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 Forum index » DIY Hardware and Software
DS 7 clone
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umschmitt



Joined: Jun 29, 2011
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PostPosted: Tue Mar 27, 2012 3:05 pm    Post subject: Re: AK47 Reply with quote  Mark this post and the followings unread

chguigoz wrote:
What effect has the switch LFO?

Hey. I think jumunius wrote about this (pages 10-11), search for "UFO" (It's also in M. Bareille's DS-8 schematics, under J7-J10 / S1-S0).

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chguigoz



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PostPosted: Wed Mar 28, 2012 4:48 am    Post subject: Reply with quote  Mark this post and the followings unread

Thank you!

Looking at the diagram of the AK47, it is clear that this is pin 1 on the potentiometer that is connected to the oscillator. Therefore, the LFO rate should vary with the frequency of vco if i understand?


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umschmitt



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PostPosted: Wed Mar 28, 2012 8:35 am    Post subject: Reply with quote  Mark this post and the followings unread

Oops you're right. Then it has to be something else (which I don't get, sorry - bypassing the 3k3 resistor ? what for ?). xpmtl should be able to tell you what.
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xpmtl



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PostPosted: Wed Mar 28, 2012 10:24 am    Post subject: Reply with quote  Mark this post and the followings unread

the LFO switch simply takes the LFO modulation out of the circuit. The VCO pot doesn't have an effect on the LFO, only the MODE pot has.

A friend has asked me to build him a coron so i'm in the process of doing that based on the schematic I posted. That would allow me to see if there's any problem with it and report back. Waiting on parts, so be patient...

@chguigoz : for your buzz problem, check if you don't have a short to ground somewhere, as dubdummies has the noise part working ok. Also i've compared the noise part in the schematic with the one of Marc Bareille and it's the same.

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chguigoz



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PostPosted: Wed Mar 28, 2012 11:33 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello xpmtl.
I ve seen that your shema was identical to the marc`s shema for the noise parts.
But i'm surprised to see that the load resistor is only 330 ohms!
Therefore, we can only obtain a very low level of noise! The following amp circuit is also designed with a high gain to obtain a sufficient level . On the ds8 i make, i had the same noise level by removing the first transistor and the buzz disapeared.
I will change the value of load and feedback resistors to the same way of the shema I put above. The original design would need a review at this level i think.
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feggster



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PostPosted: Sun Apr 01, 2012 5:34 am    Post subject: Reply with quote  Mark this post and the followings unread

if it helps i have a gut shot of an original ds8 and that load resistor is 330r Smile
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chguigoz



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PostPosted: Mon Apr 02, 2012 3:56 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello !

I checked several times components and pcb.
I also made ​​the noise circuit on a stripboard for testing several components(741 and bc547C) and resistors values . It still does not work properly. The noise level is too low.
The highest level I got is putting a zener diode instead the BC547C, change the load resistor to 10k and powered the noise circuit with 9 v .But it is still not sufficient ! I don't understand !!!! Shocked
I consoled myself by adding an audio input on my DS7 Confused
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richardc64



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PostPosted: Mon Apr 02, 2012 6:29 am    Post subject: Reply with quote  Mark this post and the followings unread

(sigh) The problem is one transistor reverse-biased at less than 12volts or so doesn't generate enough noise unless you select an especially noisy one. I guarantee the circuit below generates a sufficient level at 9volts and may even be enough at 5volts. I tried a 2712, 2222 and 3904 and they all sounded the same.

Depending on where it's injected into the ota/vca you might not even need the op amp.

chguigoz wrote:
Hello !

I consoled myself by adding an audio input on my DS7 Confused

Hello to you, too. Self-consoling is good for the soul.


