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Post by Gary Cook on Nov 27, 2016 20:23:53 GMT -5
The power supply is spec'd to use the most watts that the average US 110 volt power outlet can supply. Which is a bit of a shame as we have 240 volts in Australia. What is the implication of that staement, Gary? We have 230 Volt in Denmark - 10A circuits. Does that reduce the power output from the the XPA Gen 3? Not an electric engineer, as you can hear! It's all about the watts; 110 volts @ 15 amps = 1650 watts (in the USA) 240 volts @ 10 amps = 2400 watts (in Australia) That's watts in (to the power supply) not watts out (to the speakers). So an amplifier with a power supply rated for a 20 amps circuit @ 100 volts = 2200 watts in the USA doesn't need a 20 amp circuit in Australia as it can access 2400 watts via normal standard power outlet (i.e.; 10 amps). Watts out e.g.; 200 watts per channel x 5 channels = 1000 watts, is dependant on the efficiency of the power supply and the amplifiers itself. A Class AB power amplifier (and its power supply) is often somewhere around 60% efficient (i.e. it can be more and it can be less, so let's not get hung up on whether is 60% or 65% or 55%). So in order to get 1000 watts out we need 1666 watts in, which is a bit more than 110 volts x 15 amps can supply. Keeping in mind that a 110 volt circuit doesn't always have 110 volts, it can drop (commonly called voltage sage) a few volts, so even 1650 watts may not be accessible all the time Hence why Emotiva recommends a 20 amp circuit in the USA. Cheers Gary |
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Post by dwaleke on Nov 27, 2016 20:58:34 GMT -5
Huh? On the other hand, I don't think you realize how much power people actually use during high dynamic instantaneous peaks. I've spent more than a few minutes playing with SPL calculators. For home theater, to get 110db or more at 10+ feet - it takes quite a few watts. Average listening isn't many watts. Dynamic peaks can use boat loads of power. There are a lot of factors. I know exactly what you are talking about. It's not my first rodeo. I sit 16.5' feet back and thought I needed lots of power for dynamics. I have FP10000Q amplifiers that I had connected to my 95 db efficient full range JTR 215RT mains. The FP10k can burst over 9kw and run full steam around 2800 watts (similar design - shared class H power supply and channel boards to xpa g3). Speakers are capable of playing 128db each. Guess what? It's ridiculous. If you use bass management and crossover you mains to subwoofers you'll be surprised how little power your mains use for those peaks. And significantly less for surrounds. There are no SPL calculators that tell you how much power you need if you keep the signal > 80hz. I'm now using the XPA-7 G3 for the majority of my 5.1.4 setup. I easily get 105db uncompressed peaks per speaker at my listening position. I can see the guys running low efficiency stuff needing more power, but that's using the wrong tool for the job. Most low efficiency designs will compress like crazy way before hitting 105db peaks regardless of their power handling. |
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Post by dwaleke on Nov 27, 2016 21:01:49 GMT -5
What is the implication of that staement, Gary? We have 230 Volt in Denmark - 10A circuits. Does that reduce the power output from the the XPA Gen 3? Not an electric engineer, as you can hear! It's all about the watts; 110 volts @ 15 amps = 1650 watts (in the USA) 240 volts @ 10 amps = 2400 watts (in Australia) That's watts in (to the power supply) not watts out (to the speakers). So an amplifier with a power supply rated for a 20 amps circuit @ 100 volts = 2200 watts in the USA doesn't need a 20 amp circuit in Australia as it can access 2400 watts via normal standard power outlet (i.e.; 10 amps). Watts out e.g.; 200 watts per channel x 5 channels = 1000 watts, is dependant on the efficiency of the power supply and the amplifiers itself. A Class AB power amplifier (and its power supply) is often somewhere around 60% efficient (i.e. it can be more and it can be less, so let's not get hung up on whether is 60% or 65% or 55%). So in order to get 1000 watts out we need 1666 watts in, which is a bit more than 110 volts x 15 amps can supply. Keeping in mind that a 110 volt circuit doesn't always have 110 volts, it can drop (commonly called voltage sage) a few volts, so even 1650 watts may not be accessible all the time Hence why Emotiva recommends a 20 amp circuit in the USA. A 15-20 amp breaker can pull over 80 amps for short periods of time. If the breaker isn't tripping then you do not need a larger circuit (higher amp breaker). As you mention I'd be more concerned with the wire size to combat voltage droop over the size of the breaker. |
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Post by dwaleke on Nov 27, 2016 21:03:35 GMT -5
Uhhh. So what's your point exactly? You basically just listed a bunch of reasons why lots of power is necessary. I shared an example of why you do not need as much power as you think. Just because you can doesn't mean you should or need to. That was the point. I no longer run the amp that can burst 9kw. It (the amp) is completely unnecessary in order to hit reference level of 105db per speaker at my MLP. In fact the XPA-7 G3 is already overkill. |
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Post by Jim on Nov 27, 2016 21:05:22 GMT -5
Yeah - I reread your post and understood what you were getting at.
