Pioneer RG-9 Dynamic Expander (1981) - Demonstration

This is a Pioneer RG-9 single-band expander from 1981. It basically makes quieter music passages more quiet, and loud music passages louder, thus, expanding the dynamic range of the music.
The maximum expansion is 16dB, the minimum expansion is 4dB. The expansion starts when pressing the "processor" button.
This unit had the common fault of a non-latching processor button (broken plastic clip on the inside of the button). This button is a Pioneer specific model, but can be replaced with a commonly available button if the metal frame holding it is removed. This unit is also recapped with high quality long life capacitors from Nichicon. When used with moderation, it adds a nice effect to the sound.

[@martyjewell5683]

I picked up an RG-2 in 1981for $125. Have used it ever since. I find it indispensable for listening to the tape format. It does, in fact, provide noticeable noise reduction on both open reel and cassettes. Though that's not it's intended purpose. I keep expansion to a minimum, using 7 for classical music and 10 for rock/jazz. Setting expansion too high has a "breathing" or pumping effect and sounds unnatural. Some folks do like that sound, not me. Not as effective as the DBX two and three band units but considerably cheaper. It helps with FM broadcasts too. Just remember that these expanders have no amp, they use your main amp for power. So use the input dial judiciously. A worthwhile addition to any two channel hifi system. Thanks to Robert Grodinsky.

[@outermarker5801]

Had one back in the day, stuck processor switch and all 😁If I remember correctly the purpose was to restore the dynamic range lost in the making of vynil records. Certainly did liven things up.
Kept using it even when CDs came into fashion, though CDs supposedly didn't need it.

[@ralphlauwaert2245]

Indeed, those processor switches broke quite often. I had the replace the one in my unit as well. Yeah, it works quite well when used with moderation.

[@calebwayte7122]

The manual of this device made reference to a noise reduction function, in which position the knob must be used in decibels?

[@ralphlauwaert2245]

The 'noise reduction', if any, is attributed to the slope filter in the circuit. The amount of noise reduction will be very limited. You can set the knob for dynamic expansion to whichever value that sounds best for you.

[@calebwayte7122]

@@ralphlauwaert2245 thanks for you answer 🙏

[@lucianobartolomeo331]

David byrne