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1. 

   hollowman
   

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   Expecting a review weren't you? Well that was the intent but you can thank Tom Oberheim for this not being a review. You see my test-bench power supply is exactly the same design as the one he made for the SEM modules. It is a lovely and cost-efficient thing that works superbly with a load on it. However, if you do not have a load connected to it the thing likes to blow its positive regulator chip when you tuurn it off due to current reversal or some such thing that I do not care to elavborate on or explain. Tom's circuit was meant to be always attached to an SEM or two. Mine is on a test bench where it may or may not be attached to anything. So thanks to this situation I managed to blow the positive regulator while powering up my Living VCOs for the 1st time!
   Yay!

   But while I am here I would like to delve into the construction details of this VCO circuit. IT HAS BEEN A HUGE FUCKING PAIN IN MY ASS!!!!
   I have designed circuits including custom printed circuit boards from partially reverse engineered synth modules drawn on napkins which contain some of the oddest topologies and components known to electronics engineering and had them working in a fraction the time this freaqking thing has taken me to construct!

   I mean Mr. Haible no harm here. The man is brilliant and a genius with synthesizer design. Howver his circuit board design leaves me wondering....

   There are decoupling capacitors for which go between the power rails to ensure stable operation of the opamp chips. These capacitors are available as through-hole components which require no more space than the surface mount components he designed this PCB to use. I have a very large and unremmiting hatred for SMT components because they are complete madeness to try and solder by hand. They are designed for robotic insertion machines NOT PEOPLE! Why he chose these components is a mystery because there is plenty of space to use through-hole parts in their place.

   Component-wise it has been a nightmare to source the very common parts this PCB requires. One particular capacitor value seems to be unavailable world-wide!!!! I ordered thes eon a 2 month backorder and then received notice 3 months later that the parts will be further delayed by another two months!!!! Other parts have become so scarce that I am dredging the back-waters of Ebay and cannibalizing older projects to obtain them. Fuck sakes!

   Finally after months of this nonsense I fire up the oscilloscope and signal generator so I can test my VCOs and bang, Tom Oberheim shits all over me for not buying his new SEM instead of these German designed fancy-pants VCOs from Mr. Haible.

   You wanna get into DIY? Go for it. Just have 200 times more patience than me or don't bother. Personally I will not be buying PCBs or kits after this. The shit I design myself works for me with parts I know I can get. Nuts to this shortcut DIY I'm going back to doing it ALL from scratch after this.

   Anyway, keep an eye on the HP9 website. On the Studio page there will be a new project for these VCOs and it will contain much more details as well as the results of finally firing them up when I get my SEM power supply functioning again. So close but so far. Shouldn't be more than a few days now.

   Posted 9 months ago #
2. 

   metaball
   

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   ::Component-wise it has been a nightmare to source the very common parts this PCB requires. One particular capacitor value seems to be unavailable world-wide!!!!::

   i hear a lot of bitching about how they don't make 'such & such' like they used to & at least half the time this seems to be the case. music gear manufacturers & DIY guys account for a small percentage of the components market, so it seems we are often at the mercy of whatever the big guys are ordering by the ton.

   when i worked tech distribution this kind of crap would happen all the time, some massive assembly like & tons of demand all ready to move thousands of units, held up by some $.05 part that was in the original design they ran out of & can't find anymore.

   Posted 9 months ago #
3. 

   hollowman
   

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   Audio Electronics are considered a niche market by component manufacturers. This is one of the reasons sourcing parts for synth-DIY can be a headache.

