29-Jul-2020, 20:56
@BoyScout ,
What you're going to hear with SAM depends a fair bit on your speakers and what SAM can do with them, but also and probably to a greater degree on your room, where you place your speakers, and where you sit.
Take a look at the plot in @Delija 's post. The biggest change is at around 25 Hz where he already had a peak, and that peak is maybe 6 dB higher with SAM. The peak itself is probably a room mode. How much a room mode is activated by the speaker depends on where the speaker is placed in the room so if his speakers were placed in the corners, for example, the peak would probably be higher. It also depends on where you sit, or in this case, place the mic for your measurements. Sit/place the mic in a high pressure zone in the room and the peak will measure higher than if you place it in a low pressure zone. If you have the speakers in places where they aren't maximally activating the mode you won't get as big a peak and if you then sit or measure at a point in a low pressure zone for that mode you'll also reduce the level of the peak further.
I don't know your room, where you have your speakers placed, or where you're sitting but it's probably quite possible to produce a bigger difference than the plot shows, and it's also possible to produce a smaller, even a much smaller difference. I was once auditioning a speaker in a dealer's showroom with one of my own CDs and I could not hear a prominent repeating bass note when sitting in the listening chair but when I stepped about a pace forward as I got up to change the disc I moved into a pressure zone and suddenly got a strong bass note. The combination of speaker placement and listening position can make a very big difference in what you can hear in the bass. SAM doesn't change that behaviour. You'll get more bass output from the speaker but how audible the bass will be, both with and without SAM, depends on speaker placement and listening position..
Take a look at the dip around 50 hz in the plot. Between roughly 40 Hz and 60 Hz there's virtually no difference with and without SAM. It may be that SAM is providing little correction in that area because the speaker doesn't need correction in that area but the reason for the dip in that region will be probably be that the mic is in a low pressure zone for those frequencies and the cancellations occurring at the measurement point there are minimising the difference. Compare the plot at that point around 50 Hz and then at the dip below 30 Hz where the difference is bigger, even though the with and without SAM plots are showing the same dip.
As @Delija said, the difference SAM makes can be pretty significant but speaker placement and listening position choices can make that difference difficult or impossible to notice, especially when you also add in the fact that at those frequencies the sensitivity of our ears is dropping pretty strongly.
You could try moving your listening position forward or back a bit a foot or two at a time to see if that makes a difference, and also moving your speakers but if you can't hear a difference I'd be inclined to run without SAM and give the amp an easier time because SAM works the amp a fair bit harder getting that boost it can give and if you can't hear it then there's no point in driving the amp harder.
So, the main reason for the difference in your experience and @Delija 's experience with SAM and how noticeable it is may well be largely due to where each of you have your speakers and listening positions placed in relation to your respective room's pressure zones at low frequencies. SAM works on speaker behaviour but room behaviour determines what you're going to hear at low frequency.
What you're going to hear with SAM depends a fair bit on your speakers and what SAM can do with them, but also and probably to a greater degree on your room, where you place your speakers, and where you sit.
Take a look at the plot in @Delija 's post. The biggest change is at around 25 Hz where he already had a peak, and that peak is maybe 6 dB higher with SAM. The peak itself is probably a room mode. How much a room mode is activated by the speaker depends on where the speaker is placed in the room so if his speakers were placed in the corners, for example, the peak would probably be higher. It also depends on where you sit, or in this case, place the mic for your measurements. Sit/place the mic in a high pressure zone in the room and the peak will measure higher than if you place it in a low pressure zone. If you have the speakers in places where they aren't maximally activating the mode you won't get as big a peak and if you then sit or measure at a point in a low pressure zone for that mode you'll also reduce the level of the peak further.
I don't know your room, where you have your speakers placed, or where you're sitting but it's probably quite possible to produce a bigger difference than the plot shows, and it's also possible to produce a smaller, even a much smaller difference. I was once auditioning a speaker in a dealer's showroom with one of my own CDs and I could not hear a prominent repeating bass note when sitting in the listening chair but when I stepped about a pace forward as I got up to change the disc I moved into a pressure zone and suddenly got a strong bass note. The combination of speaker placement and listening position can make a very big difference in what you can hear in the bass. SAM doesn't change that behaviour. You'll get more bass output from the speaker but how audible the bass will be, both with and without SAM, depends on speaker placement and listening position..
Take a look at the dip around 50 hz in the plot. Between roughly 40 Hz and 60 Hz there's virtually no difference with and without SAM. It may be that SAM is providing little correction in that area because the speaker doesn't need correction in that area but the reason for the dip in that region will be probably be that the mic is in a low pressure zone for those frequencies and the cancellations occurring at the measurement point there are minimising the difference. Compare the plot at that point around 50 Hz and then at the dip below 30 Hz where the difference is bigger, even though the with and without SAM plots are showing the same dip.
As @Delija said, the difference SAM makes can be pretty significant but speaker placement and listening position choices can make that difference difficult or impossible to notice, especially when you also add in the fact that at those frequencies the sensitivity of our ears is dropping pretty strongly.
You could try moving your listening position forward or back a bit a foot or two at a time to see if that makes a difference, and also moving your speakers but if you can't hear a difference I'd be inclined to run without SAM and give the amp an easier time because SAM works the amp a fair bit harder getting that boost it can give and if you can't hear it then there's no point in driving the amp harder.
So, the main reason for the difference in your experience and @Delija 's experience with SAM and how noticeable it is may well be largely due to where each of you have your speakers and listening positions placed in relation to your respective room's pressure zones at low frequencies. SAM works on speaker behaviour but room behaviour determines what you're going to hear at low frequency.
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
