@Confused
One important addition to my post above, probably more important in some ways than the post above.
You said you wanted peaks of 95 dB. That means you only need peaks of 92 dB. You've got 2 speakers and 2 speakers producing the same level result in a total level that is 3 dB louder than each speaker on its own. If you want 95 db peaks you want each speaker to produce 92 dB peaks and producing 92 dB from each speaker requires half the power that producing 95 dB from each speaker requires. Amp ratings tell you how much power you have for each speaker individually.
Sound falls off at 6 dB per doubling of distance in the acoustic near field and at around 3 dB per doubling of distance in the acoustic far field. Assume the boundary between near and far field is around 2 metres (it's a bit less than that).
Here's the type of calculation you were thinking of:
I listen at around 2.6 metres. At 2 metres I'd need an extra 6 dB for the doubling of distance, at 9 metres around an extra 9 dB. To be safe assume an extra 8 dB hat 2.6 metres.
My speakers are 91 dB sensitive according to Focal. I haven't seen a test report on the Sopra 2s but John Atkinson's review of the Sopra 3's measured them as around 2 dB less sensitive than rated so let's assume my speakers are 89 dB sensitive. To produce a 92 dB peak per speaker at my listening position, I need to raise 89 dB to 100 dB (92 dB for the peak at 1 metre plus the extra 8 dB for the listening distance) so I need enough amp power to deliver an extra 11 dB. According to an online calculator that requires 12.589254 watts.
I think your figure of 95 dB peaks would suit me fine as well. You probably listen at a slightly larger distance. You still need 92 dB at 1 metre but you would need to produce 9 dB more to get 92 dB at 4 metres so you need to get 101 dB at 1 metre, an extra 8 dB over what the speaker produces for 1 Watt. The gain with your more sensitive speakers more than outweighs the loss with the increase of listening distance from 2.6 to 4 metres so you would need less power than I do in order to produce the same peak level.
Let's say you had 85 dB sensitive speakers and a 4 metre listening distance. We still need to get 101 dB at 1 metre for 92 dB at 4 metres so that's an extra 16 ddB. You still need less than 100 W. 100 W would deliver a 20 dB increase in level so a pair of 85 dB sensitive speakers would deliver a 95 dB level at 4 metres with 100 W.
Assuming each speaker has to deliver the level you want at the listening position rather than 3 dB less because the sound of each speaker adds together to raise the overall level 3 dB makes a big difference when it comes to how many watts you need in order to deliver your desired SPL. For each 3 dB you raise your desired peak listening level you double your power requirements.
One important addition to my post above, probably more important in some ways than the post above.
You said you wanted peaks of 95 dB. That means you only need peaks of 92 dB. You've got 2 speakers and 2 speakers producing the same level result in a total level that is 3 dB louder than each speaker on its own. If you want 95 db peaks you want each speaker to produce 92 dB peaks and producing 92 dB from each speaker requires half the power that producing 95 dB from each speaker requires. Amp ratings tell you how much power you have for each speaker individually.
Sound falls off at 6 dB per doubling of distance in the acoustic near field and at around 3 dB per doubling of distance in the acoustic far field. Assume the boundary between near and far field is around 2 metres (it's a bit less than that).
Here's the type of calculation you were thinking of:
I listen at around 2.6 metres. At 2 metres I'd need an extra 6 dB for the doubling of distance, at 9 metres around an extra 9 dB. To be safe assume an extra 8 dB hat 2.6 metres.
My speakers are 91 dB sensitive according to Focal. I haven't seen a test report on the Sopra 2s but John Atkinson's review of the Sopra 3's measured them as around 2 dB less sensitive than rated so let's assume my speakers are 89 dB sensitive. To produce a 92 dB peak per speaker at my listening position, I need to raise 89 dB to 100 dB (92 dB for the peak at 1 metre plus the extra 8 dB for the listening distance) so I need enough amp power to deliver an extra 11 dB. According to an online calculator that requires 12.589254 watts.
I think your figure of 95 dB peaks would suit me fine as well. You probably listen at a slightly larger distance. You still need 92 dB at 1 metre but you would need to produce 9 dB more to get 92 dB at 4 metres so you need to get 101 dB at 1 metre, an extra 8 dB over what the speaker produces for 1 Watt. The gain with your more sensitive speakers more than outweighs the loss with the increase of listening distance from 2.6 to 4 metres so you would need less power than I do in order to produce the same peak level.
Let's say you had 85 dB sensitive speakers and a 4 metre listening distance. We still need to get 101 dB at 1 metre for 92 dB at 4 metres so that's an extra 16 ddB. You still need less than 100 W. 100 W would deliver a 20 dB increase in level so a pair of 85 dB sensitive speakers would deliver a 95 dB level at 4 metres with 100 W.
Assuming each speaker has to deliver the level you want at the listening position rather than 3 dB less because the sound of each speaker adds together to raise the overall level 3 dB makes a big difference when it comes to how many watts you need in order to deliver your desired SPL. For each 3 dB you raise your desired peak listening level you double your power requirements.
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
