DYohn
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Post by DYohn on Aug 8, 2010 11:10:05 GMT -5
There is a difference between the standard continuous power rating and what you're talking about, which is amplifier design for thermal management (which, by the way, is one of the things I do for a living.)
Continuous power rating does not require any specific time to test AFAIK, only long enough to attain measurements of voltage and distortion at each frequency under test. Like I said earlier, the APx-515 we have in our lab can do this test in under a minute.
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Post by johndavidson on Aug 8, 2010 11:45:09 GMT -5
And that is my point. These are not true continuous numbers they are short duration numbers. There needs to be a standard if you are going to call them continuous.
As I stated my background is industrial electronics and controls. If you slap the word continuous on it, it better mean just that! If I buy a AC motor and drive rated at 100hp it had better be able to do that long term, 24/7 for years.
While I don't expect that for a consumer product as I stated there was a time that it did mean that the amp could run a sustained amount of time, more than a few hundred Milli seconds. However, it does not appear to now. So stop using continuous! define you test and procedure and make it clear you numbers are achieved under short duration test. Or why not do both?
As you mention the thermal management comes in to play as well as transformer loading on longer sustained test. What can a test that last less than a minute to obtain all critical data tell me about how robustly the amp can handle these factors?
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DYohn
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Post by DYohn on Aug 8, 2010 11:56:20 GMT -5
And that is my point. These are not true continuous numbers they are short duration numbers. There needs to be a standard if you are going to call them continuous. As I stated my background is industrial electronics and controls. If you slap the word continuous on it, it better mean just that! If I buy a AC motor and drive rated at 100hp it had better be able to do that long term, 24/7 for years. While I don't expect that for a consumer product as I stated there was a time that it did mean that the amp could run a sustained amount of time, more than a few hundred Milli seconds. However, it does not appear to now. So stop using continuous! define you test and procedure and make it clear you numbers are achieved under short duration test. Or why not do both? As you mention the thermal management comes in to play as well as transformer loading on longer sustained test. What can a test that last less than a minute to obtain all critical data tell me about how robustly the amp can handle these factors? As I've said at least three times now, "continuous power rating" does not mean what you think it means in the audio world.
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iceman66
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Post by iceman66 on Aug 8, 2010 12:07:55 GMT -5
And that is my point. These are not true continuous numbers they are short duration numbers. There needs to be a standard if you are going to call them continuous. As I stated my background is industrial electronics and controls. If you slap the word continuous on it, it better mean just that! If I buy a AC motor and drive rated at 100hp it had better be able to do that long term, 24/7 for years. While I don't expect that for a consumer product as I stated there was a time that it did mean that the amp could run a sustained amount of time, more than a few hundred Milli seconds. However, it does not appear to now. So stop using continuous! define you test and procedure and make it clear you numbers are achieved under short duration test. Or why not do both? As you mention the thermal management comes in to play as well as transformer loading on longer sustained test. What can a test that last less than a minute to obtain all critical data tell me about how robustly the amp can handle these factors? Have you contacted any other manufacturers to discuss this issue? Have you gotten any responses?
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petie
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Post by petie on Aug 8, 2010 12:13:56 GMT -5
This sure has been an interesting thread. I had never thought about the time duration used for the "continuous" power rating. I have to agree that a standard time frame should apply to give a better comparison of build quality. If everyone was required to test at something reasonable - what ever length of time that would be - seconds? - the ratings would be more understandable. Then, if a meanufacturer wanted to offer an amp capable of full power for multiple times the required period, they would have a true claim of superior amp build. There is no way that a 5 channel amp would ever be required to deliver full power at the same time to all channels other than a possible peak lasting only a couple cycles but still having a defined test would have benefit I believe. Pete
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DYohn
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Post by DYohn on Aug 8, 2010 12:27:21 GMT -5
This sure has been an interesting thread. I had never thought about the time duration used for the "continuous" power rating. I have to agree that a standard time frame should apply to give a better comparison of build quality. If everyone was required to test at something reasonable - what ever length of time that would be - seconds? - the ratings would be more understandable. Then, if a meanufacturer wanted to offer an amp capable of full power for multiple times the required period, they would have a true claim of superior amp build. There is no way that a 5 channel amp would ever be required to deliver full power at the same time to all channels other than a possible peak lasting only a couple cycles but still having a defined test would have benefit I believe. Pete The test requires applying a continuous signal into a predetermined load and ramping up the level until rated distortion is exceeded, or to program in a design parameter level and simply measure that distortion levels do not exceed a programmed threshold when that signal is applied. "Continuous power" does not require a time duration, it is a rating of continuous signal input within given specs. It is assumed that this level can be sustained "forever" but this does not mean the test should last "forever." That is not only impractical, it is in most cases impossible.
