The Passinwind Open Source Preamp

[Tassieviking]

In Australia 6mm building wire is 7/1.04mm, 4mm building wire is 7/0.85mm. (7 strands of solid wires)
I don't know what sizes any other country uses but there are usually lots of cut off pieces at building sites.
You can usually buy it at hardware stores as well by the meter and one meter would go a long way.

 

[Passinwind]

In Australia 6mm building wire is 7/1.04mm, 4mm building wire is 7/0.85mm. (7 strands of solid wires)
I don't know what sizes any other country uses but there are usually lots of cut off pieces at building sites.
You can usually buy it at hardware stores as well by the meter and one meter would go a long way.

Cool, that looks completely workable. I think I may be able to do something that just uses Tayda sourced angled header pins if JLCPCB will make small enough breakout boards for the straight pin pots, I will investigate further. But when I checked te other day Tayda were nearly out of 20KC dual pots...

Meanwhile, I've started mocking up a simple UV print file for Tayda. I can do a few in different text colors once I settle on a general format, I'm thinking something very basic like this:

 

[Tassieviking]

This is the front panel I made up for the Mk2 build I'm doing now, it's just a 1mm thick PCB.
I do like to have the in/9v/out marked along the top upside down, I also liked the way the curve leads from the switch to the Mid pot.

 

[Passinwind]

This is the front panel I made up for the Mk2 build I'm doing now, it's just a 1mm thick PCB.
I do like to have the in/9v/out marked along the top upside down, I also liked the way the curve leads from the switch to the Mid pot.View attachment 5012467 View attachment 5012468

Lookin' good, let's keep that option open for builders for sure. Simple, inexpensive, and easy, what's not to like?

 

[dcoyle]

It's Spring, and the hope of blossoms is in the air: A through-hole v2 of the pre/LPF, thank you Tassieviking, and a through-hole HPF, thank you Charlie! You know how to tell when the stage is level? The bass player drools out of both sides of his mouth, equally.

Tassieviking, I'm really glad to see you're working with the V.2 pre in through-hole. When you're ready to share what your plans are for your boards, I'm very interested.

Having the graphics on a pc board is a great thing, as it looks pro and can be sourced with the boards. I'm clueless on digital graphics, but it would be cool if there were an option to use the label graphic to etch the copper. One could then get a black board with copper or silver (tinned) labeling and clear over that. The black board would go with any color box, and the labeling would be pretty high contrast for low light. But most of all, it would be flash.

Your swoop from the mid pot to the mid frequency switch is definitely an improvement.

It would be useful to have some sort of indication on the frequency and resonance labels indicating the most flat position. In post 1131, Jim C mentions "flat = Res full left / Freq full right". ? Replace one of the indicator dots with an "L" on each pot?

Charlie, can you specify a certain place on the V2 bass and mid Bax controls as "0" boost, more or less? It would help someone starting out to have a reference point. ? Replace one of the dots with a "0" ?

 

[Tassieviking]

I have only recently started to make the PCB's for the fascia panel, only because I am useless at graphics or else I would do the graphics and have the 125B box printed by Tayda.
I can easily leave all the KiCad files so anyone can use KiCad and change the a fascia to what they like.
Just remember to order 1mm or thinner PCB's for the fascia or else there won't be enough tread to put the nuts on the pot shafts to lock them in.

I made a fascia PCB for the Sunn Beta PCB I made up for a 1590BB box, I have Lead on the front of the PCB and BASS on the back, just flip the fascia over depending on which version I am building.
Yes you can have printing on both sides so why not make 2 different versions.
I don't know if other brands of 125B boxes have thicker walls, but it works for the Tayda boxes.
Cheers

 

[Passinwind]

27354754[/URL], member: 166898"]It's Spring, and the hope of blossoms is in the air: A through-hole v2 of the pre/LPF, thank you Tassieviking, and a through-hole HPF, thank you Charlie! You know how to tell when the stage is level? The bass player drools out of both sides of his mouth, equally.

Tassieviking, I'm really glad to see you're working with the V.2 pre in through-hole. When you're ready to share what your plans are for your boards, I'm very interested.

Having the graphics on a pc board is a great thing, as it looks pro and can be sourced with the boards. I'm clueless on digital graphics, but it would be cool if there were an option to use the label graphic to etch the copper. One could then get a black board with copper or silver (tinned) labeling and clear over that. The black board would go with any color box, and the labeling would be pretty high contrast for low light. But most of all, it would be flash.

Your swoop from the mid pot to the mid frequency switch is definitely an improvement.

It would be useful to have some sort of indication on the frequency and resonance labels indicating the most flat position. In post 1131, Jim C mentions "flat = Res full left / Freq full right". ? Replace one of the indicator dots with an "L" on each pot?

