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Buchla 106 discrete mixer etch artwork
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Author Buchla 106 discrete mixer etch artwork
Peake
NOTE: NEW VERSION OF ETCH ARTWORK IS AVAILABLE WITH FATTER TRACES AND LARGER SOLDER PADS. It's the first attachment with the appropriate comment. The old version's pads could be eaten by #65 and similarly-sized drill bits.

New artwork for the 106 design by Buchla and Associates. Don did not reply to my email requesting permission to publicly release this for DIY purposes only...if this is the straw which breaks the camel's back so to speak, I blame society.

4"X6" PCB size, Buchla format.

I have built one of these and confirm functionality. However...

-NOTE: THE INVERTER SECTIONS DON'T REALLY WORK, IGNORE THEM. (July 2014)
-The transistor gain appears to be very important in setting the overall gain. This will distort with Buchla-level osc inputs (1.2VRMS+, "consumer level" as in CD players, etc.)
-You may wish to use matched pairs with less than 300 Hfe each; both channel matched pairs would have to be the same, checking to see if they overload the sum section

-All transistors should be the same gain (Hfe) value, 5% or less deviation.

-Added inverting outputs per section as a falling saw sounds different through a filter than a rising saw...subtle but there
-The inverting transistor adds as well; have not checked to find a unity value
-Designed for Mouser PN3565, EBC, per the original.
-Low Hfe 2N3904 or BC550A might work just fine
-Designed IIRC for Elna Silmic II type audio grade capacitor pitch
-This has no seeming intrinsic magic or character, sorry; just a mixer.
-The schematic says +12V; it is a +15V circuit although; untested on Euro.
-This was designed from a schemo predating the CBS schemos common on the net, which apparently have purposeful mistakes.
-The original had 10uF and 100uF used throughout the circuit; I'm not sure which were where in the original. All pads appear to be for 100uF. Check the CBS schemo but note there is a mistake and two sections do not mirror each other.
-The original electrolytics were Mallory 150 types.
-I don't have a printer handy; I don't remember if the ART will print at the proper size. Should be easy to measure due to the provided ruler graphic.
-Potentiometers should be Audio, not linear.
-There are two jumper wires, one from each section to the summing section.

Sorry for the incomplete nature of the project.

Here is the CBS schematic. I believe it is correct with 10uF before the transistor pairs and 100uf afterward. You will note one of them is different, not a mirror of the first section.

http://rubidium.dyndns.org/~magnus/synths/companies/buchla/Buchla_1060 _1_200.jpg
decaying.sine
When I emailed him about the 259 it took a couple weeks for him to get back to me. Heck, I just emailed a few days ago to buy something and I didn't hear back!

Looks like you redid the artwork so I am sure it's not a problem. The lines are a nice thickness for home etching. Smart thinking. You redid the schematic too. I think you are fully up to speed to proceed.
Peake
It was done for me; I don't have the programs or ability to use them...and I asked Don well over a year ago, in general regard as I also have a Buchla 258B clone derived directly from the original schematic, new artwork/layout etc. using original parts; one of his Associates replied a few times but there was never a specific "Okay" or blessing, so the 258B remains unreleased (plus it's not 1V/Octave and uses the uA726 and other relatively expensive/rare components. If you've seen my posts in J3RK's mutant 258 build thread, you'll know.

I figure a mixer might not be "bad" to post. I hope I'm correct. I have vast regard for Don and his work and will remove all of this if need be. Thanks.
djs
decaying.sine wrote:
When I emailed him about the 259 it took a couple weeks for him to get back to me. Heck, I just emailed a few days ago to buy something and I didn't hear back!


out of curiosity, what was his response on the 259?

"I'm planning to re-issue it for $200 for an assembled module, so don't bother" ? smile
decaying.sine
djs wrote:
decaying.sine wrote:
When I emailed him about the 259 it took a couple weeks for him to get back to me. Heck, I just emailed a few days ago to buy something and I didn't hear back!


out of curiosity, what was his response on the 259?

"I'm planning to re-issue it for $200 for an assembled module, so don't bother" ? smile


I think I posted his exact response in DIY, which a search should bring up. Basically, it read that PCB designs and schematics are artworks protected by copyright. My work was a 1:1 clone, which is exactly how I described it to him. He asked that it not be released for profit (which I did not plan on doing) or to the public in electro-music or Muff Wiggler. He also said that he wondered why people were so interested in old designs when they could get something like the 261e.

