Quote:
Originally Posted by Oldmadham
I don't think the bandwidth has been reduced since, but with the obsequious attitude of the regulators to "world's best practice" anything can happen!
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The irony is that Australia and New Zealand probably represented best practice as far as AM broadcasting was concerned. The change from 10 to 9 kHz channelling c.1978-79 was probably neither needed nor beneficial downunder, but was done to conform to international practice.
The Australian and NZ equipment makers, such as Audiosound, Allen Wright, AWA and Fountain offered decent, wideband AM tuners through the 1970s and into the 1980s. But very little imported equipment offered this facility, and in that period most of the Japanese manufacturers (Sansui being a notable exception) fitted quite atrocious AM sections to their hi-fi equipment. “Electronics Australia” (EA) magazine called out this practice. As an example, in its 1979 January review of the Technics SA-400 receiver, it said:
“Once again, the AM tuner in the SA-400 is just about as poor as any in typical Japanese stereo receivers.” And in a 1985 December review of the Sony ST444ES tuner, it said:
“It’s a pity that the AM performance is but the merest shadow of the standard for FM. While the signal to noise ratio was quite respectable at 61 dB with respect to 100% modulation, the audio bandwidth was particularly narrow, with a -3 dB response between 200 and 950 Hz.”
EA also included wideband AM tuners amongst its constructional projects, but it also had some designs with conventional narrowband AM sections. One of the latter was the Playmaster AM-FM Stereo Tuner-Clock, described in the 1978 November and December and 1979 January issues. Of its AM performance EA said:
“While the AM performance is nothing to become excited about, the AM specifications of this tuner are actually better than those obtained from many commercial tuners. This may be hard to believe, but it’s true.” The AM frequency response specification was 30 to 3000 Hz at the –3 dB points!
In respect of transmitted quality, a comment that was made by Allen Wright about the two wideband AM tuner models he had produced:
“Both sounded like good FM , just in mono, from the superb quality non-commercial government stations. Compressed commercial stations sounded just that - compressed!”
Cheers,