The Passinwind Open Source Preamp

[Passinwind]

At the moment, I am upgrading a friend's old Carvin fretless. Looks like we're going to change the bridge to Hipshot with Ghost piezo saddles, Tone Capsule Preamp, EMG Active Balance Control, GraphTech Acousti-Phonic preamp, 18 v source. His is a lineless fretless, beautiful bass. I want it to sound at least as good as it looks. I have an almost identical Carvin fretless that I did the exact same thing to.

Way cool. I did a 3 band preamp for a friend's Warmoth fretless Jazz Bass build earlier this year, it came out really well. Helps that I've been nearly fretless-only myself for close to 50 years by now. As much as he loves the preamp, he still raves more about the setup I put on it.

 

[Tassieviking]

If I used a 9v battery on top of the 2 pots I can fit a 100mm x 35mm PCB in the Yamaha
If I changed the input jack to a pot and relocated the jack to the edge I can get 3 pots in, no change to the holes in the front of body. I am not a big fan of the cable coming out from the front next to the knobs so I might change it anyway.
This bass needs to be sanded down and redone, someone gave it to my daughter for free. (Tipfind apparently)
The neck is nice and it will go in for a full setup and new strings soon.

 

[dcoyle]

CE, That looks useful. Might the preampbuffer/gain board be available, someday?

 

[Passinwind]

CE, That looks useful. Might the preampbuffer/gain board be available, someday?

Yep, it's already slated for the Github repository as an official option. I should probably at least listen to it first though! I might do a two channel one on a single board too, I reckon.

If I used a 9v battery on top of the 2 pots I can fit a 100mm x 35mm PCB in the Yamaha
If I changed the input jack to a pot and relocated the jack to the edge I can get 3 pots in, no change to the holes in the front of body. I am not a big fan of the cable coming out from the front next to the knobs so I might change it anyway.
This bass needs to be sanded down and redone, someone gave it to my daughter for free. (Tipfind apparently)
The neck is nice and it will go in for a full setup and new strings soon.

I've done Jazz Basses that way, let me think about this a little. I do have a legacy pot-mounted two band board design kicking around that uses a concentric tone pot, that may be the best option.

 

[Tassieviking]

Charlie, if I need to make the hole bigger its no problem, I have 2 routers and I know how to turn them on.
Plastic covering material is easy to come by, I think I have some from when I made my Les Paul copy guitar.

 

[dcoyle]

I might do a two channel one on a single board too, I reckon.

I hope you reckon right.

 

[Passinwind]

I hope you reckon right.

Two of the single ones fit in the same matchbox as the older (v1) HPF does, FWIW:

 

[dcoyle]

That's a small total package. Each individual board is small enough to fit, on edge, in a Jbass rout, I believe. And each IC is locally decoupled from the power supply demands of the other with mono boards. And they're already built.

 

[AudioTaper]

That 2-band (B/M) would have fit nicely in my J bass control cavity if I wasn't crazy enough to put so many push/pull pots on it...

 

[Passinwind]

That 2-band (B/M) would have fit nicely in my J bass control cavity if I wasn't crazy enough to put so many push/pull pots on it... View attachment 5205162

Yep, that’s a lot o’ switches, plus that version’s a little bigger than the current OS one.

 

[Passinwind]

Update:

Mouser BOMs are up for the v4 boards on GitHub now, so on to the pots, switches, jacks, enclosure, etc. next. A lot of that stuff is going to come down to individual builder preference, but I want to make sure we at least have the basics covered decently.

Also, it looks like another NAMM trip is pretty likely. Not sure exactly what form my involvement may take this time around, but I'm hoping to have at least a few v2 and V4 pedals in booths where they will actually be easily accessible and not an afterthought. A lot of the usual suspects have been biding their time on booking, but January isn't all that far away! I'm sure there will be a few legacy onboard installs at the Marco Bass booth, and maybe one or two new ones if things go right. But I've mostly moved on to pedals for now, and also to other applications than just bass guitar, so...

 

[Passinwind]

Heads up: the old project Wiki here on TB has been removed, as it was just too cumbersome to edit and had way too many dead pages. I'll put up a simple one to link to GitHub and this thread, and eventually put all the legacy info for the now obsolete V1 on GitHub for posterity.

