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
    Not fast enough for your purposes. If I ordered parts today, assuming none on hand, it would take me around 3-4 weeks to get one built. No one else has even started that process yet, and there are bound to be gotchas for early adopters. That's why I'm starting with very experienced test builders, but most of those guys have busy lives and many other priorities. I'm hoping that by about two months from now the whole process will be well vetted and relatively painless for experienced DIY'ers. No ETA on eventual availability of assembled ones, since that's not what this project is about from my point of view. Yel_wink.gif
     
  2. Thanks for the answer, I'll just follow the thread and check in when I can then :)

    Whatever happens, happens, and I'm looking forward to the results.
     
  3. That new board looks great! Did you say it's physically smaller than the DLX?
    I had no problem fitting that in, but my cavity areas usually have plenty of room.
    Dirk
     
  4. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Yep, about 1/4" narrower, but still not exactly tiny. From top: DLX, LPF, MM2B (Uncle Fluffy redux):

    Onboard_Preamps_Dec2016.jpg
     
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  5. SeanOnBass

    SeanOnBass

    Oct 23, 2005
    Seattle
    Endorsing Artist: MTD Basses, Bartolini, Genzler Amplification, GHS, Tsunami Cables, Sonic Nuance
    I've been meaning to post in this thread for quite a while now. Thanks for this, Charlie! It's a great service to the community.
    I'm very curious about filter based preamps, having never tried one, and I wonder if this active filter w/ adjustable resonant peak on this one would be a good way to tame some of the active pickups I use, and go further to "tune" them a bit more with an actual resonant peak (most of the actives I've used tend not to have a big peak at their resonant freq., but a gradual dropoff that extends much higher than many passives and can lead to the brittle thing that many don't like from actives). I'm pretty interested to try.
     
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  6. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Hey Sean, you'll get your chance soon enough!

    But to answer your question: yes, this preamp should work really well with active pickups. It would be possible to reduce the already low-ish input impedance of my design even further, which can potentially reduce the noise floor a bit more. It should also work well with low impedance passive pickups, which is something Marco Cortes and I intend to work on after NAMM.

    I personally really like a very extended high end for my fretless basses, but IMO and IME everything in the signal chain needs to be carefully optimized in order to make it sound sweet rather than harsh. That's a big part of why I bother to build my own amps, which is certainly not the most sensible thing to do unless you have some really compelling reason. I hope you can find time at the show to check out how I did active/passive switching on my amp, as one of the main design goals was to kill brittleness when using active basses. If we can get there by just using the right onboard preamp, all the better.
     
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  7. SeanOnBass

    SeanOnBass

    Oct 23, 2005
    Seattle
    Endorsing Artist: MTD Basses, Bartolini, Genzler Amplification, GHS, Tsunami Cables, Sonic Nuance
    Sounds great to me. I'll be at your booth for sure. Although I'm bringing a passive pickup equipped bass, it still has quite a bit of super high end with its dual coils on parallel and i can defeat my onboard pre - it'll be really cool to see if I can sculpt the timbre enough to approximate a different coil configuration or at least a different pickup type.
     
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  8. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Likewise, of course. It's a long walk, what, 40-50 feet? Or_wink.gif
     
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  9. I just like the LPF for the high end. To me, a gradual drop off sounds so much more natural than the huge null in the low treble most OBP's have from cutting their fixed center freq.
     
  10. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Probably my last update for about ten days since I have to ship everything out tomorrow morning and won't get my hands on any of it again until late next week. I got a chance to audition two pretty different build specs today, one with the v1 board and the next one with v2. All the mid centers are different from build to build, bass hinge points are different, and the treble sweep ranges and max peak amounts are also different. Both sounded fine and the final suggested starting spec will depend a lot on whatever the NAMM consensus turns out to be. As usual, there were a lot of unforeseen complications, so I'm glad I held off on setting anyone else up for test builds just yet. Here's how candidate #1 came out, which has mid shift frequency centers at 600/840/1.28KHz:

    NAMMstomp1.jpg

    The other stompbox is set up for 740/1.1K/1.66KHz at the moment. Both of these builds are using the inexpensive Alpha pots available at places like Tayda for a buck or less apiece. The one going into a really high end bass for the show uses much more expensive Bourns box pots that will fit in a lot more basses, so we'll see how much if any difference that makes.
     
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  11. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Just got this video from my buddy Marco, looks like he managed to do the preamp install in his personal bass and shot a quick clip:



    So that's three different build specs for people to try so far, but I'll probably bring along at least one or two more. Yel_wink.gif
     
  12. Marco's hair is off the chain!
     
  13. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    At least he still has some. Pretty sure that something close to an all nighter was involved. So much work goes into exhibiting at NAMM, even for something as humble as my little demo thing. I've been snowed in and could never manage to get over there to help out, but c'est la vie.
     
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  14. Any news now that NAMM is over?
     
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  15. I am just curious how close the PW3-LPF is to the traditional passive tone control SOUND wise. Since the passive uses the pickup's resonance, and the PW3-LPF tries to negate the pickups resonance effect, is there any pickup timbre difference? Is there a way to model a pickup (a signal source into a resonance circuit?) and compare the two in LTSpice?

    This all comes about because it seems the tones I really like best come from the Pope pre with a passive tone control, or from some other mixture of a passive tone control and an active circuit. Or, i guess, just passive basses, too.

    The pickups I have, or the ones I might swap to, are both lower output due to their hum cancelling configuration, so they really benefit from a preamp. Plus, I just like the flexibility of a preamp. Otherwise I would probably just run passive.
     
    Last edited: Jan 27, 2017
    gregmon79 likes this.
  16. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Only a handful of people tried any of the three preamps I brought along. Most of what the treble section does was completely lost in the din anyway though. The booth they were in was exceptionally busy, and the amp I had in there was in use virtually every minute of all four days, which figures, since it's not for sale and I don't plan on making any more. I'm probably going to send one box to Seattle and one to the east coast. I would be happy to put you on the list, and you can tell me what you think. Yel_wink.gif

    It's not close at all to a passive control the way I use it, more like a more subtle take on the Alembic thing. I've barely even tried cut mode though, I pretty much always boost treble fairly substantially. In all honesty, I haven't owned a passive bass in about 30 years, save one brief interlude when the onboard preamp croaked in my Travis Bean. I have done a bit of Spice modeling of pickup/amp interaction, but that only shows a rudimentary approximation of actual frequency response. Besides which, every pickup is different and my models don't account for pickup location at all. Recording before and after clips seems like the best bet to me. I'm working on getting a nice fretted bass that could be run passive, but until that happens I think things are effectively stalled for now. Hopefully I can it back on track in within a couple of weeks, but NAMM really took a lot out of me and the awful weather here has created a monstrous domestic chore list.
     
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  17. 40Hz

    40Hz Supporting Member

    A post mortem on your NAMM experience as an indy builder/exhibitor could be a worthwhile read for any aspiring music gear builder/inventor here. If you have the time, a thread about that would be pretty cool. It's not too often you can hear about the whole NAMM exhibitor thing directly from the mouth of somebody who's actually done it.
     
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  18. Marial

    Marial weapons-grade plum

    Apr 8, 2011
    Having visited Portland recently I can attest to how monumentally challenging the conditions have been down that way.

    Good on you for making it at all, Charlie!
     
  19. We have friends in Cascade Locks and I saw the pictures from Damien Erskine. You guys got HAMMERED!
     
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  20. Is there a way to add a tone control. Like do a volume volume tone then into the pre?
     
  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 28, 2021

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