Changing the Turntable on a Zenith Cobramatic and making a hybrid

jrcbriones

New Member
Hi AudioKarma!

I acquired a mint mid-century modern zenith with tube amps. It sound beautiful & everything works perfectly. However, I know the tone arm on these turntables are heavy and can damage records so I want to change the turntable. Here is a few scenarios I have in mind and hopefully you all can point me in the right direction.

Scenario 1: I remove the current turntable and switch it with the BIC 914 I have in my closet. I'd cut the BIC wires that go to the RCA outs and solder them connector plate to where the removed zenith record player connected to the amp. Plug in the BIC to the wall and hope for the best. Is this a good idea? Will it work that easily or are there power considerations I need to keep in mind? Will I start a fire or fry my whole system? If it's any help, the power to the turntable comes from a different cable, and it's not connected to the audio cables form the tone arm.

Scenario 2: I switch out the record players like scenario 1, but instead of trying to connect it to the internal phono amp, I just buy a pre-amp (like http://amzn.to/2n0LxnR) and just plug into the aux/tape RCA connectors in the back and call it a day.

What do you guys think? I would like scenario 1 better and have everything integrated without having to buy another piece of audio equipment but open to suggestions.

Thanks so much in advance!
 
Most consoles were a ceramic pickup, so you'd need a phono preamp to use a turntable with a magnetic cartridge. Ceramics are basically line level input, so you can simply put it between the existing phono input and the new changer. I've done it myself, works fine.
 
Many of the Zenith Cobra-Matic changers used an unusual cartridge. It was equivalent to a ribbon microphone with 2 plates. The stylus is attached to one of the plates and changes the capacitance as it moves. This requires an oscillator in the amplifier to demodulate the signal from the cartridge. If you are going to replace, you may need to modify the amplifier.
 
The ones in the 40s did that, definitely. Later ones were just a Voice of Music changer with a common crystal cart. Pretty sure all of the stereo era ones were that way. Those stereo era VM changers are actually not that bad in terms of record abuse. I've got one from about 1964 sitting out in my shed, branded as Cobramatic MicroTouch. I think they claim 2 grams of tracking force, and its pretty close to that.
 
That makes sense. I didn't know that they continued to use the Cobra name on later equipment. It would also be very difficult to design a ribbon cartridge for stereo. The mono design is very inexpensive, but has NO vertical compliance.
 
I think Weathers had a similar sort of thing on their early tables. It was also abandoned when things went to stereo. The VM changer I have uses a fairly typical ceramic stereo cartridge, the only thing odd about it is that its got a spring mount to allow the cartridge itself to move independent of the arm. I guess that was to help make up for the friction on the arm pivots.
 
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