Topic: Acoustic Recording Techniques

[fanofjam]

Nothing to add other than to say how much I love the simplicity of a bluegrass band playing/singing acoustically around a single omni mic, then leaning in when their lead comes around.  And how often does that recording sound as good as anything anyone can do with a much more elaborate rig.  'Bigger' doesn't always translate to better...guess it all depends on what you're after.

[HealthCov Chris]

Yep.  I love this style as well.  Sometimes a 2nd lower (instrument) mic comes in handy to make solos a bit easier for the musicians and cleaner for the recording.  I have wanted to setup something like this for years backstage at a local bluegrass festival.  Grab whoever I can get to play 2-3 songs together throughout the weekend.  Thinking single LG for vocals and a lower SD for instruments > into a Zoom F3, so all I need to do is hit Record and Stop.

[Gutbucket]

^ and ^^..
The on-stage setup Chatham Co Line uses for their center mic-stand (or at least used to) is a good one for up close taping of blue-grassy stuff with vocals.. you know, bands doing the typical "step up close for solos" and "all lean in for harmonies" thing.  That's a LD mic up at face height with a ORTF-ish near-spaced pair at instrument height a foot or so lower.  Very doable with taper gear. [Edit- to be clear, CCL uses this setup on stage feeding a PA for reinforcement, however the reason I mention it here is that it works great for recording non-PA reinforced bands playing to just themselves, a handful of people, or whatever in a non-PA reinforced situation using a single mic stand.  Easy to setup backstage or at camp or whatever.  Best to push the LD vocal mic something like a foot or so forward of the near-spaced pair for easier access to it, gets it closer to the center of a half-circle of singers]

[Gutbucket]

Been contacted again about recording a choir that has minimal instrumental accompaniment - an acoustic guitar on a song or two, some hand held doo dads like sleigh bells for a Christmas song not sure they are being kinda vague. Small ensemble of a dozen. A lot of them are in higher education and have access to spaces in the music department so I've been pushing them to find a larger more lively sounding space than a treated rehearsal room.

They are accustomed to their physical arrangement (five in front seven on a riser behind straight line no curve) but I'm curious about what y'all think about where the instruments should be located? I'll put a spot mic on the guitar so it can be panned in the mix later but with the split omnis and wide ORTF subcards I plan to use as the main pairs to choose from later - in addition to two LDC cardioid vocal spots - there's going to be location cues in the main mix already especially if it's all the way to one side. I'm guessing I can just mix the spot mic for instruments and find where the panning works best but curious how any of you have approached this. Also guessing that whoever is jangling the bells and whatnot will just be doing that from their set location in the ensemble so I don't have much to do on those tunes except hope for the best. The guitar is a whole different thing though.

Sounds like you have a good plan already. Definitely push them to perform in the best hall available; a dead rehearsal room will sound like what it is.

A lot depends on the rep they are performing. If you get a good hall, you may not need any spot mics at all and your CM3s might cover everything. Or, your omni's alone. 50 cm is usually my starting point depending on the SRA. You might even try the Tony Faulkner 47/67 phased array of subcards and omnis here, but again a lot depends on the room and the repertoire.

I've done choir with acoustic guitar (in a beautiful sounding church) and didn't need a spot for the guitar. I would also be surprised if you need choir spots for an ensemble this small, unless you wind up in the dead room.

I would locate the guitar in the center. Put aux percussion to either side, but not wider than the side boundaries of the choir. I find it really distracting in a recording when percussion is hard L or R with choir - it keeps pulling my focus off-center, making the whole recording seem off-center.

How'd this go?

Fully agreed with all points discussed.  Particularly about pushing for a good hall,  also on percussion or any other supporting instrument being way too far off to the side.  Although probably not necessary I'd spot mic the guitar if its not a hassle, as it can be easy for that instrument to get lost at not much of a distance, and its nice to have the option of reinforcing its subtle details and panning that wherever is best.

[voltronic]

Heads up - an amazing recording techniques book I purchased a couple years ago is on sale:

https://www.routledge.com/Classical-Recording-A-Practical-Guide-in-the-Decca-Tradition/Haigh-Dunkerley-Rogers/p/book/9780367312800

(also added to the Resource List in a post reserved for print resources)

[WiFiJeff]

Very good book.  When it came out I got it for $50 (paperback) at Amazon, it now seems to list for $55.  But Amazon is offering it for $41.63, which is even cheaper than this listing. 

