Originally Posted by notnyt
Not really worried about a 25' dedicated run here. Even 12awg wire can carry 30 amps that far without a drop, they're just not up to code for in wall installation. I think you're getting a bit carried away here.
You're right, it's not necessary. But saying 12 gauge can carry 30 amps without voltage drop isn't true. Also, any discussion must include length. It's fine if it's not a concern of yours, but that doesn't mean it doesn't exist. Up-sizing branch circuits for voltage drop is very common, especially if the load approaches the circuits limits. A 25 feet run, I'd up-size it. It will exhibit voltage drop under load, period. Will it affect the performance of your amps? I don't know. I prefer to eliminate that concern and up-size any amplifier circuit.
Having spent a career in the electrical industry (and a multi decade foray in live sound), the final decade of which I spent centered around event power for the largest events you can imagine, down to the smallest and most technical situations imaginable. Load calculations, voltage drop, borderline scenarios were a way of life.
So, that said, no a 12awg line of any normal length can not carry 30amps without drop. Will it carry it, absolutely. You'd may actually be surprised how much amperage wire can carry. If the connection points are tight and sound, a circuit in open air
can carry extraordinary amounts of current. Enough to get so hot you can't touch it! I've seen the finest Hubble cord caps melt into liquid with breaker interruption. But the heat being produced as a by-product of current flow, is manifested as voltage drop. Not under load, it's not present, under load,..however brief, it's there. With the voltage drop come a corresponding increase in current, this is the insidious aspect. Just as the kick drum beater hits, the large signal voltage demands peak current from the PS, thereby sucking the line voltage down, raising the current lowering the voltage even more. Some amps deal with this better than others.
Amp design isn't within my wheelhouse, so I don't know which amp designs are more immune to line drop than others. conventional wisdom would lead me to believe big, conventional and non-switching designs would be more immune. But I'm really out of my league with amp design.
Back OT. A
25 foot run, in general is medium in length IMO for amps, and borderline. Your
25 foot run, if accessible, I'd use one size bigger. Especially given your LF rig is absolutely non-compromise and world class in nature. I also felt your SS relays used before were a concern
Bottom line, will it matter? Yes, it matters. I've seen it, I've measured it. Is it discernible in your rig? I don't know. I just don't like to entertain the thought, so I up-size.