Re-working things, adapting things, etc. are different. I can only speak of what he reported for my specific instance. There are obviously examples of re-designs and re-implementations of his work. Thomas White, as an example, reproduces the 292c with permission of Mr. Buchla.

It's a complicated area. However, ,my case was simple because I intended for it to be a clone, namely a 1:1 replica, for myself, and I chose to do this for personal reasons (e.g., I greatly admire the PCB artwork aesthetic, as an example).

@Mike Did you find a good source for UA726?
Peake
No, I have no source for them, and I'm getting edgier about leaving this up without his permission. I have no idea if any of the many clones floating about in this and other fora all have his permission or not.
decaying.sine
Peake wrote:
No, I have no source for them, and I'm getting edgier about leaving this up without his permission. I have no idea if any of the many clones floating about in this and other fora all have his permission or not.


I am pretty sure you can guess the folks who have received permission versus not. I think it's reasonable to believe most do not have permission because if they did they'd report it in a clear manner. Josh and Thomas White are very clear examples of use with permission for the 281/4 and 292c. I think if you make a good attempt to redo the schematic or at least not release it and update the PCB artwork then you are pretty clearly not infringing on a copyright. I've been impressed with how Dustin handled the 258J. He takes the circuit, does a new layout with his own artwork, and adds some features to help update the design but also leaves the possibility of doing an authentic approach.

Most people just want these cool designs available and genuinely enjoy sharing with like minded folks who all care about respecting the original designer, that persons wishes, and the associated work and legacy.

In my years at Muff's and EM, I can really only think of one or two folks who rubbed or currently rub me the wrong way.

Talk to Luka in PM. He's good at helping make these decisions.
decaying.sine
And, BTW, I appreciate you sharing your efforts. I feel comfortable thinking your in this for the right reasons and I've always liked your desire and thoughts on doing the vintaj and investing in the parts for the vintaj!
Peake
Don's work is brilliant on so many levels; it's wonderful to see more and more people adding his designs to their DIY rigs.
Jarno
Seems like a fun thing to build. As for the origin of the work, judging from his replies for other work I think he has moved on electronically, his 200e stuff is so different from the older work. The only thing he doesobject to is the use of his artwork, which is still the same recognisable style. Understandable from a brand management standpoint. I also like his statement on how he feels these circuits are obsolete, they are still worthwhile to us tinkerers though, because of the funny stuff they contain.
Peake
I just can't help imagining that this would be better with vactrols hihi
Jarno
Guinness ftw! Vactrols FTW!

Does Don still use vactrols in his current modules?
nrdvrgr
Jarno wrote:
Guinness ftw! Vactrols FTW!

Does Don still use vactrols in his current modules?


Hell yes! Plenty of them also!
Rod Serling Fan Club
Peake wrote:


-The transistor gain appears to be very important in setting the overall gain. This will distort with Buchla-level osc inputs (1.2VRMS+, "consumer level" as in CD players, etc.)


The mixer distorts at normal buchla levels?
Peake
Yes, even from a single oscillator when the input gain is at or near full. Then again, my 258B clones are a bit hotter than 1.2VRMS, but not -that- much. I'm not sure if the 100 series oscillators were of lower level; I don't imagine they are.

Edit July 2014: The input level pots should easily be able to trim the hotter 200-series sources out of distortion.
camelneck
Thanks for sharing this project with us. I was contemplating building a small Buchla synth (10 - 12 modules) that uses genuine Buchla circuitry, and this is the only Buchla Mixer Project (with detailed build info) that I've ran across. (Too bad nobody has done a similar project for the Buchla 207 Mixer/Pre-amp.)

As for getting Don's permission, I wouldn't worry too much about it. Maybe Don hasn't had time to reply, or perhaps he might think a simple mixer project like this wasn't worthy of a reply. Unlike the Buchla 258, 259, 266, 281, 292, etc., there's nothing special about the design or sound of this module (as you pointed out yourself). Actually, this design is about as generic as you can get.

