dlaloum wrote:Is the 4000D series the same body as the 4000XL series? (impedance/inductance)
ie: was the only difference the needles, or the generator as well?
I wish I could answer your question definitively but I'm afraid I can't.
I have never measured a 4000XL and, although one would think that Empire would have used the same generator within the same series, you just never know with cartridge makers from back in those days.
The database indicates they are 47K but I still say you can't know for sure unless you can find original source literature with specs. or measure it.
In any case, it's not really that important. The 100K spec. was originally included in the CD-4 specs. to ensure the ultra sonic frequencies would not be attenuated before they got to the demodulator. A lower source impedence (500 ohms DCR) working into a higher load impedence (100K) would preserve these frequencies better than a higher source impedence (1000 ohms DCR) working into a lower load impedence (47K).
It has been found, however, that this spec. is probably the least important of the CD-4 specs. and many have used stereo cartridges fitted with Shibata styli successfully with CD-4, myself included.
The reverse is also true. Quad cartridge meant for CD-4 reproduction will work fine with a 47K load.