View Full Version : Stereo Image expander

12-16-2009, 01:01 AM
I think the Parallax Propeller is an ideal candidate for the following application with minimal hardware.
The Propeller object will have two audio inputs, two audio outputs, (stereo L & R) and three audio paths. The third path being the difference between the two audio inputs. (L - R) The Propeller object will pass through the two inputs directly to the outputs as two separate paths. The object will subtract the L & R channels to create a L-R third audio signal. The object will delay that signal by 140 uSec. The object will then split the delayed signal into two. Delayed L-R and delayed R-L. The delayed L-R will be summed with the L audio output and the R-L will be summed with the R audio output. The delay will be variable by +/- 70 uSec and the delayed L-R amplitude will be variable by +/- 6dB power and or +/- 3dB voltage. This creates an effect that can only be described as follows. Place your stereo speakers 6 to 8 feet apart, stand 10 to 12 feet away, play the following; Pink Floyed Time. Close your eyes. Each clock will have a position on the sound stage, you can point to them and count them. The stage will be 10 to 14 feet wide depending on the quality of the original material. I have done this with BBD but I have not been unsuccessful with a discreet sigma delta and or delta modulator and memory.
What are your thoughts? Can this accomplished with the Parallax propeller? It looks like it can and there are plenty of objects available to work from.


12-16-2009, 01:31 AM
Somewhat different, but I once used a Hilbert filter on a DSP to simulate what one hears on a binaural radio receiver that some radio amateurs were using some years ago. It seemed to add the same spatial quality to the signal.


Amateur radio callsign: G1HSM