   Sourcing electronic components is always my least favorite part of any DIY activity. You have to find who carries the part, whether or not it is actually stocked and what the best price is. This sounds simple enough but there is so much that can go wrong. Part numbers themselves can be misleading as there may be several prefixes or suffixes for each PN that may denote anything from the physical package to performance characteristics. So you need to research this via manufacturer's datasheets to make sure you have the correct PN. You have potentially dozens of distributers you might have to compare against each other for best price and S+H cost. These distributers may or may not have accurate reporting of on-hand quantity, price or any number of other important data. So you need to verify as much as is possible. You have to place potentially several orders to different distributers and they all have a different process, form, system and you need to be sure you are ordering the right part from the right place. To make things more complicated I have a large inventory of components I keep on hand. Sometimes they are leftovers from other projects or just common items that should always be available for repairs or whatever. So I have to go through all of this crap too to see what I have that I don't need to waste money on ordering again.

   It is a real headache. But the actual construction is usually relaxing for me. I get very Zen-like while soldering. Then there is much excitement from getting the thing to work for the first time. And finally there is a long-lasting sense of accomplishment which comes back every time you use the thing you made with your own two hands. Best of all is that you have a piece of equipment that is exceptionally unique in that you have built it for your own needs and to your own standards. That makes it worth the headaches.

   Posted 9 months ago #
4. 

   dogmeat
   

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   shit...sourcing parts....try doing that from Serbia....you would have seen what hell is like...
   oh, and the moment you finish soldering everything at 5am, your eyes are red, hands tremble, several times deadly amounts of solder fumes inhaled, and then you connect the power....and the shit does nothing....you start high pitched cursing of the cruel fate, then you found out you reversed the polarity of a capacitor, then you fix that....and it works...tears of joy wash your face, you made SOMETHING...it is your baby! then you start fucking with it, it is great and all, but what if i....it would be awesomest! oh, and case design should definitely be dieselpunk inspired! then you dismantle it, make some schematic changes to your notebook before collapsing to bed, tomorrow you put it aside for something urgent, and for several years it lays on the bottom of a plastic "ideas" container awaiting your attention span of a goldfish to return to it.....ahhhh beautiful DIY :)

   Posted 9 months ago #
5. 

   hollowman
   

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   What always gets me is the never-ending DIY Zombie! For example I am building these VCOs and the test PSU goes tits-up on me so now I have to stop everything and fix that! And that may spawn into some unforeseeable weird problem which generates yet another side project. And before you know it you are completely surrounded by brain-gobbling quasi-functional DIY monsters that haunt you in your sleep and you can't get away!
   Refurbishing my old mixing console is just such a DIY zombie. It never ends. When I think I am close to the end something else pops up its glitchy head and I'm behind another month or so in getting to where I thought I should be by now.

   Posted 9 months ago #
6. 

   Tsarik
   

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   WILL PROBABLY PISS YOU OFF.

   i'm envious of you guy's DIY prowess... but i've barely begun to learn patience.... there are so many interesting things available to build synthwise... the prices are so attractive but i know it would be an exercise in frustration... i'd probably end up delighting in the smashing of whatever failed circuit i endeavored upon

   Posted 9 months ago #
7. 

   dogmeat
   

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   then why dont you get some flight of harmony barebones? everything complicated is soldered, it is rather cheap, and you get to make your own panel, cut your own metal, or use the american variation of schaeffer, it cannot be that hard, and is a rather nice introduction to DIY

   Posted 9 months ago #
8. 

   hollowman
   

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   Paia kits are great for beginners. They come with excellent instructions, are affordable and provide alot of functionality per module. I built their vocoder many years ago and it was a good learning experience.

   Posted 9 months ago #
9. 

   Tsarik
   

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   WILL PROBABLY PISS YOU OFF.

   f(h) is really cool. i have their quad plague bearer but i'm not really interested in many of their other modules

   most of the kits i would be into are probably above my skill set, besides i don't mind paying for quality construction

   Posted 9 months ago #
10. 

    dogmeat
    

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    @hollowman i was thinking of getting their theremin last year, but then heard i needed an oscilloscope, which at that time i didn't have, to make it work properly, so i went with moog kit instead. very satisfied! this year? i hope i can complete midi drumkit, it is arduino based, and i have all the parts, but little time :(

    @tsarik baby steps, that is the key

    Posted 9 months ago #
11. 

    hollowman
    

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    @dogmeat, yeah the O-Scope can be a tall order. But once you make the jump to one you will be glad you did. They are helpful for almost any type of measurements. And priceless for troubleshooting when shit goes wrong.
    The drum kit sounds interesting you have a link for that?