What kind of speakers do you have that could handle that kind of power??
That sounds like pro audio gear..
Edit : I can't read tonight. I see what mains you have.
I'm loopy tonight.
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Post by leonski on Nov 27, 2016 21:06:23 GMT -5
We are talking the difference between 'Continuous' and maybe 'peak' power. If you are coasting along at 5 watts RMS and hit a +10db PEAK? You instantly need 10x the power, or 50 watts. For an instant.
As near as I can tell, you can have 2 different conditions, or even a 'blend' of the 2.
First? ZERO headroom. X watts RMS and NO power above that without huge distortion.
Second? (example) 6 db headroom against RMS. So, your X watts turns into X times 4 (2 doublings) to 4X watts on peaks only, and than for a short time period. This was the NAD approach for a while. You see they STILL don't advertise big power bumps as impedance drops, but DO make an issue of the Dynamic power at lower impedance.
Like the guy with Maggies (HEY, that's me!) who may have an amp of 500 watts RMS @8ohms AND @4ohms. Somebody might say that the amp is No Good for panels since it doesn't 'double its power when impedance goes to 1/2'.
But, I say, it is STILL 500 rms.
So I'd ASK, what is the DYNAMIC HEADROOM of the given amp? 50rms with 200 watts at peak?
This is why I objected to a recent EMO amp. 50@8 with a very low distortion. 90@4 with 1% distorion. THat tells me maybe 80 or so at a more reasonable distortion and minimal headroom. But with the intended speaker in a reasonable space?
Not generally a problem.
You actually have VERY LITTLE need for huge RMS power numbers, but much MORE use for good dynamics. And with 7 speakers? Less power per speaker still yields good loudness in the listening area.
And I'll agree with Chuckie. Power Handling is important. But don't forget that at least for music, maybe ONLY 10% or so of total system power is used above 10khz and maybe 50% BELOW 350hz.
MOVIES with effects? Totally up for grabs, as near as I can tell. But the REAL movie sound guys (not me, with a 2.1 system) are also most likely to have HT oriented gear. This implies more sensitive speakers which are
also somewhat easier to drive. For example, I don't know of ANY HT receiver capable of driving my Magnepans.
And to get back to another point, somebody asked if some countries power sacrificed an amps power? (PCGA) I see from specs looking at some 'D' amps that they have Universal Switching PS. These amps actually put out LESS power in the United States. How much less? Nobody's talkin'. I'd be WARY, or if buying a HYPEX or nCore module, consider a DIY linear PS.
