Hi!
I want to use the SSM2166 IC for a noise gate. Specifically though, I want to use the Buffer Out as a send, and have a return connected to the VCA In. The idea being that envelope detection occurs on the clean signal going in, then my effects all go between the send and return, and the output goes to the amp. This gives long natural decays and yet also mutes the hiss and prevents feedback if I take my hands off of the bass.
So I'm thinking I want to put an op amp buffer in front of the Audio In, as it's got issues with high impedance sources and higher gain ratios.
I also want an op amp buffer between the buffer out and the send jack, as the buffer out is only intended to drive the VCA In, per the datasheet.
The VCA In needs a buffer too, because it's meant to have a buffer in front of it in typical deployments, per the datasheet.
And finally the output needs a buffer because the sample circuit calls for one and we've already got 3 in there, so we may as well use a quad op amp IC.
Other than that, there's going to be nothing to this thing. I'm going to expose the gain, compression ratio, rotation set and noise gate set controls as full pots. Now with all of that in mind, have I made any glaring errors with this schematic?
Assume the voltage divider will use 10k resistors, the bias resistors are all 1M, and everything else follows the example in the datasheet here: http://www.analog.com/media/en/technica ... SM2166.pdf
THANKS!
SSM2166 Noise Gate - Need comments on schem
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Pruttelherrie
- Solder Soldier
Oooooh! Interesting!
A few years ago I built a variation on the 'quick and dirty compressor' based on the SSM2166 that included phantom power for the tillman fet, but I never realised one could add an effectsloop to it!
As far as I can see, your loop is correct as far as opamps and decoupling goes, but you might want to add send- and return level pots? (probably not needed on a pedalboard, once you get the levels right)
A few years ago I built a variation on the 'quick and dirty compressor' based on the SSM2166 that included phantom power for the tillman fet, but I never realised one could add an effectsloop to it!
As far as I can see, your loop is correct as far as opamps and decoupling goes, but you might want to add send- and return level pots? (probably not needed on a pedalboard, once you get the levels right)
-
astrobass
- Cap Cooler
Well, the send should be the same as the level coming in. There's no gain applied prior to it, just buffering. So I don't feel the need to have a level control there.
Also if I have a hot guitar signal entering the SSM2166 and then trim it down prior to send, there's the increased likelihood that the fuzz following the send will end up with dead air entering it while the last bit of the hot guitar signal continues to decay in front of the SSM2166. Then you get hum, and the whole goal here is to have absurd fuzz with no hum between notes.
Level on the return isn't a bad idea, but the last effect in the loop is probably going to have a level control anyways and I may as well use that instead of adding complexity.
So for me, I wouldn't. If you're going to implement either, I'd put the level controls on the outside of the buffers, rather than between the buffers and the SSM2166. You might want to add another dual op amp to isolate the level controls from the outside world too, given that it would cost little and eliminate loading issues.
Also if I have a hot guitar signal entering the SSM2166 and then trim it down prior to send, there's the increased likelihood that the fuzz following the send will end up with dead air entering it while the last bit of the hot guitar signal continues to decay in front of the SSM2166. Then you get hum, and the whole goal here is to have absurd fuzz with no hum between notes.
Level on the return isn't a bad idea, but the last effect in the loop is probably going to have a level control anyways and I may as well use that instead of adding complexity.
So for me, I wouldn't. If you're going to implement either, I'd put the level controls on the outside of the buffers, rather than between the buffers and the SSM2166. You might want to add another dual op amp to isolate the level controls from the outside world too, given that it would cost little and eliminate loading issues.