22-Jan-2024, 12:40
Daniel,
Your technical knowledge and measurement capability far exceeds mine, my smattering of technical knowledge is in a very different field, health and safety, but there is one thing I was taught which still sticks with me today. That is "measurements tell you a lot about what you measure but they tell you nothing about what you don't measure".
You said one of the 2 things you've wanted to check for a long time but haven't been able to is the phase correction that SAM 0% makes. I think phase correction is critical to understanding what SAM does, it's really the only thing that Devialet tells us about what SAM does. What I would like to know is what SAM is doing with phase at all points of the SAM scale from 0% to 100%. We know that SAM delivers maximum bass extension at 100% because Devialet say that BUT how is that bass extension achieved? Is all phase correction applied at the 0% level and what happens at higher levels just the addition of an increasing amount of level boost via an equalisation profile, is what happens above 0% an extension of the application of phase correction to lower frequencies, is what happens a combination of those 2 things, or is their some other "secret sauce" addition added to the mix? We really don't know.
What I do think is that in the absence of a fuller account of how SAM works from Devialet, I don't think we've got any hope of knowing just what is going on without having access to phase measurements at 0% and at least a sampling of higher SAM settings up to 100%. I think knowing what's going on with phase correction over the whole 0-100% setting range there's no hope of knowing what SAM is doing.
In relation to the measurements you made you said "These measurements reflect the SAM effect in my audio system and in my room. I think it is not correct for someone to consider that SAM effects are the same in other audio systems or in other rooms." I think the room is clearly a significant confounding factor in your results. Looking at the peaks and valleys in your 9-500 Hz chart, it's clear that what you're measuring is an in room speaker response rather than simply the effect of SAM. You're making your measurements in the same way you would measure a room for a "room correction" program and the problem with that is that if you move the microphone to a different location and repeat the measurements your results will be different. The same will happen if you leave the microphone at the same location and move the speakers. You aren't measuring what SAM is doing, you're measuring what the speaker/room combination is delivering at the microphone position.
You need to make your measurements at the amplifier's speaker terminals in order to get a result that just shows what SAM is doing rather than what SAM plus whatever the speaker, room, and microphone location are contributing to the results. What SAM does occurs before the speaker, room, and microphone location get involved. Change those things and your results will change but what SAM is doing to the signal going to the speaker does not change with changes to the room, speaker location or microphone location.
And, since Devialet say that SAM is applying phase correction, you must also measure phase response at different SAM levels as well because it's obviously a significant part of what SAM does. That means you can't understand SAM without knowing what it's doing to phase response and whether that changes at different setting levels.
Bear in mind also that as you increase the SAM setting your amplifier volume setting may become important because of the speaker protection aspect of SAM which starts to ease off whatever SAM is doing at higher volume levels in order to protect the speaker.
@gianventu: SAM is not a "room correction" system, it's a system intended to do 2 things, correct woofer phase response below 150 Hz and to extend the speaker's bass response to some degree without risking speaker damage. It's not intended or designed to modify or correct room caused frequency anomalies which is what systems like ARC, Room Perfect, and Dirac are intended to do. SAM can't do what they do and they can't do what SAM does. SAM and those systems are designed to address different problems and Sweet Room, not SAM, is the room correction system Devialet has implemented in order to do the same sort of thing as ARC, Perfect Room, and Dirac do.
Your technical knowledge and measurement capability far exceeds mine, my smattering of technical knowledge is in a very different field, health and safety, but there is one thing I was taught which still sticks with me today. That is "measurements tell you a lot about what you measure but they tell you nothing about what you don't measure".
You said one of the 2 things you've wanted to check for a long time but haven't been able to is the phase correction that SAM 0% makes. I think phase correction is critical to understanding what SAM does, it's really the only thing that Devialet tells us about what SAM does. What I would like to know is what SAM is doing with phase at all points of the SAM scale from 0% to 100%. We know that SAM delivers maximum bass extension at 100% because Devialet say that BUT how is that bass extension achieved? Is all phase correction applied at the 0% level and what happens at higher levels just the addition of an increasing amount of level boost via an equalisation profile, is what happens above 0% an extension of the application of phase correction to lower frequencies, is what happens a combination of those 2 things, or is their some other "secret sauce" addition added to the mix? We really don't know.
What I do think is that in the absence of a fuller account of how SAM works from Devialet, I don't think we've got any hope of knowing just what is going on without having access to phase measurements at 0% and at least a sampling of higher SAM settings up to 100%. I think knowing what's going on with phase correction over the whole 0-100% setting range there's no hope of knowing what SAM is doing.
In relation to the measurements you made you said "These measurements reflect the SAM effect in my audio system and in my room. I think it is not correct for someone to consider that SAM effects are the same in other audio systems or in other rooms." I think the room is clearly a significant confounding factor in your results. Looking at the peaks and valleys in your 9-500 Hz chart, it's clear that what you're measuring is an in room speaker response rather than simply the effect of SAM. You're making your measurements in the same way you would measure a room for a "room correction" program and the problem with that is that if you move the microphone to a different location and repeat the measurements your results will be different. The same will happen if you leave the microphone at the same location and move the speakers. You aren't measuring what SAM is doing, you're measuring what the speaker/room combination is delivering at the microphone position.
You need to make your measurements at the amplifier's speaker terminals in order to get a result that just shows what SAM is doing rather than what SAM plus whatever the speaker, room, and microphone location are contributing to the results. What SAM does occurs before the speaker, room, and microphone location get involved. Change those things and your results will change but what SAM is doing to the signal going to the speaker does not change with changes to the room, speaker location or microphone location.
And, since Devialet say that SAM is applying phase correction, you must also measure phase response at different SAM levels as well because it's obviously a significant part of what SAM does. That means you can't understand SAM without knowing what it's doing to phase response and whether that changes at different setting levels.
Bear in mind also that as you increase the SAM setting your amplifier volume setting may become important because of the speaker protection aspect of SAM which starts to ease off whatever SAM is doing at higher volume levels in order to protect the speaker.
@gianventu: SAM is not a "room correction" system, it's a system intended to do 2 things, correct woofer phase response below 150 Hz and to extend the speaker's bass response to some degree without risking speaker damage. It's not intended or designed to modify or correct room caused frequency anomalies which is what systems like ARC, Room Perfect, and Dirac are intended to do. SAM can't do what they do and they can't do what SAM does. SAM and those systems are designed to address different problems and Sweet Room, not SAM, is the room correction system Devialet has implemented in order to do the same sort of thing as ARC, Perfect Room, and Dirac do.
Roon Nucleus+, Devilalet Expert 140 Pro CI, Focal Sopra 2, PS Audio P12, Keces P8 LPS, Uptone Audio EtherREGEN with optical fibre link to my router, Shunyata Alpha NR and Sigma NR power cables, Shunyata Sigma ethernet cables, Shunyata Alpha V2 speaker cables, Grand Prix Audio Monaco rack, RealTRAPS acoustic treatment.
Brisbane, Qld, Australia
