Advice on low maintenance recording of large orchestra, please.

[Hugh Robjohns]

Blumlein Faulkner Gerzon et al didn't just magically ooot the ether pull out their arrays, they would have experimented to reject various configurations.

Er... actually all three had/have a thorough understanding of the acoustical and physical science involved, and both Blumlein and Gerzon derived their famous arrays via mathematics first and foremost!

This is called audio engineering for a reason....

Still feel free to do our own experiments : we are not slaves to others concepts. No one's going to die doing such experiments.

Absolutely. I'm a big fan of experimentation as a way of realising and understanding the underlying science and the practical implications of, for example, changing the mic spacing or mutual angles, or even adding additional mics.

[Bob Bickerton]

...... and while we're at it: A shout out for the Neumann Microphone app, Recording Tools. A nice graphic display that shows you what happens when you 'experiment'.

oooooh and I've just noticed they have a new section on it for calculating gain and level - must have an explore.....

Bob

[tea for two]

Just as an aside I have wondered how much of a design, engineering challenge it might be for hand held recorders :
to be able to move their built in cardi mics so that we could attach them to an ORTF mic bar, NOS, DIN, Gerzon;
to be able to swap in couple figs8 capsules included with the recorder to then be able to move them to Blumlein, Faulkner;
also couple swapable omni capsules included with the recorder.
Ofcourse easier less fragile to plug mics into their xlr ins to get these arrays, still I wondered.

Also to have their mic capsules go down to 20Hz. Afaik Nagra Mezzo, Sony D100 D10 built in mics go down to 20Hz. There's prolly some others.

[Hugh Robjohns]

Also to have their mic capsules go down to 20Hz. Afaik Nagra Mezzo, Sony D100 D10 built in mics go down to 20Hz. There's prolly some others.

Every mic goes down to 20Hz... the question is what the sensitivity is at that frequency relative to the sensitivity at 1kHz? Few manufacturers specify tolerance limits.

But from a quick scan of specs, I'd say the 20Hz figures on those machines relates to the electronic bandwidth, not the built-in mic responses.

Going back to the physics and maths, there is a fundamental problem getting a good low-end response from any directional mic because the phase shift across the capsule, and thus the pressure difference tends to zero at low frequencies. This can be compensated mechanically or electrically, to a degree, but this introduces other undesirable compromises, especially in a hand-held device. Consequently, almost all directional mics roll-off quite steeply below about 40Hz. Physics is a bugger....

[Hugh Robjohns]

...... and while we're at it: A shout out for the Neumann Microphone app, Recording Tools. A nice graphic display that shows you what happens when you 'experiment'.

It is excellent. I use it a great deal.

https://www.soundonsound.com/reviews/ne ... ding-tools

Another similar one worth exploring is Sengpiel's Visualisation, which also shows the angular distortion of different arrays.

https://sengpielaudio.com/HejiaE.htm

oooooh and I've just noticed they have a new section on it for calculating gain and level - must have an explore.....

Not new. It's always been there. I find it helpful for calculating headroom margins and initial preamp gain settings.

[tacitus]

I’ll just add my two penn’orth to this, largely so you kind people who’ve trued to steer me in the right direction will know I have been listening and might even have learnt something.

As a player/recordist I fully sympathise with the situation one is in, being part of the sound being recorded and not hearing what you’re doing with it.

The other aspect is the lack of time even to set up mikes and the tendency of people to move themselves or the mikes to avoid what they perceive as the spotlight.

And the other, other aspectvis that often the msin mike stand wants to be directly in front of the conductor, awkward if they talk to the audience, and obscuring their egos, too.

On several occasions I’ve had to put an omni pair up in the little semicircle of dead space between the conductor and front row players. It’s not ideal but -

It’s very present, at the expense of picking up much ambience.

It’s not how you expect an orchestra to sound, but at least you can hear it not sounding like an orchestra (or Concert Band, as I’m usually recording).

As you’re pretty close, the flat response of Line Audio mikes isn’t a real problem, and if you have enough height, the balance is usually OK, too. In a church with plenty of height, the results are probably closer to what people expect on headphones/earbuds.

And with the stand performer-side of the conductor, audience noise and potential interference with the rig is reduced.

I don’t necessarily plan to work this way when I go out to record a concert, especially as I’ve had the luxury of recording gigs I’m not playing in recently. But I find it’s a fairly reliable way of getting at least the sound of the players, if not so much the room, when time, space and cooperation are running low.

I’d echo the field-recorder method with 32-bit uncrashable dynamic range, though at the moment I’m doing OK with 24 bits, running the control app for the recorder on my iPad. The band I’ve recorded several things for recently has actually been least satisfied with the traditional spaced omnis behind the conductor. I wouldn’t say that’s solid ground, but it’s working for me and current “clients”.