[TSNéa]

Classical Recording A Practical Guide in the Decca Tradition
https://www.routledge.com/Classical-Recording-A-Practical-Guide-in-the-Decca-Tradition/Haigh-Dunkerley-Rogers/p/book/9780367312800
£31.99 + VAT £1.76 + free shipping to France (from UK).

C'est fait !
Thank you, Voltronic!

[voltronic]

Classical Recording A Practical Guide in the Decca Tradition
https://www.routledge.com/Classical-Recording-A-Practical-Guide-in-the-Decca-Tradition/Haigh-Dunkerley-Rogers/p/book/9780367312800
£31.99 + VAT £1.76 + free shipping to France (from UK).

C'est fait !
Thank you, Voltronic!

C'est un prix fantastique !

[voltronic]

Here are samples from a recent concert. I did an experiment with a mic arrangement used for a time by Onno Scholze at Phillips. DPA 4006A with only 32 cm capsule spacing, angled out 90 deg. On paper, this shouldn't work, but I think it came out pretty decently. I'm curious to hear comments on how you perceive the imaging. Not sure if I'll do this again or go back to my usual starting point of 42 to 52 cm spacing, straight ahead or with a slight opening angle.

The third track adds a pair of Line Audio OM1 in a similar arrangement but further back. That one involves over 600 student singers.

Before listening, go to Audio Options at the bottom and enable Lossless.
https://samply.app/p/4T0HHxD3xntJcLu3qYGn

[Gutbucket]

Looking forward to giving a listen tonight..

I did an experiment with a mic arrangement used for a time by Onno Scholze at Phillips. DPA 4006A with only 32 cm capsule spacing, angled out 90 deg. On paper, this shouldn't work,  [..snip]

Because on paper the spacing is overly narrow?  I suspect it will produce some binaural cues and have a solid center but not sound as open or wide as it would with increased spacing.  At that spacing a center baffle is likely to be helpful. The 90° inclusive angle should help provide a bit more stereo interest and openness up top.

I just modeled it in Image Assistant. SRA is somewhat strongly dependent on distance from the source.  If placed relatively close, ~2m away, total SRA is 119° (75% SRA = 71°). If relatively far ~10m away, total SRA is 143° (75% SRA =  79°).  A difference in SRA of 24°.  Perhaps of greater importance than image distribution, DFC (Diffuse field correlation, lower is better) remains high (>0.9) up to around 100hz, then drops off between there and 500Hz where it reaches zero, remaining fully decorrelated above that point.

Not sure if I'll do this again or go back to my usual starting point of 42 to 52 cm spacing, straight ahead or with a slight opening angle.

Modeled that too for comparison- At 42cm, SRA is less strongly dependent on distance from the source than at 32cm.  If placed relatively close, ~2m away, total SRA is 86° (75% SRA = 54°).  If relatively far ~10m away, total SRA is 93° (75% SRA =  58°).  A difference of 7°.  DFC improves slightly, remaining highly correlated (>0.9) up to around 70hz, then drops off between there and 400Hz where it reaches zero and remains fully decorrelated above.

And at 52cm with the array ~2m from the source, total SRA is 67° (75% SRA = 44°). 10m away, total SRA is 72° (75% SRA =  46°).  A difference of just 5°.  DFC is improved somewhat further, remaining high (>0.9) up to around 60hz, dropping off between there and 200Hz where it reaches zero, remaining fully decorrelated above.

I don't think any of those configs are wide enough to have any problem with hole in the middle.  Preference for one over the other is likely to come down to 3 things: Image distribution (SRA), the portrayal of reverberance (DFC), and possibly, the alteration of frequency response ripple in the upper bass from the constructive/destructive interaction of wavelength as it relates to the spacing between microphones.

The DFC corner frequencies are somewhat high for all of them IMO, but that can only be improved further by increased spacing.  I suspect I would likely prefer your wider 52 cm spacing because of the difference in reverberant portrayal, unless weaker voices in the center of the ensemble needed help from the wider SRA, image-distribution-wise.

