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Post by lrobertson on Jan 7, 2019 12:41:57 GMT -5
You can get a furman asd 120 and call it good. 240 60 amp service that supplies 6 treated 120 20 amp circuits with 12 outlets that can operate off of a trigger and uses timed sequences for switched power to pro amps or whatever. It has its place for some rooms I’m sure.
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Post by leonski on Jan 7, 2019 13:39:10 GMT -5
Good Info, MGB
The other effect of linear V switcher is that te linear will have more / better dynamic headroom....
And yes, for sure, since a breaker is not a 'brick wall', they with pass much more than rated current for a very brief time.
My flickering lights in time to the music made an indellible impression on me many years ago.
A mechanical engineer will design a structure to sustain 2x or 3x or more of 'Maximum Anticipated Stress'.
I suppose in EarthQuake areas, you need other rules, too,
But for Electrical? For a modern high-power stereo or HT, I'd ALSO have some multiple of maximum anticipated load......
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klinemj
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Post by klinemj on Jan 7, 2019 16:15:56 GMT -5
I was fortunate that I did all the construction for my theater, and my electrical panel is merely feet away from my theater/critical listening room. So, I ran the wiring myself, and I have 2 dedicated circuits running to my system. One with a plug to the left side of my system, and one plug to the right side. If I ever need to switch them to 20 amp, it would be really easy...a short cable pull and outlet swap. I have a 3rd circuit that powers some of the lights in the area and my projector.
Mark
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Post by pknaz on Jan 7, 2019 21:35:15 GMT -5
120v and 15 amps is Indeed, 1800 watts. That however, is a SHORT TERM rating. The real, continuous or 'long term' value is a -20% 'derate'. That's 1440 watts on a 15 amp circuit and 1920 on a 20 amp circuit. In addition? And I'm less clear about this, I'm certain that Voltage Sag play a part in further reductions in power. Also, the fact that FEW loads are actually pure resistive is ANOTHER 'derate'. This is called Power Factor and is basically the effect of a load appearing as a capacitor or inductor to the power supply.... Back to Voltage Sag? I RARELY have 120v at my house. In the Hottest part of the summer, during the hottest part of the day? I'll frequently see <115v on my line. Based on experience, at that point I'm thinking Brown Out. This IS after all, California, where new generating capacity is tough to come by and all it takes to bring down the house is somebody tripping on the ExtenSion Cord from Arizona. It's happened and resulted in 12 hours of blackout at MY house, shorter and longer elsewhere. We (the nation) are making things worse with all-electric automobiles. These frequently charge at night, during the low-demand time when MAINTENANCE is typically done on power plants. Rates are also lowest then, in areas where this has become the norm. I cringe when I think how much it will cost to FIX all the electric cars plugged in when a lightning induced surge takes out part of the grid. I'd be REAL careful were I to live in a lightning-prone state.....Maybe anywhere in the South East / Tornado Belt or FLORIDA. For ADABOY? My panel is pretty stuffed. My changes and addition of my 20 amp circuit was accomplished with 1/2 width breakers. If I were doing a clean-sheet install? I'd have a sub panel of 4x20 amp breakers. And maybe some expansion room? Feed the panel with CONDUIT, not ROMEX so it could be grounded / RFI insulated and run 6ga or 4ga to the panel. Whatever's right. Again, a derate for temperature and 'bundling' of multiple conductors. It was rock music, the peaks where less than 10db above average, average was around 110. the 1,000 watts per sub is RMS, and they're linear power supplied A/B amps. they were clipping at that level. it was ridiculously loud, and I only did it for a song or two at that level, which is fine. |
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Post by Ex_Vintage on Jan 7, 2019 21:53:16 GMT -5
Easy (ohms law) calculation for figuring voltage drop. Distance from distribution box to power outlet X2. 14AWG at 0.0025 ohms per foot. Volt drop is I*R. For a 40 ft distance from power panel to outlet for a 15 amp circuit there is a 1.5V drop at 15 amps continuous load. For a 20 amp circuit, .095 volt drop at a continuous 20 amp load. For extreme cases, tripping a breaker may be an issue, but voltage drop will not be. The matter of upgrading a power cable is even more moot when you consider its 3 ft long, so by the time you are tripping a 15 amp breaker, your voltage drop on the power cord is 0.22 volts.
