I picked up a used one in nice condition for $0.99 trough an eBay auction, so basically I just paid for the shipping.
It is a very basic unit but it has a vari-blend circuit across the front and rear pairs. That makes it similar to the Sony SQD-1000. I set it up so that I could monitor it via the small Minimus speakers that surround my computer and work bench.
I wasn't expecting a whole lot but tried it out on "Super Session" which actually sounded great. More a tribute to the mix than the decoder I'm sure. I then switched to "Beck, Bogert & Appice". The vocals stayed upfront while the overall surround effect was still very good. Listening to the back speakers only you could hear the action of the blend circuit. There was a fair bit of vocal breakthrough and you could notice the narrowing and widening of the soundfield. The rear vocal breakthrough varied in level slightly. Those anormalities were not so noticeable with all four speakers in operation.
I opened up the unit and was surprised to see that both the power supply and the decoder board were fully enclosed in their own metal shielded compartments! A bit of overkill for line level circuits but it does say something about the overall quality of this basic unit. Looking at the schematic the output coupling capacitors are only 0.33 µF, rather a low value unless you are running a high impedance tube amplifier. I didn't notice excessive bass roll off with the small Minimus speakers however.
What am I going to use it for? I'll add it to the shelf with all the others, collecting this stuff is an addiction!