I’d love to using a Decca Tree more, even if it’s not the final choice for posterity. I just had the Decca Sound 50-CD set for my birthday and I’m blown away by the sound quality. But as has been pointed out, we’re talking top engineers in lovely venues with large Dexion frames holding mikes in large casings. Not a live option, but perhaps the slender stands Hugh recommended me to use could hold a Line Audio or similarly small mike without intruding overmuch.

Only in the right church or hall, though.

[timcmit]

I’d love to using a Decca Tree more, even if it’s not the final choice for posterity. I just had the Decca Sound 50-CD set for my birthday and I’m blown away by the sound quality. But as has been pointed out, we’re talking top engineers in lovely venues with large Dexion frames holding mikes in large casings. Not a live option, but perhaps the slender stands Hugh recommended me to use could hold a Line Audio or similarly small mike without intruding overmuch.

I really like the Decca tree although I have read that it is normally only used for large ensembles. I rationalise it as placing the mikes above the main string section players. I fashioned my Decca Tree out of 15mm copper piping as the off-the-shelf options were quite pricey, though I paid a bit more for the chrome finish to make it a little more presentable! With compression joints and a partially elasticated inner wire, it folds down quite neatly.

So far, I have tended to record the on-the-day rehearsal rather than the concert - we play everything, but it means I get several options of recording for the tricky bits. It also means I don't have to consider the audience in placing the mikes.

[Hugh Robjohns]

I really like the Decca tree although I have read that it is normally only used for large ensembles.

It is commonly used for large ensembles — in which case it's more typically a 6 mic array (central tree, outriggers, and basses accent) — but a smaller version is frequently employed for smaller ensembles too, where the acoustics and material suit it.

A very good place to learn about it and other techniques for classical music recording is here:

https://www.soundonsound.com/reviews/cl ... -tradition

I fashioned my Decca Tree out of 15mm copper piping...

I'm sure it's fine, but safety has to be top priority with DIY mic rigs. Any mic falling from 3m, or tall mic stands toppling over, can do a lot of damage, and HSE prosecutions can and do have life-changing consequences.

[timcmit]

I'm sure it's fine, but safety has to be top priority with DIY mic rigs. Any mic falling from 3m, or tall mic stands toppling over, can do a lot of damage, and HSE prosecutions can and do have life-changing consequences.

I agree with your concern. I did give this consideration - though will revisit the design to be sure. Currently I have a dual redundant design preventing the various arms from coming apart and an independent arm (fixed to the main stand) to provide extra support for the long central arm. The piping is relatively low mass and will require pretty deliberate action to topple it.

Thanks for the Decca Tree references!

[tacitus]

Yes, I had the Decca book ordered before I’d finished reading the review in SOS. Real stuff from the real experts. Most books on recording cover Decca Tree use with something like the opening of The Go-Between (“The past is a foreign country; they do things differently there”).

When I did a recording course, a full 20 years ago, the tuition on Decca Tree technique was very hazy. With this book have a much clearer idea of what they did, how they did it, why they did/do it and how it turns out.

If I did more recording in suitable situations, I’d claim it changed my life. For the moment I’ll just say it’s enriched it.

[Arpangel]

Low maintenance? I can remember recording a choral society and small orchestra with a friend, one Olympus LS10 MiniDisc recorder, a Sennheiser MKH30/40 MS pair, press record and that was that. We spent most of the time in the refreshment tent.

[timcmit]

one Olympus LS10 MiniDisc recorder, a Sennheiser MKH30/40 MS pair, press record and that was that.

I'm interested where you put the microphones and what you thought of the results?

(Different device, but when I used the Sony minidisc I seemed to spend an eternity working out Sonicstage!)

[Arpangel]

one Olympus LS10 MiniDisc recorder, a Sennheiser MKH30/40 MS pair, press record and that was that.

I'm interested where you put the microphones and what you thought of the results?

(Different device, but when I used the Sony minidisc I seemed to spend an eternity working out Sonicstage!)

A very large church, very large.
Mic's up high, on a tall stand, about 15ft in front of stage, to be fair, I think we put a couple of spot mic's out, there were a few solos that needed boosting, on those I think we used a couple of Beyer M201's, can't remember.
The results were fine using Sennheiser HD600 cans on site, back home on our K+H 310's sounded fine too, my friend was happy as he got paid, so his clients must have liked it!

[tacitus]

Clearly, refreshment-based sound engineering is not as lacking in merit as I thought.

Further development could be interesting, maybe.

[Hugh Robjohns]

I can remember recording a choral society and small orchestra with a friend, one Olympus LS10 MiniDisc recorder, a Sennheiser MKH30/40 MS pair, press record and that was that. We spent most of the time in the refreshment tent.

Erm... the Olympys LS10 is a tiny handheld SD card recorder with no facilities for balanced mics or phantom power.

However, as I recall, Mike Skeet often used a Sharp minidisc recorder, along with his own 'ITZA' preamp/mixer hardware. Perhaps you're thinking of that?

Mike certainly had both the ears and experience to know where to get a good sound from an MS array.

[Arpangel]

Clearly, refreshment-based sound engineering is not as lacking in merit as I thought.

