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Cheap Champ from China? Joyo / Fame JTA-05

Discussion in 'Glowing Bottle Tube Amp Forum' started by engineer, Apr 3, 2016.

  1. engineer

    engineer Tele-Meister

    214
    Feb 26, 2013
    Sweden
    So, I have been looking for a Fender Champ for a while now, and like most I was sold on the '57 Champ. I just didn't feel like parting with so much money for an original one with questionable electrical safety (thanks for all those videos and threads of people restoring and fixing up old amps).

    I also went down the path of building my own, like many here have done (thanks for sharing your experiences). But in the end I decided soldering is not really for me. Maybe the occasional one or two for a cable or a speaker, but a whole turret even in the Champ size? No.
    Not to mention the prices aren't that different if you combine the cost of the kits, tubes, speaker and cabs.

    Then after a visit to Copenhagen (I'm in Sweden) I found a chinese made, handwired point-to-point clone that looked like a Champ for peanuts. But it had a 10" speaker and some weird rectifier I didn't recognise, so I didn't bite (later deduced the rectifier to be a 6Z4 tube with no western replacements). I also found out later that the amp was more a 5F2, than a 5F1.
    Still, interesting for those that want that type of amp and don't have the necessary soldering confidence.

    After that I found the Joyo JTA-05 through an eBay advert and later some threads on it here.
    It looks like a simple 5F1 design on a PCB. It has a single 12AX7 and a 6V6 with a 5AR4 rectifier that can be replaced with a 5Y3 instead.

    From there I found the a german reseller had it but called it the Fame JTA-05. Same, just rebranded and they have changed tubes and speaker. The Fame came with Ruby tubes which sounded totally fine and a Celestion Super 8 ceramic speaker. All for about 200 dollars (177 Euros).

    UPDATE: In the US it is also sold as the Chickenhead F51 Little Juke, but it looks to have different speakers. (Sorry, for being Euro-centric)

    I took some photos of the internal components and removed the chassi from the cab.

    First, here is the chassi removed:

    [​IMG]

    Then, the top with the trannies (no markings here):

    [​IMG]

    Here are the tubes. There are also two speaker outputs. 4 ohm and 8 ohm.

    [​IMG]

    Here is the PCB. The marking on the power transformer reads: SHDX76-90A

    [​IMG]

    I also found som e direction printed on the PCB. What's it for?

    [​IMG]

    They even put in that ol'sticker. Nice touch!

    [​IMG]

    It looks really nice, doesn't it? My plan is to change speaker and the tubes and eventually the cab (we all want that Tweed). But to me it sounded really nice as it is. So I will keep stock. At least for now. I already have a 5Y3GT so I will probably test that for comparison.

    Any feedback from our resident electronics wizards? Thumbs up?
     
    Last edited: Apr 3, 2016
    Duotone and Alamo like this.

  2. engineer

    engineer Tele-Meister

    214
    Feb 26, 2013
    Sweden
    I also did a quick recording of the amp as it is, playing the riff to Brown Sugar. Don't judge my playing, I totally get why "Keef" only has 5 strings on his guitar.
    I use a nice band mic with the amp just below 8. There is also a reverb pedal in front.

     
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  3. ultra80096

    ultra80096 TDPRI Member

    81
    May 15, 2015
    IA
    I have that same amp under the "Chickenhead" brand name. Neat little amp. Mine is biased pretty hot from the factory. Also it has 4 and 8 ohm speaker outputs, with the instruction of not to use both at the same time.
     

  4. engineer

    engineer Tele-Meister

    214
    Feb 26, 2013
    Sweden
    Oh yea! I saw that earlier. I have updated my original post to reflect that. Sorry for being "euro-centric". :)
     
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  5. overlock

    overlock Tele-Afflicted

    Aug 25, 2009
    N. Ireland
    Thank you for posting such excellent pictures, Engineer. The transformers certainly don't look undersized, which is often a problem with budget amps. And it's good to see that the valve sockets are fixed to the chassis instead of being PCB-mounted. It's still possible that the pcb they connect to might suffer a bit of heat damage over time, but even if that did happen it would be a simple enough fix. All in all, that looks like a really decent Champ clone for the money. I'm tempted again.
     

  6. engineer

    engineer Tele-Meister

    214
    Feb 26, 2013
    Sweden
    I'm sorry. Didn't mean to tempt you. ;)

    Does the numbers on the back of the power transformer mean anything to you? Or more that it will supply the power needed?
     

  7. andyfromdenver

    andyfromdenver Friend of Leo's

    Dec 21, 2011
    grandpa's
    do you like crunchy gain/ distortion? want a sweet little lead tone for you studio?

    if so, i'd be in a big hurry to put a 10-25mfd/25V electrolytic across R4 (aka put a radial in C7. no i didn't look at the schematic so proceed at your own risk, but it's so obvious.)

    as they say in the South (US) be in a hurry
    [​IMG]
     

  8. engineer

    engineer Tele-Meister

    214
    Feb 26, 2013
    Sweden
    Thanks for the tip!

    I'm sure I'd like that on a switch! But I think I'd need pointers to the exact component and the placement. Do I put it in R4 or C7?
    Did I say I didn't get electronics? Or as we say in Sweden: Tala ur skägget, pöjk! <----(if you use Google Translate on that it will not translate properly. The meaning, yes, but not the intended nuance)
     

  9. andyfromdenver

    andyfromdenver Friend of Leo's

    Dec 21, 2011
    grandpa's
    been to Sweden a couple times :) played the Emmaboda fest a couple times. such a lovely country
    so i will need to see the back of the board or a schematic before i can tell you above a 99% certainty, and i would only share under that condition.
     

