Re: [DML] Re: Re: Grounding Each Speaker Individually

[Peter Lucas <lucas@xxxxxxxx>]

On Mar 26, 2004, at 3:33 PM, Scott Mueller wrote:

> How does a Floating ground adaptor work?

I'm only guessing, but very likely it is simply a pair of isolation 
transformers that permit the use of a common return on the speaker side 
while maintaining DC isolation on the amp side.

Part of the confusion here is that there are really two separate 
issues; (1) sound quality, and (2) electrical "correctness":

1. Sound Quality - - As David T. correctly points out, speakers are AC 
devices -- it is the change of relative voltage between the two wires 
that makes the speaker cones move; "ground" is a red herring (which why 
"return" is a more correct term). Speakers don't really have + and - 
terminals--they are only marked that way so that they get connected 
consistently so they stay "in phase" (i.e., you don't want one 
"pushing" while the other is "pulling", else they tend to cancel each 
other out).
In theory, it doesn't matter whether or not two speakers share a common 
return, as long as that return has sufficient capacity to carry all the 
current spikes that are produced by both of the speakers. In a 
high-power audio setup, these spikes can be very significant, and with 
a common return, one wire has to support both speakers. If it can't, 
the speakers won't be independent from each other, and you will get 
various kinds of distortion.  Rather than using a single huge return 
wire, it makes more sense to just use separate returns and be done with 
it, which is what most high-end amps are designed to do.

2. Electrical "Correctness" -- Given the above, designers of said 
high-end amps feel free to design their circuitry under the assumption 
that there will be D.C. isolation among all the speaker "return" 
connections. If you connect them together, you create D.C. 'leakage' 
paths that may or may not seriously degrade the performance of the amp, 
or even possibly damage it. Depends on your amp.

A "floating ground adpator" can easily address the second issue, only 
rewiring can address the first.

When I did the "Invisible Audio Upgrade" ( 
http://www.dmcnews.com/Techsection/invisibleaudio.htm ), I first tried 
it without the adaptor. It mostly worked, but there was significant 
distortion at high volumes.  The adaptor cleared it up completely to my 
ear. But, as Dave says, "purists" will insist that separate returns are 
essential to that je ne c'est qua of the listening experience. [Of 
course, they will also insist that Monster Cable would sound better 
than an electrically-equivalent piece of Romex  (oops, just started a 
flame-war  :-) ]

--Pete Lucas
   VIN #06703




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