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Re: [IRCA] SPR4 audio
I was going to suggest the same. I couldn't use my AOR AR7030 with the
original 2.2 kHz filter, but when Murata CFJ455K4, a 2.9 kHz filter was
added, I could understand speech again! Even in tight listening situations I
seldom get any benefit using the narrower filter.
73, Mauno
----- Original Message -----
From: "Walter Salmaniw" <salmaniw@xxxxxxx>
To: <irca@xxxxxxxxxxxxxxxx>
Sent: Tuesday, November 29, 2005 3:42 AM
Subject: Re: [IRCA] SPR4 audio
> At 11:38 AM 11/28/2005, you wrote:
>>Message: 8
>>Date: Mon, 28 Nov 2005 11:18:33 -0800
>>From: mwdxer@xxxxxxxxx (Patrick Martin)
>>Subject: Re: [IRCA] SPR4 Audio Help
>>To: cafe@xxxxxxxxxxxxx, irca@xxxxxxxxxxxxxxxx (Mailing list for the
>> International Radio Club of America)
>>
>>Colin,
>>
>>No, the SPR4 is solidstate and nothing was added except a couple
>>switches. The 2.3 khz filter was there already for SSB. It came with the
>>SPR4 stock in 1971. The change was made to the SSB filter would work in
>>the AM mode. That is all. The skirts are very sharp and the splits pop
>>out of nowhere. The sellectivity is great. I just want to clean up the
>>audio. It works fine in the regular wide (4.8 khz) filter mode and the
>>audio is very clear and crisp. It just gets muffled in the 2.3 mode too
>>much.
>>
>>Thanks.
>>
>>73,
>>
>>Patrick
>
>
> Patrick, isn't this just the result of using too narrow of a filter.
> Every receiver I've ever owned (must be 25 or 30 now) have all had muffly
> audio once you narrow below 4 kHz using AM and 2.8 kHz in SSB. I rarely
> use the very narrow filters just for the same reason. Muffly
> unintelligible audio. The best solutions seems to be the use AM
> synchronous detection when that works, or something like the Sherwood SE-3
> and shift the carrier of interest away from the offending splash, but keep
> the wider bandwidth. I gather this is a limitation that can't be
> overcome. i.e. you'll never get clear audio using a 500 Hz filter, even
> though it in theory would be useful in tight situations. Human speech is
> between several hundred Hz and about 6000 Hz (the consonants), so it makes
> sense that too narrow filters simply can't work in processing human
> speech. Am I making sense (I'm speaking here as a physician rather than
> any kind of technical expert!)........Walt Salmaniw, Victoria.
>
>
>
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