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Post by AudioHTIT on Oct 5, 2017 4:04:41 GMT -5
Kill-A-Watt meter. 20$ from Amazon. All questions answered.. How can it answer a question for an amp you don’t own? That’s what this thread is about. |
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Post by Gary Cook on Oct 5, 2017 9:26:15 GMT -5
Measuring high power amps sounds simple. But a few things are involved. You'll need a 7 channel dummy load. Amp rated to 200 watts? Load should be maybe 3x the expected maximum load. Power resistors are inexpensive and you'll need some 10ga wiring and connectors, not to mention a caged 'case' for safety and ventilation. Make sure your AC for the room is up to snuff! You'll also need an Industrial Strength Variac. This to maintain line voltage TO the amp. This ensures real reading and you KNOW going in that most persons power line will 'sag' some so they may not get what YOU get on the bench. The example I link has 17% 'one star' ratings AND though rated as 20 amp, has only 15 amp outlets. I'd skip to the REAL Variac 'brand' which goes nearly 1000$ for what I'd have on MY bench. www.amazon.com/Electronix-Express-16VA520T20-Variable-Transformer/dp/B006NG9OTI/ref=sr_1_3?ie=UTF8&qid=1507187156&sr=8-3&keywords=variacThan meters, scope, signal generator and MORE. Meters get Calibrated on a annual basis, as does the scope and signal generator. I can't see any of the above not being used to measure/test the distortion and wattage output of a power amp. The amp manufacturer and the reviewer simply note down and report the power draw at the same outputs as the distortion is tested. Cost = zero and additional time required = minuscule. Cheers Gary |
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Post by AudioHTIT on Oct 5, 2017 10:15:58 GMT -5
Measuring high power amps sounds simple. But a few things are involved. You'll need a 7 channel dummy load. Amp rated to 200 watts? Load should be maybe 3x the expected maximum load. Power resistors are inexpensive and you'll need some 10ga wiring and connectors, not to mention a caged 'case' for safety and ventilation. Make sure your AC for the room is up to snuff! You'll also need an Industrial Strength Variac. This to maintain line voltage TO the amp. This ensures real reading and you KNOW going in that most persons power line will 'sag' some so they may not get what YOU get on the bench. The example I link has 17% 'one star' ratings AND though rated as 20 amp, has only 15 amp outlets. I'd skip to the REAL Variac 'brand' which goes nearly 1000$ for what I'd have on MY bench. www.amazon.com/Electronix-Express-16VA520T20-Variable-Transformer/dp/B006NG9OTI/ref=sr_1_3?ie=UTF8&qid=1507187156&sr=8-3&keywords=variacThan meters, scope, signal generator and MORE. Meters get Calibrated on a annual basis, as does the scope and signal generator. I can't see any of the above not being used to measure/test the distortion and wattage output of a power amp. The amp manufacturer and the reviewer simply note down and report the power draw at the same outputs as the distortion is tested. Cost = zero and additional time required = minuscule. Cheers Gary Right, we don’t want to test amplifiers, we want the manufactures to do it. |
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Post by tchaik on Oct 5, 2017 10:53:00 GMT -5
I'm still trying to figure out what the Stereophile review has to do with the power supply...... (the two are actually unrelated). However, about power supplies..... The world moves on..... Cars get better mileage, and have much better acceleration, and better endurance, than horses.... And airplanes cost more, but they're a lot faster than cars, and also a lot safer. Horses are still nice, but, the next time I go to California, I'll either be driving or flying. And, in many but not all applications, switch mode power supplies deliver better performance, cost less, and weigh less, than old-style linear supplies. Performance is important; reliability is important; but wasting money on old technology when there's newer and better technology is... well... wasteful. It really is that simple. (And, yes, both linear power supplies and SMPS can be reliable - or not - depending on how well they're designed and built.) I've also got to sort of vent a little bit here......  