As this is my first post here, I'd like to thank Amir for hosting the site and for all the work that goes into equipment measurement. Debunking marketing claims and helping consumers to make informed choices is important work.
Whilst I understand the need for standardised measurements, a lot of nuance is missed if we only look at the headline dashboard figures obtained with 2V or 4V output.
If I typically listen to TV at -30dB (on a room corrected AVR) how do I find the SINAD that I should expect on an intermodulation distortion plot like this one for the Denon AVC-X4700h?
Should I project up from -30 to the curve - which yields a figure of approximately -80dB?
However, the scale on the horizontal axis is dBFS (dB full scale). I believe that reference level is supposed to be at -20dBFS. Does that mean that I should actually project up from -50dBFS and hence get a figure of just -60dB?
Additionally, much of the comment on this site is biased towards the use of seperate pre/pro and power amps (even in the case of AVRs). Many people will purchase an AVR intending to use the internal amplification and to listen at sane levels; however, it can be difficult to know how many watts will actually be needed.
Taking the 8 ohms amplifier performance as an example (also from the AVC-X4700h):
And using this online SPL calculator:
With sensitivity of 90 dB SPL, and two speakers near a wall, 15ft from the listening position.
If reference level is 85dB SPL and I listen at -30dB from reference then the target should be -55dB SPL. The calculator suggests that I only need 0.00165 W to reach this level. This seems ridiculously low (not even on the plot). Am I missing something here?
Whilst I understand the need for standardised measurements, a lot of nuance is missed if we only look at the headline dashboard figures obtained with 2V or 4V output.
If I typically listen to TV at -30dB (on a room corrected AVR) how do I find the SINAD that I should expect on an intermodulation distortion plot like this one for the Denon AVC-X4700h?
Should I project up from -30 to the curve - which yields a figure of approximately -80dB?
However, the scale on the horizontal axis is dBFS (dB full scale). I believe that reference level is supposed to be at -20dBFS. Does that mean that I should actually project up from -50dBFS and hence get a figure of just -60dB?
Additionally, much of the comment on this site is biased towards the use of seperate pre/pro and power amps (even in the case of AVRs). Many people will purchase an AVR intending to use the internal amplification and to listen at sane levels; however, it can be difficult to know how many watts will actually be needed.
Taking the 8 ohms amplifier performance as an example (also from the AVC-X4700h):
And using this online SPL calculator:
With sensitivity of 90 dB SPL, and two speakers near a wall, 15ft from the listening position.
If reference level is 85dB SPL and I listen at -30dB from reference then the target should be -55dB SPL. The calculator suggests that I only need 0.00165 W to reach this level. This seems ridiculously low (not even on the plot). Am I missing something here?