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  1. drew.spriggs

    Submini Wreck-ish SE Build

    12x7x2". Not socketing them - the footprint is pretty big so if they ever need to be replaced it won't be too bad Found my miter saw was busted, so a circ saw and speed square did the job! No finger joints, but there are some internal braces added that should be strong enough. Still needs a lot...
  2. drew.spriggs

    Tubes 102 - Intro to Power Supplies for Tube Circuits

    If you are designing from scratch, there is absolutely no reason to use a 555 these days - it's noisy and shockingly inefficient. Even if you were going to for some crazy reason, the IRF740 is a terrible choice as it's more expensive option than other MOSFET choices that have half the Rds or...
  3. drew.spriggs

    Submini Wreck-ish SE Build

    Nothing like some half-assed measurements to drill an enclosure from. Enclosure is a laser cut, CNC bent job from 1.5mm steel I had a friend whip up. If I was doing it again I'd probably use 1mm steel, but this will do the job. It looks like shit, but hammercoat covers all mistakes :ROFLMAO...
  4. drew.spriggs

    Submini Wreck-ish SE Build

    It's not finished yet. These are the inverter modules. They have a lot of input noise which can be solved with a good electrolytic, and their switching frequency is about 60khz so output noise isn't terrible. They do need mechanical isolation from any sensitive circuits.
  5. drew.spriggs

    Submini Wreck-ish SE Build

    Yep, but it's got onboard rectifier diodes so you can grab an unfiltered DC off of it
  6. drew.spriggs

    Submini Wreck-ish SE Build

    Probably. The carrier/amp boards are 125x75 and 150x75 in total, but if you wanted to compress it to a single board you could easily get there.
  7. drew.spriggs

    Submini Wreck-ish SE Build

    317 technically doesn't even require a heatsink with that dissipation and anything below a 40 degree ambient so I'm not too concerned. The matching was with a gain response, not frequency response - plate impedance/etc is all totally different so if you wanted it sound as identical as possible...
  8. drew.spriggs

    Submini Wreck-ish SE Build

    NTC/ICL info: wanted a better way to manage tube inrush, so grabbed a stack of ICL's when I did my last Mouser order. Some didn't have a hot resistance so needed to test them. Setting up some 20w resistors to get 900mA of draw through the heater circuit, I got the following info: ICL cold...
  9. drew.spriggs

    Submini Wreck-ish SE Build

    Howdy, Thought I'd document some of a build I'm doing here in case anybody is interested in how you approach making custom boards/etc for an amp. I've got a stack of submini tubes, and a guy has been harassing me about making him a mini Trainwreck-inspired head for a while. Decided to see what...
  10. drew.spriggs

    Circuits on AliExpress that are worth it

    Idles at 300v with ~6w or so of draw
  11. drew.spriggs

    Pedal/Amp-Specific Kicad Files

    G'day, Uploaded all my Kicad libraries into a .rar file - there's symbols linked to footprints linked to 3D models for just about everything you could ever need to build a pedal or amp. All basic parts have suitable fab house/CNC option for footprints, and have a much wider range of stuff than...
  12. drew.spriggs

    How Can I Bias a Push-Pull Fuzz?

    Make the 10k resistor to the power rail a 50k trimpot. Pro tip: you can also add a 1k pot between the power rail and the emitter of Q3 and you've got a nice little octave control pot.
  13. drew.spriggs

    Am I understanding RC filters correctly?

    It does, but it also forms a RC filter with adjacent components
  14. drew.spriggs

    Circuits on AliExpress that are worth it

    These are all from memory, so please consult the board/schematic before trusting anything I say. Remove the cap connected to the AC output to isolate it (should be C2, 22nf ceramic) Bridge B/C pads Drill a small hole in the D pad Connect C2 + 1/2w 470k resistor between B/D (massive noise...
  15. drew.spriggs

    Circuits on AliExpress that are worth it

    https://a.aliexpress.com/_mKX6pn1 With a little bit of finagling (and some much needed safety features added) these are a very compact, shockingly quiet HV supply for running tube preamps (and even power amps up to about 5w). I've been running them for a few years with zero failures
  16. drew.spriggs

    Notakliche Diode Option Question

    More signal out, which can change harmonics slightly as well as interact with any additional drive stages differently. We're talking like 0.2-0.3v of difference minimum needed before you'll notice anything, and even then having diodes with a different Fv knee is likely to make more of a...
  17. drew.spriggs

    Notakliche Diode Option Question

    You will not hear one iota of difference whatsoever. Use whatever looks coolest ;)
  18. drew.spriggs

    Soviet-ish Distortion+

    All done!
  19. drew.spriggs

    Damage from wrong charge pump IC

    They are fully interchangeable. Your issue is elsewhere in the circuit
  20. drew.spriggs

    Soviet-ish Distortion+

    Alright, TIL about input/output compensation networks. Output was easy - a small value cap from pin 5 to out. Tried a few values while I had a sig gen/scope on, and about 47pf everything seemed to come good - about 3x the output and much less noise than without it. For the input, most examples...
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