Announcing 'hifi-am', to discuss High Fidelity AM tuners and

[Jon Noring]

Hello,

I've created a discussion group (mailing list) to discuss high
fidelity AM tuners and hobbyist transmitters. Appended below is the
more detailed group description.

To subscribe to this group, either go to the group home page (at
Yahoo) and subscribe there (you will need a YahooID):

http://groups.yahoo.com/group/hifi-am/

Or, if you don't have a YahooID, send a blank email to:

hifi-am-subscribe@yahoogroups.com


Looking forward to seeing you there!

Jon Noring


**********************************************************************


Group Description for hifi-am:
==============================

The purpose of hifi-am is to explore the possibilities of high
fidelity AM tuners and hobbyist transmitters for medium-wave (or
better known as the broadcast band, appr. 520 to 1720 khz.)

Although most commercial AM broadcasts are definitely not high
fidelity (due to various factors including, in many countries, audio
bandwidth restrictions), there are nevertheless a few commercial
stations which broadcast with audio quality approaching high fidelity.
For example, in Australia, because the number of stations is fewer and
the country quite large, many stations broadcast with quite wide audio
bandwidth, approaching 15 khz.

There is steady growth in interest (in the U.S.) for non-licensed
hobbyist broadcasting in the BCB (per FCC "Part 15"), which is
restricted to 100 milliwatts and a three meter antenna (among a few
other minor restrictions). With a high efficiency antenna, it is
possible for such neighborhood broadcasting to be heard about 1/2 to 1
mile from the transmitter. There are quite a few progressive and
alternative stations broadcasting this way. For a wonderful example,
see Radio KMTZ.

More importantly, it appears there is no specific restriction on audio
bandwidth for Part 15 transmissions. Thus, if this is true, the
broadcasts can approach high fidelity (15 to 20 khz audio bandwidth.)

Although discussion can focus on the general topic, it is hoped this
group will catalyze the development of hobbyist kits for high fidelity
AM tuners (digital, solid state, and tube) and for high fidelity
low-power (Part 15) AM transmitters. It should be fun to consider the
many possibilities.

 

[Neil]

Hi-Fi AM....what the hell is that????!!!....I thought it died out 10 minutes
after it was announced about 5 years ago.
Kim



"Jon Noring" <jon@noring.name> wrote in message
news:8g6re0pn5c72ls4qnc1midumv0b4j6jv24@4ax.com...

Hello,

I've created a discussion group (mailing list) to discuss high
fidelity AM tuners and hobbyist transmitters. Appended below is the
more detailed group description.

To subscribe to this group, either go to the group home page (at
Yahoo) and subscribe there (you will need a YahooID):

http://groups.yahoo.com/group/hifi-am/

Or, if you don't have a YahooID, send a blank email to:

hifi-am-subscribe@yahoogroups.com


Looking forward to seeing you there!

Jon Noring


**********************************************************************


Group Description for hifi-am:
==============================

The purpose of hifi-am is to explore the possibilities of high
fidelity AM tuners and hobbyist transmitters for medium-wave (or
better known as the broadcast band, appr. 520 to 1720 khz.)

Although most commercial AM broadcasts are definitely not high
fidelity (due to various factors including, in many countries, audio
bandwidth restrictions), there are nevertheless a few commercial
stations which broadcast with audio quality approaching high fidelity.
For example, in Australia, because the number of stations is fewer and
the country quite large, many stations broadcast with quite wide audio
bandwidth, approaching 15 khz.

There is steady growth in interest (in the U.S.) for non-licensed
hobbyist broadcasting in the BCB (per FCC "Part 15"), which is
restricted to 100 milliwatts and a three meter antenna (among a few
other minor restrictions). With a high efficiency antenna, it is
possible for such neighborhood broadcasting to be heard about 1/2 to 1
mile from the transmitter. There are quite a few progressive and
alternative stations broadcasting this way. For a wonderful example,
see Radio KMTZ.