Stereophile routinely tests amps that cost tens of thousands of dollars, and whose performance is so inferior to ours that it isn't even funny. However, oddly, nobody wonders who would be dumb enough to buy the $25k tube amp that puts out 35 watts at 5% THD. And nobody suggested that the designer of the $90k a pair amp that actually blew up when Stereophile tried to warm it up to test it "learned his lesson". And neither did anybody comment that "the guy who designed it has been designing amps forever; you'd think he could make one that wouldn't blow up". And, interestingly, we've sold a LOT of XPA Gen3 amps already..... And pretty well everybody seems to agree that they sound downright awesome..... Which is kind of the whole point here. I feel like you’re making a lot of conclusions about a power supply based on a Stereophile review. The Big Boys??? if my memory serves me correctly (which is never to be assumed at my age), i remember big dan telling me that the cost of the xpa gen 3 switching power supply was still in the same realm of cost as the older transformers and storage caps. keith, can you either verify or dispute that for me? tchaik................. |
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Post by geebo on Oct 5, 2017 11:14:46 GMT -5
I don't know about the efficiency numbers but the GEN-3 runs cooler in my enclosed rack than any amp I've ever had in there including and XPA-5 Gen 1, XPA-2 Gen 1 and XPA-1L. My Crown Drivecore is the only exception. Less heat = less wasted energy. YMMV.
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Post by leonski on Oct 5, 2017 15:04:15 GMT -5
I don't know about the efficiency numbers but the GEN-3 runs cooler in my enclosed rack than any amp I've ever had in there including and XPA-5 Gen 1, XPA-2 Gen 1 and XPA-1L. My Crown Drivecore is the only exception. Less heat = less wasted energy. YMMV. The clue is in yesterdays post from Keith. The 7 channel G3amp idles about 20 watts. That's pure heat, but not much of it. OTHER choices in the amp make much of the difference. This is a low-bias design which accounts for the low idle power. Same amp, same PS with biased cranked up a little? More heat and maybe higher idle power draw. Maximum power should be effected, too. Several choices besides PS configuration / type goes into amp efficiency. Someone should chime in with power draw for a G2 amp when switched to class 'A' mode. I'd guess for the 30 watts in 'A' version, at least 200 watts idle power. or more? 'A' amps work at about 25% efficiency, give or take. And don't forget that it is ALL wasted energy, in a sense. Speakers are maybe 1% efficient. Very high sensitivity speakers can run higher, but don't count on it for normal speakers or HT. With a 500 watt amp going pretty much full-tilt, input power could be nearly 800 watts (800 x .65) and the speaker might make use of 4 watts of the 500 output = 0.8% efficiency. that's about 1/2% efficiency from plug to speaker output. I don't hear any squawking about how awful speakers are at turning electricity into sound. And this without any mention of reactance which will just make it look worse. |
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Post by geebo on Oct 5, 2017 15:14:13 GMT -5
I don't know about the efficiency numbers but the GEN-3 runs cooler in my enclosed rack than any amp I've ever had in there including and XPA-5 Gen 1, XPA-2 Gen 1 and XPA-1L. My Crown Drivecore is the only exception. Less heat = less wasted energy. YMMV. The clue is in yesterdays post from Keith. The 7 channel G3amp idles about 20 watts. That's pure heat, but not much of it. OTHER choices in the amp make much of the difference. This is a low-bias design which accounts for the low idle power. Same amp, same PS with biased cranked up a little? More heat and maybe higher idle power draw. Maximum power should be effected, too. Several choices besides PS configuration / type goes into amp efficiency. Someone should chime in with power draw for a G2 amp when switched to class 'A' mode. I'd guess for the 30 watts in 'A' version, at least 200 watts idle power. or more? 'A' amps work at about 25% efficiency, give or take. And don't forget that it is ALL wasted energy, in a sense. Speakers are maybe 1% efficient. Very high sensitivity speakers can run higher, but don't count on it for normal speakers or HT. With a 500 watt amp going pretty much full-tilt, input power could be nearly 800 watts (800 x .65) and the speaker might make use of 4 watts of the 500 output = 0.8% efficiency. that's about 1/2% efficiency from plug to speaker output. I don't hear any squawking about how awful speakers are at turning electricity into sound. And this without any mention of reactance which will just make it look worse. IIRC, my 1L drew about 260 at idle in A mode. But whatever the reason, my Gen 3 runs cooler at idle and in operation than any of the other AB amps I've had. |
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Post by leonski on Oct 5, 2017 15:57:37 GMT -5
BIAS. PS efficiency might account for a little of the difference, but BIAS is the vast majority.
