Eh? What's up? Ruby+something else.

[rockgardenlove]

So I have a ruby I just built...it's picking up alot of RF and other junk.
When I jumper one of the speaker cables(either one, hot or ground) to the ground on the input jack through a 220pf capacitor, the crap goes away.  Perfect.  So I thought I'd just hack the little extra capacitor onto the back of the PCB I etched.

Oddly enough, the cap only cuts out the RF when going directly from the input jack to tone of the cables.  The grounds on the PCB don't help it.  It even stops the hum when bridging from the grounded speaker cable to the input jack.  What!?  I checked the resistance to ground from the speaker jack, and it's 0.

What's up!?

Schem for the Ruby here:
http://runoffgroove.com/ruby.html



I'm working on a clean booster.  I thought this would have way more gain...
Haven't worked with Op-amps in ages and was never super familiar in the first place...I've been on a kind of tube amp high.  3 tube amps later and I'm stuck here again.   
Help?

Thanks!

[brett]

Hi
regarding the op-amp, you might connect the 1k via a cap (at least 10uF) to ground instead of 4.5V.  (Rule of thumb: R (k) xC (uF) should be greater than 10)
cheers

[rockgardenlove]

No luck.

Still at unity gain.

[dano12]

When I was working on my initial NC version of the Ruby, R.G. suggested a few additions to both protect the JFET and to add some noise reduction. Check out the addition of R10 and C8 on the input stage. You can ignore the rest of the schemo, but the additional cap should help filter out RF.

[puretube]

see App A...

(opamps for everyone)

~page 400

caution: 2Mb !