[sdiy] Fw: Questions about the DS7 Clone

[Bill Berzinskas]

Marc, I've changed c4 to 2nF and that seemed to give me better results for 
freq..   i definately think i'll have to change the decay pot, as i can't 
get anything really short out..   adding the CV jack is good idea i think.. 
what would i have to do to mod this for 0-10v input?

SDIY List..   As per marc's email, i've crossposted this to S-DIY for 
input..   i'm looking for some quick and dirty mods to marcs ds7 clone (Mods 
to the EG for Attack Maybe?..   Mods to just make it sound crazy?  Symmetry, 
that type of thing.. ) ..   link will follow..  any input on this would be 
fantastic..  :-  Also. Are there any other useful signals coming from the 
LFO?

http://m.bareille.free.fr/ds7clone/ds7.htm
----- Original Message ----- 
From: "Marc Bareille" <m.bareille at free.fr>
To: "Bill Berzinskas" <wberzinskas at nc.rr.com>
Sent: Thursday, February 24, 2005 1:53 PM
Subject: Re: Questions about the DS7


> Hi Bill,
>> I've seen u on S-DIY a bit, and love your projects..
>
> thanks . I do not follow the List with a hi accuracy  because i am 
> surrounded by work ...
>
>  i've just
>> completed my DS7 as per your site.. i made it with mostly junkbox parts,
>
> great that the DIY spirit :)
>
>> and i think the only thing i really changed were the 3.3uF i used 2.2uF 
>> instead..
>
> Yes,  you can also adjust the EG pot value ( say 470k)  to get more 
> accuracy on short decay times . Both method are working fine.
>
>   Well i've got it working..  and I'm wondering if i can
>> change something to make the VCO go lower..   It gets fairly low by 
>> itself, but once you start tweaking the Env and LFO, it gets a bit hi 
>> pitched..
>
> so basically, which are the main capacitors for LFO and VCO
>> and would i need to go lower or higher values to get the results i want?
> First you can remove R11 and connect RV4 directly to the ground. The 
> little drwaback is that when set to min position the VCO will stop 
> oscillate, but well you will get lower pitches...
>
> You can also increase the value of C4 . I suggest you to try 2.2nF , this 
> will divide by two the natural frequency of the VCO ... or try a bigger 
> value ... I did not expetriment that much with this , but i do not see any 
> reason it wont work...
>
> If you want to increase slightly  the VCO init pot range you can decrease 
> R12 too  ( try 22K or 18K ... )
>
>
>> Also, Besides the DS-8, are there any mod's that would be appropriate to 
>> this circuit?
> One of my favorite mod to the DS7/8 circuit is to add a CV input, so you 
> can drive/modulate the VCO with external modules ...
>
> For this you just have to add a simple resistor to the 'nodal' point who 
> join R4,R9,R12,R13 and U2B pin5 ...the other leg of this resistor value is 
> connected to your CV input jack . Resistor value should be comprised 
> between 39k to 100k depending the range you want to have for this external 
> CV modulation. You can also add an attenuator pot  between the jack and 
> the resistor... 10K to 47k will fit well...
>
> Feel free to cross post al those infos to the Synth Diy list and also to 
> ask List guru's for mods ideas too... I am sure you will get some 
> interesting answers :)
>
> Cheers,
>
> Marc B.
>
>