The Passinwind Open Source Preamp

Discussion in 'Pickups & Electronics [BG]' started by Passinwind, Dec 25, 2016.


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  1. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Yep, by about an order of magnitude I'd say. Waiting on the second vendor's quote but I've already gone ahead with the first option in any case.
     
  2. Hmmm...
    mages?q=tbn:ANd9GcQYcoJEwzcxOIXUQS3uHRZr0aQsGYQnzTP1TN4AF5pwIuIjV5-ZX7mhInO8MT9r2e7tXyc&usqp=CAU.jpg
     
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  3. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    The idea was to extend the stock 6mm mounting bushings so I could use the Taydas in a back routed install. I just superglued on the lamp tube pieces and voila, a 3/8" by 3/8" bushing!

    So last weekend I got to hear four different bassists playing a passive P-J bass through my new stompbox and learn about how it interacted with an old school sounding Ampeg rig. And then tonight I got to test my Marco fiver with the just finished newest three bander, which sweeps from 432-10.6KHz. The pot bushing hack worked great and the new mods I'm trying seem promising, so it's been a good couple of days all in all.
     
  4. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Update:

    Today I decided to take a flyer on trying a test build of the low tuned one for per-pickup applications. I've now depleted all my standalone LPF circuit boards and quite a few other important parts, and I had to wing it with a few components that will eventualy get replaced, but it works just as modeled and appears to be pretty stable. I went with a sweep from 40-1.4KHz @ ~14dB max boost for this test but many other potentially useful tunings are possible. I'll have a quick listen later today and then I will decide on the default build spec for the higher tuned one and finish up the bill of materials. If anyone has already ordered the main board at OSHpark it'll work fine, but I'll likely do a few very minor refinements related to the cabling before I move along to other things for a while. I actually need to get going on NAMM stuff already...sheesh! Some of this recent work may easily show up there in some form anyway, so it's all good.

    I'm really happy with how this week's bass install came out after another test session last night and I think I'm going to have to find another test bed so I can live with this one as-is for a while. I'll do some kind of rudimentary demo recording soon, maybe even a video. I 'm especially sucktastic on fretted bass, but so it goes.:cool:
     
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  5. Great to hear of the successes! I would definitely like to hear some sound clips or a video.

    You and I appear to have complementary sucktasticness as I'm sucktastic on a fretless! I am in the process of building my first fretless now so hopefully someday I can work on improving that.
     
    Passinwind likes this.
  6. Reviving a many year old post, but how did that work. Years ago I tried my hand at that circuit to be built in my bass but didn't succeed. I recently decided to take up pedal building and looking to try that one again.
     
  7. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Here are the frequency response curves for the default tuning of the new standalone LPF board:

    PW23BOS_defcurves.PNG

    Those who would prefer 835Hz-9KHz can just substitute a 20K dual reverse audio pot for the standard 50K one. I've bumped up max gain by another half dB or so and we're now at just under +15dB at max resonance.

    With that settled I've done up the Mouser BOM, which comes in at under $18 before shipping. Had to do a number of component subs and we all may have to be a little fluid about that for a while. I don't see any real meaningful compromises so far though, FWIW. I'll put up the BOM link later today, and then the schematic could take me another few days to clean up properly.

    As it presently stands DIY builders will need to do three orders:

    OSHpark: main PCB and two (optional) pot breakout boards
    Tayda: 20K and 50K reverse audio dual pots, 9V battery clip and/or power supply jack as needed
    Mouser: all other components

    OSH ships free, Tayda is only a couple of bucks, and I usually go with FedEx Two Day as the best bang for buck option with Mouser. I figure that right around $50 should probably get it all done, save whatever enclosure you may want to use. And if you build two or three the price per board will come down a bunch.
     
    Last edited: Jul 26, 2021
  8. A9X

    A9X

    Dec 27, 2003
    Australia
    Looks good PW. Excellent work.
     
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  9. The collars just reminded me of the old Bazooka Joe comics' character, that's all; don't know why, but the cartoon image popped in my head immediately upon seeing the pot-collars. Turtlenecks on pots...

    MLvG0Reb-wQOQ5tT0IcDEr5RuuDeCSJmgvkvbmCmToY.jpg


    Passinwind, inventor of the potentiotacticollar...

    Thank you for your gifts to the DIY community.
     
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  10. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Update:

    A temporary working schematic for the standalone LPF board is now available for early builders via PM. A few things may still change due to parts availability issues, but everything on the Mouser BOM shows as being in stock as of this morning.
     
