Hall Mics for Classical - Where should I place them?

[3rd&4thT]

Add to front array pointing back, or hang them out in the hall?

Why?

Cheers,
3rd&4thT

[audio ergo sum]

Zen master Hallmicsuki always says:
"Place them where the sound is the best"

Seriously: it depends
coloration, decorrelation, away from the audience with the asthma, acoustic predelay etc.
are some of the factors that influence the decision where to put them.

front to back separation when "added to front array pointing back" is usually with cardioids then. This gives a clean ambient sound, good for picking up the audience reaction or discrete surround sources, but for envelopment and spaciousness more delay between front and back is often needed and the spaced omnis give the decorrelated LF response that creates the envelopment.

In an unknown hall it is mostly empiric (read trial and error) and also depends on the recorded score and what is best for it.

When hanging, then often straight down, since adjusting angles in horizontal and vertical plane can be a major inconvenience. There often are a lot of logistical restrictions on the placement of room mics. (who has that key for the roof level again? No mic stands in the aisles the fire department says? We are not allowed to hang microphones over the audience the law says in this country?)

For surround signals often the mics point to the back of the hall to pick up best the HF of the rear and side reflections and have the HF of the direct signal from the front attenuated naturally (omnis are never omnis for HF). In stereo that can also be desirable, but is often less critical when mixing these signals to the front.

[fifthcircle]

Don't generally use hall mics.

Seriously, though, it depends... What kind of mics are they? What are you hoping to achieve with them? I usually will have omnis out in the hall, spaced and still aimed at the group. This allows you still get some direct sound which helps fill in the ensemble sound.

In the end, I find that most of the time a set of mics in the hall does not give you anything that is very usable. In live shows, it picks up HVAC, audience noise, etc... In sessions, unless the hall really sounds great, you don't want that sound anyways. Better to just use a Bricasti.

--Ben

[audio ergo sum]

Originally Posted by fifthcircle

D... In sessions, unless the hall really sounds great, you don't want that sound anyways. ...

I share the sentiment, but also often regret that recordings worldwide loose the different flavors and many are basically recorded in "lexicon large hall" anyway. These days younger engineers have grown up with the artificial room sound as the reference and have often problems to appreciate the unique and variable sound of real rooms.

In my work true dedicated hall mics have a renaissance since we mix for surround. Of course you need a room that sounds good...

[Ozpeter]

If you want to add room reverb without room noise, consider convolution reverb. Maybe create your own sample in the empty and hopefully silent hall.

Personally I tend to ask myself two simple questions when recording classical music and considering how many mics to use -

First question - how many ears have I got?

Second question - in how many different places at once do I normally like to have my head?

Pretty radical simplification I admit, but it's not a bad starting point.

[Corran]

Originally Posted by audio ergo sum

For surround signals often the mics point to the back of the hall to pick up best the HF of the rear and side reflections and have the HF of the direct signal from the front attenuated naturally (omnis are never omnis for HF). In stereo that can also be desirable, but is often less critical when mixing these signals to the front.

This is not correct - Earthworks mics (and I assume some others with the extremely small capsules such as Avensons, though it might be proprietary to EW) have almost linear response at all angles, except maybe directly behind them at 1 inch.

See the Earthworks site, or Earthworks - Perfomance Comparison Charts

That's one of the reasons I enjoy using them in various places and regardless of angle, and makes them very good at recording the hall.

[audio ergo sum]

Yeah, that's the "measurement microphone" department. Somehow they never really cought on in the classical music production. DPA has something like that also, it's used occasionally.

If we consider, that psychoacoustics for spatial hearing split the hearing range roughly in the HF >2kHz range where intensity differences matter and the LF range below where time differences matter, the directionality for HF in Omnis might be quite welcome. Think M50 where this is even amplified.

The omni sound we like is not because of the lack of directionality but mostly for the pure pressure receiver principle with its good LF response and good transient pickup!

