Weird problem-skippy audio

[Fieldtech1]

There is something weird going on with this track. Lots of ultra-low bass in the 4hz, 10hz, and 19hz area. Using the crossover on a robust subwoofer with electronic equalizer set to filter frequencies 31 hz and above, the woofer was oscillating quite a bit even though most of the tracks bass energy is 40hz and north region.

The audio from the clip the OP posted seems to cut out about 3-4 times per second, in line the band of ultra low bass seen on the waterfall spectrum plot.

Here is a speclab screenshot.......... The track is in .wav from the November Mainstream PromoOnly CD ..........

http://imageshack.us/photo/my-images/825/brunomarswillitrainsl.jpg/

 

[TomT]

Bruno Mars--Will It Rain

I think this is the Bruno Mars cut we air, drove me nuts trying to figure out what the buzzing sound was until I figured that it was coming from the song, not something else in the chain.

Looks like two possible related explanations as to what is going on.

1. The processor brings up these super low frequencies (which are only present during part of the song);

2. Either the low frequencies unlock the AFC in the STL or exciter--which would cause the song to "skip" on-air...or

3. The transmission system successfully passes the audio, only to drive various models of radios nuts--causing them to "loose lock."

Simple solution: Play the song off your source CD or download through an EQ, then save the equalized version into your air computer. We use Sound Forge, which has EQ as one of its processing functions & could probably clean this cut up.

 

[Radio Boogie]

Just curious... I didn't notice anyone looking at the mod monitor when this occurs to see if there are negative peaks? That 4 - 10 Hz is going to sneak around a lot of processors simply because of the extremely low frequency. Imagine your bass-band limiter getting bottomed out because it's likely not designed to handle frequencies below around 20Hz... that's pretty excessive.

And look for this kind of scenario to come along more often since these idiots who master audio anymore have no clue. Some even intentionally do crap like this just to mess with radio people. That's nothing new, either. Think of songs which pump or distort no matter what kind of processor you throw them at... been going on since the 60's.

 

[TomT]

Classic example--from '69: Mercy--Love Can Make You Happy

Listen to that pump--could swear that was recorded with something like a Level Devil or a Collins 26U limiter.

 

[Radio Boogie]

TomT... that's a totally real possibility.

A lot of Capitol and Apple stuff was DBX'ed quite heavily in the late 60's and early 70's. Some even pumped straight off record... the Raspberries "I Wanna Be with You" and "Go All the Way" pops into mind off hand. These didn't play well with AGC's of the period at all as they seemed to double the hole-punching effect.

Prince, and his buddy Roger had a thing about mastering bass drums about +15 dB hotter than everything else. "Controversy" and "Do It Roger" were probably the worst.

How about "Too Shy" by Kajagoogoo? That heavy bass drum over the long synth notes just plain made anything pump.

And I'll never know what the problem with both Greg Guidry's "Goin' Down" and Steve Perry's "Oh, Sherrie" was, but someone had to have been deaf not to hear the distortion and crosstalk in these 45's. Of course, they're both Columbia products. A few of Kenny Loggins records were pretty distorted too.

Gino Vanelli's "Living Inside Myself" was another hideous mastering job, but I'm not surprised, as Arista formed from what was essentially left of Bell/Amy/Mala from the 60's... remember those cheap styrene pressings with the super-thin center rings and the blue painted labels... they were good for exactly ONE clean play on a... well, anything. One play on one of those old tonearms and the highs were gone. Cue it once, there was a burn. I think they used to mix in shredded styrofoam and cellophane from the garbage into the styrene on these pressings. They were HORRIBLE. I remember they'd leave fine strips of styrene if played on a "Close-N'Play" (remember THOSE???)

Umm... I'm not nearly as old as this makes me sound!!!

 

[Tom Wells]

I never got to have a Close-N-Play. :'( I remember wanting one really badly.... about 1965/66?
Good thing too, cause all my records from then still sound good.

 

[CDJCD5]

I never had that skipping problem, but I remember years ago we were running on our back up composite STL's, There would be some sound effects in our Imaging that would cause something to go out of whack, sounded like we went off the air for a few seconds... On our Starlinks we never had had any issue like that...

 

[cgould]

What you heard would be the AFC (Automatic Frequency Control) loop getting fooled by the low bass. Really low bass frequency energy
can cause some AFC loops to think the transmitter is off frequency, and shut down for a moment until the system feels things are on-frequency again, and at that point, the transmitter comes on again.

In this case, it was your STL transmitter, for others it could be the main transmitter itself. Most FM transmitters made recently (about 35 years or so now) didn't have this problem. Now, as things age, components can deteriorate to the point where this becomes a serious problems in a system that has otherwise been A-OK for years.

Regular preventative maintenance, and being proactive about replacing components (mainly capacitors) as they approach the 5-10 year mark will keep you ahead here.

Digital STL's (linear - uncompressed) do not have any issue with any bass as the modulation sections never see anything resembling the actual audio...only "digital noise". So, they'll either work great, or not at all.

-Cornelius

I never had that skipping problem, but I remember years ago we were running on our back up composite STL's, There would be some sound effects in our Imaging that would cause something to go out of whack, sounded like we went off the air for a few seconds... On our Starlinks we never had had any issue like that...