8040A and accurate input level - Forum
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8040A and accurate input level
eduardoc, modified 12 Years ago.
8040A and accurate input level
Youngling Posts: 22 Join Date: 11/3/09 Recent PostsI own a pair of 8040A that I use with a Sonos Zone Player 90 (multiroom music system - this is not professional hardware). The maximum output level of the Sonos (RCA) is 2Vrms.
http://www.sonos.com/products/zoneplayers/zp90/default.aspx?rdr=true&LangType=2057
Considering that 0dBu is 0.775V, can I say that this level is 8.23dBu ?
When you look at serious DAC such as Lavry Engineering or Benchmark DAC1 HDR you have maximum output level of 21dBu and 27dBu (XLR).
http://www.benchmarkmedia.com/dac/dac1-hdr
http://www.lavryengineering.com/productspage_comp_da11.html
So I have two questions:
1/ What is the maxium level that can be put into 8040A and, in the same way, what are the recommanded levels (a range) to be used with 8040A ?
2/ What is the purpose of the input sensivity button at the rear of 8040A : from -6dBu to +6dBu ? Do I have to turn it to have better results with my Sonos ?
Thank you!
Cédric
ilkka-rissanen, modified 12 Years ago.
Re: 8040A and accurate input level
Yoda Posts: 2564 Join Date: 3/23/09 Recent Posts
1/ What is the maxium level that can be put into 8040A and, in the same way, what are the recommanded levels (a range) to be used with 8040A ?
Hi,
The maximum input level can be limited either by the electrical components in the input stage or the acoustical maximum output of the speaker, in a properly designed speaker it's always the latter one. So for the 8040A the maximum usable input level is around -1 dBu (with max -6 dBu sensitivity setting) to +11 dBu (with min +6 dBu sensitivity setting). There is no recommended setting because it all depends on the output level of your source.
Since your Sonos can output around +8 dBu, I would turn the sensitivity to the maximum -6 dBu (yes, -6 dBu) so that you will ensure that the speaker is able to output its maximum SPL if requested.
2/ What is the purpose of the input sensivity button at the rear of 8040A : from -6dBu to +6dBu ? Do I have to turn it to have better results with my Sonos ?
Please read this first. If you have still have further questions, I'd be happy to help.

http://www.genelec.com/faq/applicable-t ... nsitivity/
eduardoc, modified 12 Years ago.
Re: 8040A and accurate input level
Youngling Posts: 22 Join Date: 11/3/09 Recent PostsIf I chose a sensitivity of -6dBu, the 8040A will need -1dBu to get the maximum SPL level.
Mathematically, using a source that can output +8dBu (Sonos), a sensitivity of +3dBu gives the maximum SPL level:
Input sensitivity is +3 dBu = 100 dB SPL@1m
Max rms output SPL stated on the datasheet 105 dB SPL@1m
Additional rms input level required for maximum rms output +5 dB
Max rms input level required for maximum rms output +3 dBu + 5 dB = +8 dBu = Sonos maximum output level
So, using a sensitivity of -6dBu will always give the maximum SPL, because you only need -1dBu!
So this sensitivity is useful when you want to temper the maxium acoustic level (depending of you source of course, that's why you can adjust this level on serious hardware such as Benchmark DAC1 using calibration trimmers).
Is it correct ?
Thank you for all
Cédric
ilkka-rissanen, modified 12 Years ago.
Re: 8040A and accurate input level
Yoda Posts: 2564 Join Date: 3/23/09 Recent PostsOk I think I understand.
If I chose a sensitivity of -6dBu, the 8040A will need -1dBu to get the maximum SPL level.
Mathematically, using a source that can output +8dBu (Sonos), a sensitivity of +3dBu gives the maximum SPL level:
Input sensitivity is +3 dBu = 100 dB SPL@1m
Max rms output SPL stated on the datasheet 105 dB SPL@1m
Additional rms input level required for maximum rms output +5 dB
Max rms input level required for maximum rms output +3 dBu + 5 dB = +8 dBu = Sonos maximum output level
That is correct.
So, using a sensitivity of -6dBu will always give the maximum SPL, because you only need -1dBu!
Not always, only when the output level of the source device is -1 dBu or above. Meaning near the maximum volume settings of the Sonos (9 dBu below maximum volume/output level). Usually the whole range of volume control is something around 70 - 90 dB.
So this sensitivity is useful when you want to temper the maxium acoustic level (depending of you source of course, that's why you can adjust this level on serious hardware such as Benchmark DAC1 using calibration trimmers).
Is it correct ?
No.


eduardoc, modified 12 Years ago.
Re: 8040A and accurate input level
Youngling Posts: 22 Join Date: 11/3/09 Recent PostsIt is very interesting!
Cédric
daguei, modified 12 Years ago.
Re: 8040A and accurate input level
Youngling Posts: 1 Join Date: 6/24/11 Recent PostsI'm not sure if I'm just being stupid which is quite likely, but still would be happy if you could spare another couple of minutes and clear this up for me!
Cheers
ilkka-rissanen, modified 12 Years ago.
Re: 8040A and accurate input level
Yoda Posts: 2564 Join Date: 3/23/09 Recent PostsYes, +4 dBu output and -6 dBu input sensitivity is the loudest setting. I would recommend turning down the input sensitivity, even down to +6 dB if needed.