New approaches in Buchla format DIY

Discussing some incredible modules that don't quite fit into the other forum categories.

Moderators: Kent, Joe., luketeaford, lisa

tarandfeathers
Wiggling with Experience
Posts: 344
Joined: Wed May 07, 2014 3:02 pm
Location: Leeds, UK
Contact:

New approaches in Buchla format DIY

Post by tarandfeathers » Tue May 19, 2020 2:35 pm

Like most people here, I love the Buchla 200 format, and like many I also love to DIY. There are increasingly a bunch of great resources out there for DIY in terms of parts and information, but for a variety of reasons I always wished there were some slightly different options that fit my personal preferences better. Since we're talking DIY, it seemed only reasonable for me to do just that, so here are my first two offerings, new boards for 258 and 281 style modules. For ease, lets call them the 258D and 281D.

258D.jpg
281D.jpg

Briefly, the 258D is a 2 layer board, similar in concept to the 258V/J - i.e. the Electronotes option 3 expo converter and triangle core with 258-like waveshaping, plus a few tweaks for better tracking and stability, a calibrated 1.2V/O input, and a buffered copy of the triangle core on the rightmost output of each osc. Saw/Square waveshapes are selectable per osc, but I have left this as a behind the panel option as recalibration of the waveshape control is required after changing.

The 281D is a four layer board, and I believe the first single board implementation of the 281. It's broadly similar to the original circuit but has correctly implemented auto-start when entering cycle mode, buffers on both CV and pulse outputs to improve behaviour when stacking CV outs to multiple destinations and when stacking multiple pulse outs together to create unpredictable/non-repeating poly-rhythmic pulse sequences. There is an option to implement the transient/sustain behaviour either the original way for use with Buchla pulse/gates, or using Dave Brown's transient mod if using with standard gate signals. There's also some general tidying up around the logic/control circuit.

Here's what I've tried to bring to the table:
  • Known good designs - I have built multiples of both modules and spent a lot of time testing and verifying their operation and builadbility, so there are no nasty surprises waiting for anyone attempting to build either of these.
  • Comprehensive, publicly available documentation - each project has a github repo with full documentation, available from day one. KiCad project files, PDF schematic, BOMs, interactive assembly guide, build options/calibration procedures, etc.
  • Predominantly SMT construction, excluding connectors and panel controls. I much prefer working in surface mount these days. The parts are cheaper, assembly is faster, and in addition this means there are no obsolete parts in either build.
  • Component designators you can still see after populating the boards - probably needs no elaboration, but in the event that any troubleshooting of a build is required this, along with actually having documentation, is fairly critical
  • Boards fit with any panel based on the EMS drill files (though the 258 will need the hole for the scale trimmer drilled out if you're using an existing panel.)
Possibly some other things that I forget at the moment. Primarily I am trying to help to point things in the DIY world in a more open, co-operative direction.

Github links for your perusal:

https://github.com/DunningtonAudio/258D
https://github.com/DunningtonAudio/281D

All comments and queries are welcome.

Now, the caveats: as indicated in the notes, although I've made every effort to make sure hand assembly is doable, these aren't necessarily recommended as a first SMT project. The build notes are very much a guide, not intended to hand hold you step-by-step through soldering each component - some common sense will be required, though if anyone thinks I have missed anything critical, please let me know. For the most part these are SOIC/0805/SOT-23, the smallest part on both boards is a SOT-363 package which is comfortably hand workable.

It would of course be remiss of me not to mention that I have a few boards of each for sale (281 currently sold out but more are on the way) - Julian at http://thebeast.co.uk will also have boards in his store shortly so you can order the PCB and a panel from the same place - he will also have 258D panels specifically for these boards. I will also shortly have a handful of each module pre-built in case SMT isn't your thing. I'll keep the "sales pitch" to that, primarily I would just like to get these out into the world and, I hope, add something useful to the DIY side of things.

Thanks.

====
Moderator addition by Kent


Be sure to keep the build discussion confined to the threads in the DIY section:

281D Build Thread.