More importantly, it appears there is no specific restriction on audio
bandwidth for Part 15 transmissions. Thus, if this is true, the
broadcasts can approach high fidelity (15 to 20 khz audio bandwidth.)

Although discussion can focus on the general topic, it is hoped this
group will catalyze the development of hobbyist kits for high fidelity
AM tuners (digital, solid state, and tube) and for high fidelity
low-power (Part 15) AM transmitters. It should be fun to consider the
many possibilities.

 

[Ken Taylor]

AM has always been relatively 'hi-fi' (15 to 20kHz), but the bandwidth of
most receivers is such that you receive crap. A half-way decent receiver
will give really good sound, making all those red-necks on talk-back sound
like they were in the same room, dammit.

Ken

"Neil" <ksleep@sympatico.ca> wrote in message
news:gcmHc.34876$WM5.1749530@news20.bellglobal.com...

Hi-Fi AM....what the hell is that????!!!....I thought it died out 10
minutes
after it was announced about 5 years ago.
Kim



"Jon Noring" <jon@noring.name> wrote in message
news:8g6re0pn5c72ls4qnc1midumv0b4j6jv24@4ax.com...
Hello,

I've created a discussion group (mailing list) to discuss high
fidelity AM tuners and hobbyist transmitters. Appended below is the
more detailed group description.

To subscribe to this group, either go to the group home page (at
Yahoo) and subscribe there (you will need a YahooID):

http://groups.yahoo.com/group/hifi-am/

Or, if you don't have a YahooID, send a blank email to:

hifi-am-subscribe@yahoogroups.com


Looking forward to seeing you there!

Jon Noring


**********************************************************************


Group Description for hifi-am:
==============================

The purpose of hifi-am is to explore the possibilities of high
fidelity AM tuners and hobbyist transmitters for medium-wave (or
better known as the broadcast band, appr. 520 to 1720 khz.)

Although most commercial AM broadcasts are definitely not high
fidelity (due to various factors including, in many countries, audio
bandwidth restrictions), there are nevertheless a few commercial
stations which broadcast with audio quality approaching high fidelity.
For example, in Australia, because the number of stations is fewer and
the country quite large, many stations broadcast with quite wide audio
bandwidth, approaching 15 khz.

There is steady growth in interest (in the U.S.) for non-licensed
hobbyist broadcasting in the BCB (per FCC "Part 15"), which is
restricted to 100 milliwatts and a three meter antenna (among a few
other minor restrictions). With a high efficiency antenna, it is
possible for such neighborhood broadcasting to be heard about 1/2 to 1
mile from the transmitter. There are quite a few progressive and
alternative stations broadcasting this way. For a wonderful example,
see Radio KMTZ.

More importantly, it appears there is no specific restriction on audio
bandwidth for Part 15 transmissions. Thus, if this is true, the
broadcasts can approach high fidelity (15 to 20 khz audio bandwidth.)

Although discussion can focus on the general topic, it is hoped this
group will catalyze the development of hobbyist kits for high fidelity
AM tuners (digital, solid state, and tube) and for high fidelity
low-power (Part 15) AM transmitters. It should be fun to consider the
many possibilities.

 

[Keith]

On Fri, 09 Jul 2004 14:43:35 +1200, Ken Taylor wrote:

AM has always been relatively 'hi-fi' (15 to 20kHz), but the bandwidth of
most receivers is such that you receive crap. A half-way decent receiver
will give really good sound, making all those red-necks on talk-back sound
like they were in the same room, dammit.

Huh?! At least in the US the AM channel is 5kHz wide, hardly enough to
broadcast 15-20kHz audio. Even the FM audio channel is only 10Khz (with
two for stereo). TV is the same. Where are you getting 15-20kHz????

--
Keith

 

[Activ8]

On Thu, 08 Jul 2004 23:35:21 -0700, Keith wrote:

On Fri, 09 Jul 2004 14:43:35 +1200, Ken Taylor wrote:

AM has always been relatively 'hi-fi' (15 to 20kHz), but the bandwidth of
most receivers is such that you receive crap. A half-way decent receiver
will give really good sound, making all those red-necks on talk-back sound
like they were in the same room, dammit.

