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i finished my GSSL PCB's yesterday... all the parts are there... now i only need to do some more wiring and i will see if i get sound out of it... or smoke
i've been thinking about taking on a cheap diy synth project of some sort...does anyone have any recommendations for beginners? i remember someone (maybe sneakthief?) posted a link to a site a while ago that looked interesting...specs for modding some easy to find circuit board....
i've been thinking about taking on a cheap diy synth project of some sort...does anyone have any recommendations for beginners? i remember someone (maybe sneakthief?) posted a link to a site a while ago that looked interesting...specs for modding some easy to find circuit board....
As a beginner myself, I've found www.musicfromouterspace.com and www.cgs.synth.net projects very manageable...Really good documentation.
was about to post the same:)
i'd like to give the cgs bi n tic filter a try
was about to post the same:)
i'd like to give the cgs bi n tic filter a try
Yeah I was thinking about the same one.
Dez has the good DIY links covered. I'm more of a CGS/Ken Stone guy myself.
Speaking of which, he bi-n-tic is the most insane filter I've ever heard. It's like listening to c-beams on the shores of orion lol.
...and it's a full-blown 1v/oct oscillator too. I modded mine to have the outputs for each of the pulse divider's 4-octaves. There's another mod which lets you get the saw wave out from it too.
Ooh, I love CGS/Ken stone!
Need to do a big order from there in the future.
I'm just one module short from finishin my modular. I've built 23 modules so far.
The latetst is a breadboard of the CGS Wavetable module. It's not functioning properly. But I'll solve that.. somehow in the future 
<- waveform from the VCDO
i finished my GSSL PCB's yesterday... all the parts are there... now i only need to do some more wiring and i will see if i get sound out of it... or smoke
cool!
that's where I am, too.... though put it aside for the last 2 days to investigate website software. Really need to get back to it and pass some audio this week.
Anyway - did you mount the switches in the switch PCB, or did you wire them off-board? And are you planning on making it a straight GSSL, or are you planning on adding oxford/thrust/etc mods?
Echolot wrote:i finished my GSSL PCB's yesterday... all the parts are there... now i only need to do some more wiring and i will see if i get sound out of it... or smoke
cool!
that's where I am, too.... though put it aside for the last 2 days to investigate website software. Really need to get back to it and pass some audio this week.Anyway - did you mount the switches in the switch PCB, or did you wire them off-board? And are you planning on making it a straight GSSL, or are you planning on adding oxford/thrust/etc mods?
finished wiring. should i dare plugging it in..? just need to make some y-cables to insert in my desk.. don't have enough xlr's here atm.. damn
i mounted the lorlins on the pcb for now. but we'll see how it all fits in my planned wooden enclosure - i can still desolder them if necesarry... (actually the front will be left overs frrom my laminate floor, but it looks really vintage, kind of dark oak.. great!).
i placed it all in an improvised cardboard box for now so i can carry it around all together. can post some pics later maybe
and i want to include oxford mode, but i want to get it working first on it's own before i add further mods
oooh...... you put the bridge rectifier in the spot for an on-board transformer.
:-)
but that should be fine if you wire the secondaries of your PSU transformer to the pins for the on-board transformer secondary...
It's like listening to c-beams on the shores of orion lol.
Best description ever!
oooh...... you put the bridge rectifier in the spot for an on-board transformer.
:-)but that should be fine if you wire the secondaries of your PSU transformer to the pins for the on-board transformer secondary...
yes that was how i intended it... saw some pics of people who did it the same way so i thought it would be ok like this...
though i'm still puzzled a bit about the toroid, not that its hard to understand how it works and what to do with it, i just have the fear i forget something in my pot brain and the whole thing goes up in smoke... though it seems quite simple, from the toroid i have two yellow cables going to the mains, and for secondaries i have red-green and brown-blue wich go to the pins on the MB, so basically . . . it should work
whats with yours? you passed some audio yet?
going to order Trevor's DIY9090 boards after payday.
Anyone have experience with these? As far as sound quality relative to the real 909?
Going to be sequenced with esx/rm1x/rs7000 or something.
Klee in Wiard format.
2 more Klee sequencers to finish
thats so hot...thats a schaffer panel right?
Schaeffer yeah
yes that was how i intended it... saw some pics of people who did it the same way so i thought it would be ok like this...
though i'm still puzzled a bit about the toroid, not that its hard to understand how it works and what to do with it, i just have the fear i forget something in my pot brain and the whole thing goes up in smoke... though it seems quite simple, from the toroid i have two yellow cables going to the mains, and for secondaries i have red-green and brown-blue wich go to the pins on the MB, so basically . . . it should work
whats with yours? you passed some audio yet?
cool! just checking.... yeah it can definitely work that way!
:-)
so you have 2 separate secondaries? well in that case, the 4 connection points on the transformer footprint will come in handy.
the secondaries should work connected either way around, but do you have a diagram of the transformer windings? Ideally you just want to have the "bottom" of the top winding connected to the "top" of the bottom winding...
No I haven't passed audio yet.. need to make up some i/o wiring. But I'm still stuffing about with website stuff, and other things over here.