258D Build Thread

This thread can be used as an announcement, advert, and celebration of sorts but tech stuff should go in the aforementioned DIY thread. We normally don't allow cross-posting of very similar material across sub-fora, as it gets confusing and messy for users as thread expand. The mods also get accused of having deleted posts when they are actually perfectly fine, but in another thread. We'll allow this and see how it goes as the topics are slightly different.
Dunnington Audio - Various Buchla format accoutrements available

jimfowler
Veteran Wiggler
Posts: 650
Joined: Mon Feb 22, 2016 1:13 pm
Location: New York
Contact:

Re: New approaches in Buchla format DIY

Post by jimfowler » Tue May 19, 2020 2:44 pm

Huge thanks for doing this. I'm very excited to give it a go!

- Jim

maxl0rd
Common Wiggler
Posts: 79
Joined: Mon Aug 05, 2013 1:51 pm

Re: New approaches in Buchla format DIY

Post by maxl0rd » Tue May 19, 2020 3:01 pm

tarandfeathers wrote:
Tue May 19, 2020 2:35 pm
Primarily I am trying to help to point things in the DIY world in a more open, co-operative direction.
thank you!

djs
Super Deluxe Wiggler
Posts: 1183
Joined: Wed Sep 01, 2010 8:36 am
Location: South Beloit, IL

Re: New approaches in Buchla format DIY

Post by djs » Tue May 19, 2020 4:22 pm

These are awesome- thanks for sharing them! Thoughts on what you might do next?
"Noise is what the Earth is made of" - David Bowie

User avatar
cackland
Super Deluxe Wiggler
Posts: 2207
Joined: Thu Dec 28, 2017 5:42 pm
Location: Los Angeles, California

Re: New approaches in Buchla format DIY

Post by cackland » Tue May 19, 2020 4:25 pm

This is great. Thanks for sharing :)

User avatar
peloazul
Common Wiggler
Posts: 130
Joined: Wed Dec 02, 2015 7:09 pm
Location: NM
Contact:

Re: New approaches in Buchla format DIY

Post by peloazul » Tue May 19, 2020 5:33 pm

Super exciting! I'd always wondered to myself how this hadn't happened already? Looks like pretty easy hand soldering as SMT goes. In any case, happy to know when Julian is ready, and to put an order in over there.

Thanks tarandfeathers! Thanks a ton!

User avatar
Reese P. Dubin
Super Deluxe Wiggler
Posts: 1362
Joined: Wed Dec 17, 2008 12:33 pm
Location: Absolute Elsewhere

Re: New approaches in Buchla format DIY

Post by Reese P. Dubin » Tue May 19, 2020 6:17 pm

I will absolutely start my own system when this hits the critical mass (259/281/292/266)

AMAZING!

User avatar
momo
Ultra Wiggler
Posts: 910
Joined: Wed Jun 17, 2009 4:40 am
Location: London, England

Re: New approaches in Buchla format DIY

Post by momo » Tue May 19, 2020 7:25 pm

Wonderful and welcome

User avatar
cygmu
Super Deluxe Wiggler
Posts: 1552
Joined: Mon Feb 15, 2016 3:33 pm
Location: UK

Re: New approaches in Buchla format DIY

Post by cygmu » Wed May 20, 2020 3:05 am

These look great and I am sure I won't be able to resist. Comprehensive documentation, available parts, and reasonable price -- what a revolution!

Probably there should be a build thread or similar, but for now please forgive me for asking here: do you have any more information on how to select the J201 for the sine shaper? Measuring for Vgs(off) exactly 1.13V seems pretty demanding. The Buchla lore was to select based on Idss and I'd love to understand the interaction or whether the new selection criteria are better.

Also, are the PTC resistors from Smallbear really 3300ppm coefficient? I see that the manufacturer is willing to make them to order in various coefficients -- if that's what Smallbear have done then that is amazing news.