  11. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Update:

    A few builders have contacted me about doing per-pickup filter builds and this will be my primary focus for a while now. I've decided that I can probably come up with a better mixing/blending solution than the one I was originally going with, one big potential improvement being lower current draw due to lower active parts count. I think I have just enough parts on hand to do a proof of concept build this week, and if that pans out I already have a full board layout done. If any of you guys get antsy PM me and we can explore breadbaording a temp (or even permanent) solution. The new mixer board is likely to come in at ~1.2" by 1.0", and I again did away with all the pesky SMD film caps to make fpr a much more DIy friendly build.

    And then for those who want to stick with the original Bass/Mids/LPF format, I've worked up a new two band B/M board layout. Same deal, SO-8 opamps and 1206 resistors with all through hole caps. Size looks to be identical to the standalone LPF board, wonder how that happened? ;)
     
  12. mdalamond

    mdalamond Supporting Member

    Feb 26, 2012
    SE , North Carolina
    i have built the PW3B V1 and it works and sounds great except.... I have Quarter pounders in my passive P bass and they are hot.Im getting break up with the bass pot maxed. I read earlier in the posts that R3 and R4 should be adjusted to bring the input gain down. I tried 2k for R4 and 12k1 for R3 but it didnt change. I also read about changing R11 and R14. Before I go desoldering and swapping can you tell me which ones I should be swapping. I did socket R3 and R4 but not R11 and R14. Not a big deal I can put sockets in .
    I do not have a volume pot before or after the circuit as I am just bench testing right now. Im just using the volume on the bass for the time being. If I turn it down all is good, thats why Im thinking the pick ups are to hot. Do you have any suggestions? Oh and I will be putting this in a box. Thanks for everything,
    Matt
     
  13. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Hey Matt,

    It'd be nice to use a scope if possible and verify if the clipping is in the first or second stage so we can attack the problem at the source. If you've already changed R3 and R4 with no joy the next logical place to cut first stage gain is right on the input with a series resistor in front of the preamp input. Something between 47K and 220K is probably where I'd start. R11 and R14 are going to influence gain at high resonance settings, but at frequencies well above the bass range. You can try changing R8 to 82K-100K ohms, which will primarily cut low midrange content at high bass boost settings in the 200-400Hz range, or R6 and R10 can be bumped up to 20K-22K to cut the max bass boost anount while moving the bass peaking frequency down a bit.

    And of course just lowering the pickup may be all that's needed as well. Best of luck!
     
    Andyman001 likes this.
  14. mdalamond

    mdalamond Supporting Member

    Feb 26, 2012
    SE , North Carolina
    Thank you for your reply. I do have a scope , a very old one. Unfortunately I haven't learned how to use it yet. It has a lot of knobs and dials,lol. I think I will try the pick up height first. Everyone else seems to have had great success so I know it is something on my end. I really like the bass and mid freqs so I don't want to alter that in anyway if possible. I was thinking of maybe using a trim pot inside the box before the input. I did try it with my Fender AM Pro with stock P/Ups and it was significantly better. Almost non existent.
    I need to see if I can find an online manual for my scope and learn how to use it. Thanks again.
     
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  15. mdalamond

    mdalamond Supporting Member

    Feb 26, 2012
    SE , North Carolina
    Tectronix 475 to be precise.
     
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  16. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Nice, and not nearly as old as the 500 Series Tek tube scope I started with and used for quite a few years.

    It figures that I just retired my 4 1/2 year old demo/test box, which I had been keeping around for just this sort of eventuality. ;)
     
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  17. mdalamond

    mdalamond Supporting Member

    Feb 26, 2012
    SE , North Carolina
    I have managed to find a couple of manuals online though I don't have a clue on where to start. I guess I will start with reading. Lol
     
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  18. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    I'd suggest starting with basic calibration with one channel. Once you get that done you will (hopefully) just have to adjust the level and time base controls and you should be good to go.
     
  19. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    I've been casting about for some wood pointer knobs with hopefully a little bit of the Alembic vibe for my singlecut and stumbled upon these on Etsy:

    Pick_Knobs.PNG


    I only really wanted two and asked the vendor if he'd be willing to split any of his similar quartets and bump the price to around what pairs usually go for. This batch looked the least labor intensive so out of respect I suggested splitting that one. So of course we ended up striking a nice deal for all four...LOL!

    I think these will make it a lot easier to suss the filter settings on a dark stage, or even in my living room.
     
  20. mdalamond

    mdalamond Supporting Member

    Feb 26, 2012
    SE , North Carolina
    Very nice looking knobs. Do they have brass inserts in them?
     
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  21. Primary

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    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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