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Thread
2017-02-05 by Stephen Richards
2017-02-05 by Ken Stone
On Mon, Feb 6, 2017 at 10:16 AM, Stephen Richards okayjustalittle@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:I have a finished version of CGS 101 in my custom panel with the Mods from the build page done and am experiencing very full on response from the Gain CV.Huge jumps in gain when CV is applied at the the Gain CV jack. Far too much for it to be workable.Is there any way to attenuate this incoming CV between the jack and RP/BP pads ? Would just a Resistor work here or is more needed ?
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2017-02-05 by Stephen Richards
I have a finished version of CGS 101 in my custom panel with the Mods from the build page done and am experiencing very full on response from the Gain CV.Huge jumps in gain when CV is applied at the the Gain CV jack. Far too much for it to be workable.Is there any way to attenuate this incoming CV between the jack and RP/BP pads ? Would just a Resistor work here or is more needed ?
2017-02-06 by Stephen Richards
I have a finished version of CGS 101 in my custom panel with the Mods from the build page done and am experiencing very full on response from the Gain CV.Huge jumps in gain when CV is applied at the the Gain CV jack. Far too much for it to be workable.Is there any way to attenuate this incoming CV between the jack and RP/BP pads ? Would just a Resistor work here or is more needed ?
2017-02-06 by charles kerr
I have a finished version of CGS 101 in my custom panel with the Mods from the build page done and am experiencing very full on response from the Gain CV.Huge jumps in gain when CV is applied at the the Gain CV jack. Far too much for it to be workable.Is there any way to attenuate this incoming CV between the jack and RP/BP pads ? Would just a Resistor work here or is more needed ?
2017-02-06 by Stephen Richards
I have a finished version of CGS 101 in my custom panel with the Mods from the build page done and am experiencing very full on response from the Gain CV.Huge jumps in gain when CV is applied at the the Gain CV jack. Far too much for it to be workable.Is there any way to attenuate this incoming CV between the jack and RP/BP pads ? Would just a Resistor work here or is more needed ?
2017-02-06 by Ken Stone
On Mon, Feb 6, 2017 at 11:38 PM, Stephen Richards okayjustalittle@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:Thanks CharlieI had indeed missed that LK pads link !! The smallest i've ever dealt with in all my years of building CGS pcb's.(Perhaps a worthy note for the build page Ken ?)It hasn't completely fixed the gain problem of the VC Gain , it's still full on.
From: "charles kerr thebadproducer@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
Sent: Monday, February 6, 2017 8:59 PM
Subject: Re: [cgs_synth] CGS 101 - Serge DCSM Ver 1.0
I had a few of issues with one I built, it was behaving very oddly - but I must say it was a while ago so my memory is a bit hazy as to exactly what the oddness was.I couldn't figure it out until I noticed I'd not added the link between the two LK pads...Not particularly helpful, but worth checking?!CharlieFrom: "Stephen Richards okayjustalittle@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
Sent: Monday, 6 February 2017, 1:12
Subject: Re: [cgs_synth] CGS 101 - Serge DCSM Ver 1.0
So i double checked the wiring , my left CV was going to the right and vice versa, That's fixed.Still problems though.As i stands : If i have a single CV going to either Channel 1 or Channel 2 response is normal.With the Gain Pot at Max the output is metering the same but effected by the CV when applied.This is identical on both Channels.(For these tests i'm feeding the DCSM CV from my DTG outputs).If i apply CV to the other channel's Gain CV input (even with the other channel's Gain pot fully CCW) while patched as above, the gain in both channels is suddenly blown out into the red on my mixer.If i try really hard i can kind of balance the two signals and the CV when both CV's and Inputs are patched but the point of everything blowing out is very easy to hit and very hard to prevent. So it's pretty much unusable for me right now.I thought i should mention that the Gain pot response is weird and the gain kicks in pretty much in the last quarter of the entire pot travel, this may be a thing to consider.I'm also curious if the matched pairs of transistors in the Panners and Gain Cells could be causing any of this behaviour ? I can't remember how much i matched if at all.From: "Stephen Richards okayjustalittle@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
Sent: Monday, February 6, 2017 10:48 AM
Subject: Re: [cgs_synth] CGS 101 - Serge DCSM Ver 1.0
I'll recheck Ken, thanks.From: "Ken Stone otherunicorn@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: cgs_synth@yahoogroups.com
Sent: Monday, February 6, 2017 10:40 AM
Subject: Re: [cgs_synth] CGS 101 - Serge DCSM Ver 1.0
I presume it is the first version of the PCB. The resistor mods on the back of it are to deal with that problem. Make sure you soldered them to the right pins, and used the right values. Those cells have enormous gain without those resistors.On Mon, Feb 6, 2017 at 10:16 AM, Stephen Richards okayjustalittle@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:I have a finished version of CGS 101 in my custom panel with the Mods from the build page done and am experiencing very full on response from the Gain CV.Huge jumps in gain when CV is applied at the the Gain CV jack. Far too much for it to be workable.Is there any way to attenuate this incoming CV between the jack and RP/BP pads ? Would just a Resistor work here or is more needed ?
