On 11/6/2019 2:34 PM, 6295LARGE . wrote:
> Hello everyone.
> I don't understand why I can get *great sound* from one Edison Diamond Disc
> and practically *NO SOUND* from another, and they're both in good condition.
> I've got the cartridge wired correctly with a 3.5FCR stylus and the cables
> from the Shure M44-cartridge is "monofied" before going into the stereo
> preamp.

How, exactly, have you "monofied" the cartridge connections? The usual 
technique of strapping a stereo cartridge for plsying mono records is to 
connect the coils of the two channels in parallel. Specifically:

L hot connected to R hot and thence to preamp input hot
L ground connected to R ground. and thence to preamp input ground.

This combines the two channels of a lateral-groove disc (which mnost 78s 
are) properly. A lot of folks do this by using a Y-connector;

Two RCA female jacks > 1 RCA male plug, which goes into the preamp input.


If you play a disc with vertically-cut grooves (like most Diamond 
Discs), the signal from the L channel will come out in reverse polarity 
to the signal from the R channel -- when the voltage from the L channel 
goes positive, the voltage from the R channel goes negative by an 
approximately equal amount -- and when you combine these two signals by 
strapping the cartridge for mono as described above, the positive 
excursions of the L channel are cancelled by the negative excursions of 
the R channel, and you're left with little or no signal. That's the 
*normal* condition when playing Diamond Discs with a strapped-for-mono 
cartridge; the thing that's hard to understand is why you had some discs 
that played properly (plenty of signal), As others have mentioned, a 
very few Diamond Discs were produced with lateral-cut groove -- maybe 
you lucked into some of those.

Please verify that the above description corresponds to the way you 
"monofied" the wiring, and we'll go from there.

Paul Stamler

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