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On 21/12/2011, Goran Finnberg wrote:

> Don Cox:
> 
>> In principle, mixing the channels should reduce
>> the noise by about one decibel (the noise in stereo
>> will be 1.414 times the noise in mono), but the
>> disadvantage of losing spatial separation makes
>> this hardly worth while.
> 
> 1.414 is in fact 3 dB less noise in mono.
> 
I had doubts about my mental arithmetic as I typed that - but isn't a
3dB reduction a halving of signal strength?


> I fail to see how there can be "Spatial separation" if a mono signal
> is being reproduced in "Stereo".
> 
The music is (in theory) identical on both groove walls, but the noise
is different. i.e. the noise is stereo.

> Due to the HAAS effect it becomes almost impossible to get a stable
> centre signal unless you set your head in a vice in the exact centre
> between the speakers.
> 
> Moving slightly off centre collapses the sound in either the left or
> the right speaker due to the precedence effect, HAAS.
> 
> There IS a reason why Bell Labs thought that one should use minimum
> three channels, left, center, right, when reproducing sound. This
> assures that centre sounds will always appear to come from the center
> even if sitting off center.
> 
> This is still the practice in film reproduction where the dialogue
> normally always come from the centre speaker.
> 
> In fact a mono signal should only be listened through one speaker the
> way it was recorded to correctly reproduce it as originally intended.
> 
>> Since I first bought a stereo record player, I have
>> always listened to mono records in stereo. There never
>> seemed to be any improvement in the sound when the
>> channels are mixed.
> 
> I can clearly hear that the amount of distortion, pinch effect, is
> much less in mono compared to "Stereo" also the amount of disk rumble
> gets significantly less as the vertical component disappears, where
> most of the rumble is, entirely when listening in mono.
> 
> I think that "Improvement" is an entirely subjective comment as the
> theory and my own listening impression entirely prefers mono for mono
> recordings and any "Stereo" or two speaker sound reproduction from
> mono disk records sounds wrong to me.
> 
> YMMV.
> 
It does.
> 
Regards
-- 
Don Cox
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