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Help with DCSM

Help with DCSM

2015-05-02 by spunraddish

Hey guys, I haven't heard from a single builder who built one of these before, so I may be treading foreign territory. I built up the DCSM, and it works, but not nearly as what I would imagine to be correct. For one, I can't seem to trim out the distortion, and the gain pots on each channel only begin to have any effect after about 60% through their travel, at which point they have about 20 degrees of movement at most before they distort. The sound of the distortion is great, though, and I can work with these touchy settings, though may consider changing to an anti-log pot if my logic is correct.


The real issue is that the center of the pan pots is not the center of the panning curve, particularly far off for one channel, and it is different for both channels. Center pan has such a narrow travel before biasing entirely to one side, maybe about 10-15 degrees on both sides. Do I just learn it and work around it, or is there another way?


Thanks,

Eric

Re: Help with DCSM

2015-05-02 by Stephen Richards

Hi Eric

Ken will probably chime in on this but have you done the Mods to the PCB as detailed here ?

CGS101 is the Quad VCA used in the DCSM.




Show quoted textHide quoted text
From: "spunraddish@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: cgs_synth@yahoogroups.com
Sent: Sunday, May 3, 2015 2:08 AM
Subject: [cgs_synth] Help with DCSM

Hey guys, I haven't heard from a single builder who built one of these before, so I may be treading foreign territory. I built up the DCSM, and it works, but not nearly as what I would imagine to be correct. For one, I can't seem to trim out the distortion, and the gain pots on each channel only begin to have any effect after about 60% through their travel, at which point they have about 20 degrees of movement at most before they distort. The sound of the distortion is great, though, and I can work with these touchy settings, though may consider changing to an anti-log pot if my logic is correct.

The real issue is that the center of the pan pots is not the center of the panning curve, particularly far off for one channel, and it is different for both channels. Center pan has such a narrow travel before biasing entirely to one side, maybe about 10-15 degrees on both sides. Do I just learn it and work around it, or is there another way?

Thanks,
Eric


Re: Help with DCSM

2015-05-03 by Ken Stone

You certainly have something wrong going on. Make sure those mod resistors are soldered in the right places. Without them, you will have crazy gain.

On Sun, May 3, 2015 at 10:22 AM, Stephen Richards okayjustalittle@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

Hi Eric

Ken will probably chime in on this but have you done the Mods to the PCB as detailed here ?

CGS101 is the Quad VCA used in the DCSM.




Show quoted textHide quoted text
From: "spunraddish@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: cgs_synth@yahoogroups.com
Sent: Sunday, May 3, 2015 2:08 AM
Subject: [cgs_synth] Help with DCSM

Hey guys, I haven't heard from a single builder who built one of these before, so I may be treading foreign territory. I built up the DCSM, and it works, but not nearly as what I would imagine to be correct. For one, I can't seem to trim out the distortion, and the gain pots on each channel only begin to have any effect after about 60% through their travel, at which point they have about 20 degrees of movement at most before they distort. The sound of the distortion is great, though, and I can work with these touchy settings, though may consider changing to an anti-log pot if my logic is correct.

The real issue is that the center of the pan pots is not the center of the panning curve, particularly far off for one channel, and it is different for both channels. Center pan has such a narrow travel before biasing entirely to one side, maybe about 10-15 degrees on both sides. Do I just learn it and work around it, or is there another way?

Thanks,
Eric





--
Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: Help with DCSM

2015-05-03 by spunraddish

Thanks for the info guys.

So far it seems that the mods were done correctly, as far as signal continuity is concerned across the correct channels. The 5k6s are in the correct spots. I know I'm tapping the CV outputs just fine as well, and I have installed attenuators for the cv anyway, for both the pan and gain cv, which are simple ccw ground lug attenuators, nothing special.

My main concern is the directional congruity between the pan knobs and the spatialization, so I guess I'll try and see if the resistors are correct on each pcb.

Re: Help with DCSM

2015-05-03 by Stevie Richards

I know I sounds obvious but did you also do the track cuts in the mod ?

On 4 May 2015, at 2:37 am, "spunraddish@... [cgs_synth]" <cgs_synth@yahoogroups.com> wrote:

Thanks for the info guys.

So far it seems that the mods were done correctly, as far as signal continuity is concerned across the correct channels. The 5k6s are in the correct spots. I know I'm tapping the CV outputs just fine as well, and I have installed attenuators for the cv anyway, for both the pan and gain cv, which are simple ccw ground lug attenuators, nothing special.

My main concern is the directional congruity between the pan knobs and the spatialization, so I guess I'll try and see if the resistors are correct on each pcb.

Re: Help with DCSM

2015-05-05 by spunraddish

Yes, the correct tracks were cut, established in the continuity testing, and I also made sure that other tracks weren't cut - actually, instead of soldering directly to the tracks as was suggested in the diagram, I just went to the next closest solder lug, so my answer may lie there - how does one scrape off just enough solder mask to solder to the tracks, anyway?

Re: Help with DCSM

2015-05-05 by Dave Kendall

FWIW, if it's a short run, soldering to the nearest lug is probably
better anyway, as it doesn't risk damaging the tracks which can be
fragile. Rigid tinned wire is best for this IMO, and can look quite
neat.

Hope you find the fault.

cheers,
Dave
Show quoted textHide quoted text
On 5 May 2015, at 13:36, spunraddish@... [cgs_synth] wrote:

> Yes, the correct tracks were cut, established in the continuity
> testing, and I also made sure that other tracks weren't cut -
> actually, instead of soldering directly to the tracks as was suggested
> in the diagram, I just went to the next closest solder lug, so my
> answer may lie there - how does one scrape off just enough solder mask
> to solder to the tracks, anyway?
>

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