Help with my Supro 1624t clone

Discussion in 'Shock Brother's DIY Amps' started by Prophetsnake, Mar 4, 2020.

  1. Prophetsnake

    Prophetsnake Tele-Meister Silver Supporter

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    Yes, I used that schematic as well as the one I posted. I found the info I found on this amp a bit jumbled, so I studied quite a few plans before I built it. In fact I have a 470 ohm cathode resistor and that has the bias at about 14 Watts, IIRC.
    What stood out to me at the time and what still does are the very small coupling caps. I'd only built tweed like contraptions before this. But I have since seen that Fender went to .005 caps with their blackface amps.

    I really expected there to be a huge difference between the inputs' tone, and I expected both of the inputs on the top there to be wild. The difference is relatively small and my problem exists on all four jacks.

    I'm thinking the thing to do is to try your suggestion with the ceramic coupling caps, and go from there. If that doesn't work, then maybe just increasing the value of all the coupling caps to say .022 and maybe changing the tone pot around a bit.
    But one thing at a time. I'll order a set of ceramic caps and try that first.
     
  2. Prophetsnake

    Prophetsnake Tele-Meister Silver Supporter

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    As close to original as I could. I think the only mods were things like grid stoppers and maybe diodes on the rectifier tube, that sort of thing.
    Also, I used a single tone knob. the earlier versions of this amp did.
    I believe I have the inputs done correctly, but it's certainly worth having a look.
     
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  3. D'tar

    D'tar Friend of Leo's

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    That surely looks better to my eyes. I'd love to see some photos of your build prophetsnake and especially the input section. I would think you should hear a difference between channels one with bypass cap and the other without.
     
  4. Badside

    Badside Tele-Meister

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    Wait... 470? That's quite high. Do you mean 14 watts per tube, or 14 watts total.

    Cathode resistor should be around 250-270 (I used 270 in mine). The 14 watts max is per tube, so times 2 (+5% for screens).
     
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  5. Badside

    Badside Tele-Meister

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    For reference, I was able to find the recording of mine before I Blackfaced it. I lost the video that goes along with the sound but it's the sound that matters.

    Note that mine had the grid leak bias 1st channel of the earlier models, but coupled with the improved tremolo and PI of the later models (same as what you have if I'm not mistaken). I did not bother with the weird input scheme though.
    The schematic is visible so you can compare.

    The grid leak channel is the only one where I used ceramic coupling capacitors.

    This is in a small open-back pine cabinet with a WGS Reaper HP speaker.

    At around 9 minutes I switch to the grid leak channel (first 9 minutes are the trem channel, with some pedals), and at around 12 I mix them together.



    I should mention, the guitar used is a highly modified Squier Classic Vibe Telecaster with a Seymour Duncan Custom 59 Hybrid humbucker at the bridge, and a Tonerider P90 in at neck, also the neck is a Fender Standard Telecaster neck MIM.
     
    Last edited: Mar 4, 2020
  6. Prophetsnake

    Prophetsnake Tele-Meister Silver Supporter

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    Per tube. With a 270 in place each tube was up around 18 watts if I remember rightly. I initially put 6CZ5 tubes I bought cheap in it until I was sure it was all stable so I didn't fry my NOS 6973s, and the amp sounds exactly the same with either tube installed, and the bias was almost exactly the same.
     
  7. Nickfl

    Nickfl Tele-Afflicted

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    Did you make sure you don't have an micorphonic components? I'd tap with a chopstick and make sure none of the tubes or caps are microphonic and also make double and triple sure you don't have any bad solder joints, those usually mainifest as intermittent static but could also create some of the sounds you are describing and there is a bit of fizzy character to the overdrive at the end of your clip that reminds me of issues I've had that ended up being caused by the end of a lead breaking loose inside of what turned out to be a cold solder joint.
     
  8. Prophetsnake

    Prophetsnake Tele-Meister Silver Supporter

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    Thanks Nick. I have done that, but I should probably do it again. Maybe get in with a magnifying glass and re-flow any suspect joints. I've swapped tubes around and it doesn't seem to be any of those, but it's certainly worth a shot. Fizzy is a good description of what's going on with it, alright.
     
  9. Prophetsnake

    Prophetsnake Tele-Meister Silver Supporter

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    A few pics of my build.
     

    Attached Files:

  10. Prophetsnake

    Prophetsnake Tele-Meister Silver Supporter

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    Nice playing!
    That has a very similar quality to mine, I think, so maybe I didn't get it too wrong after all. I'll try the caps and see what happens there, and maybe tinker with some of the inputs and decide if it is something I want to live with or?
    Thanks for digging that out for me and for the very useful advice
     
  11. Badside

    Badside Tele-Meister

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    Curious what kind of voltages you're getting? Mine had 330V on the plate (actually, voltages are listed on the schematic in the video). And I did add a shared screen resistor which the original didn't have, albeit just a 100R
     
  12. Prophetsnake

    Prophetsnake Tele-Meister Silver Supporter

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    About 340 on the plates, which I reckoned was pretty close to perfect. The PT is an Edcor I had custom made. I'm on 230V and there wasn't anything off the shelf that I could find for reasonable money. I checked all of the voltages when I built it and they were all spot on.
     
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