Test? Where's the heat coming from? From the PS side of the amp or the output device heat sinks?
High bias pure 'A' designs use a LOT of power just sitting. And as it turns out, no more power when being used for the intended purpose.
The latest XS series from Pass Labs will use a full 1000 watts just plugged in, which IMO requires its own circuit. This is for a 300 watt amp.
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Post by geebo on Oct 5, 2017 17:25:47 GMT -5
I guess what I'm saying is the the exact reason for the cooler running of the Gen 3 is not of great concern to me. The main thing is how it reproduces music and the fact that it runs cooler is a big plus. Of course I would be interested in knowing the reason(s) for less heat but I see it mainly as icing on the cake.
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Post by AudioHTIT on Oct 5, 2017 17:32:23 GMT -5
The clue is in yesterdays post from Keith. The 7 channel G3amp idles about 20 watts. ... It sounded like that was from memory, I would withhold appraisal until we have a measured value. Someone should chime in with power draw for a G2 amp when switched to class 'A' mode ... From the first page of this thread, however he doesn’t say how he arrived at that number. My XPA-1 draws something close to 400 watts at idle in class A mode. Aww yes!  Only the XPA-1 G2 and XPA-1L have a Class A mode, so there is no direct comparison to the XPA-7 G2 or G3. |
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klinemj
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Post by klinemj on Oct 5, 2017 17:33:15 GMT -5
Kill-A-Watt meter. 20$ from Amazon. All questions answered.. How can it answer a question for an amp you don’t own? That’s what this thread is about. You can buy my new product...the "guess-a-watt" It guesses the result in advance. Mark |
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Post by Gary Cook on Oct 5, 2017 18:39:11 GMT -5
How can it answer a question for an amp you don’t own? That’s what this thread is about. You can buy my new product...the "guess-a-watt" It guesses the result in advance. Mark Which seems pretty much what the manufacturers expect us to do, guess the power draw. Like picking lotto numbers, most people guess wrong most of the time. It would be nice to know things like yes one power outlet will enable us to run that pair of monoblocks you are looking at buying to their maximum output, but no you can't plug the sub woofer into the same outlet without sacrificing some power output. Or perhaps on the same circuit is ok just choose another outlet. They seem like pretty useful things to know and not an unreasonable ask of the power amp manufacturer. Cheers Gary |
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Post by leonski on Oct 5, 2017 19:15:03 GMT -5
www.cui.com/catalog/resource/efficiency-standards-for-external-power-supplies.pdfDeals mainly with Wall Warts, but you can see which way this is going. Manufacturers deal with 'value added'. Does something that costs them $$ have a ROI? ever? In short? Will providing PS efficiency data help make ANY sales or is sound what counts? I can't believe all the hand-holding that EMO needs to do with people who can't even either decide it is not needed data or won't go ahead and spend the 20$ on a meter and answer their own questions. One user remarked on how much cooler his G3 amp ran. That's pure efficiency, one way or the other. And good news for those asking for higher efficiency. That chances are the increase is at the expense of less output device bias shouldn't come as any surprise. And the cooler amp is FAR less likely to cook itself to death in an enclosure.
