Hey everybody!!! Check out this cool chip!!!

[jrc4558]

http://www.chipinfo.ru/docs/TOS/001045.pdf

I hope it's still in production! Anyone knows where to get one?

Thanx!

[Ansil]

hmmm sweets

[Mark Hammer]

Hi Constantin,

Note that while it throws the term "delay" around, that means phase delay (shift) not time delay.

Chips like these are pretty much what gets used in older televisions and portable entertainment units that have a "stereo-wide" or "stereo-enhance" switch or some other function that purports to increase the stereo field, in addition to those entertainment product that try to mimic stereo.

The block diagram pretty much lays it out.  A stereo input signal is processed to derive a sort of 3rd channel consisting of whatever is unique one-channel-only content.  The content is low-pass-filtered twice to restrict it to midband (there will likely be very little under 400hz in it anyways).  It passes through a fixed 4-stage phase-shifter (that uses caps to ground instead of resistors to ground; works the same way but looks different) and the output of that is summed and subtracted with the original stereo signal to produce complementary notches and peaks in each channel, making them sound "more different".

In theory, anyways, this could make a nice little 4-stage phaser, although you'd need to find a way to switch the caps that determine the phase shift, using some sort of electronic switch (4066?) governed by a high-frequency clock, in turn modulated by an LFO.  The chip, as is, does not provide for varying the point where phase shift maxima and minima are.

In principle, you save yourself a bit of space by having all phase shift stages and mixing (including their respective resistors) in one 16-pin dip, instead of what would probably consist of a trio of dual op-amps and surrounding real estate.  On the other hand, a conventional FET-based 4-stager does not require the use of the CMOS switch chip (another 14 pins) or high frequency clock (yet another chip).

My sense is, an interesting experiment if you stumbled onto some cheap, but not really worth extra effort to seek out. (Supremetronic doesn't carry them  :cry: )

[petemoore]

Make two Little Gem's sound 'stereoized" !!!
 This must a chip what's like behind the buttons labaled 'Stereo Wide' or "Ambience" on my portable CD/Cassette players..
 I all probablility it would make a little stereo amp sound "Bigger' or "Wider"..just like it does portable stereos...

[Mark Hammer]

Pete, note that it über-stereo-izes something that needs to start out life as a stereo signal, since the processed 3rd channel consists of only that stuff which is more in one channel than another.  Feeding a mono signal to the two inputs and then feeding the "stereo" outs to a pair of amps will essentially get you two identical channels with complementary noise.

[smoguzbenjamin]

What about using a BBD for a short (30-50ms) delay with only one repeat, feeding the wet only signal to L, dry signal to R and then have stereo that way? :?