Huh?! At least in the US the AM channel is 5kHz wide, hardly enough to
broadcast 15-20kHz audio. Even the FM audio channel is only 10Khz (with
two for stereo). TV is the same. Where are you getting 15-20kHz????

I dunno, but I'm real happy to know the BW tain'tb so wide as to be
able to smell that redneck cheap beer 'n' chile fart.
--
Best Regards,
Mike

 

[Ken Taylor]

"Keith" <krw@att.bizzzz> wrote in message
newsan.2004.07.09.06.35.11.632699@att.bizzzz...

On Fri, 09 Jul 2004 14:43:35 +1200, Ken Taylor wrote:

AM has always been relatively 'hi-fi' (15 to 20kHz), but the bandwidth
of
most receivers is such that you receive crap. A half-way decent receiver
will give really good sound, making all those red-necks on talk-back
sound
like they were in the same room, dammit.

Huh?! At least in the US the AM channel is 5kHz wide, hardly enough to
broadcast 15-20kHz audio. Even the FM audio channel is only 10Khz (with
two for stereo). TV is the same. Where are you getting 15-20kHz????

--
Keith

Channel spacing is irrelevant - it's why local stations aren't allocated
adjacent channels. Ditto the FM band. It's the difference between 'channel
spacing' and 'bandwidth'.

Ken

 

[Richard Henry]

"Ken Taylor" <ken123@xtra.co.nz> wrote in message
news:2ldqrrFbla60U1@uni-berlin.de...

"Keith" <krw@att.bizzzz> wrote in message
newsan.2004.07.09.06.35.11.632699@att.bizzzz...
On Fri, 09 Jul 2004 14:43:35 +1200, Ken Taylor wrote:

AM has always been relatively 'hi-fi' (15 to 20kHz), but the bandwidth
of
most receivers is such that you receive crap. A half-way decent
receiver
will give really good sound, making all those red-necks on talk-back
sound
like they were in the same room, dammit.

Huh?! At least in the US the AM channel is 5kHz wide, hardly enough to
broadcast 15-20kHz audio. Even the FM audio channel is only 10Khz (with
two for stereo). TV is the same. Where are you getting 15-20kHz????

--
Keith

Channel spacing is irrelevant - it's why local stations aren't allocated
adjacent channels. Ditto the FM band. It's the difference between 'channel
spacing' and 'bandwidth'.

If your local AM station violates the FCC specs for bandwidth, transmitter
power, and modulation, then you must live in or very near to Mexico.

 

[Ken Taylor]

"Richard Henry" <rphenry@home.com> wrote in message
news:tbpIc.4879$f9.2254@fed1read02...

"Ken Taylor" <ken123@xtra.co.nz> wrote in message
news:2ldqrrFbla60U1@uni-berlin.de...
"Keith" <krw@att.bizzzz> wrote in message
newsan.2004.07.09.06.35.11.632699@att.bizzzz...
On Fri, 09 Jul 2004 14:43:35 +1200, Ken Taylor wrote:

AM has always been relatively 'hi-fi' (15 to 20kHz), but the
bandwidth
of
most receivers is such that you receive crap. A half-way decent
receiver
will give really good sound, making all those red-necks on talk-back
sound
like they were in the same room, dammit.

Huh?! At least in the US the AM channel is 5kHz wide, hardly enough to
broadcast 15-20kHz audio. Even the FM audio channel is only 10Khz
(with
two for stereo). TV is the same. Where are you getting 15-20kHz????

--
Keith

Channel spacing is irrelevant - it's why local stations aren't allocated
adjacent channels. Ditto the FM band. It's the difference between
'channel
spacing' and 'bandwidth'.

If your local AM station violates the FCC specs for bandwidth, transmitter
power, and modulation, then you must live in or very near to Mexico.