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Post by dwaleke on Nov 27, 2016 21:06:48 GMT -5
What kind of speakers do you have that could handle that kind of power?? That sounds like pro audio gear.. Comes from that world. JTR Noesis 215RTs. For home theater it's all about the right tool for the job. These are overkill, but if you plan on using a dome tweeter to hit 105db peaks watch out. You will not enjoy it. That thing will compress like there's no tomorrow. |
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Post by Jim on Nov 27, 2016 21:12:55 GMT -5
What kind of speakers do you have that could handle that kind of power?? That sounds like pro audio gear.. Comes from that world. JTR Noesis 215RTs. For home theater it's all about the right tool for the job. These are overkill, but if you plan on using a dome tweeter to hit 105db peaks watch out. You will not enjoy it. That thing will compress like there's no tomorrow. Yep. I'm familiar with Jeff Permanian's company JTR and Mark Seaton's Seaton Sound. I own 2 Seaton Subs and have read quite about about JTR gear. I'm a big fan of compression drivers for HT as well. Thanks for sharing your thoughts on real world wattage needs. Interesting that the step back down in wattage still works as well. |
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pcga
Minor Hero
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Post by pcga on Nov 28, 2016 1:55:03 GMT -5
What is the implication of that staement, Gary? We have 230 Volt in Denmark - 10A circuits. Does that reduce the power output from the the XPA Gen 3? Not an electric engineer, as you can hear! The implication is that with higher voltage, it can provide more wattage using the same Ampere for the circuit.. So 10A with 230V is similar to 20 with 115V, that is usually good thing. Thanks !! |
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pcga
Minor Hero
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Post by pcga on Nov 28, 2016 1:56:55 GMT -5
What is the implication of that staement, Gary? We have 230 Volt in Denmark - 10A circuits. Does that reduce the power output from the the XPA Gen 3? Not an electric engineer, as you can hear! It's all about the watts; 110 volts @ 15 amps = 1650 watts (in the USA) 240 volts @ 10 amps = 2400 watts (in Australia) That's watts in (to the power supply) not watts out (to the speakers). So an amplifier with a power supply rated for a 20 amps circuit @ 100 volts = 2200 watts in the USA doesn't need a 20 amp circuit in Australia as it can access 2400 watts via normal standard power outlet (i.e.; 10 amps). Watts out e.g.; 200 watts per channel x 5 channels = 1000 watts, is dependant on the efficiency of the power supply and the amplifiers itself. A Class AB power amplifier (and its power supply) is often somewhere around 60% efficient (i.e. it can be more and it can be less, so let's not get hung up on whether is 60% or 65% or 55%). So in order to get 1000 watts out we need 1666 watts in, which is a bit more than 110 volts x 15 amps can supply. Keeping in mind that a 110 volt circuit doesn't always have 110 volts, it can drop (commonly called voltage sage) a few volts, so even 1650 watts may not be accessible all the time Hence why Emotiva recommends a 20 amp circuit in the USA. Cheers Gary Thanks Very clear, Gary! |
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Post by leonski on Nov 28, 2016 2:40:46 GMT -5
There are 2 ratings in the US. You have a long term rating which is lower than the peak rating.
Also? At my house I've NEVER seen 110vac. NEVER. Right this minute @2330 I see 119.2vac on my meter. In the summer, if the voltage goes to 115 or lower, I start shutting stuff OFF.
At some point below 115vac, I'm EXPECTING a brownout or a complete shutdown. That would be the hottest days of summer at peak demand.
So while 15amps @120vac is 1800 watts, the DERATE is 20% for longer time periods. Minutes? Seconds? A couple hours? I don't know, offhand.
I don't know what US standard is, either. I've seen it vary from 110 to 120 or higher. Tolerance? +-5% would be good.
FREQUENCY of 60hz is NON-Negotiable. Differing frequency will play hobs with EVERYTHING from stuff with synchronous motors to power delivery efficiency.
My power conditioner will shut off its outlets OVER 135vac and UNDER 95vac.
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Post by benbvan on Dec 19, 2016 20:05:25 GMT -5
Here's a couple question that has been on my mind, keep in mind I'm not an electrical engineer.
