We had this thread a while back. I've used several, and tested just about
all the units on the market. My subjective opinion after using them is
that the JPS NIR-12 is the top of the heap. The Timewave DSP-599ZX is also
quite good albeit a little more difficult to operate and with many
bells/whistles that most operators won't use (but should be considered). I
agree with Clark that the NIR mode, which is the basic mode in the NIR-10
adds artifacts onto the audio which many might find objectionable - it
requires some careful setting of the NIR level. It also introduces a time
delay which makes it unusable if you do QSK CW. (Same with NIR on the
NIR-12.) However, the NIR-12 adds the dynamic peaking mode which
significantly eliminates random noise.
I think the most useful mode of a DSP unit is the reduction of background
band noise. Most of them do this fairly well. For weak signal work, the
NIR-12 is tops here using only it's Dynamic Peaking mode. Close behind is
the 599ZX. Also worth considering is the W9GR unit which can be purchased
as a kit for significantly less $$. It is very natural sounding on SSB,
and does a respectable job on CW.
The best advice I can give is to BORROW a unit and try it prior to making a
decision. Experience with DSP is varies widely. I bought my first one
(Timewave DSP-9) because my IC-765's hissy IF chain and tinny audio wore me
out after an hour of operating. The DSP was a real blessing, and I was
able to pull stuff out of the noise I just couldn't copy otherwise. But,
not everyone's ears get the benefit out of DSP's and some DSP units don't
do as well as others (the NIR-10 is the one I hear this about often).
Also, some kinds of noise are better eliminated at the receiver input, and
the MFJ noise reducer is superb for this (better than JPS's ANC-4).
Sorry for the rambling, and hope this is helpful somehow.
73, Duane AC5AA
Duane A. Calvin
Server Systems Test Engineer
Dept. 76TS RS/6000 - SP Nodes
IBM Austin, TX >O< Tie: 793-3368
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