    @Tsarik, I began with this when I started with audio circuits.
    http://www.amazon.com/Electronic-Projects-Guitar-R-Penfold/dp/1870775317/ref=ntt_at_ep_dpt_6

    If you can get it used it is a very non-intimidating book of simple FX gadgets that work with synths as well as guitar. I loved the Phaser project. Was more like a Wah Wah than a phaser though....

    As for me my soldering time went to DEV/NULL tonight because I was auditioning another vocalist that I wasn't expecting this weekend. Life's full of surprises!

    Posted 9 months ago #
12. 

    dogmeat
    

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    oh i got the oscilloscope, bought some old soviet thing for less than 20 euros, ok, there is a lot i lacks, but it became indispensible when i troubleshoot diy projects.
    there is no link to it, it is just 3 piezo pads (wood-piezo-copper_plate-mouse_pad_foam configuration), they go to 3 out of 6 analog ins on the arduino, 3 pots go to other 3 analog ins (each pot changes the midi note of one pad), and there is a 2 digit 7-seg display (represents the last midi note change), and a midi out, it is my design
    when i program drums i almost always do it on the tr-like sequencer of the electribe, but when i want to add some percussion or slight variations which are not that commonly repeated, i have to do it using mouse, and i am sick of it, so this thing will allow me to do it easier, and without breaking the flow

    Posted 9 months ago #
13. 

    hollowman
    

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    @ dogmeat; that was a good deal for the O-scope! Good score! I used to do the DRMO auctions (military surplus) and that is how I ended up with the test gear I have. I do need to invest in a good DMM one of these days though. The one I have is crap.
    I had a homemade drum pad like what you describe. I would plug it into the Clock input of my Juno 6 and "play" the arpeggiator with drum sticks running through a digital delay - instant early 242 LOL!
    It sounds like a cool project. I look forward to seeing details about it on your blog or in here when you finish.

    My remaining shipment of tempco resistors has arrived today!!! Almost time to make some noise!

    Posted 9 months ago #
14. 

    dogmeat
    

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    @hollowman i forgot to ask you, is there an euro version of the living VCOs? i cursory looked at the BOM, and major semis i can find locally (or their replacements), and i've (unwillingly) soldered SM components before
    oh, another question, WTF is a ferrite bead? minimum resistance component? why are they so common in oscillators?

    Posted 9 months ago #
15. 

    hollowman
    

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    @dogmeat; The VCOs are only sold as an unpopulated PCB. You have to design your own panel to mount them (or google for other people's projects and see if they will share their panel designs).
    I had difficulty sourcing the integration caps (2700pF polystyrene). They were sold out everwhere that carries them and not many places carry polystyrene. I ended up using some box film types I had on hand after I got tired of waiting. Also the tempco resistors can be a pain to find. I ordered the extras I needed from Bridechamber. My last order of opamps came Friday and now I still need to order some CA3046 transistor arrays because it seems I didn't have as many on-hand as I thought - oops!

    The ferrite bead is essentially a piece of wire with some ferrometal around it. They increase impedance with frequency for reducing RFI. Mr Haible claims they also prevent soft-syncing between the VCOs by decoupling the local power rails for each VCO circuit on the PCB. This can also be accomplished with 10 ohm resistors in place of the ferrites though.