Further development could be interesting, maybe.

It was All Hallows church Gospel Oak, big choir, orchestra, can't remember all the details, it was a typical "are you busy, I need some help" call from my friend.
AFAIWC it was just another church gig, you can see my friends approach to things here,

http://www.saturn-sound.com/Curio's/the ... 0index.htm

He was a minimalist as far as recording goes, he liked to do a lot, with very little, he was very much "if you can't do it with an stereo pair" then there's something wrong with you
But saying that, he did use multi-mic set-ups sometimes, he couldn’t avoid it.
He had the most amazing collection of microphones, and always spent his money where it mattered, good mic's, good monitors, he also built his own mic rigs, like dummy heads etc for binaural recording.
Great guy, taught me a lot, some of it not relevant to me personally, but it was fascinating working with him, it was great knowing him, always got me going doing some recording, when I was feeling down sometimes.
Hugh, you’re right, in that case that's what we used on that day, it was ages ago, he used a mixture, and I don’t remember sometimes.
I always used to have a go at him about using MiniDisc, but, there's no denying he got great results from them

[Hugh Robjohns]

I always used to have a go at him about using MiniDisc, but, there's no denying he got great results from them

MiniDisc was a very good format in many ways, and often more reliable than the stereo digital alternatives at that time: the DAT, and the PCM F1/701/601/501.

Yes, it used a lossy codec, but Mike didn't do anything major in the way of processing so it didn't really matter that much... and ATRAC was a very sophisticated codec with minimal artefacts in normal use.

In fact, Dolby Labs challenged Sony over some of ATRAC's algorithm design which infringed Dolbys patents related to their AC3 codec... and I believe Sony ended up paying royalties to Dolby on every MiniDisc machine and disc sold!

[Arpangel]

I’ve got loads of Minidisc’s but no player, loads of DAT tapes too, but my old Tascam DAT machine is still plodding on.

[timcmit]

A very good place to learn about it and other techniques for classical music recording is here:

https://www.soundonsound.com/reviews/cl ... -tradition

I bought this book and is a surprisingly easy and enjoyable read. I noted that the separation between the left and right microphones is notionally suggested at around 1.3m, with the centre being 91.5cm in front. I've seen larger dimensions suggested, but these authors do not seem to recommend variation from these dimensions - do you have a view on this? A smaller tree is obviously easier to handle.

I have also assumed that the centre microphone is troublesome as its centre panning will mean it is combined with L and R microphones with the presumably inevitable phase issues that should ensue. My only thought was that although the front desks of the strings will dominate, the whole string section helps to consolidate the sound, tending to negate such issues of phase (which maybe why the adjustment of height is quite critical). I thought the book might me to understand this, but could not find an explanation. I do note that a 4 microphone tree (with a spaced pair and outriggers) can be used to good effect and wonder if this is due to removal of the centre microphone. You've been very kind and helpful with previous responses - I wonder if you have any explanation?

[Hugh Robjohns]

I noted that the separation between the left and right microphones is notionally suggested at around 1.3m, with the centre being 91.5cm in front. I've seen larger dimensions suggested, but these authors do not seem to recommend variation from these dimensions - do you have a view on this?

They're discussing Decca's specific evolution of the array, as used in Decca's preferred venues, and it's a 6-mic array (tree+outriggers+basses), not a simple 3-mic tree.

Other labels, other engineers, other mics and other venues all prefer or need slightly different dimensions to achieve the sound they want. There are no rules, just guidance and ears.

I don't use a tree very often, but when I do it's usually around 1.5m wide at the back, with the centre around 1m forward. Smaller ensembles usually need smaller dimensions, and I use a 60cm bar at the back with the centre mic on a 20cm bar projecting forward.

I have also assumed that the centre microphone is troublesome as its centre panning will mean it is combined with L and R microphones with the presumably inevitable phase issues that should ensue.

I don't perceive the centre mic as troublesome, at all, and it's usually essential for giving a solid, stable stereo image. If, by phase issues, you're referring to comb-filtering in mono, that's more likely if using smaller tree dimensions. The larger the tree, the better the decorrelation between channels, and it gets better still with outriggers (as in the standard Decca arrangement).

I do note that a 4 microphone tree (with a spaced pair and outriggers) can be used to good effect and wonder if this is due to removal of the centre microphone.

I'd caution against the four mic wide-spaced array, especially if you're pressed for set-up time. The inner mic spacing is very critical and both difficult and time-consuming to optimise. Theres a big risk of getting a hole in the middle of the image, or a very flat and squashed image centre.

[timcmit]

Very much appreciated!

If, by phase issues, you're referring to comb-filtering in mono, that's more likely if using smaller tree dimensions.

I was more referring to what I expect to be a problem when say the first cello is captured by both the centre and right microphones with different delay (later combined in a single channel); I expect them to still have similar amplitude and, at a relatively low frequency, are perhaps likely to experience similar gain from the polar pattern. It seems clear that this is not a problem, which probably means my understanding of the physics is wrong!