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Post by johndavidson on Aug 8, 2010 13:07:05 GMT -5
This sure has been an interesting thread. I had never thought about the time duration used for the "continuous" power rating. I have to agree that a standard time frame should apply to give a better comparison of build quality. If everyone was required to test at something reasonable - what ever length of time that would be - seconds? - the ratings would be more understandable. Then, if a meanufacturer wanted to offer an amp capable of full power for multiple times the required period, they would have a true claim of superior amp build. There is no way that a 5 channel amp would ever be required to deliver full power at the same time to all channels other than a possible peak lasting only a couple cycles but still having a defined test would have benefit I believe. Pete The test requires applying a continuous signal into a predetermined load and ramping up the level until rated distortion is exceeded, or to program in a design parameter level and simply measure that distortion levels do not exceed a programmed threshold when that signal is applied. "Continuous power" does not require a time duration, it is a rating of continuous signal input within given specs. It is assumed that this level can be sustained "forever" but this does not mean the test should last "forever." That is not only impractical, it is in most cases impossible. You do know what they say about assume! ;D Why is it not practical. I have done it. It has been many years but it use to be doable. Have we lost the technology to do this? No one is saying forever but why not 15 minutes or half an hour. Why not have a standard? You could probably take a XPA-1 cut the heat-sink size in half reduce the transformer size by 25% and still meet the testing criteria if all you need is less than a minute to test. Would the amp be as good as it is now simple because it met the test criteria. I think it would directly reflect the build quality and if the amp can handle an all day viewing of the lord of the rings trilogy at reference levels on a fairly inefficient set of speakers.
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Post by johndavidson on Aug 8, 2010 13:15:27 GMT -5
And that is my point. These are not true continuous numbers they are short duration numbers. There needs to be a standard if you are going to call them continuous. As I stated my background is industrial electronics and controls. If you slap the word continuous on it, it better mean just that! If I buy a AC motor and drive rated at 100hp it had better be able to do that long term, 24/7 for years. While I don't expect that for a consumer product as I stated there was a time that it did mean that the amp could run a sustained amount of time, more than a few hundred Milli seconds. However, it does not appear to now. So stop using continuous! define you test and procedure and make it clear you numbers are achieved under short duration test. Or why not do both? As you mention the thermal management comes in to play as well as transformer loading on longer sustained test. What can a test that last less than a minute to obtain all critical data tell me about how robustly the amp can handle these factors? Have you contacted any other manufacturers to discuss this issue? Have you gotten any responses? No, I am certain that other amp manufacture do this. Some to higher and some to lower degrees. This conversation started when I posted the link to an article that goes into how ACD testing is done and that continuous power statements are very generous to what you can really expect to get out of you amp in real world. see for yourself www.audioholics.com/education/amplifier-technology/the-all-channels-driven-acd-amplifier-test
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iceman66
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Post by iceman66 on Aug 8, 2010 13:36:58 GMT -5
Have you contacted any other manufacturers to discuss this issue? Have you gotten any responses? No, I am certain that other amp manufacture do this. Some to higher and some to lower degrees. This conversation started when I posted the link to an article that goes into how ACD testing is done and that continuous power statements are very generous to what you can really expect to get out of you amp in real world. see for yourself www.audioholics.com/education/amplifier-technology/the-all-channels-driven-acd-amplifier-testYour questions have peaked my interest, I looked at several amp makers websites: Krell, Bryston, Parasound, Rotel, Mark Levinson, McIntosh and a few others, I only looked at specs given for a couple products from each and none specify CONTINUOUS output for their power rating, although it would appear to be implied - especially on $20K amps, McIntosh was the only name that even used continuous in a spec but it was qualified as 'average output'. I am in agreement with you that real specs should be provided using standard test(s) throughout the industry.
