[TenTec] DSP Units?

[dacalvin@us.ibm.com]

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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