Charlie, can you specify a certain place on the V2 bass and mid Bax controls as "0" boost, more or less? It would help someone starting out to have a reference point. ? Replace one of the dots with a "0" ?

It’s no problem to make the noon positions on bass and mid controls be the flat position, this is how it is for the original version. Since seemingly no one ever cuts active bass controls very much I don’t find that to be most useful format personally, but many people really love the security of having detents at the flat positions, and getting detents at something lile 10 or 11 o’clock would be a very big ask. A tick mark at nominal flat is a great idea though, I think.

Resonance is currently always boosting at least a bit at any setting but full left, and frequency always cuts more highs at any setting but full up. Hence Jim C’s comment. We can put actual frequency labels on whatever the default build spec ends up being, but experience has shown me that pedal label functions are often much easier to read when placed below the knobs rather than above, and there’s only room for so much down there. I like minimalism, but these designs are not the most intuitive thing and I can see things like the mid control/switch link curve helping new users quite a bit. New eyes see new things, so as usual, you tell me!

As far as black and exposed copper graphics, look at OSHPark’s alt black/clear finish option, it allows truly stunning artwork. But an OSH board the size of Tassie’s fascia will be more expensive than a Tayda UV print, and you have to buy in threes. Pesky tradeoffs, as usual.

I now have a Github repository page parked and waiting for content. Soon all the schematics and BOMs will live there, since my own web hosting will be going away and this project has kind of outgrown Talkbass as far as I’m concerned.

 

[dcoyle]

"As far as black and exposed copper graphics, look at OSHPark’s alt black/clear finish option, it allows truly stunning artwork. But an OSH board the size of Tassie’s fascia will be more expensive than a Tayda UV print, and you have to buy in threes. Pesky tradeoffs, as usual."

It was getting stuff at Osh Park that gave me the idea.

IMO, and I gather Tassievikings, the graphics on a board is only a workaround for no graphics, or my freehand scrawl. Getting it on the box is the elegant way, and it's great if that will be available.

"We can put actual frequency labels on whatever the default build spec ends up being, but experience has shown me that pedal label functions are often much easier to read when placed below the knobs rather than above, and there’s only room for so much down there."

Labels below the knob are better, IME, too, and your choice of larger script size is real nice. In studio stuff it's nice to have frequencies marked and lots of tick marks but not on a gig pedal, where you may not be able to read 'em.

"I now have a Github repository page parked and waiting for content. Soon all the schematics and BOMs will live there."

Looking forward to seeing the current version of the HPF and the LPF on Githup, when they get there.

 

[Passinwind]

Looking forward to seeing the current version of the HPF and the LPF on Githup, when they get there.

I think I have the specs for the standalone versions of both the HPF and LPF pretty well nailed down, but since I have two WTHPF builds left to go before I move along to my last few pre-retirement DIY things I may as well see if anything new and cool pops up during those builds. I was down to the very last one, which was going to be for myself, but a close friend insisted on buying it before it was even built, so I ordered an even nicer enclosure for my own build. That one will be done to my own preferences: side jacks, no footswitch, and a less intuitive but (theoretically) technically better control layout format.

The new standalone ones will both be part SMT BTW, I have no plans to do any more straight through-hole designs or builds ever again really. But as we've just seen, there are other people around who could take that on if they feel so inspired, which is great!

 

[MoireBass]

Oh, this is great. I lost interest in this thread when the preamp became surface mount. I'm very glad to see someone is working on a thru-hole version!!

Speaking only for myself, I am quite good at soldering and have been doing it only slightly less than forever. The soldering instructor for Texas Instruments came out to our Electronics Cluster in high school, taught us the correct way to solder (thru-hole), tested us, and if our soldering passed her inspection, gave us certificates.
Years ago, I scorched and ruined three very expensive PCBs I'd designed out of our proto run of ten trying to remove and replace 88-pin gull-wing devices. And that experience left me with a strong distaste for surface mount (if I'm the one assembling it). If there was a compelling reason to use SMD, I would, but it's not something I will EVER choose to do for recreational purposes. Thru-hole is easy to solder, easier to troubleshoot, much easier to modify, and the miniaturization of SMD isn't necessary for most pedals. Speaking only for myself of course.​

Some comments: The panel graphic looks really good. I like the position dots on the controls. The idea of a simple tic mark is great, and could be just a short line. The curve is nice, maybe add an arrowhead on one end? The reverse text for input and output is also visually appealing, though why not make it mixed case like the power input text to set it off better from the all-caps of the face text?

For people who prefer wired controls over PCB-mounted controls, will it be possible to do that with this layout? If so, could you add a couple of mounting holes to the PCB for use with nylon adhesive standoffs?

Looking forward (once again!) to building one of these.

 

[Passinwind]

Oh, this is great. I lost interest in this thread when the preamp became surface mount. I'm very glad to see someone is working on a thru-hole version!!

