[TenTec] audio on Omni-VI+

[Barry N1EU]

Don and the group,

I did another round of work on the Omni 6 after posting that first
preliminary mod and I came away more pessimistic after further work
with the Omni 6 rx audio.  When I bypassed all the circuitry after the
product detector, I found the noise level just too high (i,e,
stop-band was to shallow).  The Omni 6 seems to depend on the dsp to
do some needed low pass filtering on the rx audio.  There also seems
to be a tendency for the 6.3Mhz filter to introduce ripple into the
pass-band.

73, Barry N1EU

On Sun, Feb 6, 2011 at 5:41 PM, Don Rasmussen <wb8yqj at yahoo.com> wrote:
> Dale,
>
> The OMNI 6+ will never have the audiophile range of fidelity that EAGLE, Orion, or OMNI 7 has - I think that's what Barry N1EU is indicating.
>
> If you already did the Inrad mod (solder a couple parts on the OMNI) AND you have the Inrad 2.8 filters (there are two of them), here is something to try.
>
> I found a mod on Barry's website that takes OMNI 6+ out of that audio restricted category you are referring to, which is prominant even with the Inrad 2.8 filters and the Inrad mod combined.
>
> I have a pigtail coming out of the back of the OMNI with a sub-mini female connection. I plug the amplified speakers from my computer (has subwoofer) into this jack when I want to hear the expanded audio. For CW it is a non issue, the CW is best coming out of the normal AF chain. The AGC and selectivity of the OMNI 6+ is the best I have used, just at times want a little better audio quality.
>
> The OMNI 6+ DSP comes further down in the chain than the audio take off, that is the reason for the improvement, you are taking the DSP out of the line and that has some hi-lo end rolloff.
>
> The DSP also performs the auto notch and FM functions so you dont have that when using the audio out mod. If you have a volume control on your amplified speakers you can turn that down and turn up the AF gain on the OMNI to activate the notch, do FM, etc.
>
> =======
> Omni VI
> =======
>
> The stock Omni VI(+) suffers from a very constricted passband in ssb.  ARRL measured about 1600hz in their review.  After experimenting a bit, I found a way to completely open the passband up to the full width of the xtal filters.  For those seeking hi-fi ssb rx audio from the Omni VI, and who are willing  o amplify the audio externally, a night and day improvement can be had from tapping the product detector audio off U3-6 on the if/af board through a 1uF capacitor tack soldered to the pin, and a shielded cable brought out for amplification.  It is a requirement that you then adjust C10/C12 on the TX Audio board to optimize the receive passband.
>
> The Inrad 2.8Khz filters are really a necessity to complete the "mod" for the Omni VI.  It goes without saying that the notch filter, dsp, sidetone, fm, etc. are bypassed with this audio output.
>
> Good Luck and happy listening!
>
> PS - (You dont want a 6 khz filter from Inrad)
>
> 73,
> Don
>
>
>
> [TenTec] audio on Omni-VI+
> from [yash] [Permanent Link][Original]
>
> To:  tentec at contesting.com
> Subject:  [TenTec] audio on Omni-VI+
> From:  yash at aol.com
> Reply-to:  Discussion of Ten-Tec Equipment <tentec at contesting.com>
> Date:  Sun, 06 Feb 2011 09:31:37 -0500
> List-post:  <tentec at contesting.com">mailto:tentec at contesting.com>
>
>  Have been using my ,new to me ,Omni VI+ for a few weeks,like the rig,hard to fault for a 10+ year old rig. I have one problem that I would like to change.
> The audio quality. In stock form the rig sounds "nasally" to me ,constricted and choppy. I installed the Inrad audio kit ,2 caps and 1 resister,it made a nice change in the quality of the audio. I noticed that INrad also mentions changing the OEM 6 MHz filter with a #755 of their design. Has anyone done this filter change? Is there another route to getting the audio sounding full and clean with this rig? Other than the audio the VI+ is great.
> thanks
> dale wt4t
>
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