SDA-SRS common ground problem

madmax

I know the SDA-SRS 1.2 (pin/blade) can be fitted with a transformer in the cable to isolate the grounds for non-common ground amps. The reason you can do this is that one of the two connections in the cable is a ground and the other is a signal. This feeds one side of the transformer and of course the output on the other side of the transformer is not physically connected.

Typically you cannot fit a transformer on the SDA-SRS (blade/blade) because only one wire is used and a ground is not available.

I believe all the above is correct. In the case of the 1.2 the two speakers have the ground hard wired (in the SDA cable) while the SDA-SRS counts on this ground connection to be made to each speaker via the negative speaker post and relies on the two grounds from the amp to be the same potential (common ground).

So far, so good?

Now, if you wanted to isolate a pair of SDA-SRS (blade/blade) could you do so by adding the ground connection to the SDA cable and utilizing the transformer?

madmax

BobMcG

Hi Chuck,

I believe it may come down to a crossover issue at some point. You'll notice that SOME of the early model 1Cs and 2Bs were capable of using an AI-1 with crossover changes. In addition SOME B/B models could use a modified AI-1 but not all.

My brother's early B/B 1Cs fell into the modifiable AI-1 catagory (serial # wise) so while he made some changes to his crossovers to make his 1cs biwireable Ken Swauger made him a custom AI-1 to use. You can find pictures of it in here and on our Polk SDA site. It has a built-in grounding wire and is B/B.

madmax

Do you happen to remember whether it was just adding a ground wire or other changes as well? With all the SDA-SRS out there it would be a good change to document.
madmax

BobMcG

If I remember right it was just the addition of a ground wire. You can see how it connects in the pic.

http://www.polkaudio.com/forums/showthread.php?t=27621

madmax

You da man!!!

After thinking about it I figured the ground was the missing link.

THANKS!
madmax

BobMcG

No prob-lee-mo!

I-SIG

Damn. Don't tempt me on my SRS's.

Wes