The fact is you notified Don about it. I'm sure that if he didn't want you to build it, he'd let you know.

QUESTIONS:
I do have a couple of questions about the sound of this module.
Since this is a pretty basic design that uses the original transistors, I am curious about noise levels.
1) Do you find the output of the mixer to be fairly clean and noise free?
2) Have you compared the sound of it with a mixer that uses cheap low noise/low distortion op amps which could range from cheap op amps like the TL072 (JFET) and NE5532A (Bi-polar) to the more expensive op amps like the OP275? If so, how does it compare?
3) Do you know if the Buchla 206 Mixer uses discrete circuity like the Buchla 106 or does it use op amps?

(I know a lot of people may build this module in order to build a Buchla 107 clone, or build a synth that uses original Buchla circuitry. However, I am curious about how it stacks up against a more modern, op-amp-based design.)
camelneck
xxx
Peake
camelneck wrote:
Thanks for sharing this project with us. I was contemplating building a small Buchla synth (10 - 12 modules) that uses genuine Buchla circuitry, and this is the only Buchla Mixer Project (with detailed build info) that I've ran across. (Too bad nobody has done a similar project for the Buchla 207 Mixer/Pre-amp.)

As for getting Don's permission, I wouldn't worry too much about it. Maybe Don hasn't had time to reply, or perhaps he might think a simple mixer project like this wasn't worthy of a reply. Unlike the Buchla 258, 259, 266, 281, 292, etc., there's nothing special about the design or sound of this module (as you pointed out yourself). Actually, this design is about as generic as you can get.

The fact is you notified Don about it. I'm sure that if he didn't want you to build it, he'd let you know.

QUESTIONS:
I do have a couple of questions about the sound of this module.
Since this is a pretty basic design that uses the original transistors, I am curious about noise levels.
1) Do you find the output of the mixer to be fairly clean and noise free?
2) Have you compared the sound of it with a mixer that uses cheap low noise/low distortion op amps which could range from cheap op amps like the TL072 (JFET) and NE5532A (Bi-polar) to the more expensive op amps like the OP275? If so, how does it compare?
3) Do you know if the Buchla 206 Mixer uses discrete circuity like the Buchla 106 or does it use op amps?

(I know a lot of people may build this module in order to build a Buchla 107 clone, or build a synth that uses original Buchla circuitry. However, I am curious about how it stacks up against a more modern, op-amp-based design.)


1) It's clean and AFAIR, noise-free. It's been a while since I powered it up but I did note the distortion but not any noise worth remarking upon. I don't believe it's an issue.
2) Have not compared. Would recommend JFET input opamps over standard types. I've always liked their sound better (LF353).
3) I believe the 206 uses opamps.

You'd likely get the same sort of noise performance and sonics out of a TL072-based mixer. I did this project just to see, just to experiment with the discrete. Just in case there was something magical in there hyper hihi

I'd contacted Don regarding non-profit sharing of my earlier 258B project, which works excepting some odd random foibles. And like I said, this mixer isn't full-featured and it doesn't have the fun of the later models with vactrols all over the place. It's just a plain discrete mixer...for those who must have one of them and/or experiment with it.
Rod Serling Fan Club
The minimoog mixer apparently adds to the sound because it distorts pleasantly. I guess that is the purpose of the STG .MIX. I suppose there is no objective way to talk about such things. Do you think it adds anything from that perspective? Do you think the distortion may be from the interpretation of the build or that the originals were likely that way?

From your description, I'm not sure whether I care if the circuits behind my mixer are truly buchla clones or inspired. Particularly as new/alternate components are likely to make it more divergent and per your description, there's nothing special about it anyway.
Peake
I thought the STG.MIX was from the modular (CP3a).

I've never played a 100 series so I cannot say if production units acted in this manner. I highly doubt it. I think it's just a matter of gain. Yep, I'm only interested in circuits which work great and sound good regardless of their content. This project was a "look see" experiment. I find I learn from this sort of thing and having to ask new questions.

I'm not sure what the end result is in regard to selecting transistor pairs to create the right gain throughout the circuit. This is certainly why designers joyously embraced the first operational amplifiers!
J3RK
Just to add a cent or two to this. When I did the 258J, I was actually working out of Mark Verbos' redrawn, and hacked together schematic. So, I contacted him. (it uses the old PNP pair OTA core that everyone (including myself,) use). The wave shaping circuitry is the same as the original 258 though.

