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seanbaker · Posted - Sun Feb 25, 2001 6:39 pm

Does anyone out there know the exact specific frequency ranges from low to top that are present in AM radio and also what type of limiting or compression is generally applied on air? I would like to create a band stop or pass or simply just knowing which sample rate to record in which would eliminate certain frequencies. I also want to configure the compression envelope to simulate on-air limiting/compression. My problem is I don't know specifics and my ear must not be helping because I've tried many varied things and they all sound good. I need to be able to create an AM preview for my jingles before selecting the best mix.

Syntrillium M.D. · Location: USA

Hi Sean. If you haven't already, post this question in the 'Radio' section of our forum. I'm sure someone there will be able to give you the answers you are looking for.

---Syntrillium Support

Teddy G. · Posted - Tue Feb 27, 2001 4:19 pm

1. AM Radio is capable of truly excellent quality! In the distant past, there were many fine signals to be heard. However, the last stations I worked for, the vu meter never moved from 100%. Dead-air? 100% modulation. During open-mike dead-air I could hear people chatting 3 buildings away. Unfortunately, The same can now be said of FM. You haven't been able to "hear" the phnomenon, in studio, because you haven't even been close!
2. WARNING! Don't try to duplicate modern radio, AM or FM in your studio! You don't have strong enough equipment, and you'll surely cause yourself physical harm to say nothing of emotional trauma, attempting to do any of the bizzare things broadcasters do to try to be LOUDEST(I mean, BEST)! I've seen many a battle-hardened broadcast engineer run screaming from the building after the "honchos" have proposed their ideas on how to make the station sound "just a little better, a little louder".
That being said. It will be difficult to make your in-studio system really sound like a radio station. Try listening to your production on a limited response speaker/amp at a variety of levels from very loud to almost inaudibly soft. Try listening in different environments. This might, I emphasize MIGHT give you another perspective, somewhat more like a listener. And, it'll help point out things likely to be lost in the mix after broadcast. My 29.95 Sony cassette machine(not a boom box or Walkman type) would be fine, and portable. Record to cassette through the "included" mic from your speakers and you may even get that marvelous 24 cent AGC effect! Deja-vu man, the 70's are back
I say, simply do your best, full frequency, minimalist processing job and be done with it! Just don't expect bass reproduction to loosen any bricks in the wall and don't expect dogs to come running to your highest frequencies.
One other, sort've serious suggestion. Ramsey Kits at ramseykits.com has an AM radio transmitter for 29.95 and a companion processor for 59.95! Hard to beat running your stuff through a real radio station for hearing how it sounds! FM available,too. Probably precious little difference in sound quality from these and the broadcaster down the street. Just don't come crying to me when you would like your station to be "just a little bit better, a little bit louder".
Have fun!
Ted

seanbaker · Posted - Tue Feb 27, 2001 7:56 pm

Uh....thanks, Ted,...I think maybe I wasn't clear with my question, but your infor was interesting anyway. To be more specific in my question, I'm simply wanting to know which exact bass and treble frequencies to elimiate in order to make my wav file sound like it came from AM radio. Also I was wondering which compression preset might simulate what happens to music on the radio when it is compressed for on-air. Is it 2:1 or just a peak limiter or what? I have posted this question in the Radio forum too, but since you started answering, I'll continue here.

Syntrillium M.D. · Location: USA

Hi Sean...this really is more in response to the previous post...the question being, "Why would you want your productions, in your own studio, to sound like FM radio?" Radio in general is not real pleasant, not indicative of the actual CD they are broadcasting, and quite frankly, what's extreme loudness got to do with it? When did music only become acceptable simply because it caused tinnitus? FM is great for the car, but really, most people have a hard enough time getting their 'home studios' to have flat responses and no standing waves, let alone worrying about how many dB they can squash so that the neighbors complain.

---Syntrillium Support

seanbaker · Posted - Wed Feb 28, 2001 9:21 am

Syntrillium M.D. · Location: USA

Hello. I was aware of your question, and I relate my original response. I see that no one has yet to answer you in the radio forum, so yo might want to check elsewhere if you are in desperate need. Evidently, (a) no one knows; or (b) people know, but those people are trapped under something heavy and can't get to their computers to answer you.

And please, be patient...there are other 'radio-specific' forums out there too.

Have you tried the relaxing sounds of wind chimes?

---Syntrillium Support

Syntrillium M.D. · Location: USA

You know, it occurred to me...Why don't you start a new thread in the Radio forum and title it, "AM Radio Broadcast Specs??" I think the reason you may not have had any responses is that people are thinking that you want to 'eq' a song to make it sound like AM radio, and thus, are passing it by. Try that, maybe then someone will come to the rescue.

---Syntrillium Support

MikeShivley · Posted - Wed Feb 28, 2001 7:34 pm

From the "Audio Cyclopedia" by Howard Tremain 2nd edition 4th reprint. There is a diagram on page 33 that shows the freq response of AM radio to be 50Hz to about 7,300 kHz. Which seems to go with my recollection appox. 50Hz to 8 kHz. As Far as the Compression, limiting etc. I wouldn't know exactly. I do know from working in radio stations that it really is unbelievable just how much of that they do to the signal. I would suggest calling a AM station and ask to speak to the engineer. When he gets done either laughing or crying depending on his feelings about what the bosses make him do to the signal, he should be able to give you a pretty good idea. Hope this helps.
Mike

seanbaker · Posted - Wed Feb 28, 2001 8:02 pm

MikeShivley · Posted - Thu Mar 01, 2001 1:00 pm

HI sean.....yes that eq sounds good.....also amplify the signal a lot and compress the crap out of it......lots of stations have upwards of 3 different compressor/limiters in the signal chain. All part of the "louder is better" syndrome.

Graeme · Member Location: Spain

urumuqi74 · Posted - Fri Mar 02, 2001 11:37 am

Keep everyting limited between 50 hz to 8 khz and in a 3db dynamic range! It sound pretty pessimistic but this is all about AM nowadays!

seanbaker · Posted - Fri Mar 02, 2001 1:59 pm