Joyo Sweet Baby Tweed Champ clone

Discussion in 'Amp Central Station' started by teza, Jan 12, 2016.

  1. AJBaker

    AJBaker Friend of Leo's

    Posts:
    3,162
    Joined:
    Oct 3, 2010
    Location:
    Switzerland
    It's pretty easy actually. There's an empty spot marked c7, and that's where the cap goes. It's strange they don't put it in. It looks like they designed the circuit board with that cap, but then decided to drop it to conform to the old (faulty) schematic.
     
  2. Alamo

    Alamo Doctor of Teleocity

    Posts:
    11,093
    Joined:
    Nov 15, 2006
    Location:
    Berlin
    the circle left to those three resistors is marked as C7

    [​IMG]
     
  3. AJBaker

    AJBaker Friend of Leo's

    Posts:
    3,162
    Joined:
    Oct 3, 2010
    Location:
    Switzerland
    [​IMG]
     
  4. teza

    teza TDPRI Member

    Posts:
    57
    Joined:
    Aug 20, 2012
    Location:
    France
    Thanks for this. Just did order the cap.
     
  5. teza

    teza TDPRI Member

    Posts:
    57
    Joined:
    Aug 20, 2012
    Location:
    France
    What tubes are you using ?

    For me Nos
    Sylvanis 5ygtwa brown base
    RCA 6v6gty brown base
    RCA 12ax7
    Also got a RCA 6vgt black smoked black plate.
     
  6. teza

    teza TDPRI Member

    Posts:
    57
    Joined:
    Aug 20, 2012
    Location:
    France
    Hi,

    See below the answer from Joyo when you ask them for the schematic of the Sweet Baby.

    "Hi Sir,

    I am sorry that the schematics are company confidential documents, we don't give out! hope you can understand.
    Any questions on the JTA-05, pls don't hesitate to let us know!

    Best regards."

    Unreal for me as they did stole it from Léo.
     
  7. teza

    teza TDPRI Member

    Posts:
    57
    Joined:
    Aug 20, 2012
    Location:
    France
    Did you remove the board to put the cap or did soder it straight in ?

    Thanks.
     
  8. AJBaker

    AJBaker Friend of Leo's

    Posts:
    3,162
    Joined:
    Oct 3, 2010
    Location:
    Switzerland
    I soldered it straight in, but it was tight. Also, a radial cap would have fit better than the axial one I used.

    I'm not thrilled by the stock speaker. At low volume it's ok, but it farts out when I turn it up.
    I ran it through an eminence 1258 and it sounded much better (obviously). A better 8" might be in the cards some day, but I'll wait for now.
     
  9. teza

    teza TDPRI Member

    Posts:
    57
    Joined:
    Aug 20, 2012
    Location:
    France
    I put a Weber alnico 8' signature smooth cone, not expensive and sound great. I'am thinking to buy a extention speaker cabinet 10' or 12' not sure yet.

    But when it comes to vintage sound like alnico.

    Thanks again
     
  10. teza

    teza TDPRI Member

    Posts:
    57
    Joined:
    Aug 20, 2012
    Location:
    France
    I will try with the Weber 12" alnico have got in my Blues Junior before making a choice.
     
  11. teza

    teza TDPRI Member

    Posts:
    57
    Joined:
    Aug 20, 2012
    Location:
    France
    Below is the config of the Victoria, so you right about cathode.

    • 5 watts of power
    • 5F1 Type Circuit
    • Single Ended Operation
    • Cathode Bias Design
    • Standard Speaker: One Jensen P8R
    • Standard Covering: Tweed
    • Tubes: 1-5Y3, 1-6V6GT, 1-12AX7
     
  12. AJBaker

    AJBaker Friend of Leo's

    Posts:
    3,162
    Joined:
    Oct 3, 2010
    Location:
    Switzerland
    I think they're referring to the output tube being cathode biased (the input tube is cathode biased regardless of whether a cap is there or not). But I don't know how Victoria does it, does anyone have a schematic?
     
  13. AJBaker

    AJBaker Friend of Leo's

    Posts:
    3,162
    Joined:
    Oct 3, 2010
    Location:
    Switzerland
    ...I found a picture! Victoria amps does indeed use a cathode bias cap, but I don't know what value.
     
  14. Alamo

    Alamo Doctor of Teleocity

    Posts:
    11,093
    Joined:
    Nov 15, 2006
    Location:
    Berlin
    Uncle Doug talks about the cathode bypass cap - interesting.

     
  15. engineer

    engineer Tele-Meister

    Posts:
    215
    Joined:
    Feb 26, 2013
    Location:
    Sweden
    I had a Celestion Super-8 in mine which was a decent speaker.
    I replaced it with a Jensen C8R 4 ohm speaker. You could also go for an AlNiCo one.

    BTW, the mod you did looks different from the one @andyfromdenver mentioned in the other thread.
    http://www.tdpri.com/threads/cheap-champ-from-china-joyo-fame-jta-05.625485/

    He talks more of putting it on the R4 resistor which is just to the left of the C7 position.

    But maybe there is no difference on that position? I wouldn't know.
     
  16. AJBaker

    AJBaker Friend of Leo's

    Posts:
    3,162
    Joined:
    Oct 3, 2010
    Location:
    Switzerland
    Same thing, I checked first with the meter.
     
  17. teza

    teza TDPRI Member

    Posts:
    57
    Joined:
    Aug 20, 2012
    Location:
    France
    Hello Al

    Is the cap must be 25v whatever his value ?

    Cheers.
     
  18. AJBaker

    AJBaker Friend of Leo's

    Posts:
    3,162
    Joined:
    Oct 3, 2010
    Location:
    Switzerland
    25v is what's recommended as a safe value I believe.
    For the uF, 22 will pretty much amplify everything, whereas something like 0.68 will amplify the highs more, like on a Marshall.
     
  19. csbluesman

    csbluesman Tele-Meister

    Posts:
    221
    Joined:
    May 3, 2009
    Location:
    Chehalis,WA
    It can be higher voltage but not lower than 25v.
     
  20. Alamo

    Alamo Doctor of Teleocity

    Posts:
    11,093
    Joined:
    Nov 15, 2006
    Location:
    Berlin
    I just did it, soldered in a 22 uF, 25 Volt radial cap --Wow, did that get so much louder?
    I should have done more listening before/after mod but perception tells me it's a loud, snarling beast in a good way.
    with a 10" and 8" in my Deluxe sized cab it's absolutely gigable.
    very cool, good that we talked about it.
    thanks
     
    Last edited: May 10, 2016
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.