NAD...MuchXS Champ

Discussion in 'Glowing Bottle Tube Amp Forum' started by wrathfuldeity, Nov 16, 2018.

  1. wrathfuldeity

    wrathfuldeity Tele-Afflicted

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    CL score, now the 3rd and last owner. The listing just noted, champ, pic and 6x9 skpr....I suspected it was one of Muchxs' and the seller noted it was. On very short notice was able to make an impromptu meet and took possession based on reputation without an opportunity to test. Built, surprising loud, no flub, sweet swirl, girth/grit and very responsive to gits...have yet to try pedals. It ain't no champ...it is THE CHAMP...oh btw and minty.

    Anyway got a couple question for other members of the club...
    1) skpr ohms?...have read that some have a 4/8 tap...even a toggle.
    2) This build runs fairly clean...heard that there can be a clean and/or mean toggle...Or I'll just use a pedal.
    Thanks!
    Very happy to be in the club.
     

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  2. archetype

    archetype Fiend of Leo's Silver Supporter

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    Perhaps someone has Eric's (Much's) e-mail address that they could message to you. He might remember your specific amp.
     
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  3. King Fan

    King Fan Friend of Leo's Ad Free Member

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    Cool. If you pull the back panel and post some gut shots, and also maybe see if you can visualize numbers on the transformers, smart folks here may be able to comment.
     
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  4. wrathfuldeity

    wrathfuldeity Tele-Afflicted

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    Output transformer is a Weber w022905m https://www.tedweber.com/media/import/w022905msch.JPG

    Idk...it seems the secondaries are green = 4 and yellow = 8 ohms?

    The spkr jack looks like black = ground ... along with jumper to the middle/short lug. And yellow to the tip and the green goes to the circuit board. So, I'm clueless about this stuff....what say ya'll.
    Thanks,

    edit...and this thing works well with pedals.

    DSCF9337.JPG
     
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  5. wrathfuldeity

    wrathfuldeity Tele-Afflicted

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    So upon further research/reading, fender champs could easily take 4 or 8 ohm spkrs without issue (don't want to damage this baby)...is this correct? Most of my cabs/spkrs are 8ohms.
     
  6. Wally

    Wally Telefied Ad Free Member

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    The single-ended Champs are one Fender which I do not use unmatched loads. Fwiw, I prefer a matched load on any amp.
    Looking at the speaker jack with the yellow OT secondary wire, I see only a single option for the impedance. IF that green wire going to the board is from the OT secondary, then I would suspect it is being used for the negative feedback circuit. One would have to have the amp in hand to really understand that aspect, imho.?.....unless you flip the amp over and can trace the green to the OT. If that is so, then it a guarantee I would think that that tap is being used for negative feedback.
     
  7. peteb

    peteb Friend of Leo's

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    I would unplug the speaker and measure the resistance of the speaker. That would be a good indicator of what impedance the OT is set up to see.

    While the speaker is unplugged, what’s the resistance of black to yellow?

    What’s the resistance of black to green?


    What’s the restance of yellow to green?



    It looks like the green wire is coming from the OT. It looks like it connects to ground. If it connects to ground, which you can measure and verify, that seems odd. Doesn’t it? Why would the OT connect to ground?
     
  8. Wally

    Wally Telefied Ad Free Member

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    That green wire circles around the speaker jack, but I do not think it contacts anything there. I think it makes contact to that eyelet on the board.....what that eyelet leads to is unknown because we can’t see the board. There is a high likelihood it is a NFB loop connection.
     
  9. tjnies

    tjnies Tele-Holic

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    Eric is still on the Gear Page; you can contact him there for a positive ID.

    And congrats - his amps are exceptional!
     
  10. peteb

    peteb Friend of Leo's

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    EB5340E6-7423-4B70-B249-38785B36A46B.jpeg






    Good point Wally. It does look likes it loops around the speaker jack, but why?


    Negative feedback makes total sense. The speaker is connected to the 8 ohm tap and the NFB loop to the 4 ohm tap for less NFB.

