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 Forum index » DIY Hardware and Software » The layout factory
ARP Odyssey MKII/III VCO - Eurorack Format
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steffensen



Joined: Jul 11, 2012
Posts: 85
Location: Sweden

PostPosted: Fri May 03, 2013 9:04 am    Post subject: Reply with quote  Mark this post and the followings unread

noiselector wrote:
I think you could use Nomex paper for insulating the panel from the ground board trace as an easy solution ( or you can use Furio's acrylic panels).
Thanks a lot for sharing all your experiments with this VCO board, this threat is getting hot.
Wink


As i already have a alu panel i really like, i might try fitting some Nomex or similar in there. Smile
Theres not much room, but ill see what i can do. Ill let you guys know if it helps.

Im still a bit mesmerized, about how it can work on the original and not with this. The original grounds thru the panel as well after all..
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isak



Joined: Dec 13, 2009
Posts: 627
Location: Israel
Audio files: 18

PostPosted: Fri May 03, 2013 9:47 am    Post subject: Reply with quote  Mark this post and the followings unread

Guys I think that Andy or frequencycenteral speak of this matter in the big ody thread.
Damn...can't find it Mad

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steffensen



Joined: Jul 11, 2012
Posts: 85
Location: Sweden

PostPosted: Fri May 03, 2013 9:54 am    Post subject: Reply with quote  Mark this post and the followings unread

isak wrote:
Guys I think that Andy or frequencycenteral speak of this matter in the big ody thread.
Damn...can't find it Mad


Izak!
Yes, It was mentioned that if the VCO's did not share the same Ground trace, this wouldnt occur. It solved it for Andy (and others?).
Its on the first page if i remember correctly.

But, as my VCO's share the same panel (fact would be the same if they werent tho, and just placed in the same case) they share the Ground anyway.
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noiselector



Joined: Mar 30, 2013
Posts: 21
Location: France

PostPosted: Fri May 03, 2013 12:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

The common ground in the case or panel wouldn't be a problem if you get separate ground traces for each oscillator avoiding the ground loop between them,(only common point in the power conector).
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steffensen



Joined: Jul 11, 2012
Posts: 85
Location: Sweden

PostPosted: Fri May 03, 2013 12:40 pm    Post subject: Reply with quote  Mark this post and the followings unread

noiselector wrote:
The common ground in the case or panel wouldn't be a problem if you get separate ground traces for each oscillator avoiding the ground loop between them,(only common point in the power conector).


Sure, but avoiding that connection thru the panel is pretty impossible imo. Pots are mounted on the panel, as are jacks. Even if we do manage to insulate them somehow, i bet some would leak thru anyway.. Must be a better and more simple way to sort this out. Would really like to know the real reason for this issue happening..
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noiselector



Joined: Mar 30, 2013
Posts: 21
Location: France

PostPosted: Fri May 03, 2013 12:59 pm    Post subject: Reply with quote  Mark this post and the followings unread

You don´t need to insulate the board from panel.
You need create a GND trace from power connector through oscillator 1 to chasis and other from power conector through oscillator 2 to chasis.
Original Arp VCOs are built in different boards so this issue doesn't occurs.
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steffensen



Joined: Jul 11, 2012
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PostPosted: Fri May 03, 2013 1:01 pm    Post subject: Reply with quote  Mark this post and the followings unread

noiselector wrote:
You don´t need to insulate the board from panel.
You need create a GND trace from power connector through oscillator 1 to chasis and other from power conector through oscillator 2 to chasis.
Original Arp VCOs are built in different boards so this issue doesn't occurs.


Mine are on different boards actually. Both with their own Ground trace obviously. But as panels are touching, they share Ground. (considering they are out of metal that is, which mine are)
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noiselector



Joined: Mar 30, 2013
Posts: 21
Location: France

PostPosted: Fri May 03, 2013 1:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

I see... Confused
Sync in jack socket seems to be the problem.
did you try to dismount them from panel?
(offtopic: what software was used for creating the VCO layouts? I like the components view more than eagle.)
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steffensen



Joined: Jul 11, 2012
Posts: 85
Location: Sweden

PostPosted: Fri May 03, 2013 3:06 pm    Post subject: Reply with quote  Mark this post and the followings unread

noiselector wrote:
I see... Confused
Sync in jack socket seems to be the problem.
did you try to dismount them from panel?
(offtopic: what software was used for creating the VCO layouts? I like the components view more than eagle.)


