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Re: [TenTec] AM Receiver distortion in Orion II

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] AM Receiver distortion in Orion II
From: Martin AA6E <aa6e@ewing.homedns.org>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Tue, 23 Jan 2007 20:53:23 -0500
List-post: <mailto:tentec@contesting.com>
The second half is clear far better than the first, in my opinion.  It's 
not a question of low-frequency response, but of distortion in the highs 
- almost like a little clipping, or maybe some other digital artifact.

Ron should tell us what the Audio Eq. setting was, by the way.

I ran a spectrum on the file with Spectrum Lab.  The results (for 
several playbacks) are at http://aa6e.net/aa6e/images/capt0701232044.jpg 
.  Carl was right that the "good" playback is much wider than Orion's. 
Orion's spectrum has a very sharp cutoff, but I don't think that's what 
I am hearing.

It would be neat to try this on the Orion I comparing v1 and v2 
firmware, but I've got a few other things to do right now...

73 Martin AA6E

Carl Moreschi wrote:
> The Orion recording has more bass and less highs.  With a 6 khz filter in
> the Orion, the audio passband is 3 khz on each side of the carrier.  I would
> expect this to sound bassy and have less highs.  But the quality is
> excellent.  The 870 recording clearly shows that the bandwidth is much
> greater than 3 khz which would only allow 1500 hertz of each side of the
> carrier.  I bet the 870 has a special AM filter that is in the 9 khz or
> higher range that switches in automatically in AM.  It is impossible for the
> 870 AM audio to sound like this with only 3 khz BW.  Both audios are
> excellent considering the BW.
> 
> Carl Moreschi N4PY
> 121 Little Bell Drive
> Bell Mountain
> Hays, NC 28635
> ----- Original Message ----- 
> From: "Ron Castro" <ronc@sonic.net>
> To: "Ten Tec List" <tentec@contesting.com>
> Sent: Tuesday, January 23, 2007 5:54 PM
> Subject: [TenTec] AM Receiver distortion in Orion II
> 
> 
>> One of the items on my "wish list" for the Orion II is to fix the AM
> receive audio, which sounds to me like a problem in the DSP code that causes
> distortion and 'muddy' sound.  It's most noticeable during selective fades
> that cause a serious clipping effect.  Last night, I made an MP3 of a local
> AM radio station comparing the O2 to a TS-870, and sent it to TT service.
> This morning, TT said they couldn't hear any difference between the two
> receivers.  Is it my ears or what?  The link to the clip is below.  The O2
> is the first 60 seconds and the 870 is the second 60 seconds.  Bandwidth on
> the O2 is 6 kHz, while the 870 is 3 kHz, although as you'll hear, it sounds
> just the opposite!
>> http://n6ie.com/OrionII_vs_870.mp3
>>
>> Can anyone besides me hear the difference?
>>
>>       Ron N6IE
>>  www.N6IE.com
>> (Formerly N6AHA)
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