Ungrounding an Amp--Any Danger?

Defeating a three prong power cable with a "ground lifter" etc., is not only dangerous, it defeats the UL listing (Underwriter Labs is an independant body which tests electrical devices for safety under extreme conditions), and will invalidate ANY and ALL insurance claims that occur as a result of that equipment. The ground is there for a reason (aside from causing ground loops): in the event of electrical fault within the equipment (caused by internal or external forces), the ground acts as a safety to safely shunt excess current away from the chassis and you. Solve your hum problem by finding out what is causing the hum in the first place.

Joe, I'm not sure you're right about grounding thru the amp. Yes it will provide a single ground path, but I understood that "star grounding" is when each component (or each device on a circuit board or chassis) has it's OWN shortest path to the ground point -- thus making the preamp the preferable compoinent to ground, and not the amp.

One thing a lot of people forget to do when using the preamp as the center of the "star", is to make sure ALL directional arrows (if present on the interconnects,) point to the preamp. This insures that all shielding inside the ICs will be connected to ground at the preamp. This isn't 100% true 100% of the time, but MOST cable manufacturers point the arrowheads to the end of the interconnect where they've connected the shield (the other end is not connected). The reason for all the BS about pointing the arrows in the "direction of signal flow" is so the manufacturers can get you to do the right thing without going into an explanation that might be over the head of most consumers.

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Thanks for the warnings. I am recalling a story I heard some years ago about one of the former members of the Yard Birds. He electrocuted himself while tuning his electric guitar. I assume his guitar amp wasn't properly grounded.

The hum is definately in my amp since it remains when I disconnect my CDP. Since it's an integrated, there are not separate power plugs for the preamp and amp. Besides, the preamp is passive.

I have seen several products designed to block RFI and EMI, like the Stillpoints ERS cloth ($20 at Music Direct). Would these products be of any help? If not, the hum is minor enough that I can live with it.

Bob, I'm afraid you are incorrect about "unbalanced" ICs. First of all, the correct terminology is "single-ended" ICs. Some single-ended ICs have a coaxial configuration, where the shield is indeed used for a signal carrier, but they are usually only found today in 75 ohm coaxial FM and TV cable and in some 110 ohm digital interconnect. They are no longer used for audio signal IC, except in those cheap RCA patch cords which are packed with inexpensive gear to get the consumer "up and running" -- and they don't have arrows on them.

The audio ICs I was referring to are known as "shotgun" interconnects, and were the original Bruce Brisson design which put Monster Cable on the map. Bruce left Monster early on to start MIT, which he still owns. The shotgun design is a single-ended interconnect (which means one ground conductor and one hot conductor), but there are TWO identical (double-barreled?) signal conductors surrounded by a ("floating") shield which is only connected at one end and therefore cannot carry any signal or current. The conventional (though not universal) indication for the end at which the shield is connected to the ground ring of the RCA, is an arrow which points to that end. This configuration applies to the majority of decent conventional audio cables today, from the cheapest Audioquest, Straightwire, Monster, XLO, Cardas, etc., to expensive (and even unconventional) designs like Magnan, Purist, Transparent, and Siltech. Two of the well-known brands that represent exceptions to the shotgun design (and only in certain models now) are Nordost (flat conductors) and Kimber (braided conductors). Using the old single-conductor-and-braid/shield design for audio signals anymore is just asking for "hum trouble."

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