When I bought my REL sub I used the high level connection as the instructions recommended. My amp was class AB, and that was the first case explained in the instructions.
The high level cable has 3 wires: black, red, yellow.
For an AB amp, you connect the red and yellow wires to the red binding posts of the left and right speaker-outs respectively, and the black wire to the black binding post of either right or left speaker-outs.
OK, I thought. Smart. We’re getting the signals from both stereo channels and adding or somehow combining them at the sub.
I assumed the black wire was “zero”, or “ground”, but not necessarily electrical ground. The yellow and red wires, then, would be carrying the signals offset from the black wire.
Later I got a Hypex NCORE amp by Audiophonics. (Oh I had had my eyes on Hypex NCORE…)
And I read the REL instructions again, as I knew the wiring depended on amp topology.
For class D amps and differential amps, the wiring instructions differ from the class AB case: the red and yellow wires are connected to the red binding posts, as before, but the black wire is left loose, not connected to anything.
I did not understand this. I still don’t. In a differential or a class D topology, the speaker connections still work the same, no? A voltage applied to the binding posts, then carried by the cable to the speaker. The voltages of the binding posts relative to ground are immaterial, what matters is the voltage difference between the red and black posts, right?
For class AB, I had assumed the yellow and red wires carried the signal offset from “zero” (black wire). I would not expect it to work without the black wire: if I fed the amp a mono signal, the left and right red binding posts would be carrying the same offset voltage, so … no signal between the red and yellow wires, is what I thought.
I cannot understand how class D could do things any differently.
But my assumption about the red and yellow wires must be incorrect. They must be carrying the signal *between* them, but i can’t understand how.
However, for a mono-block amp, the instructions suggest to connect red and yellow wires to the same red binding post, and black to the black binding post (all on the same monoblock, with a second sub connecting the same way to the other monoblock).
I'm totally mystified.
I read a bit more, and found the REL uses the black wire to try to “match ground” between the sub and the amp. And that many class D amps have the black speaker bindings offset above ground, hence the reason to avoid the black wire connection.
This intrigued me but also kind of scared me.
In my understanding, the amp and the sub should both have their chassis connected to electrical ground. So, why should we further match the “ground” of the signals? And if the sub wants the black wire at ground level but my class D amp keeps its black binding posts at a fixed offset from ground, would I create a short if I connected the black wire? Accident waiting to happen?
I read somewhere that Hypex NCORE modules have their black binding posts at ground level. But even then, I decided not to use the high level connection until I understood it, and instead I use an RCA splitter out of my preamp.
This is working just fine so I'll keep it, but I’m still curious about the high level connections without the black wire.
Can someone clarify?
The high level cable has 3 wires: black, red, yellow.
For an AB amp, you connect the red and yellow wires to the red binding posts of the left and right speaker-outs respectively, and the black wire to the black binding post of either right or left speaker-outs.
OK, I thought. Smart. We’re getting the signals from both stereo channels and adding or somehow combining them at the sub.
I assumed the black wire was “zero”, or “ground”, but not necessarily electrical ground. The yellow and red wires, then, would be carrying the signals offset from the black wire.
Later I got a Hypex NCORE amp by Audiophonics. (Oh I had had my eyes on Hypex NCORE…)
And I read the REL instructions again, as I knew the wiring depended on amp topology.
For class D amps and differential amps, the wiring instructions differ from the class AB case: the red and yellow wires are connected to the red binding posts, as before, but the black wire is left loose, not connected to anything.
I did not understand this. I still don’t. In a differential or a class D topology, the speaker connections still work the same, no? A voltage applied to the binding posts, then carried by the cable to the speaker. The voltages of the binding posts relative to ground are immaterial, what matters is the voltage difference between the red and black posts, right?
For class AB, I had assumed the yellow and red wires carried the signal offset from “zero” (black wire). I would not expect it to work without the black wire: if I fed the amp a mono signal, the left and right red binding posts would be carrying the same offset voltage, so … no signal between the red and yellow wires, is what I thought.
I cannot understand how class D could do things any differently.
But my assumption about the red and yellow wires must be incorrect. They must be carrying the signal *between* them, but i can’t understand how.
However, for a mono-block amp, the instructions suggest to connect red and yellow wires to the same red binding post, and black to the black binding post (all on the same monoblock, with a second sub connecting the same way to the other monoblock).
I'm totally mystified.
I read a bit more, and found the REL uses the black wire to try to “match ground” between the sub and the amp. And that many class D amps have the black speaker bindings offset above ground, hence the reason to avoid the black wire connection.
This intrigued me but also kind of scared me.
In my understanding, the amp and the sub should both have their chassis connected to electrical ground. So, why should we further match the “ground” of the signals? And if the sub wants the black wire at ground level but my class D amp keeps its black binding posts at a fixed offset from ground, would I create a short if I connected the black wire? Accident waiting to happen?
I read somewhere that Hypex NCORE modules have their black binding posts at ground level. But even then, I decided not to use the high level connection until I understood it, and instead I use an RCA splitter out of my preamp.
This is working just fine so I'll keep it, but I’m still curious about the high level connections without the black wire.
Can someone clarify?
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