Okay, I'll put it somewhat clearer - you can have a bandwidth greater than

the channel spacing if the licencing authority is smart enough to not put
someone else locally on an adjacent channel. And, in fact, they are that
smart and have done so since day one (maybe two, they were celebrating with
a few drinks on day one).

Ken

 

[Rich Grise]

on Monday 12 July 2004 05:38 am, Ken Taylor wrote:

Okay, I'll put it somewhat clearer - you can have a bandwidth greater than
the channel spacing if the licencing authority is smart enough to not put
someone else locally on an adjacent channel. And, in fact, they are that
smart and have done so since day one (maybe two, they were celebrating
with a few drinks on day one).

Please don't be spreading misinformation. You can "have a bandwidth greater
than the channel spacing" if the licensing authority is dumb enough to
let you radiate outside your allocated channel.

And somebody said earlier that FM broadcast has a bandwidth of 10 KHz.
Come on, people, some of these newbies might believe that crap!

The channel allocation for US FM broadcast is 100 KHz. I'm not sure
what the audio bandwidth is, but it's a lot better than 10 KHz. It's
"high-fidelity," remember those terms?
--
Cheers!
Rich

 

[Karl Uppiano]

"Keith" <krw@att.bizzzz> wrote in message
newsan.2004.07.09.06.35.11.632699@att.bizzzz...

On Fri, 09 Jul 2004 14:43:35 +1200, Ken Taylor wrote:

AM has always been relatively 'hi-fi' (15 to 20kHz), but the bandwidth
of
most receivers is such that you receive crap. A half-way decent receiver
will give really good sound, making all those red-necks on talk-back
sound
like they were in the same room, dammit.

Huh?! At least in the US the AM channel is 5kHz wide, hardly enough to
broadcast 15-20kHz audio. Even the FM audio channel is only 10Khz (with
two for stereo). TV is the same. Where are you getting 15-20kHz????

AM channels are allocated at 10 kHz intervals. The FCC allocates locally on
alternate channels, so during the day, you can usually get at least 10 kHz
of usable audio bandwidth. With all the de-facto pre-emphasis that
broadcasters used to overcome lousy AM receivers, the FCC standardized with
NRSC. Since the NRSC rules went into effect, broadcasters are required to
apply pre-emphasis and band-limit the audio to 10 kHz. Prior to that, you
could go out to 15 kHz. I used to maintain an old 250 watt RCA transmitter
that could modulate to 20 kHz.

FM Stereo with a pilot at 19 kHz, can have audio bandwidth of nearly 19 kHz.
Anti-aliasing and reconstruction filters limit the usable bandwidth to about
16 kHz.

TV Stereo is similar to FM, except that the pilot is tied to the horizontal
sweep frequency, so the absolute maximum bandwidth is about 14 kHz.

Broadcasters use so much audio processing, you can hardly call any of them
high fidelity anymore.

 

[Steve Roberts]

FM Stereo with a pilot at 19 kHz, can have audio bandwidth of nearly 19 kHz.
Anti-aliasing and reconstruction filters limit the usable bandwidth to about
16 kHz.

TV Stereo is similar to FM, except that the pilot is tied to the horizontal
sweep frequency, so the absolute maximum bandwidth is about 14 kHz.

Broadcasters use so much audio processing, you can hardly call any of them
high fidelity anymore.

Unless you cross the Border.

Drive along the Canadian Border and listen to a lot of beautiful
audio with noticable better clairity then US stations, I used to love
to listen to Canadian jazz and classical and techno stations in the
Buffalo area, it made long drives to service calls much more pleasent.
Also less a lot less background hiss. Evidently they do not preprocess
the audio as much to create fake "loudness" like US stations do to
increase ratings and revenue. Or does the CBC just have higher
standards?

Steve Roberts

 

[Karl Uppiano]

"Steve Roberts" <osteven@akrobiz.com> wrote in message
news:86dacd49.0407131024.79a35f74@posting.google.com...

FM Stereo with a pilot at 19 kHz, can have audio bandwidth of nearly 19
kHz.
Anti-aliasing and reconstruction filters limit the usable bandwidth to
about
16 kHz.

