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Oddball microphone technique (OMT) - part 4

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checht:

--- Quote from: Gutbucket on January 15, 2024, 02:20:43 PM ---A question related to all this that still lingers for me..

[snip]

And in that case, maybe the center Mid, being relieved of its up front vocal clarity duties, would be better as a cardioid.. or maybe go the other way and use three shotguns across L/C/R, which could allow for a tighter angle with somewhat less spacing between L and R, since that becomes problematic at narrow PAS angles.

Not sure what the right answer is.

Thinking a bit out loud here, but doing so to establishing some of the things I'm thinking about as part 4 of the thread gets rolling.

--- End quote ---

Thanks for sharing your thoughts, super interesting to reflect on.

Is there a "right" answer?

3 shotguns across reminds me of early 90s Dead shows, many folks running that setup using modified Naks. I remember liking some outdoor recordings, but indoor venues not so much. I think it's b/c those shotguns had cruddy off-axis response and didn't do well with the reflected waves. How is off-axis on your stereo shotgun?

Cheers

Gutbucket:

--- Quote from: checht on January 15, 2024, 05:16:20 PM ---How is off-axis on your stereo shotgun?
--- End quote ---
At least in the handful of recordings I've made with it so far it seems fine, both in mono (listening to its Mid channel only) and in stereo (recorded as M/S and converted to L/R in the recorder).  Stereo listening so far has all been done using a single, fixed M/S ratio, since ratio is not adjustable on the F8 during M/S decode playback.  Because of that the ratio is whatever equal input gains across all recording channels provided, since I have all eight F8 input gains linked so that while recording I can effect quick simultaneous gain adjustment across all channels with a single knob turn.

I've only used the direct M/S output mode of the microphone and have not tried it's two L/R output modes (narrow / wide stereo), but I don't really plan to use those.


--- Quote from: checht on January 15, 2024, 05:16:20 PM ---3 shotguns across reminds me of early 90s Dead shows, many folks running that setup using modified Naks. I remember liking some outdoor recordings, but indoor venues not so much. I think it's b/c those shotguns had cruddy off-axis response and didn't do well with the reflected waves.
--- End quote ---
Yeah, that made me think back on the old Dead show section 3-mic setups using shotguns too.  I've speculated in the past here at TS that the folks running an omni in the middle between two shotguns, as was somewhat common back then, may have gained some benefit of the omni masking much of the messy off-axis behavior of the shotguns, in addition to extending frequency response down to Phil bomb territory.  But I've also said I believe it probably would have worked better to flip that arrangement inside out, with a single shotgun in the center flanked by sufficiently widely spaced omnis.  Better bass, better ambiance, and probably better off axis masking too.  Personally I wouldn't want to try using three shotguns on their own without the omnis and rear-facing mics to covering the off-axis.  Spaced omnis with a stereo shotgun in the center and we're talking, but that's one more mic channel than the 3-mic Nak mixer supported. 

Very happy that in this era no one needs to commit to mixing multiple channels ahead of a two channel recorder.

al w.:
I'm happy to report that I was able to try out a 3-mic* setup at a club show last weekend!

The show was Neighbor at Putnam Place in Saratoga Springs, a classic long-rectangle room. I intentionally set up at the very back by the board because I wanted to see how good of a tape I could pull from back there. I was also running solo and was a bit worried about the crowd.

My plan was to run 3 hypers: one in front (Peluso CEMC-6), two wide spaced (3 Zigma CHI FX SD-H), PAS. Because I was so far back in a narrow room, PAS angle was about 50°. The new 3 Point Improved PAS microphone configurations PDF suggests quite a wide spacing in this situation of ~164-170cm (65-67"). I only have (and feel comfortable running that high) a ~100cm bar. Due to this, I was only able to split the side hypers about 105cm. In hindsight, I could have run them on the ends to get a bit wider, but my omnis occupied those spots. (I didn't use the omnis in the mix.) Because the wide hypers were spaced a bit narrower, I shifted the front mic forward a bit. It probably ended up 30-40cm" in front of the bar. I ran my stand about 3m high (9.5'), dead center.

There was a lot of chatter around the mics, which made me a bit worried. However, upon listening I was really, really surprised how little it impacted the recording. My suspicion is that the wide spacing really dissipates the effect, as suggested in previous posts. The chatter is there, but it's much less distracting. Hypers obviously help with this too.

The only challenge was getting the wide hypers pointed properly at the stacks, as mentioned by goodcooker in the 2023 year in review thread. I thought I set them up fairly precisely, but there was still a noticeable level difference between the two sides. The addition of the center channel helped balance this out, however.

