that OpAmp really doing the amplification.
    What's a "true" tube amp? That's something that be debated endlessly. Some people scoff if there's a solid state rectifier in there instead of "true" tube rectifier. It all depends on how far you want to take the definition of "true tube".

    Alan's assessment that the valves are acting as buffers sounds reasonable.

  4. #4
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 23,308
    I'm Geoff.

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    Quote Originally Posted by RothwellAudio View Post
    Some people scoff if there's a solid state rectifier in there instead of "true" tube rectifier.
    As I said the other week. A rectifier just rectifies. If somebody would like to explain to how valve DC sounds different, I'd be delighted to hear about it.
    Mr. Tact!

    Main system: MMs/ADCs/Low output MC's/One rare Japanese SUT/One scarce British phono stage/various tonearms/hefty Japanese DD TT and hefty Japanese BD TT and small British BD TT. 4 CD players/2 jitter buster/2 DACs/Valve buffer. TVC stepped attenuator or valve pre-amp or solid state pre-amp. Current dumping power-amp or either of two Class A SS power-amp or Class A EL34 valve monos or big Japanese (part Class A) integrated. Big dual concentric speakers/Smaller dual concentric speakers/Two way British compacts and full range speakers, amongst others. And too much more to list!

  5. #5
    Join Date: Aug 2016

    Location: Kent UK

    Posts: 121
    I'm Paul.

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    What does using the tubes as a buffer achieve regarding the sound quality.

    Been testing this unit today via an AB switch on my A-70 and to be honest I can't hear any difference.

    Paul
    Current setup Thorens TD-160 Mk1 with Denon DL-110 MC Cartridge, Pioneer A-70 Amp, Yamaha AX-592 Amp, Yamaha CDX-710 CD Player, Pioneer PD-4300 CD Player, Monitor Audio Bronze 5 speakers, Van-Damme Cables throughout.

  6. #6
    Join Date: Oct 2016

    Location: Bolton, England

    Posts: 311
    I'm Andrew.

    Default

    Quote Originally Posted by Paul-H View Post
    ... to be honest I can't hear any difference.
    A buffer is supposed to be transparent. I'd be more worried if you could hear a difference than if you couldn't.

  7. #7
    Join Date: Feb 2013

    Location: W Lothian

    Posts: 29,896
    I'm Grant.

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    If you have an impedence mismatch between units then it should sort that. Some will impart a bit of a signature too. Some regard it as a warm valvy feel, but thats just imo smearing due to poor design and parts. As above you should reall only hear differences if your say, pre and power are a mismatch.. i use a very good one after my cd player, which seems to improve things since i upgraded it. Just seems to take an edge off the digital, so may be a problem, i dont know. Not complaining
    Regards,
    Grant ....
    Sometimes incompetence is useful. It helps you keep an open mind.
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  8. #8
    Join Date: Aug 2016

    Location: Kent UK

    Posts: 121
    I'm Paul.

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    Thanks for the explanation

    Still not to sure why I bought it though as I was not dissatisfied with the phono stage in my old Pioneer A-70

    Still it looks good in the dark and was quite cheap so no great loss, and also it's no worse so might be of use should I end up with more than one turntable, not that SHMBO will allow that, although she did give in and let me get a wall mount, so I must be wearing her down, it's only taken 30 years

    Paul
    Current setup Thorens TD-160 Mk1 with Denon DL-110 MC Cartridge, Pioneer A-70 Amp, Yamaha AX-592 Amp, Yamaha CDX-710 CD Player, Pioneer PD-4300 CD Player, Monitor Audio Bronze 5 speakers, Van-Damme Cables throughout.

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