Enjoy the benefits of a premium membership!
Upgrade Account
-
TalkBass has been independent since 1998. Add your voice.
Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
Join free Log in
Want zero display ads or expanded classifieds tools? Compare plans.
The Passinwind Open Source Preamp
- Thread starter Passinwind
- Start date
- Dec 3, 2003
- 23,079
- 46,038
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
- Dec 3, 2003
- 23,079
- 46,038
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
There's a long thread on DIYAudio where the designer weighs in on various nuances between the 1656 and 1642 when used in various applications, I found it pretty interesting. Trying a few OPA1652 while I'm at it as well.
Just checked my OPA IC stash and do not have 1641, 1642, 1652, 1655, 1656...
Is this the correct link to the DIYAudio thread?
Choosing of best sounding OP AMPs for the lowest possible THD+N -really the best Way?
Is this the correct link to the DIYAudio thread?
Choosing of best sounding OP AMPs for the lowest possible THD+N -really the best Way?
- Dec 3, 2003
- 23,079
- 46,038
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
This is the one I was referring to, the OP is a TI engineer: OPA1656: High-Performance CMOS Audio Op Amp
- Dec 3, 2003
- 23,079
- 46,038
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
Ugghh, one of my two new OPA1656 chips was a dud, which I might not have caught without scope testing until much further into the pedal build process. I may have herked it with static discharge or it may have just been duff from the factory. But at least I was able to rework the board very quickly and try an OPA1642 in that build, which tests really well. And OPA1655/1656 looks great in the companion HPF board I built up this weekend. Definitely seeing a little more headroom with these higher current chips, as expected. Onward!
- Dec 3, 2003
- 23,079
- 46,038
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
v2 of the WTHPF pedal:
I played around with the HPF and LPF cutoff frequency ranges a bit this time, going a bit lower and higher, respectively. And as usual, something beween v1 and v2 very well may prove to be the sweet spot for the default spec. Just need to make the rounds to a few friends' gigs and hear this one in some varied band contexts before I decide on the final OS spec now.
I'm also playing around with both fixed and varaiable frequency HPFs to go in a 1590A sized enclosure, should have a couple of testers done by mid next week.
I played around with the HPF and LPF cutoff frequency ranges a bit this time, going a bit lower and higher, respectively. And as usual, something beween v1 and v2 very well may prove to be the sweet spot for the default spec. Just need to make the rounds to a few friends' gigs and hear this one in some varied band contexts before I decide on the final OS spec now.
I'm also playing around with both fixed and varaiable frequency HPFs to go in a 1590A sized enclosure, should have a couple of testers done by mid next week.
Last edited:
@Passinwind
Sorry if this has been mentioned, but do you or would you think about selling "parts kits" for these where you sell all the components and then the user puts it together.
Its something i wouldn't mind trying but my blocker would be sourcing the bits in Ireland.
Back in the day Big Briar (moog) sold theremins, but they also sold them as a kit to put together yourself. I built one and i was awesome.
Sorry if this has been mentioned, but do you or would you think about selling "parts kits" for these where you sell all the components and then the user puts it together.
Its something i wouldn't mind trying but my blocker would be sourcing the bits in Ireland.
Back in the day Big Briar (moog) sold theremins, but they also sold them as a kit to put together yourself. I built one and i was awesome.
- Dec 3, 2003
- 23,079
- 46,038
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
Yeah, a friend of mine did the Theremin kit eons ago and I ended up helping him getting it working. He also did a cool Aries modular synth build as well. Craig Anderton and Paia had an arrangement for years too, and then there were Dynaco, Heathkit, SW Technical Sytems, Hafler, et al.
Right now I provide a bill of materials for as many components as possible as a shared project on Mouser, so the builder just needs to check that everything is in stock and click "buy." Pots, switches, jacks, and enclosure if used are all available at Tayda, although in a pinch you can get by with Mouser for all those too. PCBs are on share at OSHpark (they make you buy at least three though), so it currently takes three vendors to get all the way there.
I've discussed making it easier for builders outside of North America with some of my friends on Basschat and two of them are ready to help out on that. I will be working on it some more just as soon as I wrap up a few things to give the best shot at getting a single board PedalPCB stomp box version going. I know it would help many DIYers if the new board(s) came with all the surface mount components installed, and there are a few ways that could happen relatively painlessly. But parts supply issues are still a big hassle at the moment, so my focus has mostly been on building a better mousetrap and then hoping that helping other people replicate it will fall into place sooner than later.
Last edited:
Youre a good man, @Passinwind and a credit to teh worldwide bass community!Yeah, a friend of mine did the Theremin kit eons ago and I ended up helping him getting it working. He also did a cool Aries modular synth build as well. Craig Anderton and Paia had an arrangement for years too, and then there were Dynaco, Heathkit, SW Technical Sytems, Hafler, et al.
Right now I provide a bill of materials for as many components as possible as a shared project on Mouser, so the builder just needs to check that everything is in stock and click "buy." Pots, switches, jacks, and enclosure if used are all available at Tayda, although in a pinch you can get by with Mouser for all those too. PCBs are on share at OSHpark (they make you buy at least three though), so it takes three vendors to get all the way there.