Speaking only for myself, I am quite good at soldering and have been doing it only slightly less than forever. The soldering instructor for Texas Instruments came out to our Electronics Cluster in high school, taught us the correct way to solder (thru-hole), tested us, and if our soldering passed her inspection, gave us certificates.
Years ago, I scorched and ruined three very expensive PCBs I'd designed out of our proto run of ten trying to remove and replace 88-pin gull-wing devices. And that experience left me with a strong distaste for surface mount (if I'm the one assembling it). If there was a compelling reason to use SMD, I would, but it's not something I will EVER choose to do for recreational purposes. Thru-hole is easy to solder, easier to troubleshoot, much easier to modify, and the miniaturization of SMD isn't necessary for most pedals. Speaking only for myself of course.​

Some comments: The panel graphic looks really good. I like the position dots on the controls. The idea of a simple tic mark is great, and could be just a short line. The curve is nice, maybe add an arrowhead on one end? The reverse text for input and output is also visually appealing, though why not make it mixed case like the power input text to set it off better from the all-caps of the face text?

For people who prefer wired controls over PCB-mounted controls, will it be possible to do that with this layout? If so, could you add a couple of mounting holes to the PCB for use with nylon adhesive standoffs?

Looking forward (once again!) to building one of these.

Hope it works out great for you!

FWIW, I can often do board rework on my part SMD builds without even pulling the board out of a pedal, and for me 8 pin SMD opamps live through removal at least as often as unsocketed through-hole ones. There was a definite learning curve and certain new tools were absolutely mandatory in my case. My designs all use the largest feasible SMD parts wherever possible, so maybe never say never...

I'm pinging @Tassieviking to address the rest since we're not at a final release stage quite yet and he can decide where he wants to take this design fork. I'm more than happy to kick back and cheer you guys on at this point, I think my work here on the pedal side is very nearly done.


............................................................................................cheers,

 

[T-34]

I peronally like SMD (when the components aren't too small), even by hand it's faster to assemble an SMD board than a through-hole for me.
Obviously can't do that with your bare eyes, but my unassisted sight isn't good enough for the TH either.

 

[Passinwind]

I personally like SMD (when the components aren't too small), even by hand it's faster to assemble an SMD board than a through-hole for me.
Obviously can't do that with your bare eyes, but my unassisted sight isn't good enough for the TH either.

I actually can do it with my 70 year old bare eyes, no problem. But that's only because I'm so farsighted.

But yeah, I find 1206 format SMD resistors a lot easier to deal with than through hole 1/4 watt ones by now. And 0.1% tolerance SMD parts are very easy to come by at least here in the US as well. And then there's the fact that so many newer opamps don't even come in through hole format, but that probably matters a lot more for battery powered applications like onboard preamps than for pedals, where old standby pieces such as TL072 et al are still very popular.

OTOH, we also have many beginnner DIY builders interested in this thread, and very experienced guys like @MoireBass who like what they like, with good reason. All of that is what has kept me interested in this long adventure all this time, and I still look forward to seeing what comes next!

 

[dcoyle]

Charlie, what you have done with this thread is exemplary in every way.

You have provided a model of the ideal in a development thread. You have given many dozens of hours to others over many years, with your gracious, perceptive and highly competent posts.

Even when you moved on to SMD, for all the very good reasons you mention, you have given considerable effort to coax folks into the SMD future and supported the through hole version of V.2.

You have created and shared the fundamental box for a bassist, the ability to shape sound in the amplitude domain, cleanly and musically.

We are richer for it, thank you so much.

 

[Passinwind]

I was down to the very last one, which was going to be for myself, but a close friend insisted on buying it before it was even built, so I ordered an even nicer enclosure for my own build. That one will be done to my own preferences: side jacks, no footswitch, and a less intuitive but (theoretically) technically better control layout format.

And here's how that will manifest:

Signal flow goes counter clockwise from side jack input at lower right to output at lower left, no inputs crossing outputs or long roundtrips on any of the three boards. Cork sniffing, maybe, but I did it "my way."

BTW, @Tassieviking has put in a request for Tayda to offer this color shifting finish, and the powder coat formulation for it is readily available from Prismatic Powders if anyone fancies a DIY go.

 

[dcoyle]

That box looks great, and that circuit being mix SMD has me again thinking about trying to get these 74 yo eyes to do SMD.

"There was a definite learning curve and certain new tools were absolutely mandatory in my case."

Please, what were the "absolute mandatory tools", and solder and flux brands that work for you, and optics and lighting intensity?

Anyone else care to comment?

Thanks

 

[dcoyle]

Next time you have the back of that box off, it would be neat to see the lay out you used.

 

[Passinwind]

Next time you have the back of that box off, it would be neat to see the lay out you used.