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Post by leonski on Jan 7, 2019 23:17:53 GMT -5
Easy (ohms law) calculation for figuring voltage drop. Distance from distribution box to power outlet X2. 14AWG at 0.0025 ohms per foot. Volt drop is I*R. For a 40 ft distance from power panel to outlet for a 15 amp circuit there is a 1.5V drop at 15 amps continuous load. For a 20 amp circuit, .095 volt drop at a continuous 20 amp load. For extreme cases, tripping a breaker may be an issue, but voltage drop will not be. The matter of upgrading a power cable is even more moot when you consider its 3 ft long, so by the time you are tripping a 15 amp breaker, your voltage drop on the power cord is 0.22 volts. So, EVERYONE who reports improvements from power cord upgrade are wrong / hallucinating? And all those who upgrade to multiple circuits are fooling themselves? I KNOW what I saw. My 200 watt x2 amp produced LIGHT DIMMING in time to the music when plugged into the common 15 amp house circuit. At that time? TV was also on that circuit and maybe another 150 watts or so of total load. I don't expect to see light dimming with 2 or 3 volts worth of momentary 'dip'. That's when I made up my mind to have an additional 20 amp circuit dropped to the stereo....it took several years more, but id DID happen. This was running the amp / speaker combo right to redline. Speakers were 5 ohm, benign load so amp was kicking out maybe 50 continuous / 500 watt peaks. Amps 'ladder' display was nearly all lit....except for peaks when it WAS all lit. The amps 15 amp standard blow fuse was fine. And it isn't based on MY usage alone, but the grid loads down substantially in peak hours of the summer. My normal voltage is 119 or so, with late nites sometimes exceeding 120.... But afternoon in summer? It's gonna drop to 115 or less....At which point i fear for brownout. |
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Post by millst on Jan 8, 2019 0:10:55 GMT -5
If I run everything full blast I see a 7-8 volt drop. Have never seen any issues with the lights, but I think they are another circuit. I’m sure that is well within spec for the amps. Would be nice to see some blind testing with isolated vs shared.
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Post by leonski on Jan 8, 2019 2:26:56 GMT -5
One other thing:
When amplifiers are Bench Tested, typically for review, many testers will use a VARIAC to keep line voltage to the amp 'steady' at some reference (120?) value.
If voltage drop were a non-starter, than other than for the sake of 'pure science' would that be so?
GOOD DATA, millet, and Thanks Much. Some kind of equipment list would be handy, to get an idea.
And one last point: Ohms law is 'the law'. But for AC circuits, you don't deal with resistance but rather IMPEDANCE. There are very FEW really 'just resistive' loads out there. Most look some what capacitive or inductive to the power source.
At that point? we get off on the tangent of Power Factor, which I'd suggest wasn't a deal breaker at low values, but might come into play when more extreme. The power company may bill its larger users a SURCHARGE based on low power factor below
some fixed value. PF Correction is a small but vital part of some power-consuming industries.
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Post by millst on Jan 8, 2019 11:46:34 GMT -5
I think the VARIAC makes sense to level the playing field for testing. It hints that the voltage can have an impact or that the reviewer believes that to be the case, but it's definitely no conclusive research on what that affect is.
QSC PLX2 for M&K 7.1 theater: 1x3602, 3x3102, 1x1804
XPA-5 for secondary KEF R setup.