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chguigoz



Joined: Mar 02, 2012
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PostPosted: Mon Apr 02, 2012 10:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thank you. I'll try your circuit. I tried several transistors for the ds8 noise circuit with no success. This is not my first noise circuit but the others module in my eurorack are 12 v powered. I note that the load resistor is 47k instead 330 on the coron. This shema look like my post above except yours is direct coupled between the two transistors .See page 13
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chguigoz



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PostPosted: Tue Apr 03, 2012 3:35 am    Post subject: Reply with quote  Mark this post and the followings unread

xpmtl wrote:
the LFO switch simply takes the LFO modulation out of the circuit. The VCO pot doesn't have an effect on the LFO, only the MODE pot has..


I changed my DS7 by adding the switch on the lfo.
If I do not put the 3k3 resistor, the switch bypasses the lfo.
With this resistor, the waveform of the LFO changes being modulated by the VCO (FM). That's what I noticed and heard by testing.
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xpmtl



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PostPosted: Thu Apr 05, 2012 11:59 am    Post subject: Reply with quote  Mark this post and the followings unread

just a thought, but why would you want to make it working perfectly? Regarding the noise being too low, it's the way that this thing was designed. Design flaw surely, but that's what give it it's character. Change it's characteristics and it won't be a DS8 anymore.

just my 2 cents....

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chguigoz



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PostPosted: Fri Apr 06, 2012 2:52 am    Post subject: Reply with quote  Mark this post and the followings unread

You are right to say that.
But I first tried the original circuit and I have not got it to work properly. I do not know why. I looked ds8 demonstations on the Web and I have not the same result. The original design for noise seems to me poorly conceived and so I try to make it work otherwise. Maybe the seventie's 741 that I used do not work well in 5 volts, I have to check it.
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tokyomatik



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PostPosted: Sun Apr 15, 2012 5:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

finally, after months of debug my DS8 make sounds!!!!
absolute disco flavour!! now i'm happy

i would like to add the cv
and also a led to visualize the lfo rate would be not so bad
anybody tried that?
in wich point of the marc bareille pcb i should try to put the led?

peace
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tokyomatik



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PostPosted: Sun Apr 15, 2012 5:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

one last thing, the "pan" between vco and noise it doesn't sound so smoth....
i mean, if i move the pot just slightly from the extreme vco position, then the noise is directly pretty loud and goes louder
i would like to have a more soft transition
i use a linear pot there, should i try with a log?
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richardc64



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PostPosted: Mon Apr 16, 2012 5:24 am    Post subject: Reply with quote  Mark this post and the followings unread

tokyomatik wrote:
one last thing, the "pan" between vco and noise it doesn't sound so smoth....
i mean, if i move the pot just slightly from the extreme vco position, then the noise is directly pretty loud and goes louder
i would like to have a more soft transition
i use a linear pot there, should i try with a log?

No. You should tweak R34 or add a resistor on the noise side of the pot.

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umschmitt



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PostPosted: Mon Apr 16, 2012 10:15 am    Post subject: Reply with quote  Mark this post and the followings unread

tokyomatik wrote:
finally, after months of debug my DS8 make sounds!!!!
absolute disco flavour!! now i'm happy

That is great news ! IIRC, more people had a similar problem, so it could be valuable if you gave details on how you've had your unit working…
Quote:
i would like to add the cv

This one shouldn't be a problem.
Quote:
and also a led to visualize the lfo rate would be not so bad
anybody tried that?
in wich point of the marc bareille pcb i should try to put the led?

This is pretty easy to do, and always nice to have aboard ! You could use a buffer in between, though, in order to leave the outgoing LFO signal unaltered. There's a full topic on the question here :
http://electro-music.com/forum/topic-49449.html
I think J11/LFO3 (M. Bareille's DS-8 layout) would be a good place to take the signal from.

