common ground issue

[Gordon]

Hi folks, on the spur of the moment, I purchased some vintage Polk SDA 2b speakers.

There is an interconnect cord between the speakers. Using this cord requires an amp with a common ground. I believe using a 2 channel amp would solve my problem but I have the 501's.

There are two solutions available to me. The first is build/purchase a "special" interconnect called a AI-1. The second, and the meat of this post is this: tie the negatives of each amp together with a jumper. Does this sound like a legitimate solution? I'd hate to blow something up on some very inexpensive speakers.

Gordon

[Face]

Sorry Gordon I don't have an answer for you, but is the SDA connection blade/blade or pin/blade?

[wakkz]

Really nice gear there, would love to see some pix Sorry for OT :P

[1KW]

Get rid of those speakers . Why would you consider damaging your 501's. ?

[Gordon]

Originally Posted by Face

Sorry Gordon I don't have an answer for you, but is the SDA connection blade/blade or pin/blade?

Not sure yet Mike. I'm going to pick them up on Sunday. Also have a lead on some C's I may look into.

Since I can't call McIntosh today, I thought I'd tap into the collective and see if the amps can be strapped. I certainly won't be hooking up anything without some solid info.

Getting rid of the speakers may happen if I don't care for them.

Gordon

[Face]

2B's are the best of the small to mid sized SDA's, don't bother with the C's. If they're P/B and you take a liking to them, the TL upgrade makes them sound better than rest of the SDA family, IMO.

[Ron-C]

Tyeing the two grounds together on MC501s is the same as tyeing the two hots together since they are quad balanced amps. The ground is not chassis ground. Please do not do this.

Thanks,

[Gordon]

Well, there it is! Thanks Ron. I would NEVER have strapped them without an ok from someone in the know.

Mike, they have the blade/blade interconnect. Have a AI-1 laying around?

Gordon

[Face]

No, sorry I don't. I'd ask on CP, but I believe the AI-1 may only be for P/B.

[tdelahanty]

I looked at the owner's manual for the 501, it has a block diagram of the amp. The 501 is a true balanced or internally bridged design. The autoformer is connected between two amp sections, one posative and one negative. There is no common ground at the output. If it were me I WOULD NOT CONNECT THE NEGATIVE SPEAKER TERMINALS TOGETHER.

Sorry for being redundant, I didn't see RON-C's post. I would just "second" his opinion !