building a buchla

my attempt at building a Buchla 208 clone .

[fi0cz]

Done / Undone

I’ve corrected all the issues and , as it seems , all the problems are gone . There was a missing soldering point on the Random PCB , I had to do a little mod for the noisy reverb and the sequencer started working as it should only moving a little bit the PCB on the motherboard . 

I’ve made some kind of  calibration , using this tutorial here and using a little bit of taste of mine . If I have to be meticulous (which I’m not ) , I would say that I’m not completely satisfied with the timbre waveshaper sound on the Complex oscillator but in the end this beast is going to keep me musically occupied for the next years for sure . 

It’s fully functional , it sounds awesome and it’s a lot of fun !! 

At this point I could say : “ I’ve build a Buchla !! “ but I feel that this synth needs a proper case to be done . I’m pretty uncertain on what it’s going to be , a flight case ? Sidewoods ? For now I’m going to put it on an Hammond box ( not without a lot of work again ) and keep on searching for the right housing solution .

[fi0cz]

Good news ,bad news .

I’ve powered it up and there has been no explosion , there was no fire and I’ve not burned my house down . This is the good news !! 

The bad news is that it has a pair of issues and I see a lot of troubleshootings in my near future . Many people claim that this is where the fun begins but I have to say that I like really much  when , at the first power up , all is working as it should . 

Just for the record , here’s the issues in no particular order :

- The sequencer works very well in 3 and 4 step , when in 5 step it goes well for a minute and then it goes in 3 step mode ......... 

- The random section does not work at all .

- There’s an awful signal bleeding from the Modulation oscillator to the reverb . 

- The 208 works only in “both” mode and “program board” mode , there’s no activity when I put the switch on “panel” mode .

There’s something else : I’ve played with it a couple of hours and it sounds GREAT !!!!!! And this is another good news .

[fi0cz]

UA726

Please allow me to introduce this two little suckers named ua726 . Take a look at their technical specification here  and try to understand why this 2 little bastards goes for 60 euros each !!! I don’t know what is their function inside my 208 but I like to think at them as they were 2 famous tenor with a wonderful voice standing out in a chorus and , for what I had to pay for them , they better sing like the fucking Pavarotti !!! Reading in the Muffwiggler forum I’ve stumbled in a conversation about them and ,as it seems , you can substitute them using 2 2N3904 .Now , I tell you how but ,as usual , don’t blame me if your synth is going to explode in your face ……..  :

"All you need to do is substitute B1-E1-C1 and B2-E2-C2 with 2n3904's. Leave the other connections open. I would recommend having 2n3904's from the same production batch, or matched.”

I don’t know if my 208 it’s going to sound the same but I think it’s worth to give it a try , I’ll try the 2 options and see what happen ……….I can always sell them again .

[fi0cz]

No money no funny

As it seems I have all the ingredients for the recipe now , all the rare parts , the sliders , the spring reverb and all the little screws that are going to let the beast sing as an angel in heaven ....... So how does it cost to put together a buchla 208 clone ? As I’ve already wrote , this is not a cheap build ....... here are the numbers : 

208 Clone PCB set ( bought with a christmas discount )  -  300 $ 

208 Panel  - 80 $

Rare parts and switch caps  - 155 $

Rogan Knobs set  - 30.90 $

Mouser orders for parts - 350 $

Vactrols - 106 $

Sliders - 100 $

Spring Reverb - 32 $

UA276 - 150 $

Other parts (screws ,some pots and switches )  - about 50 $

1353.9 $ is the crude and bleeding truth !! and this without even thinking that I’ll have to put this jewel in a case and feed him with some kind of magic power supplier . 

With this kind of numbers I cannot really accept a defeat !! This synth , in the end , is going to work and it’s going to sing like an angel for real ...............

[fi0cz]

Rogan !!

.....and they came today . Can I use the word “sexy” for a knob ? 

[fi0cz]

12 Boards . Done .

As it seems the 12 PCB’s are populated , of course I miss some parts and I keep on searching for substitutes of the  components that are no more in production or are simply out of stock .Hunting for them will be my next move before I start working on the motherboard . I don’t see a light yet but now I believe that maybe ..............

[fi0cz]

Vactrols

So here they are , vactrols , the photoresistive opto-isolators that the DIY community and the modular synth people loves so much (don’t ask me why) .These are VTL5C3 type and you’ll need 15 of them if you want to build a 208 , they are not rare but one of them goes for 6$ ..... (do the math) .

In the meantime I have populated Cards number 7 and number 8 already and I’m in a group buy for the reverb tank ........so far so good . 

[fi0cz]

Card number 6 and the hard to find uA726 .

After a very good start with this project , for the first time I feel pretty stuck . There's this ten legs big transistor that seems to be no more in production , it goes for more than 60 $ ( and I need two of them ) if you are lucky to find one . Searching on eBay I've found a Chinese vendor that sells them for 12 $ ( I don't know if they are original but I decided to give them a try and guess what ? He does not ship to Switzerland . Why this universe hates me so much ? 

