With regard to bass response, and overall response for that matter, conventionally designed transmitters can produce good response. Maybe not down to DC, but typical listening apparatus cant do that either.
Take a listen to an AMT5000 air check at http://www.sstran.com/pages/AMT5000/AMT5000_aircheck.html. If you are interested in bass response, be sure to listen on an appropriate speaker system or headphones. Response is flat down to 20 Hz. You can explore the bass and treble response with your graphic equalizer to get a feel for the actual content.
Response in the TX means nothing when the RX is choked at 4.5khz bandwidth.
You can shove as much frequency response into a TX all you want, but if your RX ain't got the wide barn door, don't expect the fat cow to moo its way on through easily.
Tends to end up sounding distorted.
RFB
Mine sounds quite good in the wide
bandwidth position on AM.
But quality control on those radios
wasn't that great, so I can't speak for
anybody else's Superadio.
The radio is still sold, but it has the
RCA logo on the front. I don't know
anything about this "new" version.
The Superadios go back a long way.
Bruce, 90.9, 88.3
About the comments you made about newcomers
and helping them, etc.
Maybe you should put something like that up
on the home page.
Also, a while back, we had talked about
maybe having pictures of other part 15
stations circulating along with the picture
of the young lady in the studio. If that
is ever a possibility, I vote for a picture
of your outside installation to be put up
on the home page.
Just a thought.
Bruce, 90.9, 88.3
Hi Bruce,
I agree on the superadios. There are also a lot of other high quality AM radios, even some that don't have a wide setting that still sound really good. There are also a ton of "antique" radios available on eBay that have excellent sound. Some, dating back to the 1930s, also have a wide setting. The old console radios with 12" to 15" speakers had massive bass response.
Nominally, current radio receivers are supposed to be designed to meet the NRSC standard, NRSC-1-A NRSC AM Preemphasis/Deemphasis and Broadcast Audio Transmission Bandwidth Specifications, September, 2007. After transmitter preemphasis and receiver deemphasis, the received response should be flat from 50Hz to "N" Hz, where N is 10kHz for normal AM, and either 5kHz or 9kHz for two IBOC modes. The standard falls apart due to recognition that stations have the right do any sort of audio processing they desire.
Here in the Philadelphia area, we only have 5 IBOC stations, but my observations in tuning across the dial leads me to believe that very few, if any non IBOC stations actually have audio content even remotely approaching 10 kHz. They are mostly talk stations and they naturally process their audio to enhance voice.
I don't think the majority of radios currently sold comply with the standard either. Most are crippled on AM. Even many current car radios and stereo receivers are crippled. Most younger generation people don't even know what AM is. I think manufacturers don't invest money in high performance AM because they know they won't be judged by it. Many new "boom boxes" don't even have AM. They have FM only and an iPod dock.
For those of us who still appreciate good AM, there are two challenges: get a good receiver, like the older Superradio, and find a good AM transmitter.
For those of us who want to do community broadcasting, a decision must be made between over processing your transmitter audio so you sound just like all the other stations, or widen your audio response for a quality signal. Trouble is, how many listeners will be able to appreciate your better audio?
"a decision must be made between over processing your transmitter audio so you sound just like all the other stations, or widen your audio response for a quality signal. Trouble is, how many listeners will be able to appreciate your better audio?"
My point exactly. Other than those who seek out specialty radios like the huge consoles or vintage stuff capable of decent sound on AM, the majority of receivers out there that will have a chance to tune in to a community station will be those found in the vehicles which has already been pointed out, are crippled.
It's a shame because if AM receivers had been given the attention they should have from the start, AM wouldn't be such a wasteland like it is today.
I know how well AM can sound...I run a C-QUAM station with that received stereo audio going out on all 3 of my station's streams.
And wideband AM mono ain't nothing to sneeze at either.
RFB
In support of the comments of RFB I will add that with a good receiver (my BC-1004-C) tuned to my transmitter the "throughput" frequency response is flat from 20 Hz to 8 kHz (the 8 kHz is due to the 16 kHz BW limit on the receiver...the transmitter is flat up to 16 kHz). When the bass and treble at the audio source are set to my liking the receiver audio is very impressive, though not stereo it is clear, crisp, and clean.
