wide stereo (was reverse engineering and help with a plug...)

[Goddard, Duncan]

>>interesting.. elaborate device.. appears that 4 filters per each channel 
> with different freq response feed in antiphase to the opposite channel,
> and 
> then a delay around each channel back to itself..
> I remember a very simple circuit in a philips app note for stereo widening
> - 
> it used the antiphase technique as well - feed l into r 180' OOP / vice 
> versa.. had a control at one end it fed 100 % across to other channel IN 
> phase [mono], other extreme was 24% antiphase [apparently 24% is the best 
> maximum stereo image, the effect just breaks up after that.. ] could be 
> pretty simple to do the phasing thing [6 opamps as a sketch here - just
> one 
> band tho, no multiband, but width control] now we just need a couple of 
> BBD's for the delay section .. Harry?<<
> 
I've seen one or two variations on this; a lot of small "ghetto blasters"
had a "stereo-wide" switch that worked by cross-patching the negative
feedback paths. I have uli behringer's version, which he called "edison" for
some reason; it's almost as crude but has some additional control over the
apparent front-back position of the centre signal and a separate width tweak
for the low frequencies. the best use I found for it (most of our stuff's
pretty wide anyway) was to put football shows through it and completely lose
the commentator's voice. fab with the eno-style rear speaker behind the
couch- more people should try that before making their stereo signal wider;
just add a carefully chosen extra speaker wired to the two "reds" of the
normal speaker connections. it won't hurt a decent amp at all.
so, remind me, what's "shuffling", in this context? besides trying to
wriggle into an increasingly small sweet-spot..... :-)

d.


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