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Thanks Ben!
It's Bren... Brenden... I'm Irish-Canadian.
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I presume that it doesn't really matter where I put this piece, i.e., before/after the other parts express piece.
No, you can put pads before or after the isolation transformer.
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Also, the other part definitely does remove the hum from my sub when installed.
Which is a start.
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And one final thing, my picture is fine when I'm not using the P/E part. Does this alter anything you've suggested?
Yes, yes it does. I think I missed the first part of your describing the issues. Didn't realize this was a fix for hum through a sub... thought you were using the iso xformer to battle the picture problems.
That adds a bunch of other layers to the issue... not sure if you've tried any other methods to remove the sub hum before this...
- a "cheater" plug on the sub... one of the ones that cuts the ground out of the plug. (use as a diagnostic tool, do NOT use it as a permanent fix - it's dangerous, the only path to ground from the sub then is the shielding on the sub cable then - and it's not rated for mains voltages, in case of a shock, it may melt and leave YOU as the only path to ground)
- "break ground" to the sub from the receiver. Most people use a basic 75ohm "video" type cable to the sub, which connects both the centre pin and the outer ring of the RCA - the outer ring doesn't have to be connected, if you use or build a cable that doesn't connect the shield at the sub end, that allows the sub and the receiver to run at their different ground planes without hum. So you'd have the conductor in the wire attached to the centre pin on both RCAs, and the shielding/drain wire attached to ONLY the RCA ring at the receiver. This still allows all interference captured by the shielding to drain to a ground (at the receiver) but keeps the ground planes separate for each piece of electronics. Technically, you should do this for all analog audio cables (but NOT video - it requires the signal return)
- try plugging the sub into the same power bar as the HT to put it on the same ground plane as the receiver.
- is your CATV even grounded as it enters the house? It should be grounded in ONE place, no more, no less... use one of
these, bring the cable in one side, and out the other, and hook up a nice big beefy piece of 12ga. copper (again - big conductor in case mains voltage hits it - you want it to carry that voltage to ground, not melt like a fusible link) to the screw terminal and clamp it to a cold water pipe (if you have metal pipes - legally this also has to be kept separate from the mains grounding, so don't try to tie it into anything of Edison's) - if your CATV isn't held to ground like this, the place it's grounded to will be probably hundreds or thousands of feet away, which would mean your ground differential between the cable and your home wiring could potentially be very large.
Hope one of these helps.
Bren R.