[TSNéa]

Classical Recording A Practical Guide in the Decca Tradition
https://www.routledge.com/Classical-Recording-A-Practical-Guide-in-the-Decca-Tradition/Haigh-Dunkerley-Rogers/p/book/9780367312800
£31.99 + VAT £1.76 + free shipping to France (from UK).

C'est fait !
Thank you, Voltronic!

C'est un prix fantastique !

En effet : je n'ai pas hésité une seule seconde !
It arrived a few days after my order, a well-packed new item.
Now I just need a classical orchestra to practice...   

[Gutbucket]

Here are samples from a recent concert. I did an experiment with a mic arrangement used for a time by Onno Scholze at Phillips. DPA 4006A with only 32 cm capsule spacing, angled out 90 deg. [snip..]

Looking forward to giving a listen tonight..

Wasn't able to do that and listen in full, but was able to give a brief listen to the three files yesterday morning, and quite like the portrayal of the chorus (listening on headphones).  Nice even distribution with a good solid center.  Also liked the image positioning of the musical accompaniment - over to the sides, yet not excessively hard panned, and didn't feel the increased diffuse field correlation at low frequencies is problematic, at least in my somewhat brief listen over headphones.

Very much like the sound with the inclusion of the OM1's, which to my ear adds a bit of depth and dimension that is attractive (which may be due to increased reverberant decorrelation).  Strong 600 student chorus!

Thanks for the listen!

[voltronic]

Here are samples from a recent concert. I did an experiment with a mic arrangement used for a time by Onno Scholze at Phillips. DPA 4006A with only 32 cm capsule spacing, angled out 90 deg. [snip..]

Looking forward to giving a listen tonight..

Wasn't able to do that and listen in full, but was able to give a brief listen to the three files yesterday morning, and quite like the portrayal of the chorus (listening on headphones).  Nice even distribution with a good solid center.  Also liked the image positioning of the musical accompaniment - over to the sides, yet not excessively hard panned, and didn't feel the increased diffuse field correlation at low frequencies is problematic, at least in my somewhat brief listen over headphones.

Very much like the sound with the inclusion of the OM1's, which to my ear adds a bit of depth and dimension that is attractive (which may be due to increased reverberant decorrelation).  Strong 600 student chorus!

Thanks for the listen!

Thanks for the feedback. I keep listening and sometimes the spread sounds natural to me; other times I think the image is a bit bunched towards the center. Still not sure if I want to do this again, but it worked better than I expected.

[goodcooker]

I reached out to a local graduate student composer who is presenting one of his orchestral pieces at the local convention center/performing arts center https://www.century2.com/plan-your-event/event-spaces/concert-hall and he looked into his contract. No recording except through the house contractor unless you pay a $1000 fee. Oddly it's not union just a "our people get first dibs" type situation. Not unusual.

He emailed me tonight and said he would like to record the dress rehearsal the night before the performance. It will be at the concert hall at the local university which will be fair game. I'm kinda excited because I'll be able to have freedom from worrying about audience sightlines.

60 performers many from the conservatory but also students and a few professionals.

[Gutbucket]

^ Right on! Very exciting recording a full orchestra in a good hall! Have you heard other orchestral performances in that university hall?  How is the room? 

I've very much enjoyed a number of new composition works performed at a couple local universities and a post-graduate organization here over the years.  I consulted with one graduate composer focused on oceanic themes who was using underwater samples as an additional element in conjunction with the orchestral performance about practical ways of extending the underwater recording techniques used for gathering them from mono to stereo and multichannel, as their hall was capable of supporting that.  I think it would have been fitting and the idea was attractive to him as one of his key motifs was oceanic flow, movement and immersion.  The primary idea behind it was to use spaced arrays of hydrophones (all of which are natively omnidirectional) with the spacing scaled up such that the time-of-arrival cues though saltwater equated to those of typical stereo/multichannel microphones arrays in air.  Underwater acoustic recording techniques!  We also talked about using scaled up sphere attachments, filled with water to achieve neutral buoyancy, but those would need to be about the size of basketballs.  Increasing the spacing was much simpler.

Unfortunately he graduated and moved on before we got a chance to try those ideas.  That hall has a nice but rarely used pipe organ, which I secretively hoped he'd employ to convey deep abyss-ness.