[TenTec] OMNI VI/OMNI VII

[Richards]

> On 9/26/2011 18:10, John Rippey wrote:
>> I'm thinking that a principal advantage of an OMNI VII over the VI Plus may
>> be an improved NR feature. Anyone care to opine on
>> the effectiveness of the OMNI VII's NR? Or any other advantages it may have?
>> (Don't need a band scope.) Overall, the OMNI VI Plus holds up well, and
>> I'm curious whether there may be some find persuasive reasons to trade for a
>> VII.
>
>> John, W3ULS
>> _______________________________________________



Good question, John.   And very difficult question to answer because it 
turns on a subjective, personal judgment whether the NR feature is 
sufficiently good or effective to justify upgrading rigs.


Sidebar: Cynical Observation -- 	

		One decides to buy a new car (or radio)...
		and then determines the reasons why.


1)   My first inclination is to say, if the Omni VII specifications and 
feature list do not persuade you their own, you should sit tight and 
enjoy your VI+.

2)   NR is a funny thing.  It means different things to different 
operators, and everyone, it seems, has different expectations as to what 
it can (or should) do.

This highly subjective nature of the beast makes it both a good question 
to ask, and a difficult question to answer.

Whether or not you should upgrade for the NR feature depends entirely on 
whether it meets your expectations for good NR filtering.  Some guys 
like it, others do not.   It will depend entirely on what you think is 
good NR filtering.

Here is MY take on DSP filters:

DSP NR is a useful tool to have in the receiver tool box.  But it will 
NOT be a huge factor in daily operation, and is NOT a panacea or total 
cure for annoying, distracting QRM/QRN when operating.   It MIGHT, 
OCCASIONALLY, mean the difference in whether or not you can make a 
contact under difficult conditions.   Or... if you use it on its lowest, 
weakest settings, you may like the way it HELPS to diminish annoying 
background noise, but it will provide somewhat subtle assistance, overall.

Whether or not that is enough to induce you to purchase a new rig is a 
purely decision.  If this is an important factor, you might wanna keep 
your VI+ and try an outboard DSP filter as a more manageable investment.

I am a big fan of DSP filtering.   I have used several DSP NR gadgets, 
including the Radio Shack DSP-40, WestMountainRadio CLRdsp,  the current 
Timewave DSP-599zx and earlier DSP-59+,  the built-in DSP filters in the 
Omni VII, and the DSP filters in the Kenwood TS-590s, and a filtered 
speaker by GAP/BHI.

Each of these did provide some real improvement, with some offsetting 
disadvantages.

	A) The Radio Shack model works well, and can be found on eBay for 
around $35, but it does not provide a lot of filtering, so it is just 
OK, although the resulting sound quality was acceptable and closest to 
going without - but that is, I think, because it is not doing as much 
filtering as other selections.

	B)  The GAP/BHI speaker was equally just so-so, in my opinion.  The 
small size of the speaker may be responsible for my disappointment in it.

	C)  The WestMountainRadio CLRdsp works OK, but you have limited control 
over what sort of filtering you can do, and if you push it too much, you 
hear objectionable digital circuit artifacts, including an annoying 
ringing sound on the crisp consonant phonemes, excessive sibilance, and 
a sort of reverberation like the other operator has moved his operation 
into the bathroom shower  (this may overstate the strength of the 
effect, but that is my best description of it...)

	D)  The Timewave DSP-599zx is my favorite DSP filter.   It does a 
serious job of filtering random noise, has an AGC to help fight fading 
from variable noise strength, and fading signal noise - even when 
sustaining selective fading,  and it has the widest range of control - 
you can vary how aggressive the noise filtering is,  plus it has a dual 
audio frequency filter that works like a high pass and a low pass 
filter,   I set it to clip (cut) sound below 250 Hz and above 3800 Hz. 
  That makes passes only the part of the speech audio frequency spectrum 
that carries the most intelligibility information.  You can use it to 
filter CW, RTTY, and data modes as well.

	E)  The Kenwood rig has effective DSP and it has a Filter A and a 
Filter B setting, each of which are easily selected, and easily 
modified, with high cut and low cut filters like the Timewave filters 
have.   You can not set how aggressive the filter is, you are stuck with 
either the A or B setting, and I think the B setting is so aggressive, 
that while it does filter a fair amount of noise, it introduces some of 
the deleterious digital artifact other DSP filters produce  (ringing and 
reverb effects.)   The A setting is fine.

	F)   The Omni VII  DSP is fairly aggressive in its current iteration. 
Earlier firmware releases had it ramp up slowly and less aggressively 
(I preferred that) but some guys complained and said it was too weak, so 
they changed it in the last couple of firmware releases and now it is 
fairly aggressive.  I find I have to adjust the RF fain upwards a bit 
(maybe 5-7% when using the 2 setting.)   The good news is that it does 
not seem to suffer anywhere near the amount of digital artifact other 
DSP filters have, although higher settings (say from 6-9) do suffer 
substantial audio distortion of a different type, the noise clears up, 
but it seems like the higher audio frequencies are cut back too severely 
- hiss is gone, but normal speech sibilance goes, too.  I preferred the 
previous, less aggressive DSP filtering of the earlier firmware releases.

OVERALL -- I doubt the Omni VII DSP NR filter will induce you to trade 
your VI+ for an Omni VII.   First, doubt satisfaction with a new rig 
will come down to a single feature,  and Second, if a single factor was 
the key, then I doubt the Omni VII NR (while good)  will not satisfy 
enough to make it worthwhile to upgrade.

Would you upgrade your sports car to the newest iteration of that model 
just because it had a newer clutch,   or a better stereo,   or a added a 
six speed gear box, while your model has a five speed gearbox ?   How 
about if it added faster acceleration so it reaches 60 in 5.8 seconds 
instead of your car which reaches 60 in 6 seconds.  Would a supercharger 
be enough better than a turbocharger?

And, similarly with the NR feature on our radios... How much better 
would it have to be to induce you to spend $2600 on a new radio?   Would 
the NR of the Omni VII,  alone, even if it is really, really much better 
than on the VI+,  satisfy you enough to justify the expense?   Would any 
single feature improvement do that?

  3)   OTHER FEATURES TO CONSIDER:
The Omni VII is, I think, a better radio overall -- but not by a huge 
margin.  You can easily compare the feature lists of the two radio to 
see whether or not the Omni VII has certain features that would induce 
you to purchase a new rig.   I favor using a comparative product matrix, 
where you make a chart of all salient features and specifications that 
are material to you ("material," meaning it could make a difference to 
your final decision) and compare the two radios side by side.   If the 
feature and spec chart suggests you want a new radio, then I suggest you 
order the Omni VII for a 30 day test drive and see how it plays, mindful 
it will operate and feel very different from the rig you know so well, 
and that it does pretty much the same job by very different methods.

There is the "Better-the-Devil-you-know"  syndrome - which means you 
will most likely favor a rig that feels, looks, and acts like the radio 
you have come to love best.  The Omni VII will not likely pass this 
test, but if you really are open to new ways and means, then you might 
like the Omni VII enough to keep it after the 30 day trial expires.

But the best way to find out is to use one.   If you find yourself in 
the Grand Rapids, MI, area... see if I am home and you can test drive mine.

I hope this help you in your decision.   Good luck, excellent question, 
with a very subjective answer.

------------------
Happy Trails.
=======================  Richards / K8JHR  =========================


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