1. Win a Broadcaster or one of 3 Teles! The annual Supporting Member Giveaway is on. To enter Click Here. To see all the prizes and full details Click Here. To view the thread about the giveaway Click Here.

Fender Super champ XD muddy

Discussion in 'Glowing Bottle Tube Amp Forum' started by Craig Williams, Oct 28, 2020.

  1. Craig Williams

    Craig Williams Tele-Meister

    Age:
    57
    Posts:
    176
    Joined:
    May 16, 2016
    Location:
    Thailand
    Got this little amp today. Had a couple of XD's before normally spectacular little amp. Everything seems to be working fine but sounds slightly muddy to my ears and normally these amps great clarity. Looks like the 2 x 6V6 originals, printed Fender GT. I can only see one valve glowing and only this valve getting warm? Is this because clean channel uses one valve and gain channel uses the other 6V6? Or does it indicate a problem?

    Speaker everything looks ok. Looks like its had little use but this amp around 5 years out of production so who knows.

    I am in Thailand and replacement valves looks like my choice Fender GT, TAD or electro harmonix. What would be the pick of those....for sweet clear sound, not overdrive. Or do the power valves not affect your tone?

    Anyone know about the valves only one glowing and any ideas on the muddy tone? Sounds slightly distorted even at low volume on the clean channel. Should I be looking at the 12AX7?
     
    Last edited: Oct 28, 2020
  2. elihu

    elihu Poster Extraordinaire

    Posts:
    8,524
    Joined:
    Dec 24, 2009
    Location:
    Texas
    Craig, I'm no tech. But I'm sure both 6V6's should be warm. I suspect one of them is bad.

    I used the JJ brand 6v6 tubes in mine because of their reputation as being heavy duty and long lasting. I believe you can also bias them slightly hotter because of this. That's what I did and the amp sounds great. There's a long thread on this amp that should tell you how to do this and more. Take a look.

    https://www.tdpri.com/threads/the-super-champ-xd-club.167992/
     
  3. Craig Williams

    Craig Williams Tele-Meister

    Age:
    57
    Posts:
    176
    Joined:
    May 16, 2016
    Location:
    Thailand
    Oh ok mate. By the way. Those valve spring retainers are stiff. What's the best way to get the valves out? Just about a two person job. One to hold the springs open and someone to pull the valve
     
  4. Peegoo

    Peegoo Poster Extraordinaire

    Posts:
    5,284
    Joined:
    Oct 11, 2019
    Location:
    Wyoming panhandle
    That amp operates the two 6V6 tubes in push-pull, so both are on all the time. Well, technically they're off for half of the sine wave...but you know that I mean. I had to mention that to head off the pedantic amp goobers that may want to correct me ;)

    Very few players know the 12AX7 is not a preamp tube; it's the phase inverter. The preamp is all digital--for both clean and dirty sounds.

    These amps do sound great, but their primary failure mode is the digital rotary encoder (amp model selector control). In your case, however, the amp may be running on one 6V6 tube.

    Here's how to find out what's going on:

    Swap the two tubes' positions (pull them and switch them one for the other). Does the originally cold tube stay cold? If so, it's the tube itself. If it warms up and the other previously-warm tube is now cold, it's either that tube's socket or the 12AX7 (or it's circuit) has failed.
     
  5. Peegoo

    Peegoo Poster Extraordinaire

    Posts:
    5,284
    Joined:
    Oct 11, 2019
    Location:
    Wyoming panhandle
    Those are called "bear trap" retainers because...this:

    [​IMG]

    Flip the amp upside down onto its top. Make a 'V for victory' sign and use those two fingers to press downward on each leaf of the tube retainer. Grip the tube with the other hand and gently rock it out of the socket. GENTLY, with a very very small rocking motion as you pull upward.
     
    Telecaster88, Wally and Blue Bill like this.
  6. elihu

    elihu Poster Extraordinaire

    Posts:
    8,524
    Joined:
    Dec 24, 2009
    Location:
    Texas
    I knew the 12AX7 wasn't a preamp tube but FWIW it sure lowered the noise/hiss when I swapped the stock tube for a quality GE.

    I'm guessing that if the digital encoder fails channel one will still function? I'm asking since I use channel one 99.9% of the time anyway.
     
    Last edited: Oct 28, 2020
  7. Peegoo

    Peegoo Poster Extraordinaire

    Posts:
    5,284
    Joined:
    Oct 11, 2019
    Location:
    Wyoming panhandle
    No, both channels are going through the digital preamp.
     
    elihu likes this.
  8. elihu

    elihu Poster Extraordinaire

    Posts:
    8,524
    Joined:
    Dec 24, 2009
    Location:
    Texas
    Curses!...

    Thanks Peegoo.
     
  9. Craig Williams

    Craig Williams Tele-Meister

    Age:
    57
    Posts:
    176
    Joined:
    May 16, 2016
    Location:
    Thailand
    I will swap them around for sure and see what's going on. The digital rotary encoder for amp modelling would only come into play on the gain channel right or would it effect the clean channel too?

