AM radio doesn’t go beyond 5 KHz (although everybody wishes it would), and it goes down to 20 Hz. That’s the proof of performance for a radio station. It does have some very peculiar noise. It can have a very low 10 KHz whistle in the background. That’s two stations interfering with each other, and any electrical noise or static you happen to have laying around. It can have two stations at once.
They do not echo.
You need to know the metaphor. Transistor radio sound is going to be very different from the AM radio in my sound system, different from the Victorian Living Room console sound and different again from a Ghetto Blaster.
You can go well on your way to that effect with just the eq. That’s how they did it, but they were spoofing the effect, not doing the real thing. Old Tyme Radio had announcers that took advantage of the response of the system by having very deep voices and slightly exaggerated pronunciation. No filter for that I’ve ever found.
Another spoof buried in there is the Rudy Vallee voice. He had no volume at all so sang through a small megaphone so everybody could hear him.
Exactly. Radio stations in the US are 10 KHz apart. During the day, everything works out, but at night, you can hear two stations right next to each other. From my childhood, WGY in Schenectady NY and WFAA/WBAP Dallas/Ft.Worth. 810 and 820 on your AM dial and both rock crusher stations. Whistle City. Most AM radios have a circuit to get rid of that, but the earlier radios didn’t have one.
AM sound fidelity is half the station spacing which gives you 5KHz sound.
If you play your cards right, you can get fading, too, as the stations drifted into each other – particularly at night.
If you lived near the Mexican border, you had another problem. Mexico had little or no limit on transmitter power, so they had stations that would melt Fiats and Volkswagens in the parking lot.
The vocal on the video orangel linked to has very little bass, (more like 1920s gramophone).
If you want the audio to sound like it’s emanating from a WWII radio, throw in a heterodyne whistle.
Audacity’s equalizer alone is sufficient: this is the equalization I used …
BTW If you are using Audacity’s native compressor I suggest you reverse the track, apply the compressor, then reverse it back the right way around.
This avoids the creation of spikes at the start of words, which Audacity’s own compressor unfortunately tends to add.
<<<Although I’m not quite sure how AM radio cross-over works into this topic.>>>
From the first line of the first post…
<<<So I’ve read all those thing about old radio/walkie talkie/PA effects on audacity, but I’m trying to get an effect that makes it sound like an old radio set from the 1940-1950s.>>>
<<<this is the equalization I used …>>>
Nothing with vacuum tubes in it ever came out that clean and sharp. I’d probably round off the corners a bit and make the curve gentle. And I’d still go down further on the left. There was no restriction to the low end on AM radio transmitters. They used to do big band shows from hotels and there was nothing wrong with the bass line.
The hetrodyne whistle in the US is always 10KHz because of the radio channel spacing. Other countries it could be 8 KHz.
<<<Audacity’s own compressor unfortunately tends to add.>>>
Which is one of the many reasons to use Chris’s Compressor. Trouble free volume leveling.
<<<Btw, what I’m trying to do is create a narration spiel for this WWII training video.>>>
On film? OK, skip the heterodyne whistle. Film doesn’t have that. Film does have those funny muffled optical track pops as dirt and film splices go through the projector. And they’re out of sync. Sound on Film is 16 frames behind, so you see a crack or splice in the film and it’s about a second later you hear the pop.
I don’t know how I would simulate optical film dirt in the track. I never tried. But optical film sound didn’t have any better fidelity than AM radio.
Maybe a brief blast of white noise and then muffle it with the equalizer.
Any serious sound production should be done in Audacity 1.3.x. Audacity 1.2 tools and filters are really simple and many of them don’t work particularly well.
I wish they had posted a little explanation with those radio samples. Three of them are an AM radio being tuned rapidly up and down the dial, one of them is a radio left just off center of correct tuning (which makes my teeth hurt), and the last one is an actual microphone sound capture of a thunderstorm, not the storm as it appears on AM radio.
None of them sound like what happens if if you listen to a half-hour radio show. One of the samples was from a small table radio and that accounts for the boxy sound with no bass.
And no, heterodyne doesn’t constantly change pitch. Sometimes on the short wave bands it can do that, but not broadcast. I thought I heard some radio teletype sounds in one of those samples, so goodness knows where they came from.