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.

Super Champ 1983 - Optimizing

Discussion in 'Amp Tech Center' started by Bendyha, Mar 29, 2014.

  1. hepular

    hepular Tele-Meister

    Posts:
    489
    Joined:
    Feb 17, 2019
    Location:
    abilene, tx

    according to the guy selling one, they won't fit in a standard 12 pin base / / / http://rover.ebay.com/rover/1/711-5...0001&campid=5338148343&icep_item=152963599949
     
    Wally likes this.
  2. Wally

    Wally Telefied Ad Free Member

    Posts:
    37,200
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    hepular likes this.
  3. hepular

    hepular Tele-Meister

    Posts:
    489
    Joined:
    Feb 17, 2019
    Location:
    abilene, tx
    & at $70 . . . well, just buy a 6c10
     
    Wally and Jowes_84 like this.
  4. Jowes_84

    Jowes_84 TDPRI Member

    Posts:
    97
    Joined:
    Mar 18, 2018
    Location:
    Munich, GER
    Agreed. Learned my lesson :)
     
  5. Bendyha

    Bendyha Friend of Leo's Silver Supporter

    Posts:
    2,521
    Joined:
    Mar 26, 2014
    Location:
    Northern Germany
    Okay, I didn't realize the 12BQ and 12BA where different sizes.
    The 6U10 is listed as having a 12FE base, and the 12D10 as having a 12BY base, yet they seem to be interchangeable in the 6C10 12BQ base (so I been led to believe)..........but not the 12BA:rolleyes:
    I guess it is because the filaments are on different pins....as are all the other bits, making it quite different....sort of a last generation miniature compactron.
    upload_2020-6-22_0-34-37.png upload_2020-6-22_0-36-10.png upload_2020-6-22_0-37-1.png
     
    Last edited: Jun 22, 2020
    Jowes_84 likes this.
  6. Jowes_84

    Jowes_84 TDPRI Member

    Posts:
    97
    Joined:
    Mar 18, 2018
    Location:
    Munich, GER
    SC-12pin-after.jpg SC-12pin-before.jpg

    Hi again,

    the 6u10-thing did not sit well with me... I realized with the latest posts that I had used my former Super Champ model with a 6u10 and actually diminished its output ... at the same time still thought it sounded absolutely fantastic back then. So I started doubting my ears (and my brain as well - but thats not new).

    This lead me to the following test setup comparing a 6c10 with a 6u10. Purpose was, to find out, what exactly I liked so much about my old Super Champ with the 6u10.

    First, I rewired the 12-pin socket in such a way that v3b (after reverb attenuator and reverb/lead mix) makes use of the high-mu triode - in place of v3c (reverb recovery).

    This way, the lead as well as clean mode do not get affected in terms of less gain. The only areas that are changed are the reverb recovery (low-mu instead high-mu) and the Phase Inverter (which has a unity gain either way, maybe slightly less using the 6u10 / 12au7 equivalent)

    Pictures are attached.

    New pinout on the 12-pin socket, basically swapping pins 4 with 6, 7 with 9, 5 with 10 is shown in the pictures.

    Second, I compared a Sylvania 6u10 against a GE 6c10 as well as the stock Fender 6c10 that came with my new SC. I used the stock Pyle speaker, and a fresh pair of matched TAD 6v6 tubes biased at approx. 85% plate dissipation. V1 and V2 were the stock 12AX7 as well as the stock 12AT7.

    Results (of course just my ears which might be compromised :) )

    6C10s:
    Both, GE and original Fender-branded tubes sounded great.
    Reverb all surfy-splashy when turned all the way up.
    Quite some crunch in clean mode, especially with the mid boost in.
    Already slightly farty bass response when cranked.
    Lead sound great, but bass needs to stay on the low side. If using my hottest neck humbucker, the SC farted out in a way I did not like.
    With the bass reduced - or at least using the bridge humbucker pick up, it sounded much better.

