Anyone who reads my blog (or my Twitter feed, for that matter), knows that I sometimes like to obsess over certain things for a period of time. My latest obsession: AM Stereo.
Now any radio engineer or radio geek whose been around the block for awhile knows what I’m talking about. Those of you who belong to the younger generation… say, my age, are probably looking for an explanation about now.
First, let me give you the back story here. I’m a 90’s kid. I was born in 1990 (never mind that I was conceived in the 80’s but we won’t go there). Ask any 90’s kid about their thoughts on AM and they’ll tell you it’s a bad sounding mono radio signal that old people talk on (you’ve gotta remember, the FM revolution had already taken place by this time). In fact, I remember driving around with my grandpa in Minot, ND around 1997-ish (who at the time was a radio engineer himself) and he had an AM station on (presumably his) that was playing music. And I was blown away you could do that. Every other AM station in Fargo had already become either a news/talk or a sports/talk, so I assumed that’s all that was ever on there. I was 7 or 8 at the time so that was a fairly reasonable assumption. There may have been one music AM in Fargo at the point, but I really don’t remember. And radio has always fascinated me, even at that age… even before I even considered working in radio myself, I was always interested in how the technology worked.
Now, fast forward to about two years ago. I was working for the radio group I work for now, but I wasn’t technically part of the engineering staff at that point. One day I was BS’ing with one of part-time engineers (whose job, coincidentally, I ended up taking when he left a few months later) about our AM station in Fargo, KQWB 1660. And he was telling me it could do AM Stereo but we had it turned off for some reason.
Hang on a second… you can do Stereo on AM?
Yes, yes you can.
To anyone whose been around long enough this is nothing new. In fact, most would say that AM Stereo has come and gone. But again, being a 90’s kid whose perception of AM its a bad sounding mono radio signal that old people talk on, I was blown away that you could actually do stereo on AM.
How does it work? Without being too technical here, your basic AM signal has a carrier (which is at the frequency of the station, which in my case is 1660), and then an upper and lower amplitude modulated (hence the name AM) signal that carries the audio information (If you’re lost already just nod your head and go with it :-) ). Well to get the old non-stereo radios to receive a stereo signal properly, you have to mono it and then send stereo information, just like we do with FM. So on the upper and lower sidebands, we send the L+R information. But unlike FM, we can’t do a stereo subcarrier; they don’t exist on AM. So we phase modulate the carrier with the L-R information 90 degrees out of phase. An AM Stereo radio knows how to decode the phase modulated carrier and gets stereo information out of that. The whole process is a bit more complicated than that (and there are three other ways of doing from which a standard didn’t get decided on until it was too late), but that’s it in a nutshell.
So, how did 1660 end up with the ability to do AM stereo and why wasn’t it turned on? I described this in a blog post made by Paul McLean of Radio World a few weeks ago (which really inspired this post). but here’s what happened:
My station, KQWB, which was on 1550 at the time, added AM stereo when it was the big thing back in the 1980s. In the mid-’90s the station changed studio locations. From their then-new location, they couldn’t get a clear STL (Studio-Transmitter Link) shot to the transmitter. So they installed an equalized phone line to the old studio, and then reused the old STL to the transmitter. The problem, however, is the phone line only supported one channel of audio. But since it was a talk station at the time, it wasn’t a huge deal, and they shut the AM stereo off.
In 2000, KQWB moved to expanded AM band and went to 1660. Part of the deal with doing that was they had to keep AM stereo, so the new 1660 transmitter was ordered with the ability to do AM stereo. But with the station being talk for so many years, the AM Stereo stayed off.
Well, 1660 now plays Classic Country. Oh, and the STL I mentioned? Yeah, we have to turn it off by the end of May. We lose our lease on that old studio building.
In the mean time, another one of my stations, KBVB, went HD a few months ago, as I mentioned in a previous post. Well it just so happens we had room for an HD3, and since we’re running short on time to replace the STL, we’re feeding the AM audio onto HD3, and we ordered an HD receiver for at the 1660 transmitter, and we’re feeding he HD off-air feed right in. So not only have we now replaced the STL, it’s now a stereo feed.
Guess what that means. Yup. We turned the AM Stereo back on.
Let me explain why I’m so damn obsessed with AM Stereo. Again, keeping in mind the notion that the 90’s kid impression of AM is a bad sounding mono radio signal that old people talk on, listen to the below audio.
First, here’s an aircheck from 1660 using a Griffin RadioShark. It’s not the best receiver on earth, but it’s certainly on par with most other AM receivers you’ll find in the average car radio.
Now, compare that audio with the same aircheck as recorded off of my Realistic TM-152 AM Stereo receiver.
Quite the difference, eh. In fact, I dare to say it sounds as good as FM! The difference of course is all in the tuner. Even in mono, the Realistic tuner sounds that much better. In fact, here’s one more A/B comparison. This is from another station in the market (who I will leave nameless) that carries the Dave Ramsey show. Here’s a short blurb of that on the two radios. First, the RadioShark.
And now the same blurb recorded on from the Realistic tuner.
Sounds pretty good, huh!
So what have I learned with all of this? First off, AM Stereo, in my opinion, sounds amazing. It’s a shame the FCC didn’t get the standards thing figured out right away otherwise a lot of stations may have made the conversion. But the fact they didn’t act until 1993 just didn’t do anyone any favors; FM had already taken over.
The second takeaway here is that AM, even not in stereo, CAN sound good! I’m just befuddled that radio manufactures aren’t putting the effort into the AM receivers as they are the FM ones. And the fact of the matter is if AM radio is to be saved (which is a TOTALLY different discussion altogether), the receivers need to sound good. Go back and listen to the RadioShark cuts. That’s how most AM tuners sound… bad. And with a bunch of 90’s kids like me becoming all grown up now (well, “grown up” is up for debate), fixing the new receivers be the only way to get some life back into AM.
One last thing… if you’re wanting to hear more AM Stereo goodness, there is a cure. WION in Ionia, MI broadcasts in AM Stereo. And they’re so proud of it, their online stream carries the off-air AM Stereo feed from a Carver tuner. Check it out, it sounds great.
Now, if you’ll excuse me, I’m going to back to listening to my station in AM Stereo. Alabama just came on.