I haven't even started stuffing the first board for that build yet, it's likely to be at least a couple of weeks. Just received the enclosure two days ago.

As far as tooling for hand soldering basic SMD boards, let's ping some actual pros who drop into this thread from time to time: @AudioTaper, @rutrho, @bowthing, and @Jerry Catanescu. Assume 0805 as the smallest parts, and no delicate film caps or anything like that. Mostly SO-8 ICs, maybe SOT-23 FETs or something like that occasionally.

I know there are several other pros lurking, please de-cloak and chip in if you care to.

For myself, I like .020" Kester 63/37, w/ type 44 rosin. I have a Hakko FX-888 iron and these are my default tips for SMD work:

Hakko T18-C1, 1mm elliptical

Hakko T18-S9, 1.2mm screwdriver

Hakko T18-S4, 0.5mm conical

The screwdriver tip gets by far the most use for the sort of builds we're talking about here. I use some considerably bigger ones for rework, up to a 4mm screwdriver tip that can catch one whole side of an SO-8 opamp in one shot when needed for non-destructive removal. Board layout is very important to facilitate that technique though, and it's not unusual to have to pull one of two through-hole caps to allow clear access to the IC pins on some of my boards.

And then tweezers. My friend who was a certified soldering trainer at Intel recommends trying several types, he said there was no consensus at all among the techs he worked with. I like a few of the basic Hakko models you can direct order from the Hakko USA website, but some cheap Ebay buys have also worked out pretty well for me.

 

[Passinwind]

Just a heads up:

I've temporarily taken down the newer OSHPark board shares and BOM while I sort out some naming conventions and new default designs. I decided that v2 should refer to @Tassieviking's 125B pedal build, and my hybrid SMD/through-hole ones will now be v3 and v4. Hopefully all of this will play out sensibly once I get revision control sorted on Github. The Wiki here is a bit painful to edit since I can't even delete my own work without getting a Mod involved, so taking on the learning curve for the Git ecosystem seems worthwhile to me. I'll also slog through updating the Wiki here too in any case though.

Beyond that, I'm going to have @dcoyle do some beta testing on a bass guitar centric WTHPF (v4) build, and try to get Spencer at Amplifyfun to write up a best practices sheet for submitting your own graphics and drill map files to his server. Still not sure what the best answer is for Tayda, but the next time I need to order parts from them I'll at least take a stab at trying another print job from them at the same time. They've just stopped offering the cheapest postal shipping tiers, so any orders I submit will need to be considerably larger to make sense now, unfortunately. DHL is a pretty poor option where I live, so FedEx it is, I reckon.

 

[AudioTaper]

I haven't even started stuffing the first board for that build yet, it's likely to be at least a couple of weeks. Just received the enclosure two days ago.

As far as tooling for hand soldering basic SMD boards, let's ping some actual pros who drop into this thread from time to time: @AudioTaper, @rutrho, @bowthing, and @Jerry Catanescu. Assume 0805 as the smallest parts, and no delicate film caps or anything like that. Mostly SO-8 ICs, maybe SOT-23 FETs or something like that occasionally.

I know there are several other pros lurking, please de-cloak and chip in if you care to.

For myself, I like .020" Kester 63/37, w/ type 44 rosin. I have a Hakko FX-888 iron and these are my default tips for SMD work:

Hakko T18-C1, 1mm elliptical

View attachment 5016561



Hakko T18-S9, 1.2mm screwdriver


View attachment 5016562


Hakko T18-S4, 0.5mm conical


View attachment 5016563


The screwdriver tip gets by far the most use for the sort of builds we're talking about here. I use some considerably bigger ones for rework, up to a 4mm screwdriver tip that can catch one whole side of an SO-8 opamp in one shot when needed for non-destructive removal. Board layout is very important to facilitate that technique though, and it's not unusual to have to pull one of two through-hole caps to allow clear access to the IC pins on some of my boards.

And then tweezers. My friend who was a certified soldering trainer at Intel recommends trying several types, he said there was no consensus at all among the techs he worked with. I like a few of the basic Hakko models you can direct order from the Hakko USA website, but some cheap Ebay buys have also worked out pretty well for me.

You have a great setup.
I prefer my Weller WD2M 40W dual wand station and a variety of small Weller RT chisel tips. They range in size from 1.2mm to 2.2mm I believe

The solder is usually rosin core Kester 63/37 with type 285 flux (because that's what I have at the moment) but the 60/40 is fine and type 44 flux is great. I do add Kester 197 liquid flux, especially if I have to work with any lead free solder.

IPC practice board

Good soldering starts with a great layout

I do have a tweezer set for the Weller, but I got the whole thing used on ebay and it needs new tips. It would be great for SO-8 IC removal, but I can do the same with two wands.

I also have a Hakko fuse extractor and a Bausch & Lomb Stereozoom microscope, which makes life way easier.