-tm
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Post by Ex_Vintage on Jan 8, 2019 14:06:34 GMT -5
Easy (ohms law) calculation for figuring voltage drop. Distance from distribution box to power outlet X2. 14AWG at 0.0025 ohms per foot. Volt drop is I*R. For a 40 ft distance from power panel to outlet for a 15 amp circuit there is a 1.5V drop at 15 amps continuous load. For a 20 amp circuit, .095 volt drop at a continuous 20 amp load. For extreme cases, tripping a breaker may be an issue, but voltage drop will not be. The matter of upgrading a power cable is even more moot when you consider its 3 ft long, so by the time you are tripping a 15 amp breaker, your voltage drop on the power cord is 0.22 volts. So, EVERYONE who reports improvements from power cord upgrade are wrong / hallucinating? And all those who upgrade to multiple circuits are fooling themselves? I KNOW what I saw. My 200 watt x2 amp produced LIGHT DIMMING in time to the music when plugged into the common 15 amp house circuit. At that time? TV was also on that circuit and maybe another 150 watts or so of total load. I don't expect to see light dimming with 2 or 3 volts worth of momentary 'dip'. That's when I made up my mind to have an additional 20 amp circuit dropped to the stereo....it took several years more, but id DID happen. This was running the amp / speaker combo right to redline. Speakers were 5 ohm, benign load so amp was kicking out maybe 50 continuous / 500 watt peaks. Amps 'ladder' display was nearly all lit....except for peaks when it WAS all lit. The amps 15 amp standard blow fuse was fine. And it isn't based on MY usage alone, but the grid loads down substantially in peak hours of the summer. My normal voltage is 119 or so, with late nites sometimes exceeding 120.... But afternoon in summer? It's gonna drop to 115 or less....At which point i fear for brownout. I'm not saying anyone is wrong or hallucinating. Your results may vary, but the illustration I gave for a 20 ft run of wire to the outlet is just a calculation based on materials and physics. The assumption is also that your voltage supply to your house is not varying wildly (if it is, internal wiring will not matter). If some one is dropping 7-8 volts, based on their equipment load at 15 amps (breaker limit), then the wire length to the outlet would have to be at least 100ft. |
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Post by leonski on Jan 8, 2019 15:27:50 GMT -5
Voltage to my house DOES go thru seasonal and daily cycling. Right this minute, it's about 63f outside and just noon......I see 120.5 +-0.3 volts. Clothes washer is ON, as is my TV and stereo.
In the Hottest part of the day, in Summer, my house voltage can drop to <115v. I've had brownouts at about that point in years past. Usage at my house is currently hovering at about 300KwH monthly.....but will rise now that I'm running the heater.
Summer usage can top 500KwH. OH! What a Bill!
I've been given a hard time about my view that Too Much AVAILABLE power is about right. I really wonder about people who own a pair of 500 watt monoblcoks for which the specs recommend a 20 amp service being run as a PAIR on a 15 amp service AND with
all the rest of either a good stereo or as part of a HT system.
I don't have enough data, but 7-8 volt drop is Too Much. I know that for apartment dwellers, more circuits are probably NOT an option.
And don't forget that due to Power Factor, the situation is really somewhat worse. We are BILLED for KW and consume VA. This throws yet another monkey wrench into power capacity and distribution. The NEW DR Series with the switcher? I'd love for someone
with one of these amps to measure the Power Factor. Use a Kill-A-Watt meter. They are cheap and available. They are Nowhere NEAR resistive.
And I agree with millst. Variac just levels the playing field. I'd like the tester to report power line sag WITHOUT just as a data point. But for those who buy those mondo-amps with 'bragging rights'? Keep in mind you are NOT getting what you paid for.
The amp I had which produced light dimming? A CARVER m400t which had some kind of different power supply which tracked need. It was even like a 'G' or 'H' in that it had several voltage rails.....but was different in that it turned on / off depending on need.
That amp probably didn't weigh as much as just the transformer and heat sinks of a 'normal' linear amp.
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Post by Ex_Vintage on Jan 8, 2019 19:46:31 GMT -5
I guess that is a bit of my point. The variation to your house (and I suspect many others) causes much more variance than the loss of the circuits feeding their equipment. This makes a good case for a regulated power supply in your amps. This is one place where an SMPS inherently shines over a unregulated conventional transformer based power source.
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Post by SteveH on Jan 8, 2019 20:05:19 GMT -5
I just purchased six pieces of Emotiva equipment, RMC-1, two XPA-DR1, one XPA-13.1 and two S10 subs. I ran six new branch circuits using 10/3 with a ground and added six Leviton 5842 125V/250V 20A dual voltage receptacles. If you are going to add or upgrade the electric, might as well make it 125V/250V. Also, the voltage drop is less with 240 volt service. My branch circuit runs are 85 feet and the 125 volt voltage drop was too much with 12 gauge, but 12 gauge was fine for 240 volts. I opted for the dual voltage 125/250 using 10 gauge. The Emotiva manuals say best performance is achieved with 240 volt service, that convinced me. Labor is the same whether it is 12 gauge or 10 gauge. Now I have six 125 volt outlets and six 240 volt outlets. With dedicated audio branch circuits, my family room lights and bathroom lights don't blink with the bass anymore!