The new simple gain board works great with the piezo in my dojo and should be a pretty useful general purpose buffering module as well. I'll try a lower current opamp next, with battery powered applications in mind.

 

[bowthing]

The new simple gain board works great with the piezo in my dojo and should be a pretty useful general purpose buffering module as well. I'll try a lower current opamp next, with battery powered applications in mind.

The new OPA205 is pretty sweet, though a bit more expensive and hard to get than the usual suspects...

 

[Passinwind]

The new OPA205 is pretty sweet, though a bit more expensive and hard to get than the usual suspects...

On my radar, I still have several OPA207 on hand to work through first though. I’m used to spending up to $10-15 a pop, so all good.

 

[Dadum]

On my radar, I still have several OPA207 on hand to work through first though. I’m used to spending up to $10-15 a pop, so all good.

Is there a preferred (excellent performance but cheaper) Op Amp when using a pedal version with a plug-in power supply?

 

[Passinwind]

Is there a preferred (excellent performance but cheaper) Op Amp when using a pedal version with a plug-in power supply?

Yep, OPA1641 and OPA1642 are my current favorites and are now spec’ed for all the v4 boards.

 

[MuseChaser]

I admit I haven't read this entire thread, so if the answer(s) to the following question(s) is contained therein, please just say so and accept my apologies.

I recently acquired a Peavey Grind 5 string, passive electronics, and the PO had replaced the original pots w CTS pots and rewired the controls from the original vol/vol/tone/tone to vol/tone/PUblend, leaving the fourth pot an unused dummy.

I've built a ton of amps and preamps from kits, and most recently did a full update and repop of a Dynaco SCA80Q I built back in the early 80s... I love to solder and build stuff, but don't have any design experience other than a bunch of scratch built speakers for home audio and theater. And... I know next to nothing about pickups, bass preamps, and electric bass electronics in general.

I'd love to build something that would improve the sound of this Peavey, just for fun, although I'm not unhappy with it as is. Would this project be a good one to implement, and if so, what version would you recommend? The link to the Wiki in the original post doesn't work any more,.. not sure where to go..?

Thanks!

 

[Jeff Siddall]

The new OPA205 is pretty sweet, though a bit more expensive and hard to get than the usual suspects...

Thanks for this tip! I hadn't noticed they had started making the OPAx205 in SOIC. Looks like they are about $12-$14 CAD for the 2205 so... yeah, more than "a bit" more expensive.

 

[Passinwind]

I admit I haven't read this entire thread, so if the answer(s) to the following question(s) is contained therein, please just say so and accept my apologies.

I recently acquired a Peavey Grind 5 string, passive electronics, and the PO had replaced the original pots w CTS pots and rewired the controls from the original vol/vol/tone/tone to vol/tone/PUblend, leaving the fourth pot an unused dummy.

I've built a ton of amps and preamps from kits, and most recently did a full update and repop of a Dynaco SCA80Q I built back in the early 80s... I love to solder and build stuff, but don't have any design experience other than a bunch of scratch built speakers for home audio and theater. And... I know next to nothing about pickups, bass preamps, and electric bass electronics in general.

I'd love to build something that would improve the sound if this Peavey, just for fun, although I'm not unhappy with it as is. Would this project be a good one to implement, and if so, what version would you recommend? The link to the Wiki in the original post doesn't work any more,.. not sure where to go..?

Thanks!

This whole project has morphed into pretty much just a pedal thing for the moment, which the new Wiki will reflect in short order. It's an ongoing huge hassle to source good quality dual reverse log pots that will fit in back-routed basses, so if you just have to have an onboard filter preamp I'd recommend buying one of the usual commercial suspects.

As far as pedals, v4 is the only design ready to go at this time: https://www.talkbass.com/threads/the-passinwind-open-source-preamp.1259692/ . I still have to post a block diagram, build tips, and so on, all of which I'm currently working on.

 

[bowthing]

Thanks for this tip! I hadn't noticed they had started making the OPAx205 in SOIC. Looks like they are about $12-$14 CAD for the 2205 so... yeah, more than "a bit" more expensive.

They are $3 US for VSSOP and $8.50 for SOIC from TI. I'm guessing the SOIC will come down, seems its the newest one.