Can anyone give me a very general ballpark figure as to how much gain
reduction (whether compression or limiting) is typical in Am radio
(mixed format - talk and music). Is it primarily limiting or is there
generally any compression as well?

Thanks,

Dan Fox

Daniel Fox wrote:

Can anyone give me a very general ballpark figure as to how much gain
reduction (whether compression or limiting) is typical in Am radio
(mixed format - talk and music). Is it primarily limiting or is there
generally any compression as well?

Once upon a time it might have just been limiting ( to save the transmitter )
but today it's compressed to f**k !

Graham

Pooh Bear wrote:

Once upon a time it might have just been limiting ( to save the transmitter )
but today it's compressed to f**k !

Are we talking 10db dynamic range reduction (average)?, 20db?, 30db?

Dan Fox

"Daniel Fox" wrote in message
ups.com...

Pooh Bear wrote:

Once upon a time it might have just been limiting ( to save the
transmitter )
but today it's compressed to f**k !

Are we talking 10db dynamic range reduction (average)?, 20db?, 30db?

Dan Fox


Dan, the types of processing and they way they are adjusted varies from
station to station. i think you could use -15dB as an estimate for an AM
station that has "medium" compression. maybe -20dB for stations that have
"heavy" compression.

remember that this compression only happens whenever the threshold set
point is exceeded.

your question however begs the question "why do you want to know?".
if you think you somehow counter the effects by production methods, i doubt
it.
just produce the best material you can and let the broadcasters do with it
what they will.

In article . com,
says...



Pooh Bear wrote:

Once upon a time it might have just been limiting ( to save the transmitter
)
but today it's compressed to f**k !

Are we talking 10db dynamic range reduction (average)?, 20db?, 30db?

Dan Fox


This is not a straightforward question because modern AM audio processors use
"silence gating" that freezes the gain of the compressors when the signal has
dropped to a level that probably represents noise.

The available range of gain reduction on a modern Optimod-AM is approximately
50 dB, divided into an AGC with 25dB range and 5-band compression, all bands
having 25 dB range except for the top band, which is 30 dB. However, because
of the level-dependent gating, this does not mean that the noise floor gets
sucked up 50 dB.

If you are serious about learning more about this, you can download the
Operating Manual for Optimod-AM 9400 he

ftp://ftp.orban.com/9400/Documentati...ing_Manual.pdf

This is a 5.38 MB download.

Bob Orban

On Thu, 18 May 2006 13:05:26 -0400, Daniel Fox wrote
(in article . com):


Pooh Bear wrote:

Once upon a time it might have just been limiting ( to save the transmitter
)
but today it's compressed to f**k !

Are we talking 10db dynamic range reduction (average)?, 20db?, 30db?

Dan Fox


Maybe 10, maybe less.

Ty Ford



-- Ty Ford's equipment reviews, audio samples, rates and other audiocentric
stuff are at www.tyford.com

"Daniel Fox" wrote ...
Can anyone give me a very general ballpark figure as
to how much gain reduction (whether compression or
limiting) is typical in Am radio (mixed format - talk
and music).

Prehaps you meant gain compression, not gain reduction.
If anything, radio stations are caught in a "loudness war"
where they try to use as much gain as possible.

Is it primarily limiting or is there generally any compression
as well?

There is more than plenty of both and other tricks besides.
Audiophiles have been complaining about it for decades.
You could likely find enough discussion of the topic already
archived to keep you busy for the rest of the summer (or
winter if you are antipodian.)

No, I meant gain reduction. Of course they'll be using as much make up
gain as possible (within legal guidelines), but I'm trying to find out
how much they are squashing music (on average) in db.

Dan Fox

Daniel Fox wrote:

Can anyone give me a very general ballpark figure as to how much gain
reduction (whether compression or limiting) is typical in Am radio
(mixed format - talk and music).

It's likely to vary by a large margin. Ads produced locally
may have greatly differing levels from those of national
agencies. Network feeds vs desk mic preamps, various
reproduce machines (cd, cart, etc) and other variables will
have levels all over the place. Even with a Chief that's very
particular about calibrated levels there's almost no way to
have extremely consistent levels.

Is it primarily limiting or is there generally any compression as well?

Some of each. A typical 'basic' chain might have an "AGC"
leveler with fast attack and fairly slow release followed by a
very fast 'brickwall' protection limiter just before the transmitter.
A more sophisticated station will have this plus maybe a
multiband compressor or other specialized processing and
enhancement.

Also note that a final limiter for AM can allow higher positive
going peaks than negative due to the amplitude modulation.

rd

Daniel Fox wrote:
Can anyone give me a very general ballpark figure as to how much gain
reduction (whether compression or limiting) is typical in Am radio
(mixed format - talk and music). Is it primarily limiting or is there
generally any compression as well?

Lots and lots. Massive compression, usually multiband, radical EQ
to meet NRSC contours, extremely aggressive limiting. The limiting is
always asymmetric (positive-going peaks limited at a higher level than
negative-going ones) and sometimes asymmetric compression is used.
Phase rotators are almost always used although some folks are using so
much compression they are dispensing with them.

Used to be you could get response out to 15 KC if there was nothing on
the adjacent channel. Then in the late eighties the NRSC standards
required a sharp cutoff around 10 KC. Now we have Clear Channel demanding
affiliates cut off at 5 KC because it makes things louder on cheap
narrowband radios.

