CV+audio problems

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sgnhh
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CV+audio problems

Post by sgnhh » Mon Feb 18, 2008 8:23 pm

Specifically, between my Doepfer Quad ADSR and my Plan B M15 VCO. I run the VCO and patch the ADSR to LFO, but DO NOT patch them together in any way, and I can hear the LFO pacing the VCO. Even though they aren't patched together. I tried moving the ribbons around... to different points on the same bus board, to different points on different bus boards, but there has been no solution thus far.

Any ideas?

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Muff Wiggler
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Post by Muff Wiggler » Mon Feb 18, 2008 8:48 pm

can you put them both on a seperate power supply and see if it still happens?

is the faceplate of your M15 grounded?

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Post by sgnhh » Tue Feb 19, 2008 12:18 am

I don't have the option for a second power supply and my M15 isn't grounded, but it's all in a wooden case (metal rails, wooden case). How would I go about grounding the M15? The M15 and Quad ADSR are on the same rail... maybe that's the problem?

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Post by Muff Wiggler » Tue Feb 19, 2008 12:22 am

i think all you need to do is ground the rail - if the rail is grounded it won't matter what modules are connected to the same rail, because any voltage would just go right to ground.....

you need to run a wire from the rail, to a ground terminal somewhere - can you send it to your power supply's ground?

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Post by sgnhh » Tue Feb 19, 2008 12:28 am

That shouldn't be a problem. The Doepfer PSU I have has three ground plugs.

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Post by Muff Wiggler » Tue Feb 19, 2008 12:35 am

excellent - shouldn't be a problem them. Let us know how this works out. I don't use a euro-rack system at all, so I'm just going on things I've overheard before.

if you can, use a multimeter to make sure the M15's panel actually has continuity with the rail. If it doesn't (I can't imagine that it wouldn't, but it's definately worth checking), you'll need to also ground the actual M15 panel to a ground plug as well.

Don't ground it to the same wire that you use to ground the rail. Run a seperate wire to either another ground plug, or the same one as the rail's wire. This is 'star grounding' (basically) and the idea is that is it quieter than serial-type wiring of your ground.

Anyway I'm sure the M15's panel will have continuity to the rail - if it didn't, you probably wouldn't have to worry about grounding the panel. So you simply need to ground one of the two rails you screw the module to, and you should be all set.

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Chuck E. Jesus
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Post by Chuck E. Jesus » Tue Feb 19, 2008 7:10 am

yeah, you should definately run a ground wire from all the rails to ac entral point and ground them to the power supply...Plan B mods have to be grounded thru the rails to function properly, Peter G wrote something about this but i don't remember where i saw it...

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Post by sgnhh » Tue Feb 19, 2008 3:16 pm

Grounding the rails didn't do anything. :(

sandyb

Post by sandyb » Tue Feb 19, 2008 3:24 pm

there's a bit of information i dug up from peter @ plan B regarding grounding in this thread

viewtopic.php?t=464

did you use the specific ground point for grounding the case (or rails) that is on the doepfer kit 1 power supply?

sandy

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Post by sgnhh » Tue Feb 19, 2008 3:49 pm

http://www.analoguehaven.com/doepfer/a1 ... 00diy1.jpg

If you look at the PSU, at the bottom right corner there is a clip for ground. I connected a wire between that clip to the rail and still nothing happened.

I'm gonna assume I'm supposed to connect that to something else.

sandyb

Post by sandyb » Tue Feb 19, 2008 4:36 pm

sgnhh wrote:http://www.analoguehaven.com/doepfer/a1 ... 00diy1.jpg

If you look at the PSU, at the bottom right corner there is a clip for ground. I connected a wire between that clip to the rail and still nothing happened.

I'm gonna assume I'm supposed to connect that to something else.
no - that was the one i meant. there was a thread on the Plan B yahoo group a short time ago about this very issue. it's a few messages long so it might be worth signing up if you aren't already - here's a link to the topic:

http://launch.groups.yahoo.com/group/PL ... ssage/1399

from having just skimmed it, as far as i remember - lfos seem to be a problem and the solution can sometimes have to be a separate power supply for control and audio modules :(
i'm building a case with the same diy doepfer kit and modules as you but haven't got any modules yet. when they arrive i'll be interested to see if there are any issues.

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Post by sgnhh » Tue Feb 19, 2008 4:38 pm

Oy. Thought so. Okay. Thanks for all the information. looks like I'll make due until I get a second PSU.

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Post by Muff Wiggler » Tue Feb 19, 2008 5:32 pm

lame :(

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Post by sgnhh » Tue Feb 19, 2008 5:33 pm

Yeah, this format definitely has its drawbacks. If only the Plan B, Livewire, and Harvestman modules weren't so cool, i'd probably be frac.

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Post by Chuck E. Jesus » Tue Feb 19, 2008 5:55 pm

i must be the luckiest kid on earth, i don't seem to have these problems...i'm curious if it is more of a Plan B thing, i'm not sure and don't mean to imply that is the case, but after poking around on Analogue Heaven years ago and then again on the net over the last couple years, i've never heard so much trouble with Euro gear until recently (and frankly, mostly here)...

my original Euro rack has the old Doepfer PSU, and my most of my stuff is in there (i'm eventually going to move things around for power consumption/future mod add-on reasons)...my cases are properly grounded and i also kind of have a cheater "star ground" setup, my audio gear in general is very quiet...

i don't mean to be defensive, i really don't care what format people use, it's all good to me...but again, i just haven't experienced the problems with the Euro Rack format that seem to be springing up lately, in fact i'm happy as a pig in shit...

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