My VCO's Sync points are hardwired, but yea, that might be it. Gonna test this when i service my pair in a bit.
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noiselector



Joined: Mar 30, 2013
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PostPosted: Fri May 03, 2013 5:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

yeah, check the GNDs in that points (i think you are using a switch for on/off sync as in the dual version but using separate boards for each vco, correct?)
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steffensen



Joined: Jul 11, 2012
Posts: 85
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PostPosted: Sat May 04, 2013 1:30 am    Post subject: Reply with quote  Mark this post and the followings unread

noiselector wrote:
yeah, check the GNDs in that points (i think you are using a switch for on/off sync as in the dual version but using separate boards for each vco, correct?)


Correct! Smile
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isak



Joined: Dec 13, 2009
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Location: Israel
Audio files: 18

PostPosted: Sat May 04, 2013 1:40 am    Post subject: Reply with quote  Mark this post and the followings unread

If the sync GND jack is the problem then I have a simple isolating solution.
Do you know the Teflon paper roll?
It's thin, white and comes in a small round package.
You can just roll some on the jack and then put it in the panel.
Tell me if it helped Smile

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noiselector



Joined: Mar 30, 2013
Posts: 21
Location: France

PostPosted: Sat May 04, 2013 4:04 am    Post subject: Reply with quote  Mark this post and the followings unread

He uses a switch for the hardwired sync instead jack sockets , some type of ground loop through this switch when sync is off could be causing the issue.
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isak



Joined: Dec 13, 2009
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PostPosted: Sat May 04, 2013 4:47 am    Post subject: Reply with quote  Mark this post and the followings unread

Let me get this straight...
Sync on/off is turned on with a toggle switch, right?
The problem happanes is when the synch is off cause the toggle switch body is grounded with other pots/jacks on the front panel, right?
Assuming that what I understand is correct ...put teflon paper on the toggle it self.
Or I'm totally out of direction and I really don't know what your talking about Rolling Eyes

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steffensen



Joined: Jul 11, 2012
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PostPosted: Sat May 04, 2013 10:06 am    Post subject: Reply with quote  Mark this post and the followings unread

isak wrote:
Let me get this straight...
Sync on/off is turned on with a toggle switch, right?
The problem happanes is when the synch is off cause the toggle switch body is grounded with other pots/jacks on the front panel, right?
Assuming that what I understand is correct ...put teflon paper on the toggle it self.
Or I'm totally out of direction and I really don't know what your talking about Rolling Eyes


Yep, you got it right. Lets hope this is the problem, then its fixable. Ill let you know when ive tested it..
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furio



Joined: Dec 25, 2009
Posts: 99
Location: Austria

PostPosted: Sat May 04, 2013 10:11 am    Post subject: Reply with quote  Mark this post and the followings unread

interesting! ...otherwise, simply a sync single wire (ungrounded) custom patch cable.
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isak



Joined: Dec 13, 2009
Posts: 627
Location: Israel
Audio files: 18

PostPosted: Sat May 04, 2013 2:34 pm    Post subject: Reply with quote  Mark this post and the followings unread

steffensen wrote:
isak wrote:
Let me get this straight...
Sync on/off is turned on with a toggle switch, right?
The problem happanes is when the synch is off cause the toggle switch body is grounded with other pots/jacks on the front panel, right?
Assuming that what I understand is correct ...put teflon paper on the toggle it self.
Or I'm totally out of direction and I really don't know what your talking about Rolling Eyes


Yep, you got it right. Lets hope this is the problem, then its fixable. Ill let you know when ive tested it..


waiting for results Smile

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noiselector



Joined: Mar 30, 2013
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PostPosted: Sat May 04, 2013 4:25 pm    Post subject: Reply with quote  Mark this post and the followings unread

waiting for success ....
A picture of my boards.
I want to use some of them as LFVCO changing the cv1 input jumper for a toggle switch to 270K resistor. I see Furio's panels don´t include this socket but I think it is interesting too in this single version. Do you think there is enough space for add a socket for a miniature toggle switch in your panel?.