Sorry for getting technical so quickly.

kevin0
Learning to Wiggle
Posts: 41
Joined: Fri May 26, 2017 6:11 am

Re: New approaches in Buchla format DIY

Post by kevin0 » Wed May 20, 2020 5:03 am

Very exciting :) Nice work!

tarandfeathers
Wiggling with Experience
Posts: 344
Joined: Wed May 07, 2014 3:02 pm
Location: Leeds, UK
Contact:

Re: New approaches in Buchla format DIY

Post by tarandfeathers » Wed May 20, 2020 5:50 am

cygmu wrote:
Wed May 20, 2020 3:05 am
Probably there should be a build thread or similar, but for now please forgive me for asking here: do you have any more information on how to select the J201 for the sine shaper? Measuring for Vgs(off) exactly 1.13V seems pretty demanding. The Buchla lore was to select based on Idss and I'd love to understand the interaction or whether the new selection criteria are better.
In the original paper from Middlebrook and Richer that describes the sine shaper Don used in the 258 and 259, Vgs(off) is the critical value. If (and it's a big if) you have a JFET whose Vgs(off) is a precise multiple of the peak value of the incoming triangle wave, you can build the circuit with no trimmer. Idss has some correlation with Vgs(off) and is easier to test which is probably why it was specified. In reality, values between about 0.9 and 1.2V should be okey for use with the circuit as is, and the Idss method is okey too, but it's not technically the "correct" way.
Also, are the PTC resistors from Smallbear really 3300ppm coefficient? I see that the manufacturer is willing to make them to order in various coefficients -- if that's what Smallbear have done then that is amazing news.
I'd have to double check with them - I've actually built with parts from Farnell in the UK which are 3000ppm, and I've found this to be good enough for rock and roll. I put Smallbear in the BOM on the grounds that most people will be interested in US suppliers. I've just noticed that Vishay have a 3400ppm part - NTCS0603E3202JLT - in an 0603 package available at Farnell as well which might be worth trying.
Sorry for getting technical so quickly.
Not at all! That's kind of the point :)
Dunnington Audio - Various Buchla format accoutrements available

User avatar
misa
Ultra Wiggler
Posts: 886
Joined: Thu Dec 29, 2011 4:18 pm
Location: Cologne, Germany
Contact:

Re: New approaches in Buchla format DIY

Post by misa » Wed May 20, 2020 1:39 pm

THis stuff is very inspiring, were it not for the fact that I’ve never built SMT before...

But I’m looking and following.

Thanks for doing this!

kainiggemann.bandcamp.com
anterasa.bandcamp.com
gratofficial.bandcamp.com
thedorf.net

solaranus
Learning to Wiggle
Posts: 37
Joined: Sat Oct 11, 2014 4:18 pm

Re: New approaches in Buchla format DIY

Post by solaranus » Wed May 20, 2020 2:06 pm

As a Buchla newbie who is used to building SMT projects, I am really excited for this development. I actually came across these by myself by chance and ordered 281D right away. I hope more modules will follow.

Also have to say, kudos for the BOM and inclusion of all the hardware parts, cleared quite a bit of questions for me.

jimfowler
Veteran Wiggler
Posts: 650
Joined: Mon Feb 22, 2016 1:13 pm
Location: New York
Contact:

Re: New approaches in Buchla format DIY

Post by jimfowler » Wed May 20, 2020 3:16 pm

Re: J201 - at $0.36 per piece (close to half that if you order 10) it shouldn't break the bank to find a good one.

User avatar
Kent
Large Member
Posts: 12001
Joined: Thu Mar 06, 2008 10:17 am
Location: Vienna, Austria

Re: New approaches in Buchla format DIY

Post by Kent » Fri May 29, 2020 6:39 am

Be sure to keep the build discussion confined to the threads in the DIY section:

281D Build Thread.

258D Build Thread

This thread can be used as an announcement, advert, and celebration of sorts but tech stuff should go in the aforementioned DIY thread. We normally don't allow cross-posting of very similar material across sub-fora, as it gets confusing and messy for users as thread expand. The mods also get accused of having deleted posts when they are actually perfectly fine, but in another thread. We'll allow this and see how it goes as the topics are slightly different.

User avatar
cnicht
Ultra Wiggler
Posts: 751
Joined: Mon Sep 23, 2013 9:23 am

Re: New approaches in Buchla format DIY

Post by cnicht » Fri May 29, 2020 6:43 am

A 208 in SMT please! :tu:

tarandfeathers
Wiggling with Experience
Posts: 344
Joined: Wed May 07, 2014 3:02 pm
Location: Leeds, UK
Contact:

Re: New approaches in Buchla format DIY

Post by tarandfeathers » Fri May 29, 2020 2:44 pm

Kent wrote:
Fri May 29, 2020 6:39 am
Be sure to keep the build discussion confined to the threads in the DIY section:

281D Build Thread.