TV Stereo is similar to FM, except that the pilot is tied to the
horizontal
sweep frequency, so the absolute maximum bandwidth is about 14 kHz.

Broadcasters use so much audio processing, you can hardly call any of
them
high fidelity anymore.

Unless you cross the Border.

Drive along the Canadian Border and listen to a lot of beautiful
audio with noticable better clairity then US stations, I used to love
to listen to Canadian jazz and classical and techno stations in the
Buffalo area, it made long drives to service calls much more pleasent.
Also less a lot less background hiss. Evidently they do not preprocess
the audio as much to create fake "loudness" like US stations do to
increase ratings and revenue. Or does the CBC just have higher
standards?

Steve Roberts

Non-commercial stations use much less processing, as a rule, because they're
usually not competing for the same listeners or revenue. The NPR stations
(US) often sound quite good. CBC is non-commercial, if I'm not mistaken. I'm
not sure what regulatory body controls the commercial stations in Canada,
and I'm not sure if they specify how much compression they can use.

The FCC used to have something in the regulations about broadcasters not
"substantially" altering the dynamic range of the program material, but no
one seemed to pay any attention to it, and it wasn't a testable (i.e.,
enforceable) constraint anyway. I haven't read the rules in more than 20
years, so I don't know if it still exists.

 

[Harry Conover]

"Karl Uppiano" <karl_uppiano@verizon.net> wrote in message news:<f1KIc.55712$qw1.20090@nwrddc01.gnilink.net>...

"Keith" <krw@att.bizzzz> wrote in message
newsan.2004.07.09.06.35.11.632699@att.bizzzz...
On Fri, 09 Jul 2004 14:43:35 +1200, Ken Taylor wrote:

AM has always been relatively 'hi-fi' (15 to 20kHz), but the bandwidth
of
most receivers is such that you receive crap. A half-way decent receiver
will give really good sound, making all those red-necks on talk-back
sound
like they were in the same room, dammit.

Huh?! At least in the US the AM channel is 5kHz wide, hardly enough to
broadcast 15-20kHz audio. Even the FM audio channel is only 10Khz (with
two for stereo). TV is the same. Where are you getting 15-20kHz????

AM channels are allocated at 10 kHz intervals. The FCC allocates locally on
alternate channels, so during the day, you can usually get at least 10 kHz
of usable audio bandwidth. With all the de-facto pre-emphasis that
broadcasters used to overcome lousy AM receivers, the FCC standardized with
NRSC. Since the NRSC rules went into effect, broadcasters are required to
apply pre-emphasis and band-limit the audio to 10 kHz. Prior to that, you
could go out to 15 kHz. I used to maintain an old 250 watt RCA transmitter
that could modulate to 20 kHz.

Indeed true!

Back in the late 1950s and early 1960s, I was chief engineer in a
Trenton, NJ radio station that employed a Gates BC-5B 5,000 watt
transmitter, and the facts were just as this gentleman posted them. At
that time you could create a great deal of problems for yourself if
you exceeded the 10-Khz channel assignment.

Broadcasters use so much audio processing, you can hardly call any of them
high fidelity anymore.

This is certainly true of any AM station of which I am aware. This
began around 1960, when someone came up with the 'bright idea' of
placing a GE 'Sta-Level' amplifier in front of an RCA limit clipper.
This increased the average level of modulation to something like 98%
without risking over-modulation, thus increasing the station's
coverage range and advertising revenues.

The downside was that the audio quality went down the toilet, since
the FCC 'Proof of Performance' requirements didn't take this factor
into account. When 'Proof of Performance' testing was performed for
the FCC, we would simply input an audio sinewave at a sufficiently low
level that no significant compression or clipping took place! Of
course, this was not true of the day to day broadcasting, where you
could get a call from the station manager if he/she saw the modulation
monitor dip below 98% for any significant period of time.

Naturally, the audio broadcast sounded like, and in fact was, total
audio crap!

Harry C.