My version of the AC15

Discussion in 'Shock Brother's DIY Amps' started by voskarp, Nov 21, 2021.

Tags:
  1. voskarp

    voskarp Tele-Holic

    Posts:
    826
    Joined:
    Feb 12, 2017
    Location:
    Uppsala, Sweden
    No, to get the Normal channel and the Top Boost together out of phase was a deliberate decision:

    About 5:30
     
  2. voskarp

    voskarp Tele-Holic

    Posts:
    826
    Joined:
    Feb 12, 2017
    Location:
    Uppsala, Sweden
    That's true, didn't even think about that... could be!?
     
  3. voskarp

    voskarp Tele-Holic

    Posts:
    826
    Joined:
    Feb 12, 2017
    Location:
    Uppsala, Sweden
    2L man likes this.
  4. andrewRneumann

    andrewRneumann Tele-Afflicted

    Posts:
    1,078
    Joined:
    Mar 22, 2020
    Location:
    Cincinnati, OH, USA
    About that "Brilliance" control. I don't think a 500k pot comes close the amount of impedance an "open switch" would provide. Unfortunately, in this context I think you would need something huge. Even a 1M pot wouldn't cut bass like an open switch.

    Try a regular CR filter there. The C could be something like 47n and the R could be a 1M variable resistor to ground. Might get you close to the original. ;)

    EDIT: The above CR is a ridiculous idea, but I’m leaving it as reminder to think stuff through before I post it. :cry:
     
    Last edited: Nov 25, 2021
  5. voskarp

    voskarp Tele-Holic

    Posts:
    826
    Joined:
    Feb 12, 2017
    Location:
    Uppsala, Sweden
    You are of course right about that, but my intention was not to get close to the sound of the original switched cap. It takes away way too much bass and low mids.

    I should perhaps call it "Bass Tamer" instead of "-cut"

    I tried it in the AC4 I built, and it worked almost like the way I wanted it too. That's why I changed the cap from 1n to 250p. But a 1M might work be even better, I'll try that. The 500k was chosen just because that's what I had laying around when I made the AC4...

    Ordered extra 1M and 2M pots, so I'll try them.
     
    andrewRneumann likes this.
  6. voskarp

    voskarp Tele-Holic

    Posts:
    826
    Joined:
    Feb 12, 2017
    Location:
    Uppsala, Sweden
    Thinking about it, with a 10% tolerance, you could actually have a 82k and a 100k both being 90k, so I don't know how important that is...
     
  7. andrewRneumann

    andrewRneumann Tele-Afflicted

    Posts:
    1,078
    Joined:
    Mar 22, 2020
    Location:
    Cincinnati, OH, USA
    My CR filter idea was poorly considered anyway. It would shunt all the signal to ground when resistance set to 0. :oops: Should have thought that one through before posting.
     
  8. voskarp

    voskarp Tele-Holic

    Posts:
    826
    Joined:
    Feb 12, 2017
    Location:
    Uppsala, Sweden
    Things like that happen when you improvise, it happens to me all the time... That's the great thing with this forum, hopefully someone finds the mistake and corrects you (if you don't do it yourself). :)
     
    Last edited: Nov 25, 2021
  9. voskarp

    voskarp Tele-Holic

    Posts:
    826
    Joined:
    Feb 12, 2017
    Location:
    Uppsala, Sweden
    Received most of the parts for the build yesterday, and the power transformer does not have the metal shield on top of it. It looks like this model don't ship with one, so nothing made wrong from the supplier.

    Is that something that makes a big difference for noise/hum, and why does some have it and this not?

    IMG_3857.jpeg

    VS

    iu.jpeg
     
  10. voskarp

    voskarp Tele-Holic

    Posts:
    826
    Joined:
    Feb 12, 2017
    Location:
    Uppsala, Sweden
    Found another error in the schematic: R27 & R32 placed incorrectly...

    Revised schematic:

    •VOP.AC.15v.1.3 .png
     
  11. 2L man

    2L man Tele-Holic

    Age:
    61
    Posts:
    891
    Joined:
    Nov 23, 2020
    Location:
    Finland
    If you are goung to install the "end bell" there usually is some insulation between it and EI core and also under the screws and nuts. I did use just cut pieces of thick cardboard. Nuts which come between EI core and chassis lift PT enough. If core holes allow, wrap screw shafts using masking tape, so they come evenly centered inside the core.

    You can carefully cut that plastic "spool" it you need when fitting the end bell.

    I think end bell is more cosmetics and mechanical protector than electromagnetic shield but it should do it as well.
     
    Last edited: Dec 4, 2021 at 2:23 PM
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.