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steffensen



Joined: Jul 11, 2012
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PostPosted: Sun May 05, 2013 11:13 am    Post subject: Reply with quote  Mark this post and the followings unread

Had a minute free, so i detached the sync-switch and tried. Same issue happens.
However, as i dont have the real Odyssey here, i compared my results to the Oddity VSTi, and its behaving pretty similar.
Tho, the VCO's do phase each other out a lot more when tuned together/close than the Oddity does.
As they are analog, they should have different cycles, but they seem to share the same cycle each time i turn it on.

I used some crappy trannies when i did my VCO's tho, so ill see how it behaves when replaced by quality ones i have here waiting..
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steffensen



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PostPosted: Fri May 10, 2013 6:02 am    Post subject: Reply with quote  Mark this post and the followings unread

Had some time over, so i went ahead and replaced all my 3904/3906's. Used some fishy ones, and the new ones are quality trusted ones from Mouser. Also made a Ground-chain between the pots on each section while i had it opened.

The Ground-chain didnt do much difference i think, but the new trannies made a lot of difference! Improved sound, MUCH lower pitch, and a lot less locking. They still lock together a bit, but the original does this too i hear.

I have also been informed on the reason behind this, and the fix is to put a 100nF cap after the 10uF caps.
The 100nF might be filtering too much, or too little, so one can decide for one self here.
Ill see if i do this at some point, it would need some hacking on this layout.
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furio



Joined: Dec 25, 2009
Posts: 99
Location: Austria

PostPosted: Fri May 10, 2013 9:34 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi everyone,
I have just finished to scketch the PCB of the Ring Modulator (version for 'Erthenvar' jacks).
If someone would like to help me check it, here is the preview ... The 150K Input2 is to be soldered on the side of the tracks .... The 5K6 and 100n capacitor can be soldered inbetween the socket in the middle/under of the CD4011. The euro power connector must be angled.


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modulardoom



Joined: Mar 13, 2013
Posts: 5
Location: portugal

PostPosted: Wed Jun 05, 2013 3:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

I have built this VCO and works fine but I hear some change in the PW when I turn the PWM potentiometer but nothing is connected in the PWM jack. This is ok? I think the PW shouldn't change turning the PWM pot with nothing in the input.
Question
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furio



Joined: Dec 25, 2009
Posts: 99
Location: Austria

PostPosted: Thu Jun 06, 2013 12:48 am    Post subject: Reply with quote  Mark this post and the followings unread

modulardoom wrote:
I have built this VCO and works fine but I hear some change in the PW when I turn the PWM potentiometer but nothing is connected in the PWM jack. This is ok? I think the PW shouldn't change turning the PWM pot with nothing in the input.
Question

This is normal. Without connecting anything, the potentiometers FM and PWM must be completely in the CCW position.
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elmegil



Joined: Mar 20, 2012
Posts: 1345
Location: Chicago
Audio files: 14

PostPosted: Thu Jun 06, 2013 5:08 am    Post subject: Reply with quote  Mark this post and the followings unread

If it's a bother, use a switching jack and connect the switching lug to ground?
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furio



Joined: Dec 25, 2009
Posts: 99
Location: Austria

PostPosted: Sun Aug 25, 2013 10:02 am    Post subject: Reply with quote  Mark this post and the followings unread

elmegil wrote:
If it's a bother, use a switching jack and connect the switching lug to ground?

The switch is on the right. The ground is always connected to the ground only. Smile
http://www.thonk.co.uk/shop/pj301bm-3-5mm-jack-sockets-x50/
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