BSIAB2 HUM ISSUE

[GVC]

I have searched under BSIAB HUM an GROUND.  But cannot find the issues that I am having:

I am getting a serious hum, even at low gain settings.  When I am touching the strings with my hand or the enclosure with my foot the hum seems to almost disappear.  I know this is a ground issue but I have never had this happen before (DOD 250, Guv'nor, TS 808, Distortion plus, etc.) so I do not know where to start my troubleshooting.  It is breaking my heart because when I play and the hum isn't there the distortion is amazing, like the Original ZZ top.

Since I have never had this issue before I do not know where to go.  please help.  I am sure there is something out there and I am searching in the wrong places.

[GVC]

Ok I found this thread:

http://www.elixant.com/~stompbox/smfforum/index.php?topic=38552.0

Whatever analog kid did sounds like what I want to do.  But the link is not working to RGs article. 

Is this as simple as detaching one or the other grounds (input or output) so that ground is happening in one place?

[Jered]

  So are you having hum problems or microphonics? Two different issues. For an excellent tutorial on proper grounding go to
  http://www.geofex.com   and read rhe "Star Grounding" pages.
  Jered

[Connoisseur of Distortion]

star grounding in a BSIAB? whew...

[analog kid]

star grounding in a BSIAB? whew...

not stargrounding per se like you do when shieding a strat(tying to a common isolated ground).  Just talking about isolating the enclosure from multiple grounds here.  Meaning , ONLY ONE point to ground, Not MANY!! (output or input jack probably) I have found this useful on very many circuits and I don't understand why so many builders don't address this. If there is more than one point of ground tied mechanically to the box then your enclosure can't truely be acting as a shield!   I mean what good is your aluminum enclosure doing you besided sturdiness if you don't wire it to ACT as a shield. And having Input and Output both grounded to the box defeats the purpose.  (which most people , I think , do)

Is this as simple as detaching one or the other grounds (input or output) so that ground is happening in one place?

sort of, but no, you're not detaching AnY grounds! Everything that should be grounded IS and should have a good electical ground from the actual ground rail of the pcb but only ONE actually flowing to the enclosure. So the enclosure is tied to ground but this way no current can flow through it. All else you should want to islolate.
" IN A BSIAB?" 
Most definitely! as RG has explained, this type of grounding with extra mechanical grounds doesn't give people alot of  trouble, therefore they don't address it, in most circuits that are low gain or just not that wide of freq response. but  HIGH GAIN monsters + circuits like this one it can wreak havok!...  "FET's and MOSFET based distortions can reach all the way into the VHF radio band" ... therefore you most definitely want the 'perty aluminum enclosure to not just be a "shield"  but to "act" as a  Shield~
Hope this helps... my bsiab and many other notorious problem noise circuits , is dead quiet at almost full gain with a decent wired guitar!  I practice paying attention to my grounding practices ever since this revalation. I probably do this even when it need not be done.

[GVC]

Thank you analog kid!  I appreciate the insight and it makes sense.  But, I am still amiss on how you executed this idea.  There does not appear to be much room to shield the jacks (swithccraft)  from the  enclosure (125b).  Where did you do this (materials, jacks, etc)??

I will get a picture when I come home from work tonight.  I think the standoffs may be touching the ground trace as well, which may give four ground points in this puppy, whew??

Thanks for your help!

[GVC]

Ok,

I have tried removing the output jack from the enclosure.  Still humming away.

can anyone give me instructions like they are talking to a six year old.  If this box wasn't humming like this it might be my favorite distortion, low OR high gain.  PLEASE HELP.  I want to use this thing on stage but I can't like this.