Audio mistake that's been on my mind for years: An ultimate-nerd challenge.

Ben Harmless

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I'd originally put this in one of my replies to Mjea80's acoustic guitar recording thread, but I felt like it was a little too off-topic. This is related to a realization I had a few years ago about my old job. Since then, I've been embarrassed but haven't told anyone. To my knowledge, we never got any complaints, but it bugs me because it compromised the output for some of the audience. I'm making this a TDPRI challenge with a reward of maximum audio nerd points.

I used to work a monthly show on a public radio station with a performing arts/recording studio. The hosts were a well-regarded couple who had guests playing (broadly) American folk and old-time music. Most of the performance was done with a small group around a single central mic - in our case, a Shure VP88. They'd gather around and move in and out when they were being featured or needed to drop back in the mix. It was fun. We had extremely talented performers, and they did most of the work themselves. I didn't appreciate it enough at the time. There used to be an online archive of all the shows, but it's sadly gone now.

Now, for the challenge: Where was the screwup? There are clues throughout. Get nerdy. There may be more than one answer, in which case that's additional things for me to be embarrassed about. Thanks for that.

Takers?
 

Ben Harmless

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The mic had a pattern that would not equally pick up performers who moved forward? Figure 8 comes to mind.
Warmish. The mic is not figure 8 however. Audio nerd point awarded.

I had to look at the product page, but it looks like a front-address mic. Ten bucks says you had it vertically and were getting sound from the secondary cartridge.
Smart move. Again, somewhat warmish. We had it positioned correctly though. Still, audio nerd point awarded.

Right here:
That is A screwup, but not audio/microphone-uber-nerd type screwup. You are absolutely right though. I'd kill to be able to go listen to those recordings again. I'd actually contact the hosts directly about it, but time and systems and egos would probably be a deal-breaker. Good taste point awarded.

It's the next day, so in addition to the above, here's another hint: In addition to my responses above, the fact that it's radio is significant. Even moreso that it's public radio. This may not be as much help to our international members who are less familiar with American public radio and its audience, but radio works similarly most places. Apologies for any exclusion. I'll reveal the answer tomorrow or something depending on how things pan out. I think it's interesting stuff.
 

Mouth

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If you were broadcasting in stereo was it connected in a way that it was only using one of the cartridges?
 

SRHmusic

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Was there a mix up with creating the correct left and right send for broadcast? It looks like there are options for matrixing. Perhaps the switch was set so that with the external routing (e.g. the rest of your processing) you ended up subtracting out the mid signal, and perhaps inverting one side?

Edit- I know for FM radio we send L+R and L-R, so I'd think this would be in the transmitter and you'd just need to send L. R. But maybe the studio had some matrix you were feeding into that in combination with this mic wasn't what you wanted.
 

mexicanyella

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Wait...you said secondary cartridge...let me go check that model out to see if it’s an integrated M-S mic...aHA!

Edit: looks like a couple others had similar thoughts while I was reading about the VP88.

So is your retroactive concern that you weren’t set up with the proper M-S signal routing/processing? Listeners on mono equipment were getting a lot of phase cancellation?

I have never tried an M-S setup before.
 
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Papanate

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I imagine you were using the mid/side in a Stereo broadcast - and so mono receivers were getting canceled out?
 
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Ben Harmless

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Were you broadcasting in mono?
I certainly wasn't intending to broadcast in mono. It was stereo in the control room.
If you were broadcasting in stereo was it connected in a way that it was only using one of the cartridges?
Well, both were in use, and are clearly audible on the recording.

Definitely some points here. Your thoughts are good thoughts.

Was there a mix up with creating the correct left and right send for broadcast? It looks like there are options for matrixing. Perhaps the switch was set so that with the external routing (e.g. the rest of your processing) you ended up subtracting out the mid signal, and perhaps inverting one side?
We were correctly matrixed at the control room, where everything sounded good. We then sent a stereo feed across the street where the master control operators sent it to air and didn't hear anything wrong. The signal was then fed to the transmitters, which themselves were properly broadcasting in stereo.

Funny thing about master control though - we had a little radio in there, tuned to our own station. Most stations have one. It's really annoying when you first start a job like this, but the idea is that you kind of get used to hearing everything twice because of our delay, and you kind of tune it out. The important thing is to notice when that radio goes silent, because then you're off the air, and it's time to panic. Interestingly, that second little radio radio might have made the problem noticeable to a critical set of ears. It never went silent though - that wasn't the issue.

Edit: Oh, and points to you, too. All of these thoughts so far show a degree of audio nerdiness.
 

BB

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The utter arrogance and shameless ef-u attitude the producer puts forth is over whelming in how under whelming it is. No what I mean? I mean now what I meen? I mean, Know What I mean Vern?
 

Mouth

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Hmm. If it was stereo in the control room, panning wouldn't be it.
 

bottlenecker

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I know the VP88 is stereo, but is it mid/side? I'm trying to think of how you could sum the fig8 pattern and cancel it, but you were broadcasting stereo. Was the control room radio mono?
 

Blue Bill

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My head is starting to hurt, I give up. As long as no performers were on the "back" side of the mic, a semi-circle should have worked fine.
 

mexicanyella

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I’m wondering what happens from a listener point of view, when a single central M-S mic is providing the stereo image, and performers step up and back from their semicircle around the mic. Does it cause a volume change and a perceived left-right sideslip, because of the M-S capsule arrangement, for the performers who are not right about inline with the M or the S capsule?

The only experience I have with the “bluegrass self-mixing semicircle” involved a cardioid LDC or an X-Y coincident pair of SDCs. Both seemed to work, but I liked the mono, volume-change-only effect of the single LDC best.
 




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