Dedicated circuits

Posting this from another thread I contributed to, and I realize some won’t be able to technically grasp what I’m discussing here:

For decades I have read about how many audiophiles have wanted to establish dedicated large gauge wired circuits with hundred dollar wall outlets, or power conditioning, to provide every milliamp of power available from their AC service to their speaker amps. I’m all for that, as I do the same. I get that. What I have a hard time understanding is that, IMO, it’s most times already there, without spending thousands of dollars on power conditioning and heavy gauge wiring. As I continue on, feel free to tell me what I’m missing here, and I’ll try to understand.

I think I know a little about AC for audio, so let me try to convey my thoughts here. First off, I hope everyone here is familiar with in-rush current. For those that aren’t, this is a momentary need for a large amount of current when an inductive device turns ON (for example, a refrigerator, dehumidifier, or air conditioner, etc.). Many times these in-rush values are in the 30-40 amp range, being pulled from non-dedicated 15 or 20 amp circuits (ie, there are other electrical devices on the same circuits). When this in-rush current takes place, not only are these spikes ignored by typical home circuit breakers, but the in-rush amps are almost always delivered on typical 15 and 20 amp wiring and circuits. If the wiring or circuit breaker wasn’t able to momentarily deliver this high current, your refrigerator, dehumidifier or air conditioner wouldn’t turn ON. IMO, momentary peak amplifier current draw could also be considered in-rush current.

I have an ammeter that is able to measure in-rush current (many ammeters aren’t capable of that). Since the conversation is revolving around improving home wiring for audio systems, I think this is the first time I ever placed my ammeter (set for measuring in-rush current) on my main audio system amplifier AC feed, while playing the passage of cannons on Telarc’s Tchaikovsky 1812 Overture CD (where they warn you that speaker damage can occur if you’re not careful when playing that passage in the song).

The ammeter was clamped on to the AC feed that provides power to my three Crown Com-Tech 400 Amplifiers (which are rated at 220 watts per ch. into 8 ohms). This particular system (I have a few in my house) is a tri-amped system, with an active 3-way crossover. The ammeter was only attached to the amplifier power feed. The circuit for these amplifiers is a dedicated one, with a 10 AWG 15’ cable running from the circuit breaker box, connected to a 15 amp circuit breaker in the load center. The 10 AWG terminates (with correctly torqued AlumiConn wire connectors/nuts) to a Tripp Lite Isobar Ultra surge protector. To soften the in-rush to the amplifiers during turn-on, I also employ a 10 amp rated variable autotransformer (aka variac), fed from the Tripp Lite Isobar Ultra.

So what I found was that when I initially turn ON the power switch on the autotransformer (without applying power to the power amps), an in-rush of 10. 3 amps occurred (that value is not always consistent, depending upon how recently the autotransormer was powered up, as it stores energy for a short period of time). After clearing that figure, I applied 120 volts to the amplifiers. As all three amplifiers sensed this voltage, they turned ON. The total in-rush current of these three amplifiers turning ON was 15.32 amps. Clearing the ammeter reading, I then played the cannons passage on the Telarc CD. I’m not sure if you’ve ever heard this CD (Telarc 80041), but when the LP came out (I have that too), it was monumental, as it was one of the few recordings that was able to record these extremely loud cannons, and transfer it to vinyl (later to CD). If my amplifiers were ever going to draw peak power, it would definitely be while playing these cannons. So with my speakers blaring, the peak power consumed by all 3 amplifiers during this passage was only 1.85 amps. I admit, I expected a value that was going to be higher, for the amount of bass that my 15" bass drivers produced.

So from my POV, your home circuits are already able to deliver lots of peak amperage when needed. Improving on that I get, but I’m not sure there really is a need for some, when peak power is probably already there when needed.

Recording of October 1979: The Telarc 1812 Overture

What is resistive load appliance? What is inductive load appliance?

