Nobody can tell the difference between 95% and 100% peak modulation.... in fact, what is important and can be detected is the average modulation, not the peak modulation.
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Music on AM?
- Thread starter vforest76
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Nobody can tell the difference between 95% and 100% peak modulation.... in fact, what is important and can be detected is the average modulation, not the peak modulation.
But we CAN hear the difference when the peaks used to hit 125-130% and now they need to stay under 95 to prevent cutoff of carrier.
It's the average modulation not being as high as it was able to be pre-iboc. And it sounds dull and flat compared
to a signal optimized to sound as good as possible in pure analog. No one could hear 5%, but the fact it's audibly
impacted is a sure guarantee that they weren't hitting 100% before, they were well over.
As link is in the Chicago area, I'm sure we're both hearing AM 1300.
I haven't been able to get 1300 to decode in HD, even with the 1925 tuned loose-coupler loop.
It's the average modulation not being as high as it was able to be pre-iboc. And it sounds dull and flat compared
to a signal optimized to sound as good as possible in pure analog. No one could hear 5%, but the fact it's audibly
impacted is a sure guarantee that they weren't hitting 100% before, they were well over.
As link is in the Chicago area, I'm sure we're both hearing AM 1300.
I haven't been able to get 1300 to decode in HD, even with the 1925 tuned loose-coupler loop.
Tom Wells said:
The limit on positive peaks is 125% and the issue there is that high positves often sound bad on cheap AM radios, or about 90% of all of them.
130% positives is illegal, and sounds horrible. Many of us kept positives well below the legal limit due to sound on average radios.
100% has always been the limit for negative peaks, and is where carrier surpression occurs, and where huge distortion enters in.
Over recent years, many engineers have noticed that lower average modulation sounds better on today's crummy AM sections in most radios.
listened to MUSIC ON AM in Myrtle Beach, SC while visiting there yesterday. I toted my hand-built Meduci 10kHz wideband AM STEREO tuner, and plugged it into a Sony boombox. I tuned 910 WNMB [the oldies station in North Myrtle Beach] in C-QUAM AM stereo – sounded great! I wish there were more stations doing that!
I was looking in this thread for some news about my friends in Chicago when I found your having tuned into our station, WNMB. Thank you. We still play music (24 hours a day) on AM, and, yes, in AM Stereo. It might surprise some of you how many cars are out there now with factory standard AM stereo radios (many Fords and Chryslers). So, when any of you are coming our way, we invite you to listen in and come visit with us. FYI, we also stream at 48 kps at www.wnmb.net
We have many friends in Chicago, including your great music group, the Buckinghams, and our former dj Dick Biondi is there as well.
I was looking in this thread for some news about my friends in Chicago when I found your having tuned into our station, WNMB. Thank you. We still play music (24 hours a day) on AM, and, yes, in AM Stereo. It might surprise some of you how many cars are out there now with factory standard AM stereo radios (many Fords and Chryslers). So, when any of you are coming our way, we invite you to listen in and come visit with us. FYI, we also stream at 48 kps at www.wnmb.net
We have many friends in Chicago, including your great music group, the Buckinghams, and our former dj Dick Biondi is there as well.
B
bub
Guest
I noticed WNMB's TV spot on You Tube recently and I thought that was neat.Bill said:
Bill said:
GREAT JOB IN BROADCASTING, Bill. I always enjoy hearing WNMB on my visits to the Grand Strand. You have the only C-QUAM AM stereo station that has ever come-in on my Meduci tuner. I love your music format and full 10kHz audio! You are doing AM radio THE RIGHT WAY! Keep up the good work, Bill!
DavidEduardo said:
Yes, 130% is illegal because it's too hard to keep from going over 125% plus without exceeding 100% minus in many instances.
Here we get to hear that plenty on WONX AM 1590 Evanston. It creates wideband splat, but still if it occurs only sporadically
it doesn't hurt as much the sound as badly as the multiple sidebands added by iboc, nor does it impact adjacents as badly as iboc AM.
Especially iif such negative peaks are truly only the "one event per ten minutes" which I recall as the maximum permissable occurance rate.
Many engineers have dropped their standards as the FCC has given up caring or enforcing engineering excellence or even adequacy.
I'm not ready to drop my standards or use crummy radios.
It's hard to think of any other medium or product where we knowingly tolerate and add even more pollution as we go.
I can't think of any place else where there's such a race to lower quality and performance standards " because everyone else is".
I was not impressed with asymmetrical 125% modulation. It caused a raspy quality on the “typical” AM radio repertoire. I “backed-off” in the interest of reducing detector distortion. I never found that extra 25% to be a coverage issue. QUALITY over quanity!
hipporadio said:
Sounds great on the 1982 GE cathedral, 1982 Sony and all my old car radios. (Sounds insane on the RS Accurian.)
Any new cars parked in front of the house, it sounds pretty damn bad on the peaks where AVC action is apparently
poorly distributed in these new radios. It sure does clump up. Two doors down, though, it sounds as good as such modern radios can. :-\
Do these new things send any AVC to an RF stage, or do they try to do it all in the IF?
If so, it would be like going back to bias ply tires in cars because it's cheaper.
Even I use radial tires on my daily driver.
I use the sound of the 1962 Bendix Mopar as the absolute reference for "by ear" modulation adjustment.
Testing tonight with an o'scope to show a lissajous pattern shows I can barely achieve tiny amounts of cutoff (-100%)
with all audio gain up, but I stop a long time before that when I hear the Mopar start to sound too full, which by the scope is somewhere over 100% positive for sure. The donut closes and the "center dot" widens out with the percentage over 100% positive.
And there's not a hint of splatter on adajacents, so no -100%.
That's the punch that makes music sound like my best memories of music on AM when WLS and WCFL ruled here.
If you ever get towards the stateline area around Rockford Il. to Beloit Wi. Tune in 1490 WGEZ-Beloit. Very clear sound on a newer tower and ground system. Also non-directional 1000 watts. They are programming Scott Shannon's True Oldies Channel. Sounds great in the car during the day when you are in Beloit, outside of town its gets a bit noisy. The station I believe is owned by the Polish National Alliance.
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