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> It is not nonsense. If you look back on the conversation, I am talking ab=
out =0D
optimum noise impedance matching=0D
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David,=0D
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my worries on your "impedance matching" comment originate from message 531=
05: =0D
Don wrote: >> I have had a Sony PCM M10 for several years and I recently p=
urchased a Rode NTG2 shotgun mic. It works and both channels show equal rec=
ording levels, but I am disappointed to find that the actual decibal levels=
shown are quite a bit lower than when I just use the on-board microphones.=
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you replied:=0D
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>Don, =0D
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>This has been answered, but another reason for lower level nay be impedan=
ce =0D
>matching. You can get over this by using a matching pre-amp,...=0D
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This comment was obviously a bit misleading. Note that the output impedanc=
e of the (battery operated) Rode NTG2 is 350 ohm and the input impedance of=
the Sony PCM M10 is 22 kohm, which means that there is definitely no imped=
ance (mis) matching problem here.=0D
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I agree that a preamp circuit should be designed in such a way the inheren=
t noise floor is as small as possible for the intended source impedance (ye=
s, one can indeed optimze a preamp either for low or high source impedances=
). This optimization does however not necessarily have anything to do with =
the input impedance of the preamplifier. A preamp optimized for a common mi=
crophone output impedance of 150 ohm could theoretically even have an input=
impedance beyond 100 kohm...=0D
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Regards,=0D
Raimund=0D
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