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Post by leonski on Jan 8, 2019 20:53:30 GMT -5
I just purchased six pieces of Emotiva equipment, RMC-1, two XPA-DR1, one XPA-13.1 and two S10 subs. I ran six new branch circuits using 10/3 with a ground and added six Leviton 5842 125V/250V 20A dual voltage receptacles. If you are going to add or upgrade the electric, might as well make it 125V/250V. Also, the voltage drop is less with 240 volt service. My branch circuit runs are 85 feet and the 125 volt voltage drop was too much with 12 gauge, but 12 gauge was fine for 240 volts. I opted for the dual voltage 125/250 using 10 gauge. The Emotiva manuals say best performance is achieved with 240 volt service, that convinced me. Labor is the same whether it is 12 gauge or 10 gauge. Now I have six 125 volt outlets and six 240 volt outlets. With dedicated audio branch circuits, my family room lights and bathroom lights don't blink with the bass anymore! Wow!, Steve, a REAL overachiever. Congrats. |
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Post by leonski on Jan 8, 2019 20:59:49 GMT -5
I guess that is a bit of my point. The variation to your house (and I suspect many others) causes much more variance than the loss of the circuits feeding their equipment. This makes a good case for a regulated power supply in your amps. This is one place where an SMPS inherently shines over a unregulated conventional transformer based power source. Than you should ADD the variation to your service TO the variation caused by load. Some minus points to a regulated PS, among them are higher parts count and possible points of failure. www.teamwavelength.com/power-supply-basics/One main and REAL strong advantage of a switcher is the wide acceptance of input voltage. This lowers manufacturing costs and lowers number of different PS needed (or just transformers) for different markets. All you need is to include the correct cord. |
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Post by creimes on Jan 8, 2019 22:52:07 GMT -5
Two dedicated 15amp services with 2 Hospital Grade outlets each circuit, why Hospital Grade, because they weren't much more in terms of cost and they look way frickin cool yo  |
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Post by leonski on Jan 9, 2019 2:28:12 GMT -5
Thanks ot ALL for your input. I don't quite know yet what to make of this, but DO see plenty of system owner with multiple circuits.
This I'll take to be a good sign.
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Post by leonski on Jan 9, 2019 2:33:58 GMT -5
Sorry I don’t understand the question, actually the range of options. My house has 8 x 220/240 volt circuits, the hot water service is on one (that’s off peak), cooking (stove, cook top, etc) is another, there is a 20 amp circuit (for the welder and the air conditioning) and the other 5 circuits service the rest of the house. My gear is split between 2 of those circuits with each one rated at 3.6 kw ie; 240 x 15 amps. Cheers Gary Maybe I mis-wrote? I just want to know how many persons have circuits for the EXCLUSIVE use of the stereo or HT? For example? I have ONE dedicated circuit and use the common house circuit for low power stuff, thru a power conditioner. I have a bunch of other circuits.....Microwave gets one. 30 amp for AC. and more....... |
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Post by Gary Cook on Jan 9, 2019 4:28:59 GMT -5
Sorry I don’t understand the question, actually the range of options. My house has 8 x 220/240 volt circuits, the hot water service is on one (that’s off peak), cooking (stove, cook top, etc) is another, there is a 20 amp circuit (for the welder and the air conditioning) and the other 5 circuits service the rest of the house. My gear is split between 2 of those circuits with each one rated at 3.6 kw ie; 240 x 15 amps. Maybe I mis-wrote? I just want to know how many persons have circuits for the EXCLUSIVE use of the stereo or HT? For example? I have ONE dedicated circuit and use the common house circuit for low power stuff, thru a power conditioner. I have a bunch of other circuits.....Microwave gets one. 30 amp for AC. and more....... My 2 circuits are relatively "exclusive" to the video and audio system, but for example right now there is a cooling fan plugged into one of the circuits (it's summer here). During winter I have the gas log fire fan assist plugged into the same circuit as its located very close by. When vacuuming I often use the other same circuit, which also has a wireless changer for the iDevices on it. All pretty minor add ons to what is the main purpose, supplying power to the system, but they're not totally exclusive. Simply because with 7.2 kw available they don't need to be.  Cheers Gary |
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Post by millst on Jan 9, 2019 12:20:36 GMT -5
Thanks ot ALL for your input. I don't quite know yet what to make of this, but DO see plenty of system owner with multiple circuits. This I'll take to be a good sign. Lots of people buy cables that cost $10k each or don't get vaccinations. I don't see any scientific conclusions to draw from that. Still waiting to see some actual research or hear from a design engineer.
All of the higher end Emotiva amps spec "Between 100 VAC and 250 VAC @ 50 / 60 Hz (automatically detected)" so I don't see how a 7-8V drop is too much. Even their low-end amps spec 115VAC.
-tm
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