Another Non-Common Ground Amp Question.

aprazer402

Kind of a two part question. I have an Adcom 5503, it's has not been connected in over two years. I probably should have it checked out first. Question one is strapping the two negative speaker connection posts on the amp with a 10 or 12 gauge quality cable all that is required? Second part would using a AI-1 (I have two AI-1's) and ALSO strapping the negatives be unnecessary? I have a pin/blade cable. Is there any way to test an original Polk AI-1 to confirm if it is working properly (voltmeter maybe) Also years ago there was post by Raife (Darque Knight) reviewing a Polk AI-1and he found that wrapping it in several layers of aluminum foil had a positive effect on the SQ. I think he said the optimum layer of foil was between 6-7 but less than ten? Is this old science by now? I've heard of the Dreadnaught. Thanks.

nooshinjohn

The dreadnaught is the way to go these days. I would not strap negatives on the amp, and as far as your AI-1 goes... not much to go wrong there, so you should be alright. Check the center pin for continuity, and you should be good.

F1nut

Regardless if the Adcom is common ground or not use the AI-1 as it will improve the sound quality. Strapping is a poor choice and there's no reason to do so since you have the AI-1. Use 10 layers of aluminum foil, no less and no more.

aprazer402

Thank you.

voltz

I have a Adcom 5503 and it is a common ground amp i swear. i tested it with my voltage meter and will do again if you like. If you have a multimeter it is easy to check.

I have some CRS+ speakers and I will hook it up Tomorrow and check it to be sure it is safe for you to use and I am going to have Dave (wessmassguy) build me a Dreadnaught as it will improve the sound even if your using a common ground amplifier.

aprazer402

I was always told the Adcom 5503 is a "Non-Common Ground" amplifier that requires strapping the negs. or using an AI-1 or a Dreadnaught with any Pin/Blade SDA's. Please correct me if I'm wrong.

ZLTFUL

The GFA-5503 is most assuredly *not* common ground.

voltz

holy smoke I made a horrible mistake on the Adcom 5503...just check it and it is not common ground, I swore when I check them all for my CRS's I check it too along with my other 3 amps, I could not have metered it and just thought I did...
I Apologize for telling you wrong

aprazer402

Glad we saved your CRS's from any damage, it was a "common" error.

Schurkey

aprazer402 wrote: »

I have an Adcom 5503...
...is strapping the two negative speaker connection posts on the amp with a 10 or 12 gauge quality cable all that is required?

Yes. It's not the ONLY way, though, IF (big IF) you have SDA speakers that can accept the transformer-coupled SDA interconnect. These are usually (not always) speakers with the pin/blade interconnect cable sockets.

aprazer402 wrote: »

would using a AI-1 (I have two AI-1's) and ALSO strapping the negatives be unnecessary?

Yes, it would be unnecessary to strap the negatives when using an AI-1. Given a choice between strapping the negative posts vs. using an original Polk AI-1, I'd test both ways...and likely prefer strapping the negatives especially as the volume went up. The tiny transformer in the original AI-1 won't handle the SDA signal at higher volume. It's just too amperage-limited. By comparison, the 12-gauge wire used to strap the negatives has no such amperage limitation; at least not in terms of audio amplifiers and the SDA signal.

To my knowledge, everyone who has claimed that the transformer-coupled interconnect "sounds better" than the strapped negative posts, has used a HUGE transformer (Dreadnought) rather than the itty-bitty AI-1. (Of course, the transformer-coupled interconnect is NOT AN OPTION for those of us with older SDAs. Only the two newest generations can accept the transformer in the interconnect.)

aprazer402 wrote: »

Is there any way to test an original Polk AI-1 to confirm if it is working properly (voltmeter maybe)

Ohmmeter. I'm unsure what you could expect for resistance readings; perhaps someone else knows and could post the specs. Wild Guess: If you have continuity through each transformer winding, you're fine. The big Dreadnoughts would measure under one ohm. The little transformer in the original AI-1 would probably have more resistance due to finer wire in the transformer windings.

F1nut

To my knowledge, everyone who has claimed that the transformer-coupled interconnect "sounds better" than the strapped negative posts, has used a HUGE transformer (Dreadnought) rather than the itty-bitty AI-1.

This was originally discovered using the AI-1.