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Post by eljaycanuck on Aug 8, 2010 15:02:11 GMT -5
Could someone please address my query in reply #35? That is to say, which tests in the the 8-ohm PDF for the UPA-5 demonstrate the following: - "Full power with all channels driven across the entire frequency spectrum." and - "125 watts of continuous power with all channels driven." Thanks!
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Post by johndavidson on Aug 8, 2010 15:10:40 GMT -5
Your questions have peaked my interest, I looked at several amp makers websites: Krell, Bryston, Parasound, Rotel, Mark Levinson, McIntosh and a few others, I only looked at specs given for a couple products from each and none specify CONTINUOUS output for their power rating, although it would appear to be implied - especially on $20K amps, McIntosh was the only name that even used continuous in a spec but it was qualified as 'average output'. I am in agreement with you that real specs should be provided using standard test(s) throughout the industry. Well you peaked my interest as well. This is copied out of the user manual for a 4B. Seeing that power consumption and heat dissipations are given I would think this amp was put under a long term continuous test. A/C power Before plugging in the power cord be sure your SST amplifier is specified for the correct a/c voltage for your locality. The voltage is listed on the label found at the upper right of the rear panel. The circuit feeding the 4B SST should be sufficient so as not to cause the circuit breaker to trip (15 amp min). Note: the 4B SST when operated with both channels delivering maximum power into 4 ohm loads, will consume all the available power in a normal household circuit, therefore a dedicated electrical circuit may be necessary with this situation. Never lift the safety ground to the amplifier nor remove the ground pin from the plug.Power Consumption & Heat Load At Idle - 170 Watts Max. Heat Dissipation - 580 Btu/Hr. 2 channels @ 300W @ 8 ohms - 1280 Watts Max. Heat Dissipation 8 ohms - 2320 Btu/Hr. 2 channels @ 500W @ 4 ohms - 2100 Watts Max. Heat Dissipation 4 ohms - 3750 Btu/Hr. Bridged @ 900W @ 8 ohms - 2040 Watts Max. Heat Dissipation 8 ohms - 3890 Btu/Hr.
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bootman
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Post by bootman on Aug 8, 2010 17:27:15 GMT -5
I think it would directly reflect the build quality and if the amp can handle an all day viewing of the lord of the rings trilogy at reference levels on a fairly inefficient set of speakers. In that real world test, the average "continuous" power output would only be a few watts.
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NorthStar
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Post by NorthStar on Aug 8, 2010 17:42:42 GMT -5
I think it would directly reflect the build quality and if the amp can handle an all day viewing of the lord of the rings trilogy at reference levels on a fairly inefficient set of speakers. Someone's calling me? ;D (From reply #66) ____________________________________ I've read this entire thread with some interest, and I believe we are juggling with words and their meaning here, as "continuous" power output, or what does it mean. Well, when I see that word (continuous) in the lab tests for Multichannel power amps or receivers in their RMS power wattage output (from an 'Audio Precision System Two 2532 Dual Domain'), as the Federal Trade Commission (FTC) standards on total power output, I see it like this: "Five channels (or seven) driven continuously into 8-ohm loads at a certain given percentage of distortion (ie.; 0.1%)". Also, it would be best if it was mentioned that it is also calculated from 20 Hz to 20 Khz, but often it is measured at an audio frequency of only 1 Khz!, which means not much at all if nothing! ...What happens at 20 Hz or 20 Khz? {I missed Edward J. Foster from "Audio" magazine with his 'Measured Data' } Sooo, " continuously" here means with all five or seven channels driven, and not power. * Am I on the right track?
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NorthStar
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Post by NorthStar on Aug 8, 2010 18:06:54 GMT -5
I think it would directly reflect the build quality and if the amp can handle an all day viewing of the lord of the rings trilogy at reference levels on a fairly inefficient set of speakers. In that real world test, the average "continuous" power output would only be a few watts. Touche! ...About 3 to 10 RMS watts at most.