[Corran]

Yes, I've grappled with that on occasion. At the end of the day, I really like the sound the Earthworks mics are giving me, regardless of the "standard" omni sound. I look forward one day to comparing them directly to some other standard mics such as Schoeps, DPA, Sennheiser, etc.

Also, and I'm going to write a lengthy post on this later this week, I just completed some plexiglass circles that fit over the end of my EW mics and they have the effect of increasing the sensitivity (thus lowering the noise floor) and giving the mics more directionality. But that's for later.

[Don S]

Originally Posted by audio ergo sum

I share the sentiment, but also often regret that recordings worldwide loose the different flavors and many are basically recorded in "lexicon large hall" anyway. These days younger engineers have grown up with the artificial room sound as the reference and have often problems to appreciate the unique and variable sound of real rooms.

Especially when the budget is there, one of my favorite things to do is feed the verb with an ambient pair and use a mix of both. Even the most ambient of recordings I've worked on needed a touch of "lex".
There is also the Eargle technique of using figure 8's with the null facing the stage for ambience, but I prefer omnis.

[3rd&4thT]

Originally Posted by Ozpeter

First question - how many ears have I got?

Second question - in how many different places at once do I normally like to have my head?

Pretty radical simplification I admit, but it's not a bad starting point.

Isn't there a flaw in that? We have two eyes, and only see in front of us. We have two ears, but hear in 360 degrees. Therefore including the sound behind us should increase realism, as we don't naturally only hear what's in front.

Cheers,
3rd&4thT

[Plush]

Hall mics can be helpful to define the width of the stage or to give bloom.

I think of hall mics as mid way back omnis pointing straight down.

In Carnegie Hall, hall mics are cardioids over the 2nd or 3rd row pointed at the stage. These help to give bloom to the sounds coming off stage.

If it's winter then the hall mics far back just pick up coughing, so then they have to be dumped out.

[3rd&4thT]

Originally Posted by Plush

Hall mics can be helpful to define the width of the stage or to give bloom.

I think of hall mics as mid way back omnis pointing straight down.

In Carnegie Hall, hall mics are cardioids over the 2nd or 3rd row pointed at the stage. These help to give bloom to the sounds coming off stage.

If it's winter then the hall mics far back just pick up coughing, so then they have to be dumped out.

Hiya Plush,

I was in Carnegie this week, and now they do hall mics according to your original concept, pointing down and almost halfway back, at 1/3 and 2/3 the width - I assume they are omni's. I believe this is how WFMT used to broadcast the Lyric Opera of Chicago in surround.

BTW, the Cleveland Orchestra is still one helluva band. Hans Smellser-Wurst asked them for arbitrary, inorganic tempo changes, limp phrasing and clotted textures, and they gave him everything he asked for. A great night out.

Cheers,
3rd&4thT

[joelpatterson]

Originally Posted by Corran

... I just completed some plexiglass circles that fit over the end of my EW mics and they have the effect of increasing the sensitivity (thus lowering the noise floor) and giving the mics more directionality....

I already know I want to order a set of these from Corran Enterprises.

But when you're talking about "getting the hall sound," it's not like any mic you place is going to "exclude" the hall sound, eh? It seems like the battle is always "getting" the performers in a clear, non-murky way. For me, "hall" and "murk" are blood brothers, so unless there's a specific need to capture the audience's contribution to the show-- a singalong?-- I just keep the mics fairly close to the talent and aimed their way.

That said, I usually place four sets of mics arrayed around the stage as though the music were filling a giant fishbowl and the mics are at the surface of this fishbowl, so maybe some or other of these would technically be "room" mics?

[3rd&4thT]

Originally Posted by joelpatterson

But when you're talking about "getting the hall sound," it's not like any mic you place is going to "exclude" the hall sound, eh?

Actually, there's always been a strong tendency to make live recordings and broadcasts that do exclude the hall sound.