I've discussed making it easier for builders outside of North America with some of my friends on Basschat and two of them are ready to help out on that. I will be working on it some more just as soon as I wrap up a few things to give the best shot at getting a single board PedalPCB stomp box version going. I know it would help many DIYers if the new board(s) came with all the surface mount components installed, and there are a few ways that could happen relatively painlessly. But parts supply issues are still a big hassle at the moment, so my focus has mostly been on building a better mousetrap and then hoping that helping other people replicate it will fall into place sooner than later.
Would you say if i was abke to put that theremin together myself, i could put one of your preamps together?.Yeah, a friend of mine did the Theremin kit eons ago and I ended up helping him getting it working. He also did a cool Aries modular synth build as well. Craig Anderton and Paia had an arrangement for years too, and then there were Dynaco, Heathkit, SW Technical Sytems, Hafler, et al.
Right now I provide a bill of materials for as many components as possible as a shared project on Mouser, so the builder just needs to check that everything is in stock and click "buy." Pots, switches, jacks, and enclosure if used are all available at Tayda, although in a pinch you can get by with Mouser for all those too. PCBs are on share at OSHpark (they make you buy at least three though), so it currently takes three vendors to get all the way there.
I've discussed making it easier for builders outside of North America with some of my friends on Basschat and two of them are ready to help out on that. I will be working on it some more just as soon as I wrap up a few things to give the best shot at getting a single board PedalPCB stomp box version going. I know it would help many DIYers if the new board(s) came with all the surface mount components installed, and there are a few ways that could happen relatively painlessly. But parts supply issues are still a big hassle at the moment, so my focus has mostly been on building a better mousetrap and then hoping that helping other people replicate it will fall into place sooner than later.
I have one of these new models and thought I might add some value to this conversation.
* The HPF works perfectly. Very smooth and usable. It replaced my other HPF.
* The mid control is very effective and musical. The center freqs are just right and it does an amazing job at cutting as well as boosting. You would have to check with Charlie but I believe the Q of the filter changes depending on knob position
* This box is not as simple as it looks. There is a huge amount of interaction between the controls. After over a month, I'm still getting acquainted with the reso / freq / mid control variations. They are very interactive.
* Very surprised that cutting a little bit of mids can really clean up a bass tone in the mix. This box is not like any EQ I have used in either a pedal form or rack mount. There is some Pultec DNA in this box.
* Highly recommended!
- Dec 3, 2003
- 23,079
- 46,038
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
Yeah, very likely. I've tried to make it so decent soldering skills and a basic ability to read component references and stuff the right components in the right places will get you a working build, without all the fine tuning and other tweaks some of us have gone on about for nearly six years now. I do highly recommend jumping into hand soldering the easier surface mount component formats a bit before committing to the new ones, and there may still be some board refinements implemented once my beta builders finish up their test units. The beta testers range from pros who work in aerospace board fabrication to people who just started in on paint by numbers pedal kit building in the last year or two. Their experiences and maybe yours are invaluable to making this all work as a community thing and not just a "look at me" indulgence.
I'm a little late to the party, but I would agree with Charlie that practicing your soldering skills makes a difference. I unfortunately went the wrong direction and dove into an earlier version before having my soldering chops in order. Now that I've build a few other pedals from kits successfully and have better quality solder, I'm more optimistic about the next attempt. I also would agree with Charlie that just go for an enclosure and pedal option. I recently picked up a G&L L2000 tribute and the pedal goes incredibly well with the MFD humbuckers. Such a great pedal and if Charlie has improved it since I got mine, I can't imagine how good it is. Jim C is also right in that little shifts here and there have big effects and almost all seem very usable.
- Dec 3, 2003
- 23,079
- 46,038
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
Just to clarify: I've only ever sold three of these pedals to bassists, and one was immediately confiscated by his guitarist wife/partner for her gigging pedalboard.
I very rarely build to the same spec twice, so "improvements" are generally just a juggled tradeoff set tailored to specific applications. In both your and @Jim C 's case control label visibility was a high priority, and I guess the new font on Jim's probably is a bit easier for many people to read. And the the smaller enclosure and added HPF are kind of cool, but we lost the bypass footswitch and topside LED indicator by going that route. A separate HPF would bring more signal chain placement options, but might lose some of the intentional interactivity I designed into Jim's pedal, or it just might interact in some better or worse way for you and/or Jim. On my side I learn a lot from user feedback, which was a big driver for starting this thread six years ago. The info on how your pedal works with MFD 'buckers is much appreciated and I've often wondered about that since I occasionally hang on a forum that started as an alt G&L user site for guys who got kicked off TB.
I'm still playing around with different HPF formats BTW. This one is always-on, fixed frequency at ~30Hz:
That's a 1590A box, for variable frequency a 1590B or 1590G would be a lot easier to work with and I'll be trying that soon. The HPF board is now well vetted and I'll be adding it to the OSHpark board share library just as soon as I get a proper BOM done. The pic in post #1058 shows the hybrid SMT/though-hole parts format, but if a lot of people want all through-hole maybe someone else can come up with a PCB layout for that?
I doubt it will ever happen but would love to see how your pedal shifts the resonant frequency on the MFD's. I have a hunch that while they're high output they still manage to be in the 2 Henry inductance range (no confirmation of this, just a hunch) and that your design moves the resonant frequency in some really interesting ways. Really Charlie it's a great design.
- Dec 3, 2003
- 23,079
- 46,038
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
You could try doing some recordings and using Room Eq Wizard to do some frequency spectrum analysis in a variety of ways, but if it sounds good it is good, I reckon.