Echolot wrote:yes that was how i intended it... saw some pics of people who did it the same way so i thought it would be ok like this...
though i'm still puzzled a bit about the toroid, not that its hard to understand how it works and what to do with it, i just have the fear i forget something in my pot brain and the whole thing goes up in smoke... though it seems quite simple, from the toroid i have two yellow cables going to the mains, and for secondaries i have red-green and brown-blue wich go to the pins on the MB, so basically . . . it should work
whats with yours? you passed some audio yet?
cool! just checking.... yeah it can definitely work that way!
:-)so you have 2 separate secondaries? well in that case, the 4 connection points on the transformer footprint will come in handy.
the secondaries should work connected either way around, but do you have a diagram of the transformer windings? Ideally you just want to have the "bottom" of the top winding connected to the "top" of the bottom winding...
No I haven't passed audio yet.. need to make up some i/o wiring. But I'm still stuffing about with website stuff, and other things over here.
yep it's whats written on the torroid it has two yellos and the four others wich in pairs give the two secondaries. so i just plug those pairs in the two power inlet pairs you mentioned on the Mb....
about the secondaries working either way round: i thought that too but wasn't sure... now that you say that too.. cool.
thats whats kinda stopped from plugging in the baby today. unfortunately i have no diagram of the toroid... just whats written on it. Yello-yelllo to mains, then pairs :red - green and brown - blue. i thought i'd just wire it in that order. was about to post on prodigy pro but talking here is a zillion times nicer 
feels more familiar
oh yea and the wiring.. that was kinda boring tinning all those wire ends. but now it's weekend maybe we get it both running till next week
If you get the secondaries wired wrong, what will happen is that current will flow into the +ve power supply through both +ve supply diodes in the rectifier for half a cycle, then into the -ve supply through both -ve supply diodes for the other half of the cycle....
so basically, you're increasing the ripple current to what you'd get from 2 half wave rectifiers off a single secondary... up from what you get on the full wave bridge rectifier.
this increased ripple current (you're doubling it) may wear out the main filter caps faster through internal heating of the caps ESR... but I reckon those caps are well overspecced that it'll make no difference.
The increased ripple, if bad enough, could also knock the 15V regulators out of regulation if the voltage drops enough between cycles.. but again, those caps look pretty big for the current that the power supply provides, and we're only talking 1/100th of a second or 1/120th of a second depending on your line voltage frequency...
Here's an idea if you really want to check if it's right: Connect the 2 secondary wiress together you are thinking of joining (off the PCB) and get a multimeter (set to AC) and measure the voltage across the other two unconnected secondary wires. - If it's right, you'll get around 2x secondary voltage, cause they're producing equal sinewaves, and you're adding them together. If it's wrong, it should read zero, cause wired wrong, they'll be producing equal but opposite sinewaves, and adding them together should make 0v... make sense?? just make sure you don't connect the 2 wires of the same secondary... then you will get problems.
I was investigating the 1U racks I bought last night.... they have a really annoying fastening method for the back panel. I'm losing about 1cm of possible connector "height" in the back panel with these things, unless I modify the assembly method. poo. and these looked like such nice racks, too. then again... racking them up is a while off... will go and get some 1/4" sockets for my test wiring today, I hope!
thanks for the lot of info! great. but i didn't work on it over the weekend. the rave got me ...
but now at least all the theoretical aspects are covered, so i hope to finish and test it some time this week..
about the racks: i decided to build a wooden enclosure.. no money for a proper metal case and front plate.. but i have a lot of wooden left overs from building other stuff (my studio desk for example). good luck with yours.. hope you'll get it fixed!
Anyone got some MN3001 and MN3101 knocking about, that I can buy....
Well... finally had a chance to spend another few hours with the GSSL.
I got the transformer wired up, the front panel plugged in (and all the off-board front panel stuff connected) as far as the IO goes, it's just wired unbalanced for now (well, I don't really have that much balanced stuff, anyway, though the balanced outs seem to work fine, too... )
one major screw up, was I put the 2180 for the sidechain in backwards (d'oh!) as in.. lined up with the other two. when it goes the other way around for some retarded reason... very hard to see what pin one is, when you're plugging into a socket on the PCB.
With the sidechain 2180 in backwards, the GSSL passed signal without any distortion, but of course didn't compress....
after a bunch of faffing about tracing signals (damn I wish these boards had proper unique component designators!!) I noticed the problem, and swapped the 2180 around. Good news is it seems to work, but sensitivity is VERY touchy. and my electribe ES-1 I was using for a test device had to be backed way off to about 25% to get less than full scale deflection on my 1mA meter I had wired up for testing... and threshold pot doesn't seem to do much at all. But ratio, attack, release & makeup gain seem to basically work as expected.
so, yeah.. I might need another 2180. will have a go at swapping one of the channel VCAs with the sidechain next, to see if the circuit behaviour changes...
Now I'm waiting on turbo boards to come, plus VU meters, plus 8 way sidechain boards, so it's a while before I'll be putting this thing in a case anyway... but good to see it basically working!
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