Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems THX calibrated speaker levels Vs optimum DAC signal level?

Whew!

Corker of a title don't you think? This one has been bothering me for a while. Firstly, thinking back to the 518 and the Gain facility, the rationale from Bob Stuart in the manual is to ensure that the DAC received full code value for best sound quality. This was readily obvious with any old Redbook CD recorded at an insuffiecient level. Increase the gain in the digital domain, the DAC gets utilised better, and hugely increased sound quality.

Why then, do we calibrate speakers to THX recommended levels, ie 75dB at volume 87, when this can frequently mean lowering the volume of the DSP speakers all round to achieve it? If each of one's speakers ends up permanently calibrated at -4.5 to -7.0dB (respectively), surely the DACs get less than optimum signal? This would appear to contradict Bob Stuart's earlier rationale? I do appreciate the need to calibrate the speakers, but why not just have as many of them at 0dB cut, and a reduced level of cut for those which needed reigned back further?

To illustrate the point, THX level calibration (with 6ks, a 5kc and a REL sub) gives me:

L -4.5dB
C -7.0dB
R -4.5dB
Sub -6dB

...but why not just calibrate at:

L 0dB
C -2.5dB
R 0dB
Sub -1.5dB

...and get better signal through to the DACs? I have tried both ways, and to my mind, the latter is better...the sound is more alive, despite subsequent final volume matching. Can anyone explain to me what I am missing here?

Thanks!

George

[This message has been edited by Mr Meridian (edited 08-03-2004).]

[This message has been edited by Mr Meridian (edited 08-03-2004).]

[This message has been edited by Mr Meridian (edited 08-03-2004).]

George

For the sub, it is actually recommended (somehwere but can't remember where) that the gain on the physical sub is altered such that it calibrates at 0db. This is to allow the full dynamic range to be utilised within the processor.

As for the other speakers...good question.

-Ian

George,

Good lateral thinking - something I've considered/used for quite a while, as it didn't strike me as 'right' reducing all the speakers levels to a greater or lesser extent.

I calibrate my DSPs in the 2nd way you described i.e. using the highest level DSP(s) as the 'datum' (in my 5.0 config. with L/R as the 0 datum, the Centre is @ -0.5dB and the 2 rears are @ -2.5 dB, so not too far off anyway). Personally, I'm not overly hung up on having the system's ABSOLUTE level matching the THX standard - for me getting the RELATIVE levels right is the most important.

On the same subject, I wonder how many of us actually listen to THX standard movies at +0 (87) all the time/at all anyway? FWIW, I use this level as a starting point, not a 'must have/can't change'. Judging by some past threads on music listening levels, one mans/womans 'loud' is another's 'quiet', as it always will be.

Just my 2-p's worth

Andy