[sdiy] sync circuit woes

[Laurie Biddulph]

A summer not only adds (or sums) together the inputs but it also has the 
function of multiplying or dividing the mixed signal depending upon the 
feedback resistor. 100K in and 100K feedback is 1:1 so make the 100K in the 
feedback adjustable so that you can trim for optimum output level with all 
inputs maxed. Suggest the feedback be a small resistor and trimmer so that 
you define the range of gain available.

Best Regards

(Mr) Laurie Biddulph
Phone: +61 (0)2 4340 0938
Mobile: 0400 257 645

Elby Designs
ABN: 70 022 727 605
http://www.elby-designs.com

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----- Original Message ----- 
From: "Dan Snazelle" <subjectivity at hotmail.com>
To: <music.maker at gte.net>; "sdiy" <synth-diy at dropmix.xs4all.nl>
Sent: Friday, November 21, 2008 4:23 AM
Subject: RE: [sdiy] sync circuit woes


>
>
> Ok
> I thought that in summer circuits, the feedback resistor HAD to be the
> same value as the summing resistors! i thought that was what made
> summers work properly. i feel very stupid right now.
> Ok, so if i was using 100k, i can maybe try a 47k?
> also...in my GUITAR PRE opamp, i am using a non inverting opamp with a
> 10k to gnd resistor and a 100k feedback resistor for a gain of X10 but
> it still isnt really loud enough compared to the other mixer inputs. SO
> i was thinking of bringing it up higher BUT i dont want any distortion.
> (there is already a dirty switch for that)
> so what do you guys think i could get away with before distortion?
> maybe 15x? i was thinking of putting in a 150k on the feedback
> resistor.
> thanks so much-diy
>
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