258D Build Thread

This thread can be used as an announcement, advert, and celebration of sorts but tech stuff should go in the aforementioned DIY thread. We normally don't allow cross-posting of very similar material across sub-fora, as it gets confusing and messy for users as thread expand. The mods also get accused of having deleted posts when they are actually perfectly fine, but in another thread. We'll allow this and see how it goes as the topics are slightly different.
Thanks Kent. That was pretty much my thinking - the specific build stuff should be in the DIY forum. Any other high-level/generic discussion about these can be here.
Dunnington Audio - Various Buchla format accoutrements available

User avatar
Peake
I'm in ur DIY. Filling cases with Buchla
Posts: 7210
Joined: Fri Nov 07, 2008 10:00 pm
Location: Loss Angeles

Re: New approaches in Buchla format DIY

Post by Peake » Fri May 29, 2020 3:36 pm

Congrats!
This is not the place I'd imagined it to be.

User avatar
hox3d
Common Wiggler
Posts: 137
Joined: Fri Feb 02, 2018 6:30 am
Location: Grenoble, Alps

Re: New approaches in Buchla format DIY

Post by hox3d » Fri May 29, 2020 3:48 pm

That's great! So finally one could build a Buchla system and get rid of those expensive EDAC connectors... :razz:
Matte-fueled habits

djs
Super Deluxe Wiggler
Posts: 1183
Joined: Wed Sep 01, 2010 8:36 am
Location: South Beloit, IL

Re: New approaches in Buchla format DIY

Post by djs » Fri May 29, 2020 3:55 pm

hox3d wrote:
Fri May 29, 2020 3:48 pm
That's great! So finally one could build a Buchla system and get rid of those expensive EDAC connectors... :razz:
My little clone system uses MTA156 connectors and normal 1/8" audio jacks instead of tini-jax. So I'm probably going to be tarred and feathered (sorry- i had to) for it, but it works for me :)
"Noise is what the Earth is made of" - David Bowie

User avatar
GryphonP3
Super Deluxe Wiggler
Posts: 1100
Joined: Tue Jan 29, 2013 3:20 pm
Location: Los Angeles

Re: New approaches in Buchla format DIY

Post by GryphonP3 » Fri May 29, 2020 11:34 pm

Reese P. Dubin wrote:
Tue May 19, 2020 6:17 pm
I will absolutely start my own system when this hits the critical mass (259/281/292/266)

AMAZING!
Plus one on this, would give me the exact push i meed to actually get around to doing my 200 clone system properly :)
My cat can eat a whole watermelon ...

User avatar
Reese P. Dubin
Super Deluxe Wiggler
Posts: 1362
Joined: Wed Dec 17, 2008 12:33 pm
Location: Absolute Elsewhere

Re: New approaches in Buchla format DIY

Post by Reese P. Dubin » Sat May 30, 2020 8:09 am

djs wrote:
Fri May 29, 2020 3:55 pm

My little clone system uses MTA156 connectors and normal 1/8" audio jacks instead of tini-jax. So I'm probably going to be tarred and feathered (sorry- i had to) for it, but it works for me :)
The system I built for my pal I used mini jacks instead of tinys. It was never going to mix with 'real' buchlas, and everything to do with tiny jacks is depressingly expensive and unnecessary.Also being able to plug a walkman directly into a comb filter without a special cable...priceless.

User avatar
papz
Super Deluxe Wiggler
Posts: 3370
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Re: New approaches in Buchla format DIY

Post by papz » Sat May 30, 2020 8:40 am

Cliff S6 sockets work fine with both mini jack and tinijax plugs.

Image
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

User avatar
Reese P. Dubin
Super Deluxe Wiggler
Posts: 1362
Joined: Wed Dec 17, 2008 12:33 pm
Location: Absolute Elsewhere

Re: New approaches in Buchla format DIY

Post by Reese P. Dubin » Sat May 30, 2020 9:29 am

Interesting, do they clear the PCBs in the stacks?

User avatar
papz
Super Deluxe Wiggler
Posts: 3370
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Re: New approaches in Buchla format DIY

Post by papz » Sat May 30, 2020 9:51 am

Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

Post Reply

Return to “Buchla, EMS & Serge”