Buchla Clone 259r

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Re: Buchla Clone 259r

Post by papz » Sun Sep 12, 2021 5:04 pm

Will 5% carbon resistors and overpriced obsolete parts bring this magic warm vintage sound ?
No, they won't.

A little interesting read : http://www.portabellabz.be/208pcbfaq.html
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I'm not a synths dealer and don't know of any cheap Synthi secret market.
I don't offer support for attempts to build clones of EMS equipment.
Please don't ask, thanks.

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Re: Buchla Clone 259r

Post by Peake » Sun Sep 12, 2021 5:46 pm

Modern production parts even of the same name as the vintage component don't always have the same operating specs and range (which is why Dave came up with a work-around in the 208/258/285 oscillator sine shaper to take into account sliding IDSS ranges in modern components...some people say the J201 FET is a literal replacement for the vintage 2N4339 but they definitely have different average IDSS and you can't just randomly swap the new part into the sine shaper and expect the desired waveform without Dave's IDSS kluge). It's certainly possible to generally use something like the 2N3904 instead of the 2N3565 or the even higher-gain 3566 but note there can be a serious difference in gain and there may be instances where a circuit expects something like 300-400 and your 3904 is around 130. I wasn't getting a good output level on 158 oscillator builds when I used 3904s. Depends upon the circuit and it's just another set of things to know regarding these modules. I don't know about "warm vintage sound" but there are absolutely components (and related kluges) which must be taken into consideration =to produce the original, expected result=, such as a reasonably clean sine wave.

Regarding the use of 5% resistors where 1% are not specified...some of the 100 Series used 10% variation carbon composition resistors, and some 1% in particular places and the world didn't come to an end...anyone who has used a Buchla system knows it is quirky and the quirks are part of the charm. Although Don increasingly used 1% resistors as they became less expensive, I personally love the quirks and exploring the slight variance between multiple circuits in the same module. To each their own, I don't come to the Buchla expecting laboratory precision, quite the opposite. If you can't please yourself you can't, please your soul.
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Re: Buchla Clone 259r

Post by Don T » Sun Sep 12, 2021 8:00 pm

papz wrote:
Sun Sep 12, 2021 5:04 pm
Will 5% carbon resistors and overpriced obsolete parts bring this magic warm vintage sound ?
No, they won't.

A little interesting read : http://www.portabellabz.be/208pcbfaq.html
If none of this matters, why bother completely duplicating the original traces and parts layout?

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Re: Buchla Clone 259r

Post by papz » Mon Sep 13, 2021 4:34 am

Because it looks nice. :party:
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I'm not a synths dealer and don't know of any cheap Synthi secret market.
I don't offer support for attempts to build clones of EMS equipment.
Please don't ask, thanks.

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Re: Buchla Clone 259r

Post by ArguZ » Mon Sep 13, 2021 5:47 am

Or as Roman said : "It's a fetish"

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Re: Buchla Clone 259r

Post by momo » Mon Sep 13, 2021 9:06 am

In 2016 I started a knarly 259 build - knarly because the boards were a 1:1 copy (i.e inclusive of the numerous erorrs) of the Kevin Lightner scans. I decided, in what I would have known at the time was a slighly bananas idea, to use as many carbon composite resistors as I could. I bought several Allen Bradley types from eBay. I used modern production Japanese made Arcol ones for the rest, easily bought from RS or Mouser. I still remember sanding the AB leads down before soldering. It was an insane way to go.

I then blew it up and resigned it to a drawer, but fetched it back out in Feb this year and cold emailed Dave Brown in hopes to not give up on the project. Dave - I mean, is there really anyone else like him? He started off giving me in depth remote help - it soon dawned on me that he was trying to help me from a-far FOR FREE. What a human being. I ended up doing some rework on the board to make it less insane, then sent it to him. I almost want other stuff to break just so I can have that back and forth email exchange again...

