The uber-rare JVC CD4-50 also had one.I don't think I've ever seen a demodulator with a volume control.
I would assume that the 4-channel mode is auto. The carrier level might be automatic like the Marantz CD-400B (a good feature IMHO).The volume control is a very good feature. In my system, CD-4 volume is controlled by the amplifier volume controls and matrix volume can be controlled by the volume control on the decoder. Just one control for all channels. CD-4 requires changing four controls on the amps- decidedly unhandy. My amps have meters to match the channels but it's still a pain.
I see that demodulator doesn't have "4 channel auto".
Yeah, the separation pots look like even smaller screw-head types than on the back of the JVC 4DD-5. Maybe the ceramic was only meant for stereo, as this unit can have three turntables connected, and do both stereo and CD-4? Think of it as THE all-in-one phono amp (except for moving coil) that Technics may have made for the Japanese market?ceramic for CD-4..!?
"low" and "high" magnetic means it can handle MC as well as MM?
the separation adjustment pots look to be a fiddly recessed screw-head type?
Did you find the user's manual for either the SH-3480 or 3580? I'd be interested to see it if so.What does the "cartridge bias" switch actually do?
"It is designed to supply a bias current to the semiconductor cartridge connected to Phono1 when the bias selector switch on the back panel is turned on.
If a MAG type cartridge is accidentally connected to Phono1, this bias current will flow, which is not desirable. To prevent such mistakes, when setting Phono1, a mechanism is adopted in which the selector does not turn unless the Lock button is pressed. I will.
The COM terminal which can share Phono1 and 2 is carried.
When a player is connected to this terminal, both semiconductor MAG type cartridges can be used properly simply by exchanging the shell and switching the selector."
So I guess it allows to have two sc carts or two mag carts connected.