Any hall with traffic problems, which is most of them, or subway rumble, or bronchial audiences, or an overhang that complicates editing, is a candidate for exclusion. The history of orchestral recording since the introduction of the electrical system in 1925 is a series of waves of trying to figure out how to record a natural sound with as little hall resonance as possible.

If you listen to Toscanini and the NBC recorded between 1950-1954 in Carnegie, you can't hear the unique signature of that hall ever. No characteristic bass, no decay, nothing. They might as well be back in Studio 8-H.

Same goes for most vintages of Concertgebouw recordings, and sessions in Boston's Symphony Hall and Vienna's Grosser Musikvereinsaal to this day are made in frantic defiance of hall acoustics.

Murk is your friend. Tame it, but use it.

My $.02 anyway,
3rd&4thT

[studentjohn36]

I just got some spectacular results with 4 AT3032's... Okay, the Allen Heath Zed14 makes them sound a whole lot cleaner than ever they did in the past.

Big church, but no chance for a "Decca" centre mic. (they contract out lightbulb changing, so they don't even have a long ladder in the house)

Main stereo pair just behind the conductor, and another pair back in the woodwinds with on-axis ends poiting away from the brass.

[Audiop]

Originally Posted by Ozpeter

If you want to add room reverb without room noise, consider convolution reverb. Maybe create your own sample in the empty and hopefully silent hall.

Personally I tend to ask myself two simple questions when recording classical music and considering how many mics to use -

First question - how many ears have I got?

Second question - in how many different places at once do I normally like to have my head?

Pretty radical simplification I admit, but it's not a bad starting point.

Good starting point for binaural, questionable for stereophony and really flawed for multi-channel. :-)


/Peter

[dtf]

Originally Posted by 3rd&4thT

Same goes for most vintages of Concertgebouw recordings,

That's probably because most recordings in the Concertgebouw's Grote Zaal were done with the orchestra on the floor of the hall, not on stage. Philips did that most of the time and Decca - as far as I know - always. When you remove all the chairs to do so, of course, the acoustical signature changes quite a bit.

There are recordings with Antal Dorati on Philips Classics (was it Smetana?) by Engineer Hans Lauterslager, which are just wonderful and do have that typical acoustic signature. Nowadays, all colleagues that I know of record with the orchestra on stage (at least that's how the RCO does it, as most of it is live).

In the Musikverein you have the issue of wooden chairs - when in session without audience, the reverberation time in the lower frequency band can rise up to 7 seconds!

As far as Hall mics are concerned, I think you can't answer the question just like that - the uses and applications are endless. One thing that I think is worth mentioning, is that in many cases, hall mics should be used in conjunction with the mains - meaning: the mains are probably too close to be used without the hall mics. It only works together.

Dirk

[d_fu]

Originally Posted by dtf

There are recordings with Antal Dorati on Philips Classics (was it Smetana?) by Engineer Hans Lauterslager, which are just wonderful and do have that typical acoustic signature.

Smetana (Ma Vlast) and some Dvorak. Me have, me like...
Good recordings indeed.

[dtf]

Originally Posted by d_fu

Smetana (Ma Vlast) and some Dvorak. Me have, me like...
Good recordings indeed.

And, if I am not mistaken, done with 3 mics only!

[d_fu]

Originally Posted by dtf

And, if I am not mistaken, done with 3 mics only!

Namely? Decca Tree with three M50?

[RobAnderson]

Hi Plush

In Carnegie Hall, hall mics are cardioids over the 2nd or 3rd row pointed at the stage. These help to give bloom to the sounds coming off stage.

This must have been some time ago. Currently there are two options for "room" at Carnegie in Stern Auditorium: there are 2 Schoeps MK2's hanging straight down in the middle of the hall, and there is also the Blumlein AKG stereo mic (used mostly for stagehand recordings and lobby feed) which can serve for closer ambience and its distance to/from the stage can be adjusted somewhat. This mic is not often used for this purpose, but can be nice for an "early reflections" option if things are being multi-tracked.

