Hi John
I've had a look through the MX391 boundary microphone guide but did not fin=
d an answer to your query.
The preamplifier supplied as standard with the MX391and MX391W (W=3DWhite c=
olour) is the Shure RP183PK. This is not supplied with the MX391LP/O - the=
mics I bought on ebay. The guide says that the preamp cam provide 12dB ga=
in or 0dB gain depending on how one positions jumpers inside the preamp bod=
y. However there is no more info as to why and when the pre amp is to be u=
sed.
I therefore did a google search and as far as I can gather the preamp is re=
ally a means of powering the MX391 from a 48V phantom supply. It is not re=
ally a normal pre amp but more of a power supply accessory probably to be u=
sed when long cable runs are necessary. Because I am using a relatively sh=
ort cable length (4 metres) and a healthy PIP supply from the LS-10 the RP1=
83PK is unnecessary and probably would not work for me as the recorder I us=
e it with does not have a phantom supply.
The most useful info I got from the google search was a pointer to our own =
naturerecordists Group. There was a longish series of posts re. the WL183 =
(MX391 is a WL183 with a boundary mounting arrangement) back on 4th August =
Message: 2006.
Subject: Message number 23831 is the one to read if you don't want to read th=
em all.
Hope this answers your questions. The info certainly has made me feel very=
comfortable with my deployment of the MX391.
Cheers, TomR
--- In "copperfin3" <> wrot=
e:
>
> Tom,
>
> I've been under the impression that the MX391 mics required a preamp in o=
rder to function. If the LS-10's input stage and PIP are enough to make the=
se mics work, why does Shure insist that you need a preamp?
>
> John Morris
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