Quote:
Originally Posted by radiotvnut
I'll add that AM sounds much better to me on a tube radio than on most modern consumer grade stuff. It seems that most of the newer stuff is designed just to pass a signal on AM and that's about it. Even the AM section in my mid '70's Kenwood receiver has poor sensitivity and fidelity. A basic 5 tube radio from the '60's has better fidelity and sensitivity than my Kenwood receiver. I was listening this afternoon on a '50's Zenith Bakelite case AM/FM with good results. The AM sounds almost as good as the FM on that radio.
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I had a Zenith integrated stereo system in the early '80s that had about the worst AM tuner I have ever heard. No kidding--mine was so bad I was getting short wave on the AM broadcast band after sundown. (The AM reception in my area at that time, near-suburban Cleveland east of town, wasn't all that great either; I think if I had held on to that system when I moved to where I live now, a small NE Ohio town some 40 miles from Cleveland stations, it would have been a setup for one heck of a letdown--in other words, the AM section of this system was good for near-suburban reception, but get out much further than 15 miles from the stations and the AM performance drops like a stone.) The irony was that the FM reception was very good, typical Zenith. That system must have had an AM tuner section designed as you said; just well enough to pass a signal--nothing more, nothing less. The fact that the AM tuner in my system was picking up shortwave stations on the broadcast band at night leads me to believe that the tuner was extremely poorly designed and usable, as I said, only in strong signal areas.
The AM tuner in my present stereo system, an Aiwa NSX-A888 mini system bought new in 1999, has problems as well--I think. There is a 1kW AM station on 1460 kHz in my area that comes in at two points on the digital AM tuner, 560 and 1460 kHz, 900 kHz apart. If this station were a big 50kW bruiser I would suspect it was overloading the front end of my tuner, but this particular station is only 1kW days and 0.5kW (500 watts) nights. Since my apartment is some five miles (more or less) from the station's transmitter, I don't think I'm getting any huge amount of signal on that particular station. That leaves only one thing--the design of the tuner itself. Again, it goes back to what you said about the slap-dash manner in which AM tuner sections of even expensive stereo receivers are built, especially models of the last 30-35 years or so. Like yourself, I have vintage table radios that sound better on AM than even my bookshelf system; lately I've been listening to my Zenith MJ1035, an early FM stereo receiver from the 1960s. Except for some hum in the sound and not a heck of a lot of audio level (but enough to get decent listening volume), this radio sounds better than any modern radio I own, except perhaps for my 1958 Zenith C-845.
The makers of stereo receivers over the last three decades or so have probably decided to concentrate their efforts on the FM tuners and just put in an AM section that isn't much better than a crystal set. There isn't that much worth listening to on AM anymore anyway (except for stations such as Toronto's AM 740 and possibly other small U.S. stations), most of it being talk, sports or other non-music programming, so there is really no need for wide bandwidth in the AM tuner these days. I don't know if very many people who own these stereo receivers even listen to them on AM (you are apparently one of those few who do); after all, when one spends a large amount of money on a stereo system, he/she will almost certainly be listening to the FM tuner and running their turntables, cassette decks, CD systems, etc. through the amplifier. AM radio was never meant to be a high-fidelity music medium in the first place; but then again, the music played by stations such as AM 740 was never hi-fi stuff either (remember, those songs are anywhere from 30 to 80 years old or more, some possibly even predating electric phonographs and having been digitally remastered).
AM stereo, which was supposed to improve the sound of AM radio, went bust in the early 1980s, as did quadraphonic sound. I'll never forget how an article in a late-sixties issue of the (now defunct) Electronics Experimenter magazine began: "It's
fantastic! It's
colossal! ... and it is also
A BOMB!"
Quad sound was a bomb, all right. It lasted through the 70s and the very early eighties, but it died long about 1983; the same thing happened with Dolby FM, though Dolby has made a comeback as it is now used extensively in home-theater audio systems. I don't know to this day if there were any FM stations in the northeastern Ohio area that broadcast Dolby-encoded signals. I have a Radio Shack SCT-11 cassette tape deck which has Dolby capability for both tape and FM, but I cannot seem to notice much of a difference in the sound when I use the Dolby decoder with my commercially-recorded (Time-Life Music Service) cassettes, almost all of which have been recorded using Dolby noise reduction.
I don't know that the sound of AM radio will ever even come close to the full fidelity of a good FM stereo signal. The reason is the difference in modes and, as I said, the fact that AM by its very nature is not a high-fidelity music medium. I don't care how much processing goes into the signal at the station; if the receiver is of poor or mediocre design, the audio will sound not much better than a table radio, and that's being kind.