    6u10 (using modified pinout):
    from what I can tell, same sound level, same behaviour in terms of output and crunch/distortion.
    The reverb on ten is not quite as splashy, but it is still enough for 95% of my playing. For a surf band, you would want the 6c10 back in - for anything else, this is fine.
    Lead sounds equally great as with the 6c10
    - but - the way the output stage (or PI) farts out now, especially with level and bass cranked, sounds a lot better to me with the 6u10 - essentially an 12au7-equivalent triode in the cathodyne phase inverter position.
    I repeated the swaps and experiments, and heard it again. This is also similar to what I liked about my old SC ... just that now there is even more gain in the amp compared to my previous amp with the 6u10 using the stock 12-pin socket wiring.

    I cannot explain what I heard, but I definitely favour the 6u10 in my new SC in heavy overdrive situations over the 6c10 - especially when there is a surplus of bass.

    I assume it is the lower PI gain, some sort of compression effect or even higher current / lower output impedance that makes for the difference. But this is really over my head.

    My SC now travels with a 6u10 in the 12-pin socket and a GE 6c10 in the back of the amp, between the reverb tank and the edge of the cab - so I can use the 6c10 should I need a lot of reverb.

    The stock 6c10 goes in the bag with all the other stock parts, including the original 6v6 tubes (which still measure and sound fine)

    Thanks for exposing my mistake, I now have yet another tonal option using a simple and cheap tube swap.
     
    Last edited: Jun 22, 2020
    Wally and Bendyha like this.
  7. Wally

    Wally Telefied Ad Free Member

    Posts:
    37,200
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    Good comparison, Jowes. The reason the bass held together better is that you have less gain going on. With an AB763 type of tone stack placement, one always has to take care with tone control settings when pushing the preamp gain. When a TMB tone stack is placed farther down the signal chain as 8n the 5F6A/big Marshall Circuit, one can drive the tone controls at any level at any preamp gain setting level. The Fender Pro Sonic is that way since it is based on the 5F6A topology....two gain stages prior to the tone stack in the clean and four gain stages prior to the tone stack in the Gain mode.
    Fwiw, it is inter3sting to read the Boogie manuals for the Mark amps...and the original which was not then call3d a MKI. Mesa advises just what every BF/SF amp 0layer needs to consider...when pushing volume, which is preamp gain in a non-MV amp, the tones need to be run at lower setitngs—especially the bass.
     
    Jowes_84 likes this.
  8. Jowes_84

    Jowes_84 TDPRI Member

    Posts:
    97
    Joined:
    Mar 18, 2018
    Location:
    Munich, GER
    Thanks Wally. Yes, that is what happened when my SC had the stock 12pin layout, the gain in the amp was reduced.
    I failed to realize this earlier. And I also agree with everything you say about the tone controls. I need to check the Mesa Mark series manuals then ... but I am afraid of getting turned on to those... they are great amps, but expensive:)

    However, I did my experiment with a modified 12pin layout, which puts the 6u10's high-mu triode in the third pre-amp stage ... making the SC's overall gain using the 6u10 ALMOST equal to using the 6c10.

    I for sure have some research and theory homework to do to back my theory. And feel free to prove me wrong at any point and time.
    But from what I heard yesterday, I smell something is up with the low-mu triode in the cathodyne PI ... either being able to provide more current to the 6v6's grids during clipping, additional distortion/imbalance/compression using the low-mu triode with the 56k plate loads designed for a 12AX7 - or equal high-mu triode... I dont know yet.

    I will do some more research, try to back it with data sheet and circuit information. If I then still think I have a valid point and don't find another thread or information readily available, I might open a new thread addressing the PI tube swap and whether it could improve heavy overdrive/clipping tone. But I am sure some people on here know already.

    On the changes:
    I had changed pins 4<-->6, 5<-->10, 7<-->9
    Triode #2 has an amplification factor of 98, vs. 100 for a 12AX7 triodes.

    The PI gain stays very close to unity - as far as I understand from reading here, using either tube:
    http://www.valvewizard.co.uk/cathodyne.pdf
    But the 6u10 triode #1 and #3 should be able to provide more current to the output tubes.