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Post by johndavidson on Aug 8, 2010 19:06:42 GMT -5
In that real world test, the average "continuous" power output would only be a few watts. Touche! ...About 3 to 10 RMS watts at most. Ya'll must be old if you listen with the volume turned down that low or married ;D
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Post by johndavidson on Aug 8, 2010 19:12:25 GMT -5
Could someone please address my query in reply #35? That is to say, which tests in the the 8-ohm PDF for the UPA-5 demonstrate the following: - "Full power with all channels driven across the entire frequency spectrum." and - "125 watts of continuous power with all channels driven." Thanks! I would like to know the answer also.
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NorthStar
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Post by NorthStar on Aug 8, 2010 19:46:05 GMT -5
Touche! ...About 3 to 10 RMS watts at most. Ya'll must be old if you listen with the volume turned down that low or married ;D Well John, I have a Radio Shack RMS watts level meter (with red lights) that indicates how many watts are output from my two front loudspeakers, and I can assure you that 3 watts average is quite loud (8 Ohms). ...Double that (6 watts into 4 Ohms). * Of course, on peaks it can go over 400 watts, but it is only for few milliseconds, wayyyyyyyyy far from continuous.
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Post by psbman on Aug 8, 2010 20:06:17 GMT -5
Ya'll must be old if you listen with the volume turned down that low or married ;D Well John, I have a Radio Shack RMS watts level meter (with red lights) that indicates how many watts are output from my two front loudspeakers, and I can assure you that 3 watts average is quite loud (4 Ohms). * Of course, on peaks it can go over 400 watts, but it is only for few milliseconds, wayyyyyyyyy far from continuous. Lets take the " LOTR" (movie) example. If your driving normal speakers (ie.... Tower fronts, bookshelf rears, center and large sub) At or near Ref levels for the entire movie.........IMO the "continuous" output of the XPA-5 should be much higher than 10 watts......should it not?
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Lonnie
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Post by Lonnie on Aug 8, 2010 20:33:37 GMT -5
Your questions have peaked my interest, I looked at several amp makers websites: Krell, Bryston, Parasound, Rotel, Mark Levinson, McIntosh and a few others, I only looked at specs given for a couple products from each and none specify CONTINUOUS output for their power rating, although it would appear to be implied - especially on $20K amps, McIntosh was the only name that even used continuous in a spec but it was qualified as 'average output'. I am in agreement with you that real specs should be provided using standard test(s) throughout the industry. Well you peaked my interest as well. This is copied out of the user manual for a 4B. Seeing that power consumption and heat dissipations are given I would think this amp was put under a long term continuous test. A/C power Before plugging in the power cord be sure your SST amplifier is specified for the correct a/c voltage for your locality. The voltage is listed on the label found at the upper right of the rear panel. The circuit feeding the 4B SST should be sufficient so as not to cause the circuit breaker to trip (15 amp min). Note: the 4B SST when operated with both channels delivering maximum power into 4 ohm loads, will consume all the available power in a normal household circuit, therefore a dedicated electrical circuit may be necessary with this situation. Never lift the safety ground to the amplifier nor remove the ground pin from the plug.Power Consumption & Heat Load At Idle - 170 Watts Max. Heat Dissipation - 580 Btu/Hr. 2 channels @ 300W @ 8 ohms - 1280 Watts Max. Heat Dissipation 8 ohms - 2320 Btu/Hr. 2 channels @ 500W @ 4 ohms - 2100 Watts Max. Heat Dissipation 4 ohms - 3750 Btu/Hr. Bridged @ 900W @ 8 ohms - 2040 Watts Max. Heat Dissipation 8 ohms - 3890 Btu/Hr.I don't see where anything is stated about how long the test was run or am I missing something?
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Lonnie
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Post by Lonnie on Aug 8, 2010 20:39:00 GMT -5
Well John, I have a Radio Shack RMS watts level meter (with red lights) that indicates how many watts are output from my two front loudspeakers, and I can assure you that 3 watts average is quite loud (4 Ohms). * Of course, on peaks it can go over 400 watts, but it is only for few milliseconds, wayyyyyyyyy far from continuous. Lets take the " LOTR" (movie) example. If your driving normal speakers (ie.... Tower fronts, bookshelf rears, center and large sub) At or near Ref levels for the entire movie.........IMO the "continuous" output of the XPA-5 should be much higher than 10 watts......should it not? 10 watts average is probably pretty close.
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