The Passinwind Open Source Preamp

[Passinwind]

Nice to see the plans finished! Will have to build one finally!

There are still a few details to attend to: UV print graphics and drill files for the footswitchable version, wiring diagrams for the mid switch and all the pots, something detailing overvoltage and/or reverse polarity protection, and some suggestions on insulating and mounting the individual modules. I’ll keep grinding when I can, but it’ll likely be at least a couple more weeks before I consider it done. And then I may eventually work on documenting the standalone iterations of each board, maybe one or two onboard formats, and a few small utility boards for buffering, mixing, and gain staging. But once v4 is truly done I intend to take a long break and I very well may never get to the rest, in all honesty.

 

[Jim C]

Thanks Charlie! I'm very happy with mine.
Sounds like no other EQ pedal I've ever tried.

 

[Passinwind]

Thanks Charlie! I'm very happy with mine.
Sounds like no other EQ pedal I've ever tried.

Thank you Jim. That v3 one you own has a little extra something something going on, for sure. And I'll always be grateful to you and the other small handful of people who I've done builds for, I never could have kept this whole thing going for so long otherwise.

 

[-Asdfgh-]

The biggest problem with onboard installs in many cases is the need for custom pots, which you would likely need to buy at least ten of. But they do come from the UK, at least.

I'm building them as externals. I don't have a bass I could reasonably squeeze one into without a great deal of routing I would not be confident with.

 

[Passinwind]

I'm building them as externals. I don't have a bass I could reasonably squeeze one into without a great deal of routing I would not be confident with.

Cool, I feel that's a much better way to go for that and many other reasons.

 

[Feral Feline]

Thank you Charlie.

In the truest sense — you are a gentleman and a scholar.

 

[-Asdfgh-]

Cool, I feel that's a much better way to go for that and many other reasons.

I have more basses than I have the appetite for building preamps. I have the parts for two as it's good to have a spare.

 

[BQFS]

I would like to build two of these units, one I want to give to a friend, and the other for myself, but have no SMT skills and am so busy with other projects that I don't know when I would have time to acquire the knowledge. So, I will just ask. If anyone is willing to do the assembly work, I would be willing to pay a reasonable amount of money for their services. Please PM me if you are able to help me out.

 

[Passinwind]

Update:

@AudioTaper is taking a stab at a few pedal builds, and as usual he found a few things in my documentation that needed cleaning up. That's been done and added on the Github repository now, and recently I've been revising the footswitchable pedal layout and graphics, which are pretty close to finished at this point. I've done a few more tweaks to my two filter onboard config, and that bass works great now and will be going away just after NAMM. I also did a new lower tuned onboard LPF board layout and expect the first testers to show up in about a week or so. I was able to0 eke out an 80Hz lowest tuning from the old board, but had to use polyester caps and a bit of an ugly parallel cap kludge to make it so. Now we'll be able to go back to tight tolerance polypro ones, with fine tuning via parallel caps being a much easier, neater proposition. The board got a little longer, but should still fit edge wise in most standard cavity routes if needed.

And now that the weather has finally relented a bit I can finally get back into my shop and put together the new all in one two filter pedal for my dojo this week:

Oh, and if any of you will be at NAMM drop by at the Sushi Box and/or Marco Bass booths and check out a few instruments featuring my onboard preamps if you are so inclined. I'm staying home this time around, as too many of my usual hang mates decided to bail for various reasons.

 

[BQFS]

Looking forward to building the pedal version with being able to footswitch it for on/bypass with leds to show on (green) and bypass (red). So when you wonder why you can't hear anything, the drummer can announce through the PA, hey that box that just fell off your amp has a red led.....

 

[dcoyle]

I used that bicolor arrangement, it let's you verify you have power at the box " when you wonder why you can't hear anything".

 

[Passinwind]

I used that bicolor arrangement, it let's you verify you have power at the box " when you wonder why you can't hear anything".

I might need to do a different daughtercard for the footswitch if bicolor LEDs are going to be in the mix. I despise LEDs in general though.

 

[BQFS]

At least a couple of us would like some indication of when the preamp is on vs. when it is off or in bypass mode. I am okay with just on (green) or bypass (red). Can't speak for anyone else though. I would settle for green only, lit while on, off while in bypass if that makes it easier.

 

[Passinwind]

At least a couple of us would like some indication of when the preamp is on vs. when it is off or in bypass mode. I am okay with just on (green) or bypass (red). Can't speak for anyone else though. I would settle for green only, lit while on, off while in bypass if that makes it easier.

That's how the current 3PDT footswitch daughtercard is configured, but not using the card and doing whatever instead via hardwiring is always an option.

 

[Feral Feline]

For pedalboards, as most pedals use a red LED for ON, then unless you mod all your pedals to have ON-LEDs to be a colour other than red, it can become challenging or confusing to have red LEDs indicate power to the pedal and an alternate colour for ON.
A few DIY pedals mixed with commercial pedals on a darkened stage...
"Is that pedal ON or just powered up... oh, it's one of my own builds..."
I suppose it's not so bad if you're a minimalist and have only 3 pedals.

When I first got into DIY I was going to adopt the red=power, green=on (or blue or amber or white or ...) for my entire pedalboard; I really liked the idea, but in the end it was just too much work to swap out all the red LEDs from my commercial pedals. I suppose the solution is to ditch all the commercial pedals and just have an all DIY board.


For an onboard bass-pre, I think I'll go red for power and BLUE for ON.

So... bicolour LEDs ... What's your preference? Common-anode or common-cathode?

 

[dcoyle]

I used red for power, blue for in circuit, worked fine, but the blue may not register as strongly to your eye. I have different R's in series to red and to blue leg.

 

[Tassieviking]

So... bicolour LEDs ... What's your preference? Common-anode or common-cathode

I used to use the ones from Tayda, Dual Led Stomp Switch. Many colours to choose from.
Invalid Link Removed

 

[Passinwind]

New LPF boards for lower tunings:

I ordered and paid for 4 and got 5 free ones thrown in, a new record for the DKred service. One or two bonus pieces seems to be pretty standard given the size boards I typically order from them, FWIW. Lots more options with parallel caps now too, regardless of the chosen frequency sweep range.

I also found a couple of hours to build up yet another new V2 tuning, which I will test tomorrow. I'd like to be able to at least hand @Tassieviking a more reliable tuning to jump start his project, and I do have some alternative layout ideas that may aid that as well.

 

[Sanj]

Spent a long but satisfying day on Sunday assembling these. Looks like I'll have two spare HPF boards if anyone is in need.

 

[Sanj]

Update:

@AudioTaper is taking a stab at a few pedal builds, and as usual he found a few things in my documentation that needed cleaning up. That's been done and added on the Github repository now

@Passinwind , I don't see any changes in the repository, am I looking in the wrong place?

Also, if using the larger mid-switch board, what is CH?

Thanks!