I have an XPA-2 Gen 3.. I've looked at the test data and see it plays clean to 325wpc and distortion only raises slightly up to 400wp, driving two channels. So question 1) how much power is needed from the power supply to get that much power out of the amplifier channels? And 2) if I have a 3.2kw power supply, does it need to pull 3200 watts from the wall to produce 3200 watts to the amps if necessary?
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Post by benbvan on Dec 27, 2016 5:48:48 GMT -5
Anyone?
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Post by dwaleke on Dec 27, 2016 14:17:16 GMT -5
Here's a couple question that has been on my mind, keep in mind I'm not an electrical engineer. I have an XPA-2 Gen 3.. I've looked at the test data and see it plays clean to 325wpc and distortion only raises slightly up to 400wp, driving two channels. So question 1) how much power is needed from the power supply to get that much power out of the amplifier channels? And 2) if I have a 3.2kw power supply, does it need to pull 3200 watts from the wall to produce 3200 watts to the amps if necessary? You'll have waste in the power supply and waste in the amplifier channels. All pretty common. With a 3200va power supply that does not translate into 100% of the power being available cleanly at the speaker. Emotiva will have to comment on how much. But based on specs it appears the Xpa gen 3 can output around 1400 watts of clean output continuously with a 7 channel unit. To get 325wpc in a 2 channel amplifier you're probably consuming around 950-1100 watts at the wall. Most of the time you're probably using less than 150 watts of power from the wall. Unless you listen to sine waves at ridiculous volume levels. |
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Post by benbvan on Dec 27, 2016 14:52:50 GMT -5
Thank you. I'm curious as to how much power at the wall I need available to feed the power supply for heavy two channel use mainly.
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Post by dwaleke on Dec 27, 2016 14:59:41 GMT -5
Thank you. I'm curious as to how much power at the wall I need available to feed the power supply for heavy two channel use mainly. Use 50℅ efficiency as a worst case. If you are not tripping the breaker you have more than enough. And I doubt you would be but it depends on what else is on the same circuit. |
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Post by benbvan on Dec 27, 2016 15:10:46 GMT -5
I'm not too sure what else is on it besides a subwoofer and a receiver lol. My lights dim when I push it.
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Post by leonski on Jan 1, 2017 3:46:44 GMT -5
My old Carver Cube with an early version of a 'tracking' power supply would dim the lights of the house IN TIME to the music.
Amp had a 15amp fuse. It was only 200x2 and ran fairly cool except when 'redlined' for longer time periods.
The idea behind the PS was that it stored Very Little energy but rather turned on/off in time to the demand.
'Brownouts' are not good, which is why those who TEST AMPS on the 'bench' will use a variac to provide constant line voltage.
BenBvan? You need at least ONE dedicated circuit, if not more for your gear. IMO, you are not doing yourself any favors with self-induced brownouts.
How sensitive are the speakers? How large a room and how loud is LOUD?
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Post by benbvan on Jan 1, 2017 4:00:47 GMT -5
Thank you for the response leonski. The lights do indeed dim to the beat, usually with heavy bass hits though, so sub pulling hard also.. speakers are Rti-a7, 89db sensitive.. looking to sell them and go with the a9 which are 90-91 db sensitive. Room is small, loud is uncomfortably loud. Dimming starts just before that. Plays loud well and starts to dim at extra loud. Are you thinking I should have a circuit just for the Gen 3, or Gen 3 and receiver? Or receiver, amp and sub? I'm also wondering if it's a panel issue.. when the electric clothes dryer starts a cycle the lights in the entire house dim slightly for a split second.
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Post by leonski on Jan 1, 2017 13:33:18 GMT -5
You need some professional help. I'd start with an electrician evaluating your house wiring.
An electric dryer really draws some juice and I think may be a 220v appliance.
If your house has a 100amp service, you should be able to 'afford' a separate circuit for the stereo. As to WHAT gets plugged in there?
I'd start with the amp and sub.
3db of speaker sensitivity would be roughly the same as a 2x increase in amp power. But PEAKS would still be very demanding, especially if at +10db or more.
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