With a volume setting of say 50db pink noise, what peak volume is expected ?

[IWC Doppel]

I am back to analogue out from the disc player and an old Naim based set up, interesting after trimming bin the 5.3 set up (I will be 7.3 when I have time to solder a lead) I set them up at 65 volume and they are measuring within 2db of that, I set the subs at 67 together and the centre at 66.5, by preference. playing a film at 49 volume it only took 10 minutes to see a peak on the mic at the MLP of 104.6 db, It's sounding very dynamic but that is more than I expected at that volume and I am sure there are louder peaks on the film, what does a volume of 49 actually mean for the peak volume in a film ?

 

[Todd Anderson]

THX reference volume standard is 20dB above your reference level setting. So, I'd hazard to guess you're likely landing in the 70dB range?

 

[IWC Doppel]

Hi, apologies for the somewhat confusing question. I have seen that THX suggests 85 db as the reference level and this attains 105db peaks, I am seeing 105db peaks at 49 db pink noise level, is THX reference level out of date or completely meaningless ?

 

[Todd Anderson]

Nope, I think everything is working correctly. Sorry for my confusing reply! Let me explain.

Pink noise on your processor (THX Certified or not) is designed to calibrate your system to a reference level of 85dB (the pink noise actually measures at 75dB because your system presents it 10 dB lower than 85dB to keep your ears from shredding during manual calibration).

A reference level of 85dB allows for peaks of +20dB, which is why you’re hitting 105dB.

I think the confusion on your end is the result of you using the Absolute volume scale (0-99) versus a Relative volume scale (presents volume as a negative number, typically up to a positive number of around +8dB).

You should switch your processor to the relative volume scale in settings. When you channel level your speakers to 75dB using Relative Volume, you’ll want your volume setting to read “O.” That’s reference, or 85dB. You’ll rarely listen at that level, but you’ll have a clear, standardized reference point.

Absolute volume indicators are all over the map in terms of what they actually mean. I’m guessing that 49 on your system roughly equates to 0 on the Relative scale.

With that in mind, go into settings, make the switch, and I believe you’ll see everything is working as intended.

 

[Roger Dressler]

I set them up at 65 volume and they are measuring within 2db of that... playing a film at 49 volume it only took 10 minutes to see a peak on the mic at the MLP of 104.6 db, It's sounding very dynamic but that is more than I expected at that volume and I am sure there are louder peaks on the film, what does a volume of 49 actually mean for the peak volume in a film ?

As Todd rightly noted, "Absolute volume indicators are all over the map in terms of what they actually mean." Some of the uncertainty relates to the nature of the noise signal. While many products use the nominal level for THX calibration, there are plenty of others that do not. In your case the disc player is not connected digitally, so we have no way to know how the movie's soundtrack level fits into the equation. Is it a 2-ch analog output, or 5.1? That will add additional uncertainty because if it's 2-ch, there's some downmixing happening if the movie is 5.1.

If you can play movies through an HDMI connection, the best way to find out how your volume control relates to reference level is to use a known source. That can be either a proper test disc or you can use REW's signal generator to output a bandlimited pink noise at -30 dBFS (this will produce 75 dB SPL in a reference calibrated system).

Lastly, the reference level in a cinema does aim to support up to 105 dB peaks, but that's only in one channel. With additional channels running the max loudness can be 6-9 dB higher.

 

[IWC Doppel]

Roger thanks, this makes sense. The munsil disc is I believe 'calibrated' and I am using 7.3.0 (the 3 being time aligned and EQ's subs a s a group) Whilst some of my kit is 30 years old, I am sure most of the speakers will be capable of 105db peaks and as I use very meaty mono blocks for each channel nd the fronts are bi-amped, headroom is not a problem (even though they are 'only' 135W, they will drive 2 Ohms with ease), for the home and comfortable listing I am quite happy at a base volume of 49 (most channels measure 49db), I might try something like Blade runner and see what a scene in there delivers at '49' out of curiosity

Be good is there was a test disc that played two or three test tone and small scene clips and allowed you to see what dynamic range you actually achieved at home at the MLP it would be interesting (

 

[Sittler27]

I'd be about 50db