Common Ground or Not - Why can't we agree?

FheBlackPassat

I'm starting a new thread for this topic as it is spread out between a few other posts I have.

I have a Onkyo M506-RS (European version) dual mono block amplifier.
I have confirmed it is a common ground.
With nothing connected to it, I have done ohm tests accross all negative (-) binding posts and from binding posts to the chassis.
It clearly is a common ground amplifier.

So why do some say 'It will NOT work' and others say 'You'll be fine'.

I'm curious to know why the veterans here can't agree on this issue?


edited

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I have been informed about a possible scenario that the interconnect cable might be an issue here.

I have the Blade/Blade interconnect cable.

Now this begs another question.
Do the different interconnect cable types have different connection schemes to the XO's?

dcmartinpc

I have a Parasound HCA-3500 dual monoblock that MANY people say is not common ground. If you search around on this forum, there are several people that have confirmed it works fine with SDA's and have confirmed with Parasound that the output stages share a common ground, despite having separate power cords for each mono block...

I would contact Denon Customer Support and see if they can verify that the output stages share a common ground... Unless someone here has tried it already


Don

FTGV

As long as the negative output terminal(s) is at ground potential(common ground) then they can be strapped together regardless of whether they are in a single chassis or a pair of mono blocs.In the case of an amp (be it stereo or pair of mono's)that utilizes a briged/balanced output stage configuration the negative terminals cannot be strapped together.

dcmartinpc

Don't know why I said Denon Onkyo obviously. FTGV is spot on...

Don

Schurkey

The confusion is because people see "mono block" and ASSUME that there are two separate amplifier chassis with no ground connection between them. It's a matter of inattention on the part of people reading your post(s).

You do NOT have a problem with the interconnect PROVIDED you have a common-ground amp. The ONLY time the interconnect can be an issue is with non-common-ground amps; and the complicating factor is that Polk supplied a SPECIAL interconnect for SOME speakers that allows non-common-ground amps to be used. This SPECIAL interconnect (model # AI-1) does not fit Blade/Blade speakers like yours and mine without serious modification--so it's not an issue for you. Polk used at LEAST two different wiring methods to create the SDA effect; your SRS-2 and my 1Bs use two electrically-live conductors in the interconnect. The later SRS-2 with pin/blade and the 1C (and others) use an interconnect with ONE electrically-live conductor. The second conductor is un-used except when the special AI-1 interconnect/isolation transformer is installed.

FheBlackPassat

^^
Schurkey, Thanks for the clarification.

As for my M-506RS amp. I think I'll remove the cover and investigate to see exactly how this thing is constructed. Through the top panel you can plainly see 2 completely different amp 'blocks' but electrically things could be different. Even though ohm testing shows a shared ground I really want to know what is 'true' inside this thing.

heiney9

FheBlackPassat wrote: »

Even though ohm testing shows a shared ground I really want to know what is 'true' inside this thing.

The Ohm test is the "true thing". It shares a common ground, so therefore is not technically a dual mono design in the purest sense. It's fun to take the top off gear, but looking in there won't change the answer you already have.

H9