With the 291 adaption, I used a couple of different redrawn schematic, and did the PCB layout from scratch.

I've been a bit more diligent with this sort of thing now though. Most of my design work now is my own, or co-developed with a friend, but anything that I borrow I do make sure to contact the original developer. Some of them take a long time to get back to me, and some of them are very quick to answer. I haven't come across anyone yet that wasn't extremely nice to deal with, and even excited about some of my adaptions. (Rene Schmitz, Thomas Henry, Nicholas Woolaston, and Ken Stone come to mind as being extremely nice to talk to about such things.)

I haven't yet contacted Don himself about any designs, but I've kind of veered off toward making my own designs that do similar Don/Serge/West Coast functions using other means/methods. I've kind of lost interest in exact clones for the most part. (except maybe the ARP 1047... That one is still calling my name, even though I'm working on my own state variable...) Some kind of odd universal pull from it. Must be those new Boson particles or something.... screaming goo yo
Peake
Not calling you out bro, I like your stuff 8_)
camelneck
Peake wrote:
New artwork for the 106 design by Buchla and Associates. Don did not reply to my email requesting permission to publicly release this for DIY purposes only


There may be a good reason why Don hasn't been responding to requests for permission to clone these old modules. As many people know, he sold the company earlier this year and it is now called Buchla Electronic Musical Instruments (BEMI) instead of Buchla & Associates. I know Don works for BEMI as their chief product designer, but maybe he feels that he no longer has the power to grant such permission.

Its only been a few months since the company changed hands, and I'm sure there are all kinds of power struggles going on. Maybe it is still unclear who should make these type of decisions or maybe Don is just being careful and don't want to be accussed of overstepping his boundaries. The company is probably still in transition and Don may be so busy with reorganization and planning that he just hasn't had time to reply.

On the other hand, Don has been overwhelmed with requests from the DIY synth community asking for permission to build quite a few of his old modules. Who knows? Maybe BEMI is considering selling kits & PCBs themselves. smile

IMO, all these DIY projects have generated a widespread interest in Buchla products that wasn't there before these projects began. I know I was never that interested in Buchla modules until these DIY projects started becoming available.

I also know several DIY builders who have bought 200e modules to use in conjunction with their DIY 200 modules. I know these people would not have bought the 200e modules if it wasn't for the fact that they had already built some DIY Buchla modules.

I honestly believe that all these DIY Buchla projects have boosted sales of 200e synths and will continue to do so. Let's hope the new Buchla company believes this, also.
J3RK
Peake wrote:
Not calling you out bro, I like your stuff 8_)


Just saw this. I didn't feel like you were. Just chiming in. w00t
camelneck
Rod Serling Fan Club wrote:
The minimoog mixer apparently adds to the sound because it distorts pleasantly. I guess that is the purpose of the STG .MIX. I suppose there is no objective way to talk about such things. Do you think it adds anything from that perspective? Do you think the distortion may be from the interpretation of the build or that the originals were likely that way?

From your description, I'm not sure whether I care if the circuits behind my mixer are truly buchla clones or inspired. Particularly as new/alternate components are likely to make it more divergent and per your description, there's nothing special about it anyway.


The reason why the Minimoog's Oscillators overdrive the filter is because a Moog Engineer made a mistake and the audio signal entering the VCF is at least +10db too high. This results in the distortion that you hear when the mixer controls are turned up above 6 or so. Moog didn't discover the error until 3 or 4 months after they started selling Minimoogs to the public. They could have easily reduced the level of the audio so there would be no filter distortion, but they were smart enough not to mess with a "good thing".

Nevertheless, the Minimoog's Mixer is rather unique because ithe signals from the oscillators are mixed via a passive mixer--a very crude mixer that doesn't use op amps or transistors. Unlike an active mixer (one that uses op amps, etc), the output gain of a passive mixer isn't regulated with a feedback path.

Thus, unlike an active mixer the attenuator pot for oscillator 1 can effect the gain of other oscillators and maximum output from the mixer isn't achieved unless all 5 of the Minimoog's Mixer pots are set on 10.
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