Beautiful work! Thank you for sharing it, your feedback and the kind words.hazmo wrote: ↑Wed Jul 18, 2018 10:51 am
I designed and ordered the pcbs already quite a while ago, but only recently got around to building it. It's a great and neutral sounding compressor! It works really well for me in almost any setting. With clean sounds for non-invasive dynamic reduction as well as distorted sounds for long and standing tones. So thanks!
But I have a couple of questions if you don't mind. What was your reasoning behind choosing the 4316 over the 4315? The website states +-60dB gain range for the 4315 vs. +-50dB for the 4316. In the datasheet for the 4315 it says +-50dB though. Do you know which is right? I'm asking because I'm wondering which part to use for a gating circuit. Would you consider 50/60dB "off enough" or would you rather recommend the 4320 with -100dB range? Since noise already should be a fair bit lower in level compared to the signal I would think it should suffice. The datasheet advises to keep the EC pins within 0,5V of VCC/2, 60dB would be 0,36V of control voltage. Could it possibly be driven further for higher attenuation? Rising distortion or non-linear gain law wouldn't be an issue for my application.
Send us some sample sound files!
We used a 4316 in that circuit to introduce the part.
I just checked the 4315 data sheet and it says ± 50 dB.
I think the 4315 product page may have an error.
In either case, for maximum cutoff, I would use differential Ec control to double the attenuation vs. Ec.
That works for the Blackmer® cell in the 4315 and gets you more attenuation so that you can stay within 500 mV of Vcc/2.
I've used differential Ec with the 4316 and 218X-series to minimize AC-feed-through in a modulator application and it works very well.
I think JR has said somewhere he used differential Ec in a VCA application.
The 4316, which is not a Blackmer cell, also benefits from differential Ec in a modulator so it would seem to offer benefit as a gate to keep Ec within 500 mV of Vcc/2.
But I don't think it could provide -100 dB.
Its worth trying though - you don't need a lot of linearity in Ec in deep attenuation when using it as a gate and 50 dB might be enough in an MI application.
BTW in an update to the original circuit I found that a TL072 was much quieter than the MC33178.
We used the '33178 for its low power and IIRC sims showed it to be as quiet as a TL072 but its not.