    Original schematic Super Champ, third pre-amp gain stage after reverb/lead input:
    New pins:
    7 for grid
    5 for plate
    6 for cathode
    upload_2020-6-23_18-30-29.png


    upload_2020-6-23_18-20-57.png
    upload_2020-6-23_18-20-22.png
     

    Attached Files:

    Wally and hepular like this.
  9. hepular

    hepular Tele-Meister

    Posts:
    489
    Joined:
    Feb 17, 2019
    Location:
    abilene, tx
    so: were 1 to rewire the socket pins like above, it really changes nothing for how a 6c10 operates, but optimizes 6u10?
     
    Wally likes this.
  10. Jowes_84

    Jowes_84 TDPRI Member

    Posts:
    97
    Joined:
    Mar 18, 2018
    Location:
    Munich, GER
    really not sure anymore. haha. but yes, maybe I am missing something again, but rewiring the 12pin like I did should not change anything for the 6c10 operation, because it has 3 equal triodes, yet, for the 6u10, it moves a bit closer to stock in the main signal path. Reverb will be a bit tame/potentially weak, the PI will be different too.

    But maybe wait for the pros to jump in, I am just starting to wrap my head around this. I like to try things first and then make sense of what I did. Sometimes that is stupid, sometimes I get a lucky punch.
     
    Wally likes this.
  11. hepular

    hepular Tele-Meister

    Posts:
    489
    Joined:
    Feb 17, 2019
    Location:
    abilene, tx

    yep: seems like if that's correct, it's a fairly straight-forward mod that could address one of the big concerns with the amps with respect to price/availability of 6c10s.
     
  12. Wally

    Wally Telefied Ad Free Member

    Posts:
    37,200
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    The low mu triode that is now the PI is a large change from the 12AX7 triode that is in that position with the 6C10. Yes, the cathodyne PI is a bit below unity gain, but that does not change the fact that the triodes in the 6C10 have an amplification factor of 100 while two triodes in the 6U10 have an amplification factor for 17....in effect they are 12AU7 triodes in more ways than one. Whether one prefers one over the other is a personal decision. For my money, I will run 6C10s because I like the gain structure and the high freq harmonic Overdrive that occurs in the lead mode. But then....I have had these two SCs for over 25 years and prepared way back when for the possible decline in the number of available replacement 6C10 tubes. imho, Bendyha’s replacement rig using two noval sockets to replace the duodecar socket is the route I would take if I did not have spare 6C10s and did not want to pay the piper his market price for them. Fwiw, neither of the 6C10s in my SCs has failed or shown any other weakness.
     
    Jowes_84 likes this.
  13. Jowes_84

    Jowes_84 TDPRI Member

    Posts:
    97
    Joined:
    Mar 18, 2018
    Location:
    Munich, GER
    keep in mind the SC‘s PI is not designed for a low-mu Triode like an 12au7 or #1/#3 in the 6u10, it’s designed for the 6c10/12ax7.

    Same with the reverb recovery.
     
  14. hepular

    hepular Tele-Meister

    Posts:
    489
    Joined:
    Feb 17, 2019
    Location:
    abilene, tx

    think i have 3 6c10s squirreled away + 6u10. & the only tube I really noticed a decay in was the 12at7 that was in it when i got it

    i was also thinking that rewiring the socket would be a less invasive mod than doing the bendyha conversion, mostly since things are so tight in there & i'm such a horrid solderer
     
    Last edited: Jun 23, 2020
    Jowes_84 likes this.
  15. Jowes_84

    Jowes_84 TDPRI Member

    Posts:
    97
    Joined:
    Mar 18, 2018
    Location:
    Munich, GER
    Sorry
    I posted at the same time. Yes. If you have 6c10 use them!
    I just wanted to clear the air on my 6u10 fail. And I like the result with the 6u10-if the pins are changed. But the circuit is not designed for it. All agreed. :)
     
    Bendyha and Wally like this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.