In the mix, I quite had a hard time taming the low end. I had to apply considerable EQ and compression to bring it to an acceptable level. Perhaps skipping shock mounts was a bit optimistic!

I'm very pleased with the outcome, especially considering the recording location and chattiness. To my ear, it definitely doesn't sound like a back-of-the-room recording. Thanks Gutbucket for all the info and guidance.

If anyone wants to play with the raw tracks, I'm happy to upload some. I had to leave at setbreak, so I only caught the first set, which you can listen to here:

https://soundcloud.com/al-w-5/sets/neighbor-2024-01-19-saratoga-springs-ny-set-1-full-set

* It's actually a 4 mic mix; I also ran a rear mic because I have the channels, but it's so low in the mix that it's barely noticeable.

Gutbucket:
Thanks Al!  I intended to give an extended listen last night but was unable to, so I squeezed in a brief listen this morning before work.  Sounds very good given that far back of room recording location, with good vocal clarity and articulation, and decent management of the chatter back there.  Very happy to find the arrangement working as intended.  Much thanks for trying it out, posting about it and linking the recording here.


--- Quote from: al w. on January 23, 2024, 10:34:52 AM ---The new 3 Point Improved PAS microphone configurations PDF suggests quite a wide spacing in this situation of ~164-170cm (65-67"). I only have (and feel comfortable running that high) a ~100cm bar. Due to this, I was only able to split the side hypers about 105cm. In hindsight, I could have run them on the ends to get a bit wider, but my omnis occupied those spots. (I didn't use the omnis in the mix.) Because the wide hypers were spaced a bit narrower, I shifted the front mic forward a bit. It probably ended up 30-40cm" in front of the bar.
--- End quote ---

How far away would you estimate the recording position was from the stage/PA?

To gain some additional insight into the specific arrangement you ended up using, I modeled it in Image Assistant, using the maximum distance from the sound source that Image Assistant allows, which is 10m (~33') away.  Other settings were: 3 supercardioids;  L/R pair in PAS angled +/-25° (50° total) and spaced 105cm apart; center mic 35cm forward.

Here are the results:
Direct/reververant ratio stuff-
The powersum is pretty strongly forward-biased, which keeps the direct/reverberant ratio as high as possible and is a significant factor in what helps it work from a distant recording position. This due to the narrow inclusive microphone angle needed to achieve PAS in combination with the tight polar patterns.  Specifically, the difference in sensitivity for sound arriving from directly in front verses 90° off to either side is ~8dB (unfortunately, Image Assistant only provides powersum info for the front 180°, I wish it provided a full 360° view). The powersum isn't strongly affected by changing the spacing between microphone positions.

Imaging-
The Total Stereo Recording Angle (SRA) is 112°. A 50° PAS angle is 45% of 112°.  The stereo image of the band in your recording struck me as filling the stereo field pretty well (listening on headphones). I based all the 3-point PAS spacings on PAS angle = 75% SRA. That offset value is somewhat arbitrary but seems a good starting point. I can talk more about specific reasons for that choice if you like, and the most appropriate range of values for it is one of the main things I'd like to better determine with the help of folks like yourself trying these things out, so thanks again!  75% of 112° = 87° (er 84°, but that's value is what IA reports and is within 3°).   ..so maybe we can get away with a lower offset value that equates to less spacing. ..or maybe it would be even better with some additional spacing and sound more upfront like at least in terms of image distribution.  Over time we'll be able to better determine this, thanks to the help of folks like yourself.
^
[In comparison, based on a 75% offset the suggestion to use an L/R spacing of ~170cm (67") for a PAS angle of 50° produces an SRA of 67°]

The extra forward spacing probably didn't help.  But didn't seem to cause any obvious problem to my ear either. Playing around with the 105cm / 50° arrangement in Image Assistant to optimize it as much as possible, it appears the best image alignment occurs with the center mic 23cm forward.  In terms of imaging, shifting the center mic forward and backward changes the total SRA angle as well as affecting how closely the edges of the L/C and C/R stereo pair imaging sectors line-up and hand-off to each other across the center.  Pushing it farther forward actually increases the SRA and messes up that center hand-over.  This is good news as we don't need to extend the center mic position out much further than about 20cm to optimize things for most PAS angles.

More later.. gotta run..

rocksuitcase:
We record in that bar a lot and I'm going to say the soundboard half-wall where the mics were is about 60 feet from stage. Al, what do you think?

Additionally, there is a back room wall about ten feet behind where the mics were, which could have something to do with your bass taming need. (I do not know the bands material if it is bass heavy by design, etc)

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