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
    I just posted some new graphs of the Bass and Mid control responses in the Wiki Tech section. I have the one in my Crescent Moon bass set at 800-1600-2400, and the silver box is at 400-800 right now, but those guts are going into one of the NAMM boxes and I haven't decided what freqs to set each box at yet. They'll be different from each other for sure though, since getting lots of user feedback is my main reason for going to the show.

    I'm only switching the parallel cap in the mid circuit, so Q and gain change quite a bit across that range. That's actually a bonus in some ways IME, since there's more energy in the bass signal at the lower frequencies and big boosts down there often tend to sound bad. With a standard DPDT on-on or on-off-on switch instead of a DPDT on-on-on one we could switch the series cap too, opening up many other possibilities, which I will eventually cover in the Wiki's Mods section. I also like the on-on-on format because the operation is linear going from lowest to highest mid center freq.
     
    Last edited: Jan 6, 2017
    b-b-b-bass likes this.
  2. considering how popular the Darkglass stuff has been, and their upper mid center freqs, I would think 800-1200-1600 would be pretty spot on. Well, accept for the guys who like the "boxey" mid freqs....
     
  3. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Yep, those work well with the old one and many other commercial preamps. But with all the potential interactivity inherent with lower range frequency settings of the LPF section, it's kind of a new world here. OTOH some people may want to be able to cut those 'boxey' frequencies too. And then there are the fretless-only kooks like myself to consider too... Or_wink.gif
     
    Marial likes this.
  4. My feeling is almost every bass amp has a mid EQ near 500hz. They almost never have one at 1200hz. Plus, if the bass itself is "boxey" you can just boost the lows to compensate.
     
  5. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    I hear you, and I use my 1600Hz setting quite a bit. A big part of my whole thing is trying not to duplicate control functions when there might be some better use for that hole.
     
    Last edited: Jan 6, 2017
  6. rufus.K

    rufus.K

    Oct 18, 2015
    SoCal
    Thanks for the pics of the box. I think I'll go that way when I pull the trigger.
     
    Passinwind likes this.
  7. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    One nice thing about using a box is that you can get away with much cheaper pots that probably won't fit in a lot of basses due to the short-ish mounting bushings. I'll be asking the community at large to keep their eyes open for dual gang 5K and 10K linear pots with bushings that are longer than the often seen 5-6mm ones. I could also use more feedback on how many instruments those shorter ones do fit in OK as well.
     
    tombowlus, rufus.K and Marial like this.
  8. rufus.K

    rufus.K

    Oct 18, 2015
    SoCal
    This may be a tangent, but here i go...

    As my hamster wheel turns, and I think about going outboard, I see me wanting 2 things.
    I'd like to put a power supply in the box, or the option for plug in and battery. I can handle that.

    I'd like to add a defeatable driver after the output to bring the level up to drive a power amp directly, and of course share the power supply. What are your thoughts on this?
     
  9. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    It'd be way cool if someone else took on designing that part, but I am going to need to do that for other purposes eventually anyway. The slick deal would be to port my design to bipolar power supply config and then build in a 9V-->+/- 15V converter circuit, which is more or less a single chip solution these days. At that point you can readily get around 10 volts RMS output, dead clean. I could do all that, but I'll have to think about how far I want to take the open source aspect of all this. For right now I think my hands are pretty full already. Yel_wink.gif
     
    rufus.K likes this.
  10. ahc

    ahc

    Jul 31, 2009
    No. Virginia
    Total neophyte when it comes to this stuff but I keep reading because I might learn something, even at 66. Can someone briefly explain what resonance is/does? Keep in mind you're explaining to oh... maybe a 5 year old. Thanks!
     
    Obese Chess likes this.
  11. rufus.K

    rufus.K

    Oct 18, 2015
    SoCal
    Well, I may explore that when I start.:bookworm:
     
  12. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    I'm 63 and I still learn something new nearly every day. Try working through this article and then get back to us with any questions or observations: BuildYourGuitar.com :: The Secrets of Electric Guitar Pickups.
     
    Last edited: Jan 6, 2017
    Obese Chess likes this.
  13. ahc

    ahc

    Jul 31, 2009
    No. Virginia
    Thanks Charlie! I promise I'll do my homework after I get some sleep.
     
    joover likes this.
  14. vbchaos

    vbchaos

    Sep 5, 2011
    Groningen, The Netherlands
    Uncompensated endorsing user: fEARful
    HaHa, I guess so :) It was nor really difficult to build, but putting it into the cavity of the bass without causing at least 5 short-circuits was hard.

    Nope, unfortunately not. And since I have the dingwall I have flats on the ibanez again, so the comparison is somewhat compromised. But with a new build there will be new sound samples

    The mids were the main reason for a different preamp in the first place. Usually preamps have the mids at 800 Hz nowadays, and I so hate that frequency on basses. Just not my cup of tea. I have the mids on this preamp at 1200 Hz and like it. It even flattens out a dead-spot on the finger board :)

    Charlie, would it be possible to add a mid-frequency switch which differs between several different caps on the mid-pot without having switching-noise or any other kind of trouble from it? That idea just popped up last night
     
  15. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    I posted the switching arrangement I've been using in my Crescent Moon bass on the Wiki Mods page. It sometimes pops just a little, more like a click really. Not enough to bother me, but YYMV. I've just posted a starter spreadsheet example showing mid center frequencies for various cap values. I'll flesh it out more later as time allows (hah!).
     
    Last edited: Jan 7, 2017
    Freekmagnet likes this.
  16. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    I use Nomex sheet cut to size as an insulator, works great.
     
  17. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    If that article makes your head hurt too much I'll look for something more basic. That one is pretty well written though, and I'd like to show some love to the people who developed prior art.

    Speaking of which, there's some good info in this thread: Variable Resonance Pickups - Fun with Buffers.
     
    ahc likes this.
  18. ahc

    ahc

    Jul 31, 2009
    No. Virginia
    OK Charlie. First part of my homework is done. The Helmuth Lemme article answered my question though I'll probably need to reread it another time or three. I glossed over the Variable Resonance Pickups thread but I'll read that in the next day or so. Thanks again. I appreciate the info! Now I might have a small clue as to what you brainiacs are talking about.
     
    Passinwind likes this.
  19. Passinwind

    Passinwind I know nothing. Commercial User

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

    Updated PCB component footprints and graphics to enhance ease of build; pot terminal references now meet typical industry standards and I upped the pad hole clearances slightly to accommodate a wider variety of hookup wire. Since so many DIY'ers use basic hand strippers and soldering rigs, that seemed like the right thing to do. 22AWG multistrand will still be a somewhat tight fit (by intention), but pre-tinned wires should now be a little easier to insert.

    PW3BLPF_OS_demosize.png

    Arranged for three beta test builders, at least two of whom will be using the latest board revision.

    Updated Mid Shift spreadsheet to three complete sets of component options.

    I'll probably move along to making a more user friendly LTspice model next, unless anyone has more pressing needs.
     
    Last edited: Jan 9, 2017
    S-Bigbottom, Marial and rufus.K like this.
  20. How fast do you think one of these could reasonably shipped? I'm leaving very soon and either order now or in five months or so at the earliest.
     
  21. Primary

    Primary TB Assistant

    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.

     
    Jul 29, 2021

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