    I am and always will only be using the clean channel. If only one valve was firing for whatever reason, is what I am describing asymptomatic of that? I mean for example with one dud tube you would still get some sort of reasonable sound out of it albeit half the volume and half the clarity? To be honest it didn't sound like it had the volume I remember the other one having set on 5.

    Is it necesary to get matched tubes for these? I thought I read somewhere they auto balance. Reason is I might be able to get my hands on one valve I have already that I know is good. Of course better to start with 2 new I guess.
     
    JL_LI likes this.
  10. Craig Williams

    Craig Williams Tele-Meister

    Age:
    57
    Posts:
    176
    Joined:
    May 16, 2016
    Location:
    Thailand
    Sorry double post :(
     
  11. Peegoo

    Peegoo Poster Extraordinaire

    Posts:
    5,284
    Joined:
    Oct 11, 2019
    Location:
    Wyoming panhandle
    The rotary encoder can affect the clean channel if it malfunctions.

    If one tube is dead, yeah..it can lower the volume and also alter the tone.

    The whole "matched tubes" thing is something that happened in the 1980s...just another reason to soak guitar players for money and give them yet One More Thing to obsess about. Prior to then, tube matching consisted of the following:

    Guitar player: "Hi, I need one of these tubes."

    TV store guy: "Hmmm, it's a 6V6. Let's see... [looks on the shelf and finds one]... Here you go. That'll be four dollars and twenty five cents."

    If it makes you feel better, pay extra for matched tubes. But you'll get much better tone by meaningful practice than you will from matched tubes.
     
    Telecaster88 likes this.
  12. Craig Williams

    Craig Williams Tele-Meister

    Age:
    57
    Posts:
    176
    Joined:
    May 16, 2016
    Location:
    Thailand
    Wow, a nice change to hear a definitive and knowledgable answer without the BS. Really appreciate your effort. Going away tomorrow but will let you know how I get on in a week when I get back. Many thanks
     
  13. Peegoo

    Peegoo Poster Extraordinaire

    Posts:
    5,284
    Joined:
    Oct 11, 2019
    Location:
    Wyoming panhandle
    There will be people that disagree with me because a tube that drifts too far from spec can make an amp perform below spec and affect the sound.

    But new/NOS tubes of the same model are all within a 'window' of specifications that allows them to work well together.
     
    archetype likes this.
  14. Craig Williams

    Craig Williams Tele-Meister

    Age:
    57
    Posts:
    176
    Joined:
    May 16, 2016
    Location:
    Thailand
    I've got a Vibro Champ that runs one 6V6 and I know thats good so will be a simple matter to take it out and try it.

    The super champ just travelled a lot of miles to get to me by road transport on bad roads so maybe that damaged the tube. Does that happen? It would certainly never come loose with the bear traps!
     
  15. archetype

    archetype Fiend of Leo's

    Posts:
    4,841
    Joined:
    Jun 4, 2005
    Location:
    Williamsville NY
    If the rotary switch/thingy fails, Channel 1 might continue to work. I can't guarantee that it will, as I don't know how the circuit's logical design works with the encoder. There's only one preamp/DSP stage in the circuit: Channel 1 is a voice just like the Channel 2's sixteen voices.
     
    Peegoo likes this.
  16. That Cal Webway

    That Cal Webway Tele-Afflicted Silver Supporter

    Posts:
    1,387
    Joined:
    Nov 16, 2012
    Location:
    Minot
    I have the Super Champ head

    Run thru a baltic birch cab w an Eminence spkr...


    Sounds, !!$$!!### !!
     
  17. Craig Williams

    Craig Williams Tele-Meister

    Age:
    57
    Posts:
    176
    Joined:
    May 16, 2016
    Location:
    Thailand
    I think Channel one uses the Blackface clean voice, the same as the gain channel. And thinking about it, on the gain Channel all the voicings seem correct albeit with the muddy sound I was talking about. I tried them out.
    So that being said I am betting it is the valve itself. Well hoping really :(
     
  18. Wally

    Wally Telefied Ad Free Member

    Posts:
    37,166
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    Not trying to be pedantic but rather simply accurate, but this is a single channel amp with options along the path. There is a single input preamp gain stage. The majority of modern amps follow this model whether they are tube, solid state or hybrids.
     
    Chiogtr4x and elihu like this.
  19. Willie Johnson

    Willie Johnson Tele-Meister

    Age:
    100
    Posts:
    258
    Joined:
    May 24, 2016
    Location:
    Chicagoland
    Seconded; I did the same, and it went from good to great. On mine, the bias pot was set at about noon, and the stock tubes read at 34.5ma there, less than the recommended 40ma; when I put in the JJ's, I intended to run them hotter, just under 50ma, and after giving the pot a few twists, I landed just a hair past that original straight up and down position, reading 49.5ma. Sounds great!
     
    Gevalt, elihu and That Cal Webway like this.
  20. Peegoo

    Peegoo Poster Extraordinaire

    Posts:
    5,284
    Joined:
    Oct 11, 2019
    Location:
    Wyoming panhandle
    The JJ version of the 6V6 is almost a 6L6.
     
    That Cal Webway likes this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.