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Post by dan000 on Sept 3, 2013 17:08:56 GMT -6
Hi to all!
This is my first post here, sorry my english.
Actually Im thinking to do digital control of switches based arond MCU, like for example an EQ freq, gain and Q.
I saw some digital switches with acceptable THD (of course, charts only 1K at XX dBu). Maybe some SPI or I2C switches can do this work.
Anyone has some info about on how Empirical Labs DocDerr was made ? inside pics to look a little ?
Some ideas to share ?
Thanks!
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Post by tonycamphd on Sept 3, 2013 18:00:38 GMT -6
Hi dan000! welcome to Realgear buddy! There are a few genius's floating around here, so i'm sure svart, b2, gar, etc.... someone, will chime in shortly, what you just asked is waaaay over my head man lol! you should also check out groupdiy, those guys are slick over there for sure.
good luck
Tony
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Post by svart on Sept 4, 2013 8:39:07 GMT -6
It really depends on what your budget is. You can use JFETs as switches with minimal problems, in fact a lot of consoles use them as mute elements. Some folks frown on this and might opt for relays. A lot of mastering switch matrices use relays instead.
Some of the CMOS analog switches can't take very high signal levels without distortion. If you are switching low levels, they would probably work ok, but it would be best to test this out on your design first.
Of course, other things like insertion loss(S21) and stuff need to be taken into account. Relays have negligible loss while CMOS might have a little.
I'd do the section bypassing with relays and the gain switching with JFETs in the feedback paths of the opamps. Not really sure how you would switch Q in the EQ, we'd need to know more about the EQ design I think.
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Post by dan000 on Sept 6, 2013 14:01:24 GMT -6
Thanks Svart and Tony!!
I have some experience with mastering switches (passive) based around relays and MCU.
But now my plan is to do add digital control to something like Sontec or SSL EQ. Relays is a way, and is the same as hardware switches in sound, but BIG unit, like 2U or 3U rack.
I would like to use some very small switching elements to do the same thing in 500 series. Like DocDerr does. I would like to know what Empirical Labs uses, to start test near there and dont loss so much time.
Thanks! great forum.
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