Of course, a visiting engineer has the option to hang whatever/wherever s/he wants in addition to these.

The problem with room mic's is ambient noise - especially here in NYC - ventilation, audience, traffic, etc. Even at Carnegie, the subway can often be heard rumbling by underneath.

If it's winter then the hall mics far back just pick up coughing, so then they have to be dumped out.

Don't get me started on this one - New York audiences are terrible - and of course they wait for the quietest moment in the music to begin their hacking and make make no attempt whatsoever to stifle the sound.

[dtf]

Originally Posted by d_fu

Namely? Decca Tree with three M50?

I'd be surprised if one of the Philips Classics teams ever used a Decca Tree for a commercial release. I believe Mr. Lauterslager used a modified Mercury M3 main system - think of 3 mics in a line with L/R approx. 3m apart. I am pretty sure he used Schoeps omnis, though in that time there was quite some experimentation with the high frequency rise (e.g. MK3 'S') and cutting off the grids, to make sure that after all analogue copy stages there would be enough treble left in the master. In my opinion, these guys were the real geniusses.

It has to be said that they had a lot of time during rehearsals to find the right balance (which doesn't change the fantastic result, of course!).

[7rojo7]

I like the word 'bloom'. 2 CCM21 @ 180 deg 4-8 m behind the main array (12 to 24 ms predelay, in the 'just noticeing' the Haas effect threshold) the distance depends on the critical distance of the space, thence changes depending on which space you're in, if I think the hall can replace the digital verb. Gives a lot of depth to the percussion and bass heavy things, the bass is better a little further back. This is for live to 2, for multitrack I can get a little farther back but the problem remains that the futher back you get, the more everything becomes mono. If you put up widely spaced omnis in the middle of a hall, you're basically getting 2 almost identical signals. You can push pull eq them for a little more stereo effect but you don't get much detail, funny as it might seem but I believe detail is important for 'murk'. Detail can make your 'murk' 'bloom'.
In the end I think my job is to use the speakers to trick the mind into believing that the speakers don't exist. I think techniques such as multitracking, multiple mic'ing, track delaying (works wonders with a drum kit too) etc..., in no way adulterate the 'sound'.Putting the wrong mics in the wrong places will do this and will not be fixable. Just because I didn't use a Decca tree or a NOS pair hanging exactly where some book told me to hang it and so on, doesn't mean I've made a bad recording, or that I'm a charleton either.
Simple mic setups often sound clearer because they have a simple time relationship between the different sources, slipping tracks around with multimic arrays can help clear up the whole 'image'.
I don't have enough fig8s or I would have tried a Hamasaki square, IRT cross is another usual suspect, binaural too, OCT, M/S? Too many channels on a budget, too much fiddlin, twiddlin and lis'nin.
Seeing a good concert in a good hall will make you crap your pants! A concert goer hears very differently than a musician or an engine-ear. It can focus on sounds with its eyes, its echo location is in tune with its physical surroundings, the animal is alive. When I go to a concert I immediately know approximately, the seating capacity, the volume of the stage area and the 'hall' and make calcultions on standing waves, check out if there are any mics around, have a look at the sound board and light board, I have to turn this all of if I want to become a listener. Your average listener isn't distracted by such things.
We don't have at the moment, maybe IMAC comes close, a medium which will reproduce, sonically or visually, a Concert. We can make it louder, but that's not really better, closeups, big screen, but it's too fantastic to be believed by the brain.
So 2 speakers have to tell a story and you must make it sound good on 1 speaker also. Use whatever you have to.
If there's some good ER I'll try to grab that and turn the ER off in the verb and play with the tail if I don't get enough from the space, that's why I like the half omnis @ 180 deg facing the sides, it gives a discrete LR, it's a coincdent pair so timing is simple making the bass tight. If I'm multitracking, I will play with the delay to maximize the low end response of the whole system. Delay or slipping is different than moving the mics closer. Omni flankers will give you a nice hall sound ER signature etc...