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2017-02-06 by Stephen Richards
Thanks CharlieI had indeed missed that LK pads link !! The smallest i've ever dealt with in all my years of building CGS pcb's.(Perhaps a worthy note for the build page Ken ?)It hasn't completely fixed the gain problem of the VC Gain , it's still full on.From: "charles kerr thebadproducer@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
Sent: Monday, February 6, 2017 8:59 PM
Subject: Re: [cgs_synth] CGS 101 - Serge DCSM Ver 1.0
I had a few of issues with one I built, it was behaving very oddly - but I must say it was a while ago so my memory is a bit hazy as to exactly what the oddness was.I couldn't figure it out until I noticed I'd not added the link between the two LK pads...Not particularly helpful, but worth checking?!CharlieFrom: "Stephen Richards okayjustalittle@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
Sent: Monday, 6 February 2017, 1:12
Subject: Re: [cgs_synth] CGS 101 - Serge DCSM Ver 1.0
So i double checked the wiring , my left CV was going to the right and vice versa, That's fixed.Still problems though.As i stands : If i have a single CV going to either Channel 1 or Channel 2 response is normal.With the Gain Pot at Max the output is metering the same but effected by the CV when applied.This is identical on both Channels.(For these tests i'm feeding the DCSM CV from my DTG outputs).If i apply CV to the other channel's Gain CV input (even with the other channel's Gain pot fully CCW) while patched as above, the gain in both channels is suddenly blown out into the red on my mixer.If i try really hard i can kind of balance the two signals and the CV when both CV's and Inputs are patched but the point of everything blowing out is very easy to hit and very hard to prevent. So it's pretty much unusable for me right now.I thought i should mention that the Gain pot response is weird and the gain kicks in pretty much in the last quarter of the entire pot travel, this may be a thing to consider.I'm also curious if the matched pairs of transistors in the Panners and Gain Cells could be causing any of this behaviour ? I can't remember how much i matched if at all.From: "Stephen Richards okayjustalittle@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
Sent: Monday, February 6, 2017 10:48 AM
Subject: Re: [cgs_synth] CGS 101 - Serge DCSM Ver 1.0
I'll recheck Ken, thanks.From: "Ken Stone otherunicorn@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: cgs_synth@yahoogroups.com
Sent: Monday, February 6, 2017 10:40 AM
Subject: Re: [cgs_synth] CGS 101 - Serge DCSM Ver 1.0
I presume it is the first version of the PCB. The resistor mods on the back of it are to deal with that problem. Make sure you soldered them to the right pins, and used the right values. Those cells have enormous gain without those resistors.On Mon, Feb 6, 2017 at 10:16 AM, Stephen Richards okayjustalittle@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:I have a finished version of CGS 101 in my custom panel with the Mods from the build page done and am experiencing very full on response from the Gain CV.Huge jumps in gain when CV is applied at the the Gain CV jack. Far too much for it to be workable.Is there any way to attenuate this incoming CV between the jack and RP/BP pads ? Would just a Resistor work here or is more needed ?
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2017-02-06 by Ken Stone
On Tue, Feb 7, 2017 at 8:46 AM, Stephen Richards okayjustalittle@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:Ah yes ; builders oversight on my part. Still stumped on this problem of excessive VC gain though.