Anyway here is a pic of the board just for fun. I do really love the art of electronics, the appearance of components, the art of stuffing a board and all that. Love it. I would highly not recommend anyone to use carbon composite for this kind of a project just because they change value so easily, with the heat of the iron, and they can change value from day to day and in session with ambient temperature and humidity (they are kind of alive, like the doors in your house that get stuck in the frame twice a year). For me though, aside from the indefinable magic some might claim with old or obsolete tech components, here we have something that is just not so good at doing its job, inherent to the manufacture process, and as Peake's post kind of alludes to, that can be seen as an interesting quirk rather than the engineering perspective of a poor component at a technical level, which I think carbon composites are a good example of, especially given their contemporaries, even carbon films.

I've not really spent a massive amount of time with this 259 yet, and it took Dave and myself quite some effort to sort out, in part due to the cc resistors - there were some cold joints and others where the values were way off, even though I measured each one before installing. Dave was rather polite and didn’t scold me so much for employing them. He did however give me a resistor lesson that has completely changed my thinking around them. Good bloke that guy.
3FD08595-9478-43A2-9473-29C54206A377.jpeg
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Last edited by momo on Mon Sep 13, 2021 9:20 am, edited 1 time in total.

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Re: Buchla Clone 259r

Post by ModHiisi » Mon Sep 13, 2021 9:16 am

Thanks for your lofty views papz & Arguz!

I'm not even sure what "vintage warmness" means these days...

And thanks Peake for your reflective and helpful post, I appreciate that very much!

And your point about quirks and tolerances is especially intriguing and I can relate to that. I know that 1% metal film resistors are 'so cheap' these days that you can easily substitute all the carbon film ones with them. And that the metal film resistors have technically better qualities. And that that can be good in many applications. But not necessarily in all applications, I wouldn't necessarily use them in certain (!) audio paths myself. Although they might deliver crispier high ends, better tracking etc. Definitely can be a matter of taste, though. But, having said that, I definitely am not in any sort of elitist 'audiophile' quest with this. Quirks make things interesting.

Anyway, and somewhat seemingly paradoxically, my point asking about this in the first place was/is that I just want to make that 259 sound and work as 'supposed' and to sound good (to my ears, but of course in the context of, well, how a 259 sounds..).
Last edited by ModHiisi on Mon Sep 13, 2021 10:07 am, edited 2 times in total.
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Re: Buchla Clone 259r

Post by ModHiisi » Mon Sep 13, 2021 9:27 am

@momo: Whoa, that board looks intense! Respect for not giving up on it, and I hope you get that sorted!

About resistors: Yeah, I probably wouldn't consider using exclusively them on a pcb. But figuring out the crucial spots where they could have interesting effect(s), interests me...
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Re: Buchla Clone 259r

Post by Peake » Mon Sep 13, 2021 9:40 am

Momo, that's a deep project! Don Buchla attempted to negate cloning through including several errors in the 259 PCB which require cuts and jumps...or the errors were there unintentionally. I'd never recommend using vintage, out-of-specification carbon composition resistors, don't do it.
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Re: Buchla Clone 259r

Post by momo » Mon Sep 13, 2021 9:46 am

Hello and thanks - the 259 has been singing sweetly since about May, and can track 8 octaves, and is rock solid, which is kind of crazy. My Canadia 259 can go as far as 6. But it has the temp comp resistors in their PCB location, not atop the NPN transistors. I actually wernt with x2 THAT340 in this build on a daughterboard. I'll see if I can find a pic.

BTW don't hang on my advice - where I said above that I matched the 2N3565 at Q3 and 4, initally they were just thrown in at random and everything worked great. It's only when I tried the vintage globe tops (see second pic down above) that I noticed a difference in the mod osc. I then looked at the schematic to track down which pair of 2N3565 might be the culprit, which led me to that pair. As I say, I then matched them for VBE and everything worked great. So if you are matching them which is pretty easy to do, you might want to match all the pairs of 2N3565 on the board located in quite close proximity to each other.

Edit for THAT340 daughterboard pic:
F3A2011E-482C-49DE-AC4A-CA10BCCF042C.jpeg
Last edited by momo on Mon Sep 13, 2021 9:52 am, edited 1 time in total.

