Technics CD-4 Demodulator SH-3480

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sjcorne

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Nice find! The phono input selector dial is an interesting feature--I guess the idea was to have multiple turntables connected and A/B the performance of different cartridges? Also surprised to see it's missing a carrier level adjustment control.

I don't think I've ever seen a demodulator with a volume control.
The uber-rare JVC CD4-50 also had one.
 

Doug G.

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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".

Doug
 

par4ken

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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".

Doug
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).

It also has a cartridge bias switch so that it can be used with a strain gauge cartridge.

Yes the high end decoders usually have volume controls so it's nice to see a demodulator with them as well.
 

surround.sound.enthusiast

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I've had either a Technics SH-3480 or SH-3580 on my long list of demodulators for a while. They appear on Jauce of Buyee somewhat frequently. Looking through my saved photos it appears that the 3480 may have automatic carrier signal lock, while the 3580 seems to have a manual carrier signal adjustment via a potentiometer on the bottom. Those are the only differences I've gleaned so far. I think the "Lock / Unlock" button has to do with allowing cartridge bias for PHONO 2. Here's a photo of the back of a 3580. Yeah, these things were apparently made to handle semiconductor, moving magnet, and ceramic cartridges.

H.jpg
 

fredblue

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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?
 

surround.sound.enthusiast

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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?
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?
 

Doug G.

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Yes, without a CD-4 cartridge, a CD-4 demodulator can easily be used as a two channel preamp or "phono stage", as audiophiles call them, using the separation controls as output level adjustments.

Also, some regular two channel preamps have/had high and low for MM inputs because there is a wide range of outputs for regular MM cartridges. It isn't necessarily for MC cartridges.

Doug
 

furui_suterioo

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What does the "cartridge bias" switch actually do?

Found it:
"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.
 
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surround.sound.enthusiast

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What does the "cartridge bias" switch actually do?

Found it:
"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.
Did you find the user's manual for either the SH-3480 or 3580? I'd be interested to see it if so.
 

surround.sound.enthusiast

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Wow. I knew they were big, but still didn't picture them being that large! That's just as surprising as the Victor CD-1, CD-10, and CD4-50, they're all that big too.
That looks very clean inside, no corrosion from poor storage. I'd guess it even still had that "new electronics" smell inside when you opened it.
 
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