There is nothing inherent in AM per se that gives rise to low fidelity. Constraints such as occupied bandwidth limits artificially degrade AM performance. Another failing is at the receiving end with modern receivers and attempts to compensate or "equalize" at the transmitter end just makes things worse for those listening on good receivers.
I have a 1936 Crosley tube table radio which sounds better tuned to my transmitter than does the modern radio in my car.
Neil
"I have a 1936 Crosley tube table radio which sounds better tuned to my transmitter than does the modern radio in my car."
Those and a good number of wood cabinet consoles really made AM stations back in the "AM Gold" era kick out serious fidelity.
And those receivers, and any other with a wide band option makes the limiting NRSC curve shine through...GAGH!
Heck back then a table top with a 6x9 oval speaker would rock!
Break out the Altec Lansing 1200's!!! 8)
RFB
Phil, I think you mentioned you
have 5 IBOC AM stations in your
area.
It's really funny. In our bedroom
we have an extremely minimal clock
radio. In order to get the local
50,000 watt flamethrower, you have
to carefully tune the radio between
the IBOC noise until you get the audio.
In my zillion years of AM, FM, and TV
DXing, I have gotten the Philadelphia
area on all three "bands."
One prized catch was WWDB, 96.5, an
FM talker in Philadelphia, when local
WTIC, Hartford, 96.5, was off because
the transmitter needed work. I think
your 96.5 has a different callsign and
I'm sure it has a different format,
but it was a thrill hearing that one.
It was decades ago.
Bruce, 90.9, 88.3 (And I have two SS-Tran
AMT-3000s, too, which I love.)
Bruce,
KYW is the big flamethrower here. The hash level is almost as high as the AM carrier as you tune across the frequency. KYW is the only big time Philly station worth listening to. They broadcast a headline news format with absolutely no commentary. All the others are the usual political talk, sports, religious formats. KYW consistently gets the highest Arbitron rating year after year. KYW is the only one that does IBOC at night.
Surprisingly, the IBOC hash isn't noticeable even on a wide band AM radio when center tuned. But, the fidelity of the AM carrier is crippled.
KYW also broadcasts on an IBOC sub-channel on one of the FM stations. If IBOC ever catches on, that may become the favored way to listen and cause lower ratings for the AM station. I personally don't see tat happening for a long time, or ever, but who knows? They have a tremendous signal coverage on AM. They would give up that range on the FM channel.
KYW has always been a first adopter of the latest AM technology. They still used CQUAM long after all the others gave it up. The funny thing is their programming is all highly processed voice, so CQUAM never made sense, just as their IBOC doesn't make sense.
To make a rough analogy, certain trends in broadcasting remind me of the wish bone, the V shaped turkey or chicken bone that competitors pry apart in the belief that the longer remaining bone would be granted a wish. I said this analogy will be rough, so let me keep going.
The stations with IBOC channels have created competitions against themselves, a point touched on by PhilB, each component of the station's forked double programming wishing for the larger audience share, but invariably diminishing the available share to either channel.
Right now I'm assuming that the average IBOC station is simply duplicating its single program schedule on these multi channels, giving its audience no incentive to do anymore than receive the same old analog signal and hope to avoid the buzz.
But when IBOC channels are used to carry other programming, different from the main analog channel, the pie gets knifed up but the audience doesn't expand, it thins out.
If all this were all there were to it, it would make little sense in itself, but there's a whole new model being added to the slaughtered pie, "Zonecasting".
There is a move afoot for stations to send select programming to particular audiences or locations by adding booster transmitters, each of which would carry tailored programming for a more local neighborhood flavor. Don't ask me to describe how programming to south city would differ from that to north city, it will be up to the hosting stations to figure out how to localize and manage a whole collection of individualized program streams.
Doing all this while slimming the staff seems symptomatic of a death struggle in which radio is trying to save itself from obscurity by trying desperate ideas as if the audience will come.
But speaking for the audience, we may laugh about what the stations are doing, but we're gone. We have our own stations now. Part 15.