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Re: Buchla Clone 259r

Post by momo » Mon Sep 13, 2021 9:49 am

Peake wrote:
Mon Sep 13, 2021 9:40 am
Momo, that's a deep project! Don Buchla attempted to negate cloning through including several errors in the 259 PCB which require cuts and jumps...or the errors were there unintentionally. I'd never recommend using vintage, out-of-specification carbon composition resistors, don't do it.
truth! But now that it exists, I'm just glad it doesn't sound like dog shit. I mean, it actually sounds absolutely immense. But it took an unholy number of hours to get here... I think I know know why Chris (Eardrill) took his hiatus. Having not turned on my system in 2 months, I think I needed some separation time to detox from squinting over the schematics (you would know all about that at least eh? ;)

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Re: Buchla Clone 259r

Post by ModHiisi » Wed Sep 15, 2021 1:42 am

8 octaves, that's amazing.

Thanks once more for all the tips and info! Duly noted again.

And yes, I'm cautious, not messing with the resistors etc. I'm just interested in adhering to the original schematics (where there could be a point in doing so..).

But yeah, I guess I won't mess around too much with this build in general...
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Re: Buchla Clone 259r

Post by Cablebasher » Mon Sep 20, 2021 3:20 am

Hey guys

I notice the various 259 clones (R,SA,B) all state 10-100k pots?

Are there specific values that are best or does it really not matter?

Cheers.

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Re: Buchla Clone 259r

Post by ArguZ » Mon Sep 20, 2021 2:56 pm

It really does not matter when splitting a voltage and ground.
It matter a lot when audio signals go through them

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Re: Buchla Clone 259r

Post by tarandfeathers » Tue Sep 21, 2021 6:59 am

ArguZ wrote:
Mon Sep 20, 2021 2:56 pm
It really does not matter when splitting a voltage and ground.
It matter a lot when audio signals go through them
YMMV - for example the main frequency controls on the 259 have tapering resistors between the wiper and either end terminal, which are designed to interact with a 10k pot to get the response of the control to match the panel legend. Same goes for the attack/decay pots on the 281. If you use a different value of pot, the tapering will change and the response of the control will not be as intended. Really, each control should be assessed on a case by case basis to see if using different values will change the behaviour. As a general rule, 200 series is 90% 10k linear pots for CV related controls and 50k log pots for audio levels, but yeah, always examine the circuit to see if there are particular requirements.
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Re: Buchla Clone 259r

Post by Cablebasher » Tue Sep 21, 2021 8:34 am

Thanks for the info guys

Interesting topic

I notice on the Don Buchla panel schematic doc ( floating online ) that the 2 big frequency pots are 10K Lin.

But the Roman, SAModular and Boops all use 50K Lin for these positions

Is there a particular reason for this?

Link to doc:

http://www.synthfool.com/docs/Buchla/Bu ... le0004.tif

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Re: Buchla Clone 259r

Post by tarandfeathers » Tue Sep 21, 2021 9:56 am

The SA and Boops ones are both derivatives (or copies) of the 259r so presumably they just copied the BOM without investigating further. The coarse frequency pots are different than the rest because you need a longer shaft for the large Rogan knobs but you'd have to ask Roman why he chose 50k when 10k is available in the same line from the same supplier. The tapering resistors on all three are the same value as the original schematic as far as I know so they're all a bit off, I think maybe Dave Brown mentions this on his 259 page, I don't remember. If I'm building PCBs from someone else (which I rarely if ever do now) I pretty much always make up my own BOMs with my own preferences for particular manufacturers, material types, value adjustments (I always use high output LEDs and up the series resistors to reduce current draw etc). This is generally a good idea, I think, since everything in Buchla format DIY is second or third hand info at best.
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Re: Buchla Clone 259r

Post by Cablebasher » Wed Sep 22, 2021 1:39 am

Interesting info Dunnington, thank you.

I shall be building my 259 clone soon so need to investigate further regarding the freq pot value

Always learning…

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