Amplifier Ground points (?)

Hello

I've recently been looking to upgrade my wires to the Supra Ply 3.4/s.

They have a ground wire which they say should be connected to the amp's "ground points".

Now, this thread is NOT about whether this is snake oil or not (it's a very reasonably priced cable), but rather about which are these ground points?

I know ONE point is the phono ground screw - but since it's not that close to the speaker terminals on my amp (Yamaha 803d), are there any other ground points? I heard somewhere that theoretically any screw on the back is one, but i'm not sure about that.

Thanks!

 

The Yamaha 803d does not have a mains (protective) ground point, which means that the amplifier must be double insulated.
Which in turn means that the ground point is a signal ground.
The only way to establish whether or not the case screws are connected to the signal ground is to do a direct DCR test with a DMM.

 

What's a "mains ground point" ? It does have a ground point in the phono stage. Are you referring to something else?

 

Power fed into a building has 3 connections - live, neutral return, and ground - at least it does here in the UK, much of Europe, North America and so on.
That is the mains ground point.
Yamaha sell that amplifier into many territories, some of which don't have a mains ground, so they've built the amp to be safe without the ground connection.

Your amplifier is isolated from mains ground.
The ground point on your amplifier is a signal ground.
The ground point on the back of the amplifier might be connected to the casework, in which case any screw will do.
The ground point might be insulated from the casework, and in such a situation you'll need to connect to the ground point.

Either way round you'll need a DMM to check continuity.

 

Ok so just to understand - if the GROUND point on the back of my amplifier (the one that's in the phono stage section) is connected to the casework - and i just checked and it IS, this means that any screw will do?

 

One more question, the cable's manual states that the ground wire can also be "connected to speaker minus terminal" - do they know what they're talking about? So am I to understand that the minus terminal of the speakers (on the amp side) is ALSO a grounding point? Because if so, that's much easier than connecting it to a screw.

 

Yes

Again, yes
The negative terminal is connected to the signal ground.

 

Thanks a lot for all the info! But I've got a final question since you seem knowledgeable in this:

Since i'm connecting my speaker cable with banana plugs, would it be ok to mix in the ground wire in the banana plug (with the negative connection wire), or should i keep it separate from the banana plug and just plug it in the side of the negative terminal as a normal wire (below the banana plug)?

 

It might lead to less swearing if you connect the two together

 

Chassis ground or earth is the same as power AC ground. the internal power supply ground is different and is connected to the signal ground. For safety professional audio equipment have a loop breaker circuit between earth and internal ground. The audio connectors must be insulated from the chassis

 

Only if the speaker post is also connected to ground. You really do need to check the continuity of the amp case to the safety ground of the outlet that it connects to. If that is at ground potential (has continuity), then you can use any screw on the back or bottom of the chassis. Also, if you have found that negative speaker post has continuity with the safety ground (third prong on the AC cord / outlet), then you could use that. Often it is only the chassis that has continuity with the safety ground.

The reason that the cable has that second ground conductor is because it is a shielded cable. It's certainly not snake oil, but it may not make an audible difference either.
-Bill