15-Jul-2019, 08:40
(10-Jul-2019, 09:44)RebelMan Wrote:(10-Jul-2019, 00:40)David A Wrote: Since they occur in the section for ADH config, I'm going to guess that the line for Voltage defines the setting for the class A amp which supplies the voltage and the 51 V that it shows for Jean Marie's 220 equates to the voltage for 220 W output per channel for a 220 in stereo mode.
"Puissance" seems to translate to power. There's a setting in the configurator's speaker section where you can set maximum power output and the maximum you can set is your amp's specified power (that's also the default setting) but you can limit to to a lower output. I suspect that the 220 shown in Jean Marie's file indicates that he has chosen to leave that setting at the maximum for his 220. If you have a dual amp setup I suspect the maximum/default will be the mono output so for a 440 which is comprised of 2 220s the figure shown would be 440 which would be the power output from 51V for bridged mode for the amp.
If you limit the power output I think you'd see a lower number for Puissance reflecting the lower wattage limit you've set and that the lower output would be reached at a 0 dB volume setting. Maximum power output, whatever you set it to, will always be reached at a volume setting of 0 dB. I don't know whether the voltage value will also change if you limit maximum volume but it may also.
Basically, taken together, I think those 2 values control the settings for the Class A and Class D amps respectively given the maximum power output you choose in the speaker settings in the Configurator.
Just a guess as I said but there''s no reason to specify ADH configuration if you don't give the user the option to vary maximum power output and given the fact that the Devialet is a Class A/Class D hybrid it would seem to make sense to have separate values for the Class A and Class D stages if you are going to be able to vary output.
I've got a 140. That section of my config file shows 41 V and a Puissance of 140. I think if I added a companion to make a 210 the file would show 41 V and Puissance 210.
The logic behind your hypothesis follows but some of the math is still elusive. Looking at the 220, max voltage is set to 51V at 0dBFS and the corresponding impedance at this voltage is 6 ohms. Power in this case computes as 434W which is almost twice what the 220 is rated for. @Jean-Marie suggests this to be peak power. If we apply the math to the 140 using your figures power computes to 280W peak which is exactly twice what the 140 is rated for continuously. If power from the Devilet 140 and 220 are not artificially limited (somewhere in the code) then where did the peak power go?
According to HiFi World the Expert 220 Pro reached a peak power of 190W into 6 ohms which is nowhere near the 434W computed from above. @Jean-Marie suspects this is due to the evaluation unit being tested with SAM enabled. However, Audio was unable to measure the peaks of the Expert 140 Pro because the sophisticated power protection circuits prevented it...
"It is worth mentioning the presence of a special protection circuit, which, after exceeding a certain input voltage (sensitivity), does not allow distortion of the terminals, so distortions do not increase, but stop at a level even lower than the standard THD + N = 1%. Hence, our results concern such conditions, because it is the highest power that can be obtained."
It would seem peak power may never be reached regardless of the amplifier's ability to produce it because it's trying to play it safe. If this is true then the 220 has a major handicap. I confirmed with Devilalet that continuous power of the 140 and 220 is as follows...
Expert 140 Pro Expert 220 Pro
8 Ohms 105 W 165 W
6 Ohms 140 W 220 W
4 Ohms 210 W 330 W
2 Ohms 420 W 330 W
If peak output power is limited to continuous output power (as multiple tests have shown) because of the protection circuits then that can be a problem for people with speaker impedances that dip below 3 ohms and mine do. For the people that still believe more power sounds better than less power, have some crow.
I have asked Devialet about the 2-ohm continuous power of 220 Pro in two different occasions before and got two different answers: 660W and 500W respectively. Not that I think the answers I got are more accurate (I shouldn't have got different answers in the first place), but I can't understand how a 220 Pro could do worse than a 140 Pro for a 2-ohm load, given that they have the same chassis and the power supply of 220 Pro should be no worse than 140 Pro (if not better). I am curious to know if the above power figures quoted for 140 and 220 were all provided by the same person?
BTW, just for additional information, I found another review from the Stereo magazine ( https://stereo-magazine.com/flipview/epaper/stereo-magazine-20-2019-20/ ) which posted somewhat better measurements for the 220 Pro than what Hi Fi World did: 173W at 8ohms and 343W at 4 ohms. Not sure which review is more correct, but to me the differences are not night and day and could be just due to different test conditions.