  10. engineer

    engineer Tele-Meister

    214
    Feb 26, 2013
    Sweden
    Cool! Emmaboda is a good festival. Did you get to see anything else?

    Of course, we need to be certain that what you recommend is actually doable and that they did not sneak in any "improvements". Taking out the board seems more invasive than the photo shoot I did. I will post it, but don't hold you breath. I need to muster up the confidence first.

    But the empty C7 signals that they used the 5F1 schematic as base, right? I mean, if you build a new amp from scratch on a PCB, then what's the point to produce unfilled holes?
     

  11. andyfromdenver

    andyfromdenver Friend of Leo's

    Dec 21, 2011
    grandpa's
    correct, it is the 5f1 circuit.
    well, don't pull anything out. you can use a nonpolar cap too. just caaaarefully solder it across the mentioned 1500 ohm resistor.
    big boost in gain, sounds way better, not even being subjective... just kidding, but it is such an improvement, imo.
    alternatively,
    here's your chance to tailor the hi pass/ lo cut a little though.
    want to advance the low freq cut off point? you can buy a range of caps
    25-20-10-5-2-1-0.68
    the lower the number the further to the R you shift the knee. if you have some clips, you can test them first.
    use a pencil tip iron and be fast but effective with the soldering.
    all at your own risk, i claim no responsibility.

    see you get to be "designer joe" the mod'n go getter

    p.s. you don't pull anything, just straddle the resistor.
    see pic
    [​IMG]
     
    Last edited: Apr 5, 2016

  12. engineer

    engineer Tele-Meister

    214
    Feb 26, 2013
    Sweden
    Is that the Fibonacci sequence? Did I mention my knowledge of electronics isn't larger than one of those resistors?

    You mean R as in resistor, right? :)

    Clips? You mean YouTube clips? :D

    Thanks Andy! But I have to chill a bit.
    I'm gonna play with tubes and speakers for awhile first.

    Can you recommend anything in that department? I got a Jensen C8R (4 ohm) today. But I need to break it in some first.
    The Celestion Super 8 that was mounted was not bad at all, but there was a real weight difference between the speakers which I assume means something.
    Should I keep the Rubys inside now? Get a 5Y3GT rectifier to lower the power a bit? Or is it only NOS tubes that will satisfy?
     

  13. andyfromdenver

    andyfromdenver Friend of Leo's

    Dec 21, 2011
    grandpa's
    i can't tell you to lower the power without knowing what the power is now.
    well, since you had messaged me re: the greta and this, this is the best i can help you. can't advise on what speaker or tubes to get without hearing it.
    best advice i can give is: if you are happy with the sound now and it's working fine, make music and don't worry about gear shiz.

    i mistakenly took your id "engineer" as possibly sound engineer.

    take care! and keep on rockin'
    [​IMG]
     
    Last edited: Apr 5, 2016

  14. engineer

    engineer Tele-Meister

    214
    Feb 26, 2013
    Sweden
    But I love gear shiz! :)

    Every time I pick up a new instrument or amp, there's a new song. That's why I try to shake things up often.
    With engineer, I mean the Miss Saigon one.
    And, I love that photo! Did you do the Fibonacci thing just for this or did you have it handy?

    I am really thankful for your input. I'm just not up to that task. At least not yet.
    I'm still in the honeymoon phase. I'll muster up the soldering skills later. I really like the idea with the lead tone. Especially on a switch.

    My intention with this thread was more to show what a great alternative this is to someone wanting a Champ to keep stock or modify.
    The specimen I have is also very quiet. I have read elsewhere that they were noisy, but I assume it has to do with that amp or environmental issues.

    So far, I am really happy with the sounds I'm getting as they really differ from the other amps I have and to me it sounds like a Champ.
     

  15. andyfromdenver

    andyfromdenver Friend of Leo's

    Dec 21, 2011
    grandpa's
    haha!! awesome :).
    coincidentally, my friend posted that pic to facebook same day you mentioned it.

    probably a lot of upgrades to do to the amp, but again, it would be hard to say without hanging out and hearing stock first.
    only thing i know is that if you boosted the preamp as stated, the cranked distortion tone would be nxt lvl :)
     

  16. engineer

    engineer Tele-Meister

    214
    Feb 26, 2013
    Sweden
    Ok, so I think the new tubes and speaker are settling in.
    I have been punishing that speaker for a few hours. Time for a new Brown sugar demo!

    You like the changes?

    This time, same everything except I have no reverb. And it's recorded in a different room, but about the same size.

     

  17. Alamo

    Alamo Poster Extraordinaire Silver Supporter

    Nov 15, 2006
    Berlin, Germany
    Here's a quick one of my JTA-05 with one 10" and an 8" speaker.
    volume between 9 and 10
     

  18. engineer

    engineer Tele-Meister

    214
    Feb 26, 2013
    Sweden
    I suppose Brown Sugar is the standard for testing JTA-05? :)
    My amp is on 8, so a little less crunch.
     

  19. AJBaker

    AJBaker Friend of Leo's

    Oct 3, 2010
    Switzerland
    Nice! Did you install the capacitor in the end?
     

  20. engineer

    engineer Tele-Meister

    214
    Feb 26, 2013
    Sweden
    No, not yet. I'm gonna keep it stock for awhile (besides changing all tubes and speaker). I'd like that cap on a switch. So sometime in the future.
    Perhaps even a pedal switch?

    Why? Did it get you curious?
     

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