Symmetric Sound Systems PS-1 Audio Pulse Swallower.

I use the PS-1 to filter out clicks and pops when capturing old records to my desktop computer. I interface my turntable to the PS-1 with my homebuilt riaa preamp.

PS-1 audio pulse swallower rear view.

This kit was featured in the May 1986 issue of Radio Electronics magazine. It was designed and sold by Symmetric Sound Systems located in Santa Rosa, California.

Capturing audio using my turntable, RIAA preamp,PS-1 audio pulse swallower and computer.

Here I am using my PS-1 with my RIAA preamp and linear tracking arm direct drive turntable. I am capturing audio into a desktop computer using the Audacity open source software program.

Basic operation of the PS-1

The unit delays the incoming signal about 40 microseconds. The detector circuit detects the scratch and activates a switch to prevent the scratch noise from reaching the output of the unit. The switch stays open the duration of the scratch noise usually from 100 to 200 microseconds but sometimes as long as 1 millisecond or more. The audio that is deleted is not perceptible to the human ear because of the short duration of time it is removed.
Even high quality magnetic tape has numerous dropouts of greater duration than most scratch deletions.

Inside view of the PS-1 Audio Pulse Swallower unit.

Here is the inside view of the PS-1 kit I built back in 1986. I use it to remove the run of the mill pops and clicks and the Audacity software program on my desktop computer to manually remove more extreme pops and do fade in fade out, etc.