07-Jul-2019, 13:56
Hold the press @Confused the math still holds.
There are several glaring errors with the first demonstration. First, nothing is said about the the SPLs they are producing, perhaps because they didn't measure them. Second, the amplifers are operating in "bridged mode". When an amplifier is operating in bridge mode the load it sees doubles. The Harbeth M40.1's dip below 6 ohms which at first glance would seem like a fairly easy load on the amplifier but that's not the case as the amplifier actually sees 3 ohm dips. Third, the "marketing geniuses" (sarcasm) in the video do not understand or do not clarify what the meters are actually telling. The amplifier may have displayed a 700W peak reading but the marketing geniuses are taking that information out of context, it needs to be qualified. Remember that music is dynamic and at any given time there is a relationship between the power a load needs and the power the load receives. At what load was the 700W produced? Was it at 30 ohms or was it at 3? I venture to say the latter.
The takeaway here isn't about needing more power but rather needing linear power.
THE MATH
How would a Devialet handle the same set of conditions? Working the problem backwards it would see a max load of 350W at 6 ohms, more than most of the units in the line could handle. But is listening to 350W at 6 ohms realistic? Again, they didn't state the listening parameters, so we will. If we assume the listener it positioned 4m away and the amplifier needed to supply 350W into a 6ohm load the SPLs would register a staggering 101.4dB! Keep in mind I am using the Harbeth M40.1's sensitivity level of 85dB in my calculations. The answer is NO, 350W at 6 ohms is not realistic at all. If we limited the power to the max output of say the Devialet 140 what then? The SPLs could reach as high as 97.5dB which is still very high, aka LOUD and also unrealistic as these are reference level volumes and no one in there right mind is going to comfortably listen to their music at these levels.
Taking power into consideration only, the thing to look for is a stable amplifier with linear output. As the load increases so too should the power supplied. The Devialet 170 is measured to deliver very linear power according to HiFi News measurements. The Devialet D-Premier for which the Devialet 240 was patterned after is not, also according to HiFi News measurements. I suspect the beefier power supply that went into the Expert series rectified that for the 240 but it's the same power supply that fuels the 170. It puzzles me why you found the 170 so lacking as compared to the 240 when driving the Kef Blades. I suspect the conditions between listening sessions differed significantly.
By the way, I also reviewed the second video and while I found the outcome more realistic there is still to little known about the setting to draw anything really meaningful from it.
The marketing geniuses are once again WRONG. Most systems do not need lots of power. They need GOOD, CLEAN and LINEAR power and proper testing proves this time and again.
There are several glaring errors with the first demonstration. First, nothing is said about the the SPLs they are producing, perhaps because they didn't measure them. Second, the amplifers are operating in "bridged mode". When an amplifier is operating in bridge mode the load it sees doubles. The Harbeth M40.1's dip below 6 ohms which at first glance would seem like a fairly easy load on the amplifier but that's not the case as the amplifier actually sees 3 ohm dips. Third, the "marketing geniuses" (sarcasm) in the video do not understand or do not clarify what the meters are actually telling. The amplifier may have displayed a 700W peak reading but the marketing geniuses are taking that information out of context, it needs to be qualified. Remember that music is dynamic and at any given time there is a relationship between the power a load needs and the power the load receives. At what load was the 700W produced? Was it at 30 ohms or was it at 3? I venture to say the latter.
The takeaway here isn't about needing more power but rather needing linear power.
THE MATH
How would a Devialet handle the same set of conditions? Working the problem backwards it would see a max load of 350W at 6 ohms, more than most of the units in the line could handle. But is listening to 350W at 6 ohms realistic? Again, they didn't state the listening parameters, so we will. If we assume the listener it positioned 4m away and the amplifier needed to supply 350W into a 6ohm load the SPLs would register a staggering 101.4dB! Keep in mind I am using the Harbeth M40.1's sensitivity level of 85dB in my calculations. The answer is NO, 350W at 6 ohms is not realistic at all. If we limited the power to the max output of say the Devialet 140 what then? The SPLs could reach as high as 97.5dB which is still very high, aka LOUD and also unrealistic as these are reference level volumes and no one in there right mind is going to comfortably listen to their music at these levels.
Taking power into consideration only, the thing to look for is a stable amplifier with linear output. As the load increases so too should the power supplied. The Devialet 170 is measured to deliver very linear power according to HiFi News measurements. The Devialet D-Premier for which the Devialet 240 was patterned after is not, also according to HiFi News measurements. I suspect the beefier power supply that went into the Expert series rectified that for the 240 but it's the same power supply that fuels the 170. It puzzles me why you found the 170 so lacking as compared to the 240 when driving the Kef Blades. I suspect the conditions between listening sessions differed significantly.
By the way, I also reviewed the second video and while I found the outcome more realistic there is still to little known about the setting to draw anything really meaningful from it.
The marketing geniuses are once again WRONG. Most systems do not need lots of power. They need GOOD, CLEAN and LINEAR power and proper testing proves this time and again.
"Dream as if you'll live forever. Live as if you'll die today."
