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Concordant Excelsior - who knows about history of this pre?

Discussion in 'classic' started by _webwasher, Apr 10, 2019.

  1. eastone

    eastone pfm Member


    Yes, sorry, there's also 2x6CG7 used, I think, as power supply rectification. I have been trying to get a schematic for the Exhilarant for ages but to no avail.

    So in theory then, the amp could be modded to use two halves of the '83 and 5965 which could allow for a reduction in gain without negatively affecting performance...?
     
  2. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Hmm... 6CG7 is a double triode, not a rectifier.

    In theory, if you were wanting to use it as a casework complete with PSU and valve sockets, vol control and phono sockets etc then the worlds your lobster... it could be made into all sorts of permutations.

    If reducing gain is your primary concern then the original could easily be modded to reduce the gain.

    6CG7 is a fairly low gain triode and could be used in a zero feedback pre.... probably with more gain than you want though...
     
  3. Yank

    Yank Bulbous Also Tapered

    He probably meant "regulation" not "rectification"...

    It had triode pass elements in a voltage regulator.
     
  4. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Quite possible... as I said earlier everything is speculation without a schematic... or having one to reverse engineer to make a schematic...
     
  5. eastone

    eastone pfm Member

    Hmm it’s a 6CG7 mystery. I was under the impression the amp had no regulation...?

    I have no great desire to rip the amp apart. I like it a lot. I suppose I just thought: lower gain; fewer valves £££ wise (= tastier NOS varieties); and possibly lower feedback... could be interesting??
     
  6. Dan K

    Dan K pfm Member

    Ian,

    When was the last time you saw another Concordat Exhilarant?

    Or even another that's pretty much mint?

    Please don't butcher it! If you fancy a change then buy something else.
     
  7. Dan K

    Dan K pfm Member

    You could work out the circuit by looking for images from Tankertop on the wam.
     
    eastone likes this.
  8. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I'm afraid that modifying it into a different amplifier whilst simultaneously leaving it standard is beyond even my abilities :confused::rolleyes:
     
    eastone likes this.
  9. eastone

    eastone pfm Member

    Just shooting the breeze Dan. I certainly wouldn’t want to do anything irreversible to it.

    I’m not looking for a change just for the sake of it. The only things that irk me about are the price of the best NOS ‘83s and the fact I have a little too much gain.

    I think it’d be fascinating to clone / play with this circuit. Probably relatively inexpensive given the low parts count.
     
  10. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    There's a simple single valve line pre in DIY section which I designed if you are looking for a DIY project;)
     
    eastone likes this.
  11. Yank

    Yank Bulbous Also Tapered

    If they are not power supply components, then I can think of two possible explanations for two dual triodes - followers for both phono and line, or totem-pole followers.
     
  12. eastone

    eastone pfm Member

    It is a line-only unit. I suspect I got it wrong above and they are doing the regulation.
     
  13. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Indeed, White followers or similar was a theory here...
     
  14. Dan K

    Dan K pfm Member

    eastone likes this.
  15. awkwardbydesign

    awkwardbydesign Officially Awesome

  16. Dan K

    Dan K pfm Member

    Yes. A quick Google should confirm that. 1.5uF, sometimes they are doubled up, sometimes not.

    Come on Jez, we want your opinion on the circuit.

    Looks like one cathode follower after another, with a feedback loop back to the second triode, which appears to have almost no bias. I have wondered if Tankertop wasn't playing a joke and rewired it like this just for the photo.

    Is this the 'ring of 3' that you mentioned? Any details on that?
     
    Last edited: Oct 2, 2019
  17. Yank

    Yank Bulbous Also Tapered

    Given the paucity of components on the topside of the board, I was expecting there to be more underneath than just jumper wires.
     
  18. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Sorry folks but I ain't about to spend hours reverse engineering this from photo's just to satisfy peoples curiosity...
     
  19. awkwardbydesign

    awkwardbydesign Officially Awesome

    Looking at the photos, and my early Concordant, the transformer is obviously missing, and it looks as if the heaters might be AC. Mine, and the Excelsior diagram I have show DC heaters, with the PSU in a separate case.
    There aren't that many components in his preamps, if you exclude the PSU.
     
  20. Dan K

    Dan K pfm Member

    Yep AC heaters, one pair appears to be balanced and the others not, this amp has almost nothing to do with the Excelsior

    Come on Jez, an Engineer of your talents could tell what was going on in seconds. The input is on the far left in the pics and the output is at the opposite end of the yellow caps. The odd part is the small red wire between the 2nd and 3rd triode.

    Maybe another pfmer can shed some light on this
     

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