    The green wire does connect to the circuit board at one end. Doesn’t it need to go back the OT, like the diagram shows.
     
  11. Wally

    Wally Telefied Ad Free Member

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    Pete, that is why it would be of interest to see the other side of the chassis....to see if that green wire comes out of the OT secondary. Now that I look at things closely, though....the OT secondaries come out just to our left of the speaker jack while this green wire comes from somewhere to our right. Odd....
     
  12. wrathfuldeity

    wrathfuldeity Tele-Afflicted

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    Got a pm in to Eric at TGP..but figure holidays around the corner and such it might be awhile. However out of respect don't want to step on his toes so haven't posted full gut shots. Next week, guess I'll try to make time to pull the chassis.
     
  13. King Fan

    King Fan Friend of Leo's Ad Free Member

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    That's thoughtful, actually, not broadcasting his trade secrets all over the internet.

    For your purposes, if I'm thinking straight, the speaker is almost certainly 'right' for the OT, and certainly safe -- I'd be 98% sure it was original, and 99.9% sure Much didn't build 'em all crossed up. Also if there was a 'dirt' switch, it seems like you'd see it in looking in and on the amp. But maybe I'm overlooking something, and maybe there's other ways (tubes?) to decrease the headroom.

    Talking it over with him seems like a great idea.
     
  14. Mr Ridesglide

    Mr Ridesglide Tele-Afflicted Gold Supporter

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    I seem to remember that MuchXS used pull pots sometimes for switches?
     
  15. Michael A.

    Michael A. Tele-Afflicted Ad Free Member

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    If you look at his activity on TGP, he hasn't posted anything since March. I also have one of his Champs and sent a PM about a repair issue with mine, now inoperative, but didn't get a reply.
     
  16. Nightclub Dwight

    Nightclub Dwight Tele-Afflicted

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    From everything I've read, Muchxs has built or modded some great stuff. But I don't get the business about protecting trade secretes by not posting photos of gut shots. I think it was Dumble who encased circuits in epoxy to keep them secret. I don't know, it just rubs me wrong. No disrespect to Muchxs, I'd love to have one of his amps one day. It just reminds me of something like, "I just read this great book, but I'm not going to tell you about it so no one copies the author."

    With all the circuits out there, I'd be surprised if someone knocked off Muchxs's intellectual property in a meaningful way.
     
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  17. JDRNoPro

    JDRNoPro Friend of Leo's

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    I think member alnicopu speaks to Eric on a fairly regular basis and has contact info. Actually, I think he also has a muchxs champ equipped with one of those 6x9 speakers. Mine has an 8" weber sig - great amp!
     
  18. Wally

    Wally Telefied Ad Free Member

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    I am sure that there is nothing about that amp that is proprietary. I am also sure that measuring the speaker’s resistance with an ohmmeter would tell one what impedance the OT secondary is. If one really wants to know what goes on in that circuit, a good tech could analyze what was built there. Pull on the pots....if none pull out there are no switching pots there. If there is no switch to change the output impedance, it is wired to one OT secondary tap with no options. This is a simple amp. It is not as if it is a Boogie mkV that requires a thick manual in order to understand how to run it.
    I say plug it in and play it.....that is it’s purpose.
     
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  19. wrathfuldeity

    wrathfuldeity Tele-Afflicted

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    Apologies, I know this is much ado about nothing. The whole ohm spkr thing is because I have a stable of various spkrs/cabs, a Weber Z matcher and the amp has an external spkr jack. Normally, in the past I'd just walk 20' to my neighbor and barrow his fancy multi-meter and be done with the whole matter...but the neighbor moved about 6 months ago.
     
  20. Wally

    Wally Telefied Ad Free Member

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    A multimeter that would serve the purposes someone other than a tech will cost less than $20....closer to $10.
    I have a Craftsman meter that cost me less than $20 many years ago. It reads comparable numbers to both of my Flukes.
     
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