DS 7 clone

[Starspawn]

Here you go, still missing a few extras for the other pads, but sounds nice imo, good low end.

Toothbrush is is an invaluable stripboard tool, when scoring lines (after soldering to prevent tiny shorts) I put alcohol on and brush away the junk





And sounds, just put them hard panned straight into recorder and played for a little while.

https://soundcloud.com/vintersmokk/ds7-mutand-sounds-first-try

And heres the finished one btw
A synwave as left hat, synchime as right, and a monotribe Bassdrum as left pad. As well as a 6 channel panning mixer with buffer for headphone out.

[tokyomatik]

[marioguzzi]

hi all, I'm posting in this thread as I recently bought synthrotek ds8 kit and was attempting a dual build along with a ds7 kit I got some years ago from ebay and I'm facing the following problem (attached a messy picture of the build):

Each synth works well on its own but I get audio out from the ds7 only if the ds8 output is not connected, while the ds8 works regardless the ds7 is connected or not

the pcbs are sharing a 9v battery in parallel, and the only difference I can see is that the on/off switches of the circuits (both placed after the 5v regulators) are cutting the ground and supply line respectively.

What could be causing this behaviour?

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[Starspawn]

It would probably be better to just use 1 regulator and jumper the 5V for the other circuit after that.

[marioguzzi]

I'm getting the exact same behaviour after bypassing the ds7's regulator.

So I tried disconnecting the ds8's output ground line: now I can hear them both, problem is this is obviously true if both of them are connected, but since only the ds7 output jack is connected to ground as soon as I disconnect it I stop getting audio from the ds8

[umschmitt]

May sound stupid, but did you check that the signal and ground wires are not interverted at the output jack (esp. on the DS-7)?

[marioguzzi]

I thought of that but after checking I noticed that though the two pcb share the same ground I found that on the ds7 there's no continuity between ground plane and the output's ground line. I'll have to trace the pcb to check why, unluckily I have no schematics for that pcb

[marioguzzi]

mmm, it seems the output ground line is coming from the non inverting input of the 3080 through a resistor

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[Starspawn]

Heres the schematic http://m.bareille.free.fr/ds7clone/ds7sh.gif

[marioguzzi]

thanks for the help!
yep, I knew that schematics, my circuit is more or less the same but there are some differences from m bareille schematics like the audio output section. I got the ds7 pcb some years ago from a ebay from r shepard, but I can't find any reference to his design

[Starspawn]

Well, lets see, R31 is your R5.
R32 is your R4.
R20, 21 and C5 is your path from the LM to + input.
All the same so far.

The difference is that your R2 and R3 is where the output from the earlier opamp should come in, but in your schematic its grounded instead!

So check if that grounding does indeed connect with the output from earlier opamp, Im sure that shouldnt be the case.
So check continuity there.

Your C1 and R4 should still be grounded.

[marioguzzi]

just found that the output's ground line is coming from an opamp and so it is at a steady 2,5V.
Now I suppose that bringing it to 0V should solve the problem, but is it just matter of replacing the opamp with ground? Do you see anything else to take care of?

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[Starspawn]

What you want to do there is cut between the R2 and C1 points, and then connect another ground point to the C1 ground/output ground.
Then it will be as the other schematic.
But be sure that youre tracing is correct first ...

[umschmitt]

So the node where R2 and R3 meet should be connected to the opamp supplying the bias voltage, not to the minus of the output (which should be your ground), as starspawn wrote. Your dotted line between R3 and R4 should lead to… nothing! Furthermore, there's no capacitor at the output of the CA3080… Maybe you zapped a couple things while reverse drawing the circuit, otherwise it's a strange design to say the least!

Edit: you posted another drawing while i was writing… Starspawn is once more right. Also please put a cap at the output of the freaking OTA!

[marioguzzi]

thanks guys, it's working fine now!

[umschmitt]

Kühl.

[Starspawn]

yay!

[marioguzzi]

here's a picture

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[benuron]

I need help

I build the dual ds7 from Uncle's stripboard layout, but I don't get any sound.
Apparently everything is fine, the only response I get is with the decay all the way up I start hearing the trigger pulse. LFO seems fine as I checked driving one led through a transistor.

Any one got the same problem? Any suggestions?

On the pic there are somecomponents missing but not anymore)

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[Starspawn]

Looks right, but what have you done with the potentiometers when testing?
Id double check the cuts under again, and check the soldering.

[benuron]

I double check everything changed the transistors (by the way I am using bc547) Is there something more I can do before changing the IC's?

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[Starspawn]

Yes, youve grounded the output pin in the jack sockets instead of the ring/ground pin (ground should be the lonely pin near panel), and your signal to the switched pin (so when somethings inserted its not connected).
Also not sure of the pot wiring, if you have a pot sitting on your table, with legs pointing to you, shaft up, then 1 is your leftmost pin.
Check against this: http://m.bareille.free.fr/ds7clone/ds7wiring.gif

[benuron]

Thank you Starspawn for the tips!

This jacks have the ground ring pin on the side. I tested for continuity and the tip is not grounded.
Also double, triple checked the pots. I did the pin 1 the most left over with the shaft up (but if I wire it backwards wouldn't hurt, just the response would be on backwards )

[strato54s]

hi everyone this my first post
im rooky in electronic
i built my ds7 clone (excellent )
and i have some question
what is the difference with vca mods and cv mods?????
how to made the cv mods i dont understand the "nodal point"

This machine is excellent and so funny

(ps someone know something about this machine)
www.youtube.com/watch?v=Nv6etgvw4GE

[roboter]

I am planning on building this, does anybody know why the filter after the VCO has such a low cutoff? Won't this cause attenuation with increasing VCO frequency? Also what is the output waveform of this VCO and is there a link where this (or a similar) VCO is explained?