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tokyomatik



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PostPosted: Fri Jun 15, 2012 4:22 am    Post subject: Reply with quote  Mark this post and the followings unread

[quote="umschmitt"]
tokyomatik wrote:
finally, after months of debug my DS8 make sounds!!!!
absolute disco flavour!! now i'm happy

That is great news ! IIRC, more people had a similar problem, so it could be valuable if you gave details on how you've had your unit working…
[quote]ehm....after months of frustration, i spend one afternoon checking really close the board with a google and and trying to fix all the suspect solder joints, i believe it was R27, but i'm not completely sure.
now i'm also trying to buid the ak47 for a friend and to have a working ds8 will be extremely useful in case of debuggin.
apart the led to visualize the lfo rate, i'm wondering if it could be possible to apply some kind of external voltage to the Mode control, would be really useful especially if u use a sequencer, using this function to morph from "kick" sound to something more "metallic"

so, using just one module to have almost a basic "drum kit"

Last edited by tokyomatik on Fri Jun 15, 2012 5:35 am; edited 1 time in total
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Uncle Krunkus
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PostPosted: Fri Jun 15, 2012 4:47 am    Post subject: Reply with quote  Mark this post and the followings unread

Sounds great!
I wish I could do an Express PCB layout for this, but I just don't have the time. Crying or Very sad
I'm startin' a new job on Monday, and things are gonna get crazy for a couple of months. shakng2

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tokyomatik



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PostPosted: Mon Jun 25, 2012 10:32 pm    Post subject: Reply with quote  Mark this post and the followings unread

finally i finished and tested the ak47 and i have to say that to me sounds even better and louder than the ds8, still trying to understand why the footswitch thing is not working, but should be not a big problem to debug it, also the lfo switch is pretty interesting, kind of "echo/flam" effect.
thanks again for this layout
i love the ak47 and now i'm already thinking about doing one also for me and another one as a gift for a friend
maybe would be not so bad to include the pads for the 68k resistor for the cv in jack....?? Wink
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feggster



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PostPosted: Fri Aug 10, 2012 6:30 am    Post subject: Reply with quote  Mark this post and the followings unread

hi, I've built a dual ds7 and its working great! (i used dan's pcb, cheers dan!)
...my question is how do you trigger it with momentary switches? it triggers ok using piezo pads but attaching a momentary switch at the same place doesn't work? any ideas?
edit: page 1 of this thread has the answer Embarassed
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umschmitt



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PostPosted: Sat Aug 11, 2012 7:12 am    Post subject: Reply with quote  Mark this post and the followings unread

DS-7s respond to an electrical signal or a pulse. In order to trigger them you need current (battery etc) that you'll briefly - or not - let flow to the triggering input of the DS-7 with the momentary switch. If it has to be brief, I'd put a cap on the way. That being said, manual (or footal) triggering works very well with piezos.
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xpmtl



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PostPosted: Tue Aug 14, 2012 2:12 am    Post subject: Reply with quote  Mark this post and the followings unread

Just to report I built a DS8 clone for my friend's Bday following the schematic I posted a few pages back.

Two things to note, footswitch doesn't work and the noise balance pot doesn't sound too good (noise comes in too abruptly, not smooth at all). I'll have to look into these problems but right now i'm too busy building my modular so it will have to wait.

Other than those two problems everything else works fine.

So for the peeps having problems with the rest of the circuit, check your builds it must be an error on your side.

hope this helps,

x

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feggster



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PostPosted: Tue Aug 14, 2012 5:02 am    Post subject: Reply with quote  Mark this post and the followings unread

thanks umschmitt, I used the method described on page 1 it works fine with a momentary switch and a 1meg resistor to +9v.
to xpmtl, I'll have a go at building the ak47 soon, would a linear pot help with the lfo noise mix? I can live without the footswitch..I never understood it, also I have an original ds7 and the footswitch doesnt work Smile
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xpmtl



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PostPosted: Tue Aug 14, 2012 9:04 am    Post subject: Reply with quote  Mark this post and the followings unread

ah, well observed feggster, now that you mention it, a linear pot would have been be more logical there.

No idea why they have put a log one in the first place. Another oddity of this circuit i guess..

As far as i can remember the footswitch on the original DS8 i cloned wasn't working either Laughing

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o-live



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PostPosted: Tue Aug 14, 2012 5:04 pm    Post subject: part list Reply with quote  Mark this post and the followings unread

hello

i'm really interested to buy my first ds-8 but i don't find the part list for the
version of ds8 with lm13700 ota

where i can found it please ?

good continuation
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