Dedicated circuits

@jea48  , thank you for clarifying that for us. 

I have had a single dedicated circuit and receptacle where my Shunyata Triton V1 is connected. Two mono block amps phono preamp preamp stresmer DAC turntable are all plugged into the Triton. This circuit is new with 12 gauge Romex.  The position of everything requires almost 15 foot power cables to the amplifiers  This makes it impossible to upgrade because I would have to purchase very expensive custom lengths that would have no resale value.  Instead of moving the outlet closer, I’ve been planning to change it to 10 ga.   I remember reading Or watching a video with Michael Fremer and I’m pretty sure he recommends one single circuit so I could run the 10 gauge and then also add a second receptacle close to the amplifiers so I could use standard length cables. I know a lot of people do what the OP did and have a completely separate circuit for the amplifiers. Nothing about money I just want to do what’s best for the sound.  I’ve added the amp ratings for all my gear and the total is less than 15 A so electrically I don’t need two dedicated circuits.  Does anyone know if I am remembering correctly, and if there is a reason to have everything, going to one circuit?

I’ve added the amp ratings for all my gear and the total is less than 15 A so electrically I don’t need two dedicated circuits.

@dhite71

That method may be fine for digital equipment, TT, phono preamp, Line level preamp, and other such equipment. Not Power amps as a rule. (Class D ???). The manufacture specs, for some reason, don’t give an instantaneous peak surge current draw, when the user is listening to music with high dynamic music passages. Especially if the user is listening to it loud. Have you seen the size of the power transformers ARC uses in their power amps? ARC over sizes their power transformers for a reason. To handle what ever demand is placed on them. Problem?  The power transformer can’t do its job if the ac mains can’t supply the quick gulp(s) of current needed, and keep the AC mains voltage steady. 

By chance did you read this? From page 1 of this thread:

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FWIW:

jea48

3,919 posts

06-07-2022 at 08:04pm 

@kijanki

+1

 

Please explain what happens if the power transformer’s secondary winding voltage is lower feeding the rectifier, due to a quick AC mains VD event, and the electrolytic capacitors voltage is higher. Just going from memory the rectifier will not conduct and the caps do not get recharged for that "(millisecond pulse)" in time.

 

Jim

Response:

kijanki

4,296 posts

06-07-2022 at 08:46pm 

@jea48   You are right - there will be no current thru rectifiers until capacitor voltage will drop below rectifier supplied peak voltage.  Theoretically it is possible to build LPS where capacitors keep average instead of peak voltage, but it requires huge inductor in series (in order of Henries) made with thick wire and AFAIK nobody is doing it.  One problem is lower rail voltage (average instead of peak) while the other is dependency on the load current.

http://www.r-type.org/articles/art-144.htm

With #12awg wire you may have been starving you power amplifiers. Depends on the length of the #12awg branch circuit wiring, the type of music you listen to, and how loud you play it.

Music with high dynamic music passages cause the amplifier to draw more power from the electrolytic caps in the power supply. The power transformer has to draw more power from the AC mains. That in turn may cause a voltage drop on the branch circuit wiring.  Then what kijanki said in the quoted material above kicks in.

It’s fine if you only want one dedicated circuit to feed your audio system. You just want to make sure the branch circuit wiring can supply the necessary power reserve to handle the high dynamic current draw needed.

#10awg copper may be big enough. Can you guesstimate the distance, length, from the wall outlet to the electrical panel. Try to figure up, down, and around as for the electrician will have to install the wiring. 

By the way, whether #10awg copper or larger, the branch circuit breaker will be a 20A breaker.( FWIW, a 20A breaker will pass quick fast draws of current of 50A or 60A all day long with out tripping.)  The bigger wire size is for voltage drop. To maintain a steady voltage. You don’t want any voltage drop on the branch circuit wiring. 

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@dhite71

Here is an article by Nelson Pass written for a layman to read on how a power supply works.  

Power Supplies: Commentary for Consumers by Nelson Pass

In an amplifier, your utility, house wiring, power cord, and transformer provide the rain. The capacitor bank is the reservoir. The capacitors receive electrical charge every 1/120th of a second, reflecting two pulses of current from the transformer for every cycle of the 60 Hz sine wave provided by the power company.

These pulses are of relatively short duration, and it is up to the power supply capacitors to store energy during the 6 millisecond or so electrical drought that occurs between charge pulses. We want a constant voltage (water level) from our power supply, and this is usually achieved by the use of large capacitors which store more charge, and large transformers which provide as much charge as is needed. You get the idea.

Since we are not designing amplifiers here, but rather trying to get a handle on what constitutes quality in a market full of hype, I want to talk about some general ideas and comment on some of the common approaches used by manufacturers. Understand that we simply want a constant, noise-free, voltage to be available from a power supply, regardless of how much demand we place on it.

Problem, for the above to happen the AC mains must be able to supply the demand of power, (volts X amperes, VA), the power transformer calls for instantly as needed. IF the power transformer is called upon to deliver more power, and the AC mains voltage drops due to a quick increase of current demanded by the primary winding of the power transformer, caused by an increase of current  demanded by the amplifier section of the amp. Then this happens:

@jea48   You are right - there will be no current thru rectifiers until capacitor voltage will drop below rectifier supplied peak voltage. 

 AC mains voltage drop, because the branch circuit wiring was not able to maintain a constant steady voltage. Reason, voltage drop was due to the branch circuit wire size. Also the length of the branch circuit wiring times two. Size of the wire and length X 2 go hand and hand.  

IF there is an AC mains voltage drop on the primary winding, of the power transformer in the amplifier, there will be a voltage drop on the output of the  High Voltage secondary winding. IF the secondary winding peak voltage is lower than power supply electrolytic caps peak voltage the AC to DC bridge rectifier will not fire. Electrolytic caps will not be replenished. Amplifier power output is lowered. If there is another high dynamic musical passage, during the event, the amplifier may clip and you may hear distortion... Depends on how hard you are pushing the amp.

If Nelson Pass over sizes his power transformers, it stands to reason the branch circuit wiring that feeds the power transformer should be over sized. 

FYI, ARC over sizes there power transformers as well as PS Audio. By bet is most High in equipment designer/manufactures do.

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