@dpop Thank you for verification of my comments.   Sadly it won't make much difference on this forum. What we have here are a lot of people who also "feel" how much better thier cars drive just after they've washed them. 😂  I read an article some time ago that answered why politicians continue to repeat a lie, long after it has been debunked.   Studies show people are much more receptive to any message that supports a current belief (no pun intended).  In order to accept any message that contradicts a current belief,  a person must be willing to analyse new information,  accept that they could have been wrong in their prior convictions and change their position.  Research shows that many people are simply unwilling or unable to do this.  Not to get political here but Trump supporters who contiue to believe the election was stolen is a classic example of this.  The insistence that over building our power supplies is just one more?

Excellent discussion and very informative. I am in the early stages of building a house and I've been researching the electrical options for my dedicated listening room. I'm certainly no expert but here are a few things that I think I've learned along the way. Please correct me if I get any of this wrong (I'm sure you will!).

One of the advantages of a 20 amp circuit is that code calls for the wiring to be larger. This should allow for a smaller voltage drop from your breaker to your outlet than a 15 amp circuit. If the service panel is close to the outlet this isn't an issue but in cases where there is a long run it could make a difference. I don't know how much difference a few volts make but I understand that higher voltages are better. This would indicate that for the marginal extra cost a 20 amp circuit would be better even if it won't be supplying high wattage components.

A few decades ago I was powering a pair of Large Advents with an Adcom GFA 555 and the lights would dim during bass transients. This was in a relatively modern house (70's vintage) on a 15 amp outlet. I installed a built in cabinet for the stereo equipment and included a new 20 amp circuit. The dimming stopped.

If you run a large Class A amp it might use more power than you think. I bought an inexpensive watt meter to measure my Krell KSA 300S and found that it uses about 1000 watts at idle and about 1700 watts when it hits the highest bias level. Fortunately I have a 20 amp outlet to plug it into (the guy who built my house was an electrician) but I would not want to run this beast on a 15 amp circuit.

At AXPONA several years ago I met Caelin Gabriel from Shunyata in their room at a slow time (really nice guy BTW). We talked for quite a while and I picked up a few tips - one of which concerned outlets. Caelin very candidly told me that Shunyata's outlets are great but if I wanted to be more cost effective a Hubbel 5362 was very good for a lot less money. I bought one (Amazon) for my 20 amp circuit and it is obviously better built than the contractor outlet. He specifically advised me not to use hospital grade outlets. These outlets are made of stainless steel which does not conduct electricity as well as copper. They are designed not to corrode in an environment where strong cleaning chemicals are used regularly. Since the medical instrument field is one of his big markets I figure he knows what he's talking about.

For the new house I'm considering a separate custom panel for the listening room similar to what Fremer did with his room (I would even use the same contractor for the panel). If anyone has done this I would like to learn from your experience.

@8th-note

You’re definitely on the right track, and probably more knowledgeable than most. When planning for audio AC circuits, it’s best when you can calculate your amperage capacity needs (in advance if possible). When it comes to audio needs, metering definitely helps in this area, with a knowledge of electricity as well. Establishing four dedicated 20 amp circuits for one’s audio system may be considered overkill for some, but may be a requirement for others. Yes, when lights are dimming when playing your system, there is some kind of starvation taking place, and in need of an inspection, improvement and probably upgrading.

I don’t claim to know everything, but I’m at least very familiar with grounding (for lightning especially), bonding, and wiring current capacity. I would agree with you on voltage drop for long distances of wiring. Those voltage-drop tables can easily be found on the internet, but probably not necessary in the home environment. Many audio-enthusiasts tend to favor delivering AC to their amplifiers via 10 AWG (as I too do the same, and have implemented it as well), but many electricians may not want to provide that for you, as I believe it doesn’t typically pass code (10 AWG on a 15 or 20 amp circuit breaker). I think someday someone needs to update the code for this application, as they have in the past with/for balanced AC power. It’s very easy to go to extremes when providing AC power for audio systems, but sometimes it’s simply not always necessary.

Do We Need Hospital-Grade Receptacles?

What exactly does "Hospital Grade" mean?

@bigtwin 

Thank you for verification of my comments. Sadly it won't make much difference on this forum.

I realize that, but sometimes I like to give it another try. It's also all about educating one on the subject too. I'm still learning myself, but like to sometimes pass along what I have learned.