Questions about reference levels

cobhc2008

Established Member
Joined
Feb 10, 2008
Messages
321
Reaction score
83
Points
96
Age
38
Hi guys,

I've been reading up on reference levels and I've come up with some questions:-

Reference levels mean calibrate to 85db for 115db peak if I'm correct.

However, even the MK speakers that Phil reviewed which are THX Select2 have a sensitivity of 92db. Does that mean that they would struggle to hit 115db? Or am I misunderstanding the measurement of nominal sensitivity?
 
Sensitivity is the value you get from the speakers when they are given 1 watt of power and at 1m from speaker. It is not a measure of the maximum the speaker can produce.
 
I think Reference Levels are 85db with 20db headroom, which would take the peak to 105db, however, the peak on the Subwoofer is up to 115db. This is all with the AV Receiver volume control set to 0db.

Though this is measured with Calibrated Test Tones, there is no guarantee that the average level of a common movie will be this loud.

As someone pointed out, the speaker Sensitivity, is rated at a distance of 1 meter with 1 watt of input for 8 ohm speakers. That is a spec that allows you to compare all speakers fairly. But remember this is with only ONE WATT.

If the speakers are rate at 92db/1w/1m the this is how the output ramps up.

1w = 92db
2w = 95db
4w = 98db
8w = 101db
16w = 104db
32w = 107db (exceeds Reference Level)
64w = 110db

Because of the limits of the ability of the speaker to travel, know as Excursion Limit, there may be a rated peak sound output. But it is typically well above 100db.

If you look at the spec on the Monitor Audio Bronze 2, as an example, its Sensitivity rating is 90db, but its Maximum SPL is 113db/pair.

Bronze 2

Sensitivity (1W@1M): 90dB

Maximum SPL (dBA @1M – each): 113dBA (pair)

Again a reminder that the Reference Peaks on the Front/Surround speakers is 105db, it is the Subwoofer that goes to 115db Peak.

Any thing 90db and above would be consider very efficient with a high output per watt of input, any thing 90db and below would be considered a bit lower output, but still a perfectly good sounding workable speaker. When speaker drop below about 85db, they start to move into the low efficiency side. Though there are many low Sensitivity speakers that sound stunning, you just need a little more amp to drive them.

Steve/bluewizard
 
Last edited:
Hi guys,

I've been reading up on reference levels and I've come up with some questions:-

Reference levels mean calibrate to 85db for 115db peak if I'm correct.

However, even the MK speakers that Phil reviewed which are THX Select2 have a sensitivity of 92db. Does that mean that they would struggle to hit 115db? Or am I misunderstanding the measurement of nominal sensitivity?

You also need to take into account listening distance from the speaker as reference level isn't at 1 metre (unless you really do sit that close). Therefore the example of the MK speakers (I'm presuming the MPS300 review, which are the speakers I have for LCR) should be capable of hitting reference even with a listening distance of 5 metres.

I used this website to calculate whether each speaker I have can achieve this:

Peak SPL Calculator

In my case I am 15' from the LCR and my amp is 230 watts per channel into 4ohms (all channels driven), so with the speakers close to the wall it calculates to 105.4dB. The MPS300 can handle more power than this, so with the full 500 watts they would hit 108.8dB at 15'. However, I prefer not to listen this loud myself, so -10dB or so is more typical for me, but it's good to know that my speakers can easily reach this level at my listening distance.

Subwoofer reference level peak is 115dB, but this doesn't account for bass management, so in reality for clean playback at reference level the subwoofer(s) may need to be capable of over 120dB due to the redirected bass from other channels. However, I have just targeted 115dB in my system as this is more than enough for my listening levels.
 

The latest video from AVForums

Is Home Theater DEAD in 2024?
Subscribe to our YouTube channel
Back
Top Bottom