I don't know what is the function of this transistor and ,to be honest , I don't really give a shit . All I know that I need it to make this synth work .So what now ? Should I wait for some of them to pop up in eBay ?Should I ask for help to some expert ?  I feel I have to move fast on this because "Passivity is fatal to us .........." (Mao Tze Tung ) 

EDIT : a friend of mine that lives in the UK ,after reading this post , ordered two and he will ship them to me once he get them . Now I have a new Hero ,now I have a great Friend !!

[fi0cz]

Card 5 - Without vactrols

I need Vactrols !! This Resistive opto isolators are optoelectronic devices consisting of source and detector of light that .... oh well , here's the Wiki link http://en.wikipedia.org/wiki/Resistive_opto-isolator . They are pricey but not difficult to find , the ones I need here are the VTL5C3 and they goes for about 5 euros each . I'm already working on card 6 and 7 and there's something else that's not cheap and , as it seems, very hard to find ............... 

[fi0cz]

CARD 4 - Pulser

The pulser card is ready . I miss the same parts on every card , some 1000 Pf and 100 Pf ceramic capacitors .The ones that are listed on the bom are unfortunately out of stock at Mouser , We are talking about some 5% // 50 V // 5mm //Class 1 with an operating Temperature Range from -25C to +85C // A radial termination style with a temperature coefficient of +350 to -1000 PPM / C . 

I don't have any idea of what I've just wrote , to me they seems just like some funny orange and red circles with soldering legs . 

[fi0cz]

Card 3 - Envelope Generator

The card number 3 is quite accomplished except (again) for a pair of missing parts . The good news is that two days ago I was looking at the BOM for the first 3 cards and I've realized that  ,apart for a pair of things that are out of stock for real , I made some errors in my orders . This means that in a couple of days most of the missing parts will arrive . 

[fi0cz]

Switch caps and rare parts

Postman came with some cool colored switch caps and some (not cheap!!) rare parts . 

We have : 2 x SN15846N // 1 x 2N3806 // 1 x DG200BA // 2 x 2N4340 // 2 x 2N4341 // 2 x 2N3565 // 2 x 2N4339 

Are this parts rare for real ? Is outhere some kind of substitute for this pricey  parts ? Only time and experience will tell . 

[fi0cz]

"Out of step" ( Minor Threat )

Pcb number 2 : Random . I know that this is going to be my favorite function on the 208 ( in the remote case that is going to work ) . We are talking about a pseudo random generator with 4 (!) uncorrelated distinct outputs . Again I miss some parts (a pair of resistors and a capacitor ) but I've decided to fill the first 5 pcb's and then make a pause to hunt the missing components .

[fi0cz]

"Voyage to Infinity " ( Bad Brains )

So it turns out that the PCB number one was the sequencer pcb , a 5 stage sequencer with a switch for every step and a selector to have it with 5 , 4 or 3 stages .It went smooth , very easy to work on it (had to unsolder a wrong resistor : ) and had no problem at all ) and as it seems I have not lifted a pad (I'm kinda scared with lifted pads 'cause I've already had that problem working on infamous Serge CGS114 DUSG ) .

Now the bad notes : I already miss some parts . Some capacitors are missed from my recent order and a 330k carbon resistor was  out of stock .That makes me  think that things are going longer than I've already expected . 

[fi0cz]

"Another dimension , another dimension" (Beastie Boys)

Today came the packet with the PCB's and ,as I've expected , they look as gorgeous as difficult to build . We are talking about a 12 little PCB's , a motherboard , 2 magic buchla program cards and a little strip with some contacts ( I have really no idea about how can it be useful……. ) . I think I'll take the easy path and start populating all the PCB's and leave the motherboard for the great finale . The 12 PCB's are labelled from 1 to 12 and (excuse me for my sophisticated sense of logic ) I'll start populating them in crescent order . I have already ordered and received from Mouser the components for the first 5 PCB's so I would say that it's already time for some soldering .... There are no indications on the pcb's about the components positioning but (for my great fortune) it's all very well described here http://electricmusicstore.com/blogs/build/12614717-stored-program-sound-source-model-208, every pcb has its nice diagram and its useful BOM . It's great 'cause every time I have to look at a schematic I always feel a light sense of nausea .

[fi0cz]

"Let's start today !! " (Gorilla Biscuits)

Here we go !! Yesterday came the panel ,it looks fantastic !! I’ve already mounted some spare bananas that I’ve had from my previous Serge build. Sadly it’s all that I can do for now until I’ll receive the pcb set that I’ve ordered from  http://electricmusicstore.com

So far so good .

                                                               .fiocz

[fi0cz]

DISCLAIMER - !! read this or you're gonna die !!

// I am NOT a professional technician // I am NOT an experienced constructor// I started building synthesizers about a year ago now // I’ve built a Serge panel and few eurorack modules // this blog is about someone building a Buchla 208 clone without having a clue of what he's doing // DON’T follow my path ‘cause the best scenario is you’re gonna burn your house down // in the worst, you are gonna lose your precious life // AGAIN // DON’T take this blog as some sort of tutorial ‘cause it’s NOT // I really have no idea if in the end this synth is going to work and it’s very likely that it’s NOT going to work . //

                                                                             .fiocz