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Post by AudioHTIT on Oct 5, 2017 19:18:50 GMT -5
How can it answer a question for an amp you don’t own? That’s what this thread is about. You can buy my new product...the "guess-a-watt" It guesses the result in advance. Mark If I send you a picture of the amp I’m interested in can you run it through the “guess-a-watt”? Sounds like a great product! |
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Post by klinemj on Oct 5, 2017 19:25:15 GMT -5
You can buy my new product...the "guess-a-watt" It guesses the result in advance. Mark If I send you a picture of the amp I’m interested in can you run it through the “guess-a-watt”? Sounds like a great product! My fee to do that is minimal. I prefer to have video of at least 1080p as opposed to pix. The fee is only $100 if I get a grainy cell phone image, but accuracy is +/- 2000%. With a 1080p video, the cost is a mere $1000 but accuracy is +/- 100%. Now, the sweet deal is if you can get me 4k video...cost jumps to $1500 but accuracy increases to +/-78%. The cost differences are due to my added cost of cable lifters, noise suppression filters, special cryogenic treatments of all wires AND the incoming digital files...but it's really worth it for the "peace of mind". Paypal gift accepted... Mark |
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Post by AudioHTIT on Oct 5, 2017 22:13:13 GMT -5
I don't know about the efficiency numbers but the GEN-3 runs cooler in my enclosed rack than any amp I've ever had in there including and XPA-5 Gen 1, XPA-2 Gen 1 and XPA-1L. My Crown Drivecore is the only exception. Less heat = less wasted energy. YMMV. Hey Geebo, have you ever measured the idle power or current on the G3? (hint, hint) |
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Post by geebo on Oct 6, 2017 6:42:15 GMT -5
I don't know about the efficiency numbers but the GEN-3 runs cooler in my enclosed rack than any amp I've ever had in there including and XPA-5 Gen 1, XPA-2 Gen 1 and XPA-1L. My Crown Drivecore is the only exception. Less heat = less wasted energy. YMMV. Hey Geebo, have you ever measured the idle power or current on the G3? (hint, hint) I have not. Maybe I'll try to do that this weekend. |
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Post by garbulky on Oct 6, 2017 9:41:25 GMT -5
The clue is in yesterdays post from Keith. The 7 channel G3amp idles about 20 watts. ... It sounded like that was from memory, I would withhold appraisal until we have a measured value. Someone should chime in with power draw for a G2 amp when switched to class 'A' mode ... From the first page of this thread, however he doesn’t say how he arrived at that number. My XPA-1 draws something close to 400 watts at idle in class A mode. Aww yes! Only the XPA-1 G2 and XPA-1L have a Class A mode, so there is no direct comparison to the XPA-7 G2 or G3. I got the number from a poster tha measured the class A and non class A mode of the XPA-1 gen 2 with a device. It wasn't exactly 400 watts but it was close. Also that number was probably for two monoblocks in stereo. I agree that we shouldn't use that to compare to the other XPA amps as the XPA-1 is very different in power consumption. |
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Post by AudioHTIT on Oct 6, 2017 10:04:19 GMT -5
It sounded like that was from memory, I would withhold appraisal until we have a measured value. From the first page of this thread, however he doesn’t say how he arrived at that number. Only the XPA-1 G2 and XPA-1L have a Class A mode, so there is no direct comparison to the XPA-7 G2 or G3. I got the number from a poster tha measured the class A and non class A mode of the XPA-1 gen 2 with a device. It wasn't exactly 400 watts but it was close. Also that number was probably for two monoblocks in stereo. I agree that we shouldn't use that to compare to the other XPA amps as the XPA-1 is very different in power consumption. It’s still relevant to the discussion on power consumption and efficiency, thanks for clarifying that the number is probably best classified as ‘hearsay’. |
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Post by DYohn on Oct 6, 2017 10:27:56 GMT -5
People worry about the silliest things. You know, if idle power consumption is an issue for you, then turn off the power switch on the back, or unplug it.
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