[dtf]

Originally Posted by 7rojo7

If you put up widely spaced omnis in the middle of a hall, you're basically getting 2 almost identical signals.

A lot of what you write makes good sense, but I don't agree with this quote. At least, I have never had this experience. The reason why you space the omnis widely is exactly to avoid too much correlation. And a diffuse sound field is not the same at different places.

As far as the topic is concerned, I find more important the balance of the instruments in the hall - sometimes adding hall mics distorts the depth of the image, as not all instruments project similarly into the hall.

Best,
Dirk

[Audiop]

Still two directional mic's will be more decorrelated than the omni pair.

I tried it and liked it.


/Peter

[Tommy like sound]

Most decent halls are designed to sound best in the middle. I've put mics in the middle and I've put them much further back. Whatever they'll tell you about phase it still ends up sounding good if they're far away from the stage and far apart from each other.

Wherever you end up putting them though, you might end up blending it with a reverb if something leaks in that you don't like. using omni mics or blumeline and such increases the chance of this happening.

The trick I use is to HPF the room mics so they have the nice untainted highs and then low pass filter the reverb on the stage mics. Because the highs are usually the weakest part of a reverb, the sound will be much better than reverb alone. And you won't have anything leak into the room mics that will distract from the performance. Kill the filters on the applause and it will add to the impact.

[Audiop]

Hi!

Some thoughts..

Originally Posted by Tommy like sound

Most decent halls are designed to sound best in the middle.

Sounding good to the human ear in that location is one thing, working with a mix of multiple mic's played back by a pair of speakers is another thing (ie. not necessarily the same thing).

I've put mics in the middle and I've put them much further back. Whatever they'll tell you about phase it still ends up sounding good if they're far away from the stage and far apart from each other.

Agree except for the fact that directional mic's give good results close to eachother as well. It depends on you goal.


/Peter

[7rojo7]

Depends on how far back they are, the middle of a hall could be really to far, I won't place anything further back than 8 meters from the main array and that's even way too far for me normally.
If you draw a line from one omni to the closest source and another line to the furthest source, then do the same with the other omni. The further you move the 2 mics back, the more the distance between these lines becomes equal, thus all lines would become (close to) equal, AB mic arrays work with volume (inverse square) and time, if the lines are all close to equal you will be missing the factors that make an AB array work. You would have to move the mics wider apart the further back you place them. To me this doesn't sound good ever, even if I can slip it forward, if I don't it sounds like a delay. And it picks up too much direct (which I already have nicely) but from further back, (when I'm looking for something to add a little bit goo)
Boundary mics can work for goo also, but it's more of an effect than capturing the sound of a space, it works, it sounds good, but it's not the best.
Simplest is a coincident pair of cardioids pointing back, placed anywhere from directly with the main array to 4 meters back (just because a cardioid is pointed away from something doesn't mean it doesn't pick anything up, it's just serioously 'filtered and attenuated', the distance would depend on the critical distance of the space and the volume of the source)
I haven't tried but there's an ATMOS mike, and a bar from Gefell that look interesting that looks like they place the mics at the spots where your monitors should be for surround (L 300, C 0, R 60, LS 240-250, RS 110-120) With equal distances to a phantom center point. Looks like it would work really well with a small to medium ensemble. But they look like spiders.
I would also like to hear some mics like Josephson's 700 and 700s as you can adjust the patterns and I've never heard a Soundfield either, and Line stuff looks interesting as well.
In any case, if you don't have enough time to set these things up and listen, tried and true methods work really well. So that would be a DECCA tree (with an XY in C position if you like), omni flankers and a rear facing ORTF on the same bar as the tree. Make sure it sounds the same in mono.