Paul Sherwin wrote:

On Tue, 08 Jun 2004 03:04:27 GMT, Jon Noring wrote:

I'm very interested in building such a tuner to match with
audiophile-grade tube amplifiers and pre-amplifiers now being built by
hobbyists (as well as those sold by commercial vendors.) There are
quite a few nice kits now being marketed for audiophile quality tube
amps/pre-amps, such as those made by diytube (http://www.diytube.com/
-- there are many others like diytube.) So why not similar kits (or
workable designs) for a tube-based AM tuner?

No offence Jon, but I think you're nuts. Most hifi listeners (never
mind audiophiles) wouldn't dream of using *FM* for serious listening,
because of the level of optimodding and other sound processing that
goes on. Quite a lot of commercial stations even adjust the playback
speed of their music to make the station sound more 'lively' and to
squeeze in more commercials.

All the audiophiles I know do listen fervently to the FM stations we have
which
take pains to transmit unadulterated audio.
Where I am is a city of only 300,000, and we have
an Arts FM station funded by subcribers and mild advertisers, and their
signal is tops.
The govt owned station, ABC Classic FM broadcasts nothing but
classical and some jazz. Electric guitars are rarely heard.
They regularly do live broadcasts each sunday and during the week,
and all are at a high technical standard.
Then we have a community FM radio station run by feminists
and mainly leftists, and that has the best specialist rythym and blues
shows.
Then there is a station for ethnic culturists.

The remaining stations are pop music, christian, or sports report based,
and thir
programmes are all just ****e to me, and the audio is little better than
the AM stations,
and I am allergic to ALL their adverts, which have the opposite effect on
me that the advertisers hope for,
ie, I WILL NOT buy coca cola after hearing an add saying things go better
with coke.


AM has all that, plus very high levels of signal compression and an
effective HF cutoff of about 3.5kHz. You can't improve this by
extending the IF bandwidth, because the stations just don't transmit
anything above this.

Here in Oz, they do transmit more than 3.5 kHz of audio,
so we get some stations worth listening to.

There's nothing wrong with building your own high quality AM tuner,
either solid state or tube, but no matter how many gold lettered
Telefunken ECC83s you use it won't sound very good.

There are programs where the content has little above 8 kHz.
If one stretches the BW of the receiver here in Oz,
its surprising how good AM radio can sound.

A Telefunken ECC83 is a useless tube in any RF circuit.
I get your point, but ppl in r.a.t are spread around the globe
where different conditions prevail.

Patrick Turner.



Best regards, Paul
--
Paul Sherwin Consulting http://paulsherwin.co.uk