From: "Ken Stone otherunicorn@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: cgs_synth@yahoogroups.com
Sent: Tuesday, February 7, 2017 8:12 AM
Subject: Re: [cgs_synth] CGS 101 - Serge DCSM Ver 1.0
LK is mentioned on the pad table.On Mon, Feb 6, 2017 at 11:38 PM, Stephen Richards okayjustalittle@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:Thanks CharlieI had indeed missed that LK pads link !! The smallest i've ever dealt with in all my years of building CGS pcb's.(Perhaps a worthy note for the build page Ken ?)It hasn't completely fixed the gain problem of the VC Gain , it's still full on.From: "charles kerr thebadproducer@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
Sent: Monday, February 6, 2017 8:59 PM
Subject: Re: [cgs_synth] CGS 101 - Serge DCSM Ver 1.0
I had a few of issues with one I built, it was behaving very oddly - but I must say it was a while ago so my memory is a bit hazy as to exactly what the oddness was.I couldn't figure it out until I noticed I'd not added the link between the two LK pads...Not particularly helpful, but worth checking?!CharlieFrom: "Stephen Richards okayjustalittle@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
Sent: Monday, 6 February 2017, 1:12
Subject: Re: [cgs_synth] CGS 101 - Serge DCSM Ver 1.0
So i double checked the wiring , my left CV was going to the right and vice versa, That's fixed.Still problems though.As i stands : If i have a single CV going to either Channel 1 or Channel 2 response is normal.With the Gain Pot at Max the output is metering the same but effected by the CV when applied.This is identical on both Channels.(For these tests i'm feeding the DCSM CV from my DTG outputs).If i apply CV to the other channel's Gain CV input (even with the other channel's Gain pot fully CCW) while patched as above, the gain in both channels is suddenly blown out into the red on my mixer.If i try really hard i can kind of balance the two signals and the CV when both CV's and Inputs are patched but the point of everything blowing out is very easy to hit and very hard to prevent. So it's pretty much unusable for me right now.I thought i should mention that the Gain pot response is weird and the gain kicks in pretty much in the last quarter of the entire pot travel, this may be a thing to consider.I'm also curious if the matched pairs of transistors in the Panners and Gain Cells could be causing any of this behaviour ? I can't remember how much i matched if at all.From: "Stephen Richards okayjustalittle@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
Sent: Monday, February 6, 2017 10:48 AM
Subject: Re: [cgs_synth] CGS 101 - Serge DCSM Ver 1.0
I'll recheck Ken, thanks.From: "Ken Stone otherunicorn@... [cgs_synth]" <cgs_synth@yahoogroups.com>
To: cgs_synth@yahoogroups.com
Sent: Monday, February 6, 2017 10:40 AM
Subject: Re: [cgs_synth] CGS 101 - Serge DCSM Ver 1.0
I presume it is the first version of the PCB. The resistor mods on the back of it are to deal with that problem. Make sure you soldered them to the right pins, and used the right values. Those cells have enormous gain without those resistors.On Mon, Feb 6, 2017 at 10:16 AM, Stephen Richards okayjustalittle@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:I have a finished version of CGS 101 in my custom panel with the Mods from the build page done and am experiencing very full on response from the Gain CV.Huge jumps in gain when CV is applied at the the Gain CV jack. Far too much for it to be workable.Is there any way to attenuate this incoming CV between the jack and RP/BP pads ? Would just a Resistor work here or is more needed ?
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2017-02-07 by guymccusker
2017-02-07 by Ken Stone
On Wed, Feb 8, 2017 at 6:51 AM, guymccusker@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:For what it's worth, I just made some measurements on my freshly built DCSM (which is no longer a smoke generator -- long story)
It also has pretty massive gain. 1V on the CV input gives a gain of 20dB, so it's pretty impossible to avoid clipping when the CV is 2V or more. What would be a normal amount of gain for this circuit?By the way, all my CGS108 gain cells distort when the input signal goes below -2V. There's a bit more headroom on the positive end. Is that normal? I've built seven of them (4 for the DCSM and 3 for the VCFQ) and they are all the same -- all using the same batch of transistors.
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2017-02-08 by guymccusker