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Full Version: Question about the Sigma Project
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I'm thinking about building the Sigma as floor based unit with the switching on the unit itself.   Since the unit is going to be remote form the amp with 20ft cable is there any concern about signal loss?  Would it be wise to have cathode follower or transformer to have a lo-z out or is that non-issue?

Thanks!
Hi makinrose

Sigma nominally has a low-z output due to the feedback around the mixing stage. You should build it as is and try it with a long cable and a short cable to hear if there's a difference. If there, the best solution is to add a BJT buffer directly to the mix stage plate. Surprisingly, this provides a better frequency response than a mosfet would.

Have fun
(01-05-2019, 12:29 AM)K O\Connor Wrote: [ -> ]Hi makinrose

Sigma nominally has a low-z output due to the feedback around the mixing stage. You should build it as is and try it with a long cable and a short cable to hear if there's a difference. If there, the best solution is to add a BJT buffer directly to the mix stage plate. Surprisingly, this provides a better frequency response than a mosfet would.

Have fun

Excellent! Thanks for the help.  If necessary the BJT will be easy to add.