70A into 8Ω is 39.2KW. Ain't never gonna happen in a power amp.
200W into 8Ω is 5A @ 40V. Even a 3x peak is only going to draw about 5A from the line for a fraction of cycle.
What type of wire for dedicated 20A AC lines?
I’m about to have two 20A dedicated lines installed. What type of wire should I use? I know there are differences of opinion on whether to use 10 AWG or 12 AWG, however the link below makes a great case for using even 8 AWG solid core copper on longer runs like mine will be (50 ft), to ensure a lower resistance, lower voltage drop over the long run, and therefore more access to instantaneous current for my Gryphon Diablo 300. The wire would need to be stepped down to 10 AWG to connect with the receptacle. The article actually states that the thickness of the wire is more important than the fact that it is dedicated…
Assuming I want to follow this advice, which again makes sense to me, where would I find such wire to give to my electrician?
Showing 8 responses by ieales
Most of what is published about increasing ampacity is rubbish. Joe AudioPhool installs his hifi in the last socket in a room with daisy chained quick connects. Then installs a direct big ass line and writes about it. The real problem is the daisy chained quick connects. My 10 year old home had a ≈5v no load drop across a dozen q/c on about 75 foot run. All quick connects removed and same, cleaned wire attached to screw terminals. Drop? 0.5v. Same problem exists in older homes with old worn and oxidized sockets.
See http://ielogical.com/Audio/CableSnakeOil.php#ACWiring for all the difference big ass wire will make. What AudioPhools don’t ever seem to comprehend is the peak amplifier current is supplied by the power supply, not the A/C line. Musical peaks are completely asynchronous to the AC line Hz. A 15A breaker can supply about 45A for a couple seconds, long enough to fry your amp and speakers. See https://www.c3controls.com/white-paper/understanding-trip-curves/ |
Yes. The lame ass electrician stripped the wire when pulled. The plaster & painter didn’t cover the boxes and the wire barely made connection is some places. About 45 years ago my mother-in-law’s house barely escaped a fire when the same sh!tttily done aluminum wiring nearly set the receptacle alight.
Where else?
calibrated Fluke.
I’ve been fixing wiring for my HiFi for 50 years. There are all kinds of idiotic claims being made. Few know that plain old Romex beats fancy wiring in a conduit. See Microsoft PowerPoint - Indy AES 2012 Seminar w-Notes v1-0.ppt (wordpress.com) by Bill Whitlock. The paper addresses N O I S E while audiophools prattle on about current which is a non-issue in a properly wired installation. We ran over two kilowatts of amp power on a single 20A breaker. Never blew once. Adding additional loop area is just plain D U M B ! |
A non-dedicated line is [almost] always a bad idea. Refrigerators, hair-dryers, SMPS, light dimmers, etc. add nasty stuff that some products cannot tolerate. When we built recording studios, the gear and the garbage were often on separate services to the street! One well-heeled owner installed 100% system isolation via battery. IIRC, Sony NYC had its own gen set in the basement. |
Someone earlier mentioned mains feed heat buildup. So I measure it. My system is 715 wpc fed from a single 20A /12ga cct. Three bottle rocket amps account for 25% of the power, so average draw is larger than if all SS. Class A would be worse, but Class A power transformers negate the issue as we shall see. After three hours of robust pop program, temperature rise on the 12ga cct was 2.9°C measured inside the yellow sheath with a T thermcouple. The really bad news is that over the 20 foot run, the resistance increase is a whopping 51mΩ or 0.051Ω for the non-technical types. This is added to the 20°C value of 32mΩ. The good news is the power transformer internal resistance also rises 1 - 2% or much more than the line feeding it. Calculated improvement in self-heating for 10ga is about 30mΩ, less than the PT and less than the connections from the power line to the transformer winding! For those posting fancy graphs of diode current, those are steady state loads. Music current draw bears no relation to those graphs. Spend all the money you want on overkill wiring. It will do no more for the sonics than a fancy faceplate or blue LEDs. Sonic improvements can be achieved by ensuring that all connections from the utility input to amplifiers are pristine. Inspect and cycle all power plugs every six months. |
Read p31ff here https://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf and call us back. |