Vicki Powys, you wrote:
>I've just made a test using two types of adapting leads, to take a 3-pin
>professional mic to a 3.5 mm stereo socket. For the test I'm using a Sony
>Walkman WMD6C cassette recorder and a Sennheiser ME67 mic. The first lead
>has a mini-plug one end and a 3-pin socket at the other. It is not wired
>exactly as described by Rich and Dan, but it does work satisfactorily.
>
>The second lead uses a Tandy adapter/transformer, part no. 274-0016, cost
>around $25 in Australia. On the adapter is written: Lo-Z Balanced to H-Z
>Unbalanced. It isn't a pre-amp, just a transformer. Using this set-up, I
>get 5-10 dB more gain, i.e. a stronger signal, than I do with lead 1.
>
>A few years I borrowed a FEL pre-amp (made in UK) which gave 20 dB better
>gain (using lead 1 set-up) but at much greater expense. I reckoned that the
>Tandy adapter was quite good enough to be used for a back-up system, and was
>certainly worth the $25 for the boost in signal.
>
>From my test with the WMD6C, I concluded that it is better to use a
>transformer of some sort, to connect to the pro mic. But maybe the
>situation is different for a consumer minidisk such as MD DR7? Would the
>minidisk have better input capacity than the WMD6C? Making an
>adapter/transformer redundant?
I think the WM-D6C's preamp is quite similar to an MD's. The "free
gain" from a transformer is often useful; it would be especially
valuable if you were using a low-sensitivity mike. With more
sensitive mikes, however, you may not need the extra gain, and the
transformer may limit the frequency response at both the low and high
ends.
>For the record, on my lead no. 1, I had shorted pins 2 & 3 which run to the
>tip and the ring of the miniplug, while pin 1 runs to the sleeve. It seems
>to work fine, but this isn't the same as Rich and Dan suggested, so maybe
>I've done the wiring wrong? Would that affect the strength of signal, or
>just be potentially more noisy?
I would connect the tip and ring together at the mini-plug end, so
the mike will feed both channels, but if you connect XLR pins 2 and 3
at the mike end together, your signal will be very low or missing
altogether. In a balanced circuit, the signal is the difference
between pins 2 and 3!
At the mike end connect 1 and 3 together to the cable shield, and the
inner conductor, which feeds both tip and ring, should feed from pin
2.
If it's a 3-conductor cable wired tip, ring, and shield at the
mini-plug end, connect the shield to XLR pins 1 and 3 together, and
both inner conductors (tip and ring) to pin 2.
-Dan
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