test for common ground amp

egp823

is there a simple do it yourself test to check if an amp is common ground or not? tks

disneyjoe7

Is this a single body amp? If so most are common ground. What is your model number, so we could double check for you?

dorokusai

If you have a VOM/Multimeter, sure....easy. Continuity is good, none is bad for SDA owners. If you don't own SDA's....who cares.

nadams

Take the cover off and trace the grounds back? That might not be a definitive test, but it'd give you a pretty good idea, pretty fast.

egp823

steve
Yamaha m-70 and 85 , adcom gfa 545II

doro,
how do i check using a VOM/multimeter? I have an SDA

thanks

dorokusai

Originally posted by egp823
steve
Yamaha m-70 and 85 , adcom gfa 545II

doro,
how do i check using a VOM/multimeter? I have an SDA

thanks

NEG(BL) - NEG(BL) binding post....Continuity = OK....None = No-Go. I'm betting AOK.

What SDA's?

Nadams offers a good idea, but I personally don't like to infer what may be inside a component, unless I've actually seen it naked.

There are sometimes changes within model lines that preclude any forward thinking.

That being said, pop the top, take a picture, file it, VOM it....now you are an expert

egp823

pls forgive my ignorance but what setting should i use in the VOM? smallest no. is 200 and highest is 2000k . at the 200 setting i get reading of .5 and at 2000k its 0 . does this mean that my amp is common ground based on the reading at 200? thanks.

disneyjoe7

Originally posted by egp823
pls forgive my ignorance but what setting should i use in the VOM? smallest no. is 200 and highest is 2000k . at the 200 setting i get reading of .5 and at 2000k its 0 . does this mean that my amp is common ground based on the reading at 200? thanks.

200 is the lowest resistor level that you can read, so anything under 200 ohm can be seen. So you can .5 ohm so you have common amp.

dorokusai

You should get a value either way, continuity is continuity. You're just checking to see if there is a electrical connection, not launching a rocket into space.

bikezappa

To use the ohm meter to check the resistance between the two black or negative speaker connections you should:

Set the ohm meter to the lowest setting, in this case it's 200 ohms.

Next touch the two wire leads together, this should be 0.0 resistance and the ohm meter should also read 0.0.

In the old days the meter reading was adjustable with a potenometer to read 0.0 when the leads were touching.

You need to do this step to determine the exact resistance of anything you are measuring. Shorting the leads will tell you if the meter is reading zero and correctly.

You have a common ground amp.

egp823

Thanks a lot for your replies. Am learning a lot from these forums and I know that I didn't make mistake when I purchased my CRS+ because of all your help and support.

PILAC

I know this is an old post but just wanted to ask if anyone knew right away before I ask an eBay seller to pull out a multimeter they might not have, is the Sonance Sonamp 260 (mk 1) a common ground amp? And if so would bridging both of the channels affect anything? I have a pair of SDA’s so I do need it to be common ground.

F1nut

In stereo mode it may or may not be common ground. When bridged it most definitely is not. Bridging raises the noise floor, cuts the ohms the amp is seeing in half and cuts the damping factor in half. Never a good idea, IMO.

PILAC

Ok thanks for the info.