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Re: Finding Shure 183

Subject: Re: Finding Shure 183
From: Walter Knapp <>
Date: Mon, 14 Feb 2005 20:18:54 -0500
From: Dan Dugan <>


>>>Could you comment on the impedance, I'm sure you understand it better
>>>than I. The MX183 has a impedance of 150 ohms,
>
>
> Transformer output

Presumably to match pro equipment better and handle longer cable runs?

>>>the WL183 is spec'd at
>>>1000 ohms.
>
>
> Direct FET output.

Intended for short runs to higher impedance mic pre's?

>>>I'm pretty sure my Portadisc is going to find the MX183 a
>>>better match, as it's designed for low impedance mics like the MKH.
>
>
> I think the operative factor is the input impedance of the recorder's
> mic input. If it's high enough to "bridge" the mic's source
> impedance, it won't lose level by loading it down. "Bridging" means a
> load 5 to ten times the source impedance.  For a 1K source, that
> would be 5 to 10K.
>
> Unfortunately, manufacturers usually don't tell you what the actual
> load impedance of a mic input is; they'll rate it with the mic
> impedance that it's designed to bridge, like a standard 150 ohms. 3K
> is a typical mic preamp input impedance. Higher is better, but it's
> hard to keep the noise down was the impedance rises, so it's a
> trade-off.

So, one could say at typical preamp input impedance the WL183 is
probably not meeting the 5 to 10 times rule for the source? But the
MX183 would meet that rule?

I believe the MD walkman have a higher impedance than 3K, probably why
they can work well with the WL183.

Walt




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