Common Ground?

Neskahi

Is there a simple way to determine if an amp is or is not common ground?
Thanks.

ben62670

Take a multi meter, and set it for continuity. Take the leads, and test across the speaker grounds. If it has continuity then it is common ground. What kind of amp is it?

Neskahi

Pioneer M-90 at this time. Plan's are to bi-amp with Adcom GFA-535's.
[2.3's]

hearingimpared

ben62670 wrote:

Take a multi meter, and set it for continuity. Take the leads, and test across the speaker grounds. If it has continuity then it is common ground. What kind of amp is it?

Some people call "continuity," "resistance." That what is on my VOM. Or it may just have the omega symbol.

Neskahi

Thank you Ben. That is kind of what I thought but was not sure.
So, why would a manufacturer make a non-common ground?
On another note, my wife is upstairs hogging the 2.3's and I get them after she
gets sleepy. But more importantly, I have the WAF for a set of 1.2TL's if
I can find them! Any ideas?

ben62670

Non common ground amps are pretty rare. I just guessing that some manufacturers make non common ground amps to have completely different circuits. I have also heard of the positive being common in rare instances.
I hunt Ebay all the time, and craig's list.

Neskahi

Watch e-bay also, and I think those were your 2.3's up for sale a while back. Would have taken them for the wife [put her downstairs],but too far away.

ben62670

Neskahi wrote:

Watch e-bay also, and I think those were your 2.3's up for sale a while back. Would have taken them for the wife [put her downstairs],but too far away.

Mine were 3.1TL's, and I sold them here. I still have my SDA-SRS's:)
Ben

hearingimpared

Neskahi wrote:

So, why would a manufacturer make a non-common ground?

In most instances you see non-common ground amps as a result of mono block designs or bridging stereo amps mono.

BrettT1

Hi all: So if I bridge two stereo amps I would put the multimeter terminals on one negative of each amp to check for continuity. If the ohms read 0, then I'm good to go?

Thanks.

Brett

TN_Polk_Lover

Neskahi wrote: »

On another note, my wife is upstairs hogging the 2.3's and I get them after she gets sleepy.

WOW! that must be awesome to have a wife who likes audio / listening to music so much that you have to wait your turn after her! I wish I could get my wife that interested. Then maybe she wouldn't give me such a hard time everytime she sees me searching ebay for more audio deals.

hearingimpared

BrettT1 wrote: »

Hi all: So if I bridge two stereo amps I would put the multimeter terminals on one negative of each amp to check for continuity. If the ohms read 0, then I'm good to go?

Thanks.

Brett

Brett if you bridge two stereo amps mono they become two separate amps. The only way they can become common ground is to strap them. You need to call your amp manufacturer and ask them if once bridged they can be strapped together.

My Adcom 565s are strapped negative speaker terminal of the left channel to the right negative speaker terminal. I've also strapped the chasis. So it goes without saying that if I connected and ohm meter to the ground terminals I would get a zero reading the same with the chasis.

BrettT1

hearingimpared wrote: »

Brett if you bridge two stereo amps mono they become two separate amps. The only way they can become common ground is to strap them. You need to call your amp manufacturer and ask them if once bridged they can be strapped together.

My Adcom 565s are strapped negative speaker terminal of the left channel to the right negative speaker terminal. I've also strapped the chasis. So it goes without saying that if I connected and ohm meter to the ground terminals I would get a zero reading the same with the chasis.

So when I bridge, use a piece of speaker wire and connect the negatives of each amp together. Would you use the same terminal you use for the negative wire to the speakers? Also, when you strap the chassis, did you just loosen a case screw on each amp and connect them with speaker wire? I just don't want to burn anything up.

Thanks for your help.

DarqueKnight

BrettT1 wrote: »

So when I bridge, use a piece of speaker wire and connect the negatives of each amp together. Would you use the same terminal you use for the negative wire to the speakers?

Yes. But you should be aware that some amps have a common ground connection through the positive output terminals rather than the negative terminals. Which amps are you using?

BrettT1 wrote: »

Also, when you strap the chassis, did you just loosen a case screw on each amp and connect them with speaker wire? I just don't want to burn anything up.

That is what I did when I strapped my Adcom GFA-565 monoblocks together. Some amps will require the additional chassis strapping wire and some will not. The chassis strapping wire is for ground loop (hum) prevention.

I would also like to reiterate this excellent advice:

hearingimpared wrote:

You need to call your amp manufacturer and ask them if once bridged they can be strapped together.

BrettT1

I'm going to try out a pair of audiosource seven t amps. 200 x 2, 500 bridged.

Got the multimeter ready to check everything out after wiring.

I called audiosource and they seemed uninformed about strapping to obtain common ground.

A friend is loaning me an AI-1 to test with, also.

Will post results.

BrettT1

Sounds excellent, but need an ai-1. Would like an original, I'm going to wait a while before I make a custom.