    Posted 9 months ago #
16. 

    dogmeat
    

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    i know it is an unpopulated pcb, but can it fit behind a 3U euro panel? i will most certainly need to design the panel from scratch, but that is one of my favorite things when DIYin'
    CA3046 i've got in a local shop...but polystyrene caps....fuck, need to search for those.

    when i stumble onto some interesting DIY project i generally try to cursory look for what seem to be the most difficult to find parts, so if something seems impossible or not worth it i don't have the said project as a Shiny Fixation in my head, helps a lot! :)

    Posted 9 months ago #
17. 

    hollowman
    

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    PCB is 4 inches by 6 and a quarter inches. It would fit Frac or Euro racks. It requires +/-15V rails so that could be an issue if you want to put it into a +/-12V Euro system.

    I have metallized poly box caps in place of the polystyrene. I'll let you know how they work out. It is a type of cap typically used for timing and integration circuits and I have seen them used for this in other VCOs. Should be fine. Polystyrene is a better type for its higher stability. Surplus Sales of Nebraska has 1% tolerance polystyrene in the proper value for this VCO but that just seemed like overkill to me and their S+H costs are high for just inside the US. I couldn't even begin to imagine what they would want for international.

    As for shiny fixations that isn't a good way to choose DIY projects. I choose them by utilitarian necessity foremost. I wanted some BIG sounding discreet transistor VCOs. My options were overpriced used synths on Ebay or the new SEM module. The SEM module is $800 for only TWO of those VCOs and with limited modulation routing so I would have had to hack the sucker to use it how I wanted to. In total I would have needed at least 2 of those modules and still had to wrench on them. Just too much. So DIY became the best choice. I get several of the kind of VCOs I want for under $150 with some hard work.

    Posted 9 months ago #
18. 

    dogmeat
    

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    size is great, but voltage is fucked...but those oscs sound great, maybe when i finish other projects, too complicated for now, maybe i could cope with parts scarcity, but starting a different format while i haven't properly set up euro...it has got to wait

    nonono....Shiny Fixation is exactly the perceived notion of utilitarian necessity (apart from a regular utilitarian necessity), you see something, anything...it seems nice, then you look more into it...it is great, like it was just made for you, oh what could you do with it, it can modulate, it can BE modulated, it can rip to shreds, it can whisper sweet nothings into your ear while you cradle it in jelaous sleep, waking in sweat, clutching it...so to circumvent something becoming "Shiny" i first look at feasibility of acquiring/making said "Shiny" thing. if it is too complicated, or if it is too much for my pockets, like a Buchla, i forget it, i can see Cortini play it, but i will not get that burning and longing sensation in my heart like you ripped out a piece of me and put it on a matrixsynth pedestal, always out of touch

    Posted 9 months ago #
19. 

    Tsarik
    

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    WILL PROBABLY PISS YOU OFF.

    Mike, do you have a new SEM or a vintage one?

    i have the patch panel version of the new one.. it has surface mount components instead of through hole like the old one... but some of the patch panel imputs are connected.. and i'd like to disconnect them... you may be someone who can help me do this

    Posted 9 months ago #
20. 

    hollowman
    

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    @Tsarik; I never had an SEM. I cloned it's VCO many years ago and the project wasn't successful. It worked but had glitches I couldn't rectify so I scrapped it after many long months of aggravation. It did sound really good though!

    Why do you want to disconnect your patch panel? I'm not sure how I can help but I'm willing to try.

    @dogmeat; You have a poet's soul my friend. It is obvious to me that you have learned this lesson from much blood, sweat, tears, burned fingers and solder fumes.

    My PSU is still jacked-up! Problem seems to be more bad than I thought. It powers up now but won't settle to the proper voltage unless I turn the adjustment trimmer down 5 turns and then back up again. It is a tracking type supply so if one rail is off, guess what? The other rail is off by the same amount!
    Somewhere in my junk pile I have a +/-18V supply. lemme dig that out and coerce into happily supplying +/-15V. Perhaps I also have some scrap aluminum to deal with the extra waste heat resulting from this coercion.

    Posted 9 months ago #

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