We won't even TALK about how IBOC-AM is destroying the band.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

(Scott Dorsey) writes:

Daniel Fox wrote:
Can anyone give me a very general ballpark figure as to how much gain
reduction (whether compression or limiting) is typical in Am radio

snip

Used to be you could get response out to 15 KC if there was nothing on
the adjacent channel. Then in the late eighties the NRSC standards
required a sharp cutoff around 10 KC. Now we have Clear Channel demanding
affiliates cut off at 5 KC because it makes things louder on cheap
narrowband radios.

Good heavens, Scott. I rarely listen to music on AM, but have spun
(punched across) the dial from time to time and aside from the awful
compression, wondered why there wasn't much top end.

Just like today's devolvement of some pop "music" into something tribal
and primitive (or less: pre-tribal screeching while swinging
tree-to-tree, perhaps), you're telling me that technology has followed
suite -- that all the tech and political work and sweat in the 1940s-70s
to get 50-15KHz broadcast bandwidth is gone, and we've returned to 1930??
(Adds dimension to the phrase "vintage audio", I suppose.)

Yarg.

Frank Stearns
Mobile Audio

--

Frank Stearns wrote:
(Scott Dorsey) writes:

Used to be you could get response out to 15 KC if there was nothing on
the adjacent channel. Then in the late eighties the NRSC standards
required a sharp cutoff around 10 KC. Now we have Clear Channel demanding
affiliates cut off at 5 KC because it makes things louder on cheap
narrowband radios.

Good heavens, Scott. I rarely listen to music on AM, but have spun
(punched across) the dial from time to time and aside from the awful
compression, wondered why there wasn't much top end.

The argument is that most current AM radios cut off at 4 KHz, so they
sound less noisy. Therefore stations have less incentive to broadcast
anything above that point.

At the NAB a couple years ago, someone presented a set of measured
frequency response plots of AM receivers. The one with the best top end
extension was a 1929 TRF set, with the All-American Five from the fifties
coming in a reasonable second (and with much better selectivity). For
the most part, AM radio fidelity has gone to hell since FM came out,
because receiver manufacturers don't perceive a demand. And so broadcasters
have no incentive to improve sound.

This is why music on AM is pretty much dead in this country. And my strong
suspicion is that AM-IBOC is just going to wreck what is left of the AM band.

Just like today's devolvement of some pop "music" into something tribal
and primitive (or less: pre-tribal screeching while swinging
tree-to-tree, perhaps), you're telling me that technology has followed
suite -- that all the tech and political work and sweat in the 1940s-70s
to get 50-15KHz broadcast bandwidth is gone, and we've returned to 1930??
(Adds dimension to the phrase "vintage audio", I suppose.)

Pretty much, except the chance of getting high end out of a 1930 radio
is probably better than getting one of a typical Radio Shack product today.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Yeah, but the traffic reports sound AWESOME!

On Thu, 18 May 2006 10:28:45 -0400, Frank Stearns wrote
(in article ):

(Scott Dorsey) writes:

Daniel Fox wrote:
Can anyone give me a very general ballpark figure as to how much gain
reduction (whether compression or limiting) is typical in Am radio

snip

Used to be you could get response out to 15 KC if there was nothing on
the adjacent channel. Then in the late eighties the NRSC standards
required a sharp cutoff around 10 KC. Now we have Clear Channel demanding
affiliates cut off at 5 KC because it makes things louder on cheap
narrowband radios.

Good heavens, Scott. I rarely listen to music on AM, but have spun
(punched across) the dial from time to time and aside from the awful
compression, wondered why there wasn't much top end.

Just like today's devolvement of some pop "music" into something tribal
and primitive (or less: pre-tribal screeching while swinging
tree-to-tree, perhaps), you're telling me that technology has followed
suite -- that all the tech and political work and sweat in the 1940s-70s
to get 50-15KHz broadcast bandwidth is gone, and we've returned to 1930??
(Adds dimension to the phrase "vintage audio", I suppose.)

Yarg.

Frank Stearns
Mobile Audio

There's music on AM?

Seriously. HD radio is supposed to "cure" the problems of AM frequency
response, but I'm guessing they'll continue to over process for loudness and
by the time enought HD radios do get to the market, the sound will be equally
bad.

Ty Ford




-- Ty Ford's equipment reviews, audio samples, rates and other audiocentric
stuff are at www.tyford.com

Ty Ford wrote:

Seriously. HD radio is supposed to "cure" the problems of AM frequency
response, but I'm guessing they'll continue to over process for loudness and
by the time enought HD radios do get to the market, the sound will be equally
bad.

The AM IBOC stuff actually sounds worse than wideband AM to me. There is
no more impulse noise, but the compression artifacts are just awful. And
of course it totally knocks out adjacent channels.

The way I look at it, what makes AM unique and wonderful is skywave reception.
AM-IBOC signals themselves aren't decodable on skip, because the Faraday
effect stuff mangles the waveform too badly. And, AM-IBOC kills reception
of adjacent analogue AM signals on skip by spewing trash all over the band.

I am thinking FM IBOC might be a good thing. Compared with Eureka-147 it's
inelegant and has poor sound quality. But it's something. on the other
hand, AM IBOC is a real disaster. It destroys the one thing that keeps the
AM band viable.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Is IBOC a transmission thing Scott?

Can you explain more about when these standards came up and what the
reason given was?