Have auto manufacturers let quality of AM radio receivers decline as well ... or does that not make sense given a well-designed circuit could probably be included in any radio for next to no cost. At least I assume that's the case with electronics these days given all the "extra" stuff they bundle as part of a smart phone now.
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Interesting article on 1090 The Fan
- Thread starter Roddybob
- Start date
Saving a few pennies per car can translate into millions in profits - and that's why most AM car radios today are so bad (but in fairness the one in my late-model Toyota has a decent sounding AM tuner).
I'm not sure the radio quality has declined, but manufacturers have had to adapt to the noisy environment and electronics in the vehicle by narrowing the bandwidth of the AM tuners. That, and most radios now days are single chip SDR (software defined radios), where the parameters and performance are dictated by software. Vehicle antenna quality have been in decline for the past 20 years, with the advent of in-glass and stubby antennas to reduce the visual impact. The problem is, for those manufacturers that still bother including AM tuners in new cars, a four inch antenna doesn't perform well when an individual AM radio station wavelength is 800 feet long.
Hmm interesting, I just noticed this today with my laptop shortly after I read that. I had the G8 on the floor bese me, computer right in front me. T computer came on and the signal significantly degraded. Trying to record 1250 was impossible without it sounding lke a DX signal even with the radio a full 3 feet away. Oddly, KOMO was pretty solid, even when KIRO wasn't. I would have thought that the noise would be across the band pretty steady, the higher powered stations able to overcome it more. That being said, I'm not sure how you can accurately measure how much of the market is covered with that kind of data. I did notice when we had the radio close to the kitchen that the microwave would cause all sorts of noise on the AM band, but that's the kind of noise I was expecting, a buzzing noise.
Re: am tuners
There are some good tuners out there, but none of them have good dynamic range. There are airchecks of KING and I think KOMO from the 70s on tophour.com. Why don't they make AM tuners that sound like that these days? We've had several cars starting with an 87 pickup truck with an after-market stereo put in in about 89, a late 80s or early 90s Honda Civic, a minivan, and several cars, none of which had tuners that sounded anything like those airchecks. Although the G8 is very selective, it doesn't have the dynamic range on AM at all.
Re: am tuners
There are some good tuners out there, but none of them have good dynamic range. There are airchecks of KING and I think KOMO from the 70s on tophour.com. Why don't they make AM tuners that sound like that these days? We've had several cars starting with an 87 pickup truck with an after-market stereo put in in about 89, a late 80s or early 90s Honda Civic, a minivan, and several cars, none of which had tuners that sounded anything like those airchecks. Although the G8 is very selective, it doesn't have the dynamic range on AM at all.
As has been mentioned earlier - single chip radios, crappy quality amplifiers, cheap manufacturing techniques, you name it. Want high quality? Pay a lot for esoteric gear or find vintage hardware.
It's always been pretty common to get noise across low frequencies while the upper part of the band remains undisturbed.
My experience is that the lower frequencies seem more subject to atmospheric noise. This is particularly pronounced in places like Florida where the summer static makes listening in the fringe areas of anything below about 900 kHz nearly impossible.
But all frequencies seem just as subject to man made noise from computers, CFLs and all the other electronic and electrical devices that emit RFI today.
First, you do not say how those airchecks were recorded. If they were recorded right off the station's board, then no radio receiver was involved in the process. If they were recorded on a stereo tuner, the radio probably had a very wide bandwidth that would make it useless for DXing but great for local AM listening. Not many radios like that around today.
Secondly, when you say dynamic range, you are probably referring to bandwidth. Most radios since the 1970's are chip based, and have had tight AGC circuits, which compress the dynamic range, and usually sound better because of it.
I think what you are noticing is the narrow bandwidth in modern radios, that cuts a lot of the highs from an AM signal.
Since the late 1970's, most AM radios of which I am aware have had ceramic filters to narrow the bandwidth, to cut the interference from nearby channels. This includes boomboxes I've had that were built in the early and mid-1980's, and a few DX AM portables made before then. GE Superadios never had ceramic filters, they added an extra IF can instead -- that's one reason they have a bigger sound on the AM band but still perform well for DXing.
A "single chip" radio doesn't necessarily have to sound bad (actually it's two chips on most of them -- an IF chip and an AF audio chip). A lot of times it's the tinny speaker that sounds bad. Or the firmware running the chip tells it to run at a narrow bandwidth (my PR-D5 is a great DX radio because of this, but not so fun for AM listening because of it also).
A lot of times radios (especially portables) have lower audio output than radios used to, because the radio is designed to run on a couple AA's instead of a pack of heavy D cells. This means when you turn up the radio, the speaker will distort a lot more quickly than a portable from 1970 would. A lack of tone controls doesn't help, either.
I have a new Sony ICF-38. It sounds pretty good. One chip -- an analog Sony IF chip with audio amp section inside it. The bandwidth is narrow enough to DX with, but a little wider than many DX portables.
The speaker is big enough to sound a little better than most modern clock radios. It's not perfect, but an example of modern AM radio that works well and has decent sound. Such radios are out there, you just have to find them.
I have no idea how those were recorded, I didn't do them. I had a piece of crap radio several years ago that sounded pretty good on AM, but even on KOMO, a 50 KW stick at about 25 miles, I could still copy another station, likely KJR, underneath. It sounded pretty good though. I got rid of it several years ago after I got a headset I had had laying around for like 10 years working. Am doesn't sound too bad on that thing, I can actually get KOMO without anything else bleeding in on it, but it's no DX radio. It did have great sound overall though, you could crank those headphones up and hear the thing all the way across the room.
None of the SDR-based car radios anymore use more than one chip for the tuner. The vast majority use the NXP single tuner chip and turn on features and performance as they choose: http://www.nxp.com/products/audio_radio/am_fm_radio_audio/one_chip_radio/
I was talking about the standard IF tuner chip / + AF audio power chip setup -- the entire radio, not just the tuner section. I.e., tuner chip plus Audio power chip(s).
Out of curiosity, is it possible that those airchecks could have been recorded off the board if the studio monitor was set to receive the live, received audio and not just the output?
It's also possible they were recorded off of a transistor radio of the day. I have several late 60's / early 70's era transistors and through the headphone jack they have a very rich sound (speaker also, but you'd think a recording would be made through the headphone jack).
They're OK to DX with, except strong adjacent locals will swamp a DX stn next door. Also, AM stations were broadcasting in a wider bandwidth back before the standards were changed -- I think sometime in the 1980's. They were putting out more fidelity than they do now.
They're OK to DX with, except strong adjacent locals will swamp a DX stn next door. Also, AM stations were broadcasting in a wider bandwidth back before the standards were changed -- I think sometime in the 1980's. They were putting out more fidelity than they do now.
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