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AB spaced pair - loss of high frequency?
Old 25th April 2020
  #1
Gear Nut
 

AB spaced pair - loss of high frequency?

Hello all,

I'm really new in recording and do it mostly for me to listen to later to analyse and fix errors in my organ performance etc.

Anyway, I bought Neumann KM-183 and have been trying to record me playing on the pipe organ in my church. I connect those microphones to Zoom H6 but always use X/Y module also to record.
I'm getting audio and the bass is much improved with the KM-183 (AB) but I think I'm doing something wrong probably in placement because when I solo what I get with the X/Y seems to be more open and high frequency seems to be more normal than with the KM-183.

Today the H6 was closer to the organ but this happened also the other day when it was almost on the same place as the Neumanns.

What is likely error on my part?
Old 25th April 2020
  #2
Lives for gear
Cardioid mics (like what is built in the Zoom) almost always have a rise in the top end, and omnis tend to be more flat (more natural and accurate). I'd wager you're hearing that treble boost. If it sounds better than the Neumanns, then my next wager is your placement of the Neumanns is not as good as it could be as you pointed out. Placing spaced omnis is trickier, but for your application (organ) I'd be surprosed if you couldn't produce a MUCH better result with the KM183s. Perhaps you're getting a little too much bass in the Neumanns where they are placed, making them sound too dark and less open.
Old 25th April 2020
  #3
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I reckon leddy's analysis is pretty much on the money...and would just add that the KM183, while it doesn't have the 'presence rise of a typical budget cardioid, certainly has the distant-field HF lift you see in the response plot here:

http://recordinghacks.com/microphones/Neumann/KM-183

So the perceived lack of HF is likely a placement thing as leddy says, and what you're getting from the 183's is probably a more accurate sound. Extra height on the mic stand might get you what you're wanting ?
Old 25th April 2020
  #4
Gear Nut
 

Maybe because I've used the H6 for couple of months now I've grown used to that sound?
The sound I get from the Neumanns is very good I think it's just different and not with as much (loud?) high frequency as the H6. I will post some compare samples later today for you to listen to so you can maybe help me more to see if there's some problem going on other than just different experience.
Like I said, I'm very new in this field and had even never recorded anything until I got my H6 in December.

Is it possible because the Neumanns give me more bass that the H6 appears more "open" or maybe "in your face" better term because of that?
Old 25th April 2020
  #5
Gear Nut
 

Here's something for you to listen to, if it helps pinpointing the possible problem.

It's unedited except I panned the two Neumann channels in hard Righ/Left.
Attached Files

Neumann-km183-solo.mp3 (1.59 MB, 1102 views)

Zoom-H6--solo.mp3 (1.59 MB, 1070 views)

Old 25th April 2020
  #6
Lives for gear
Sometimes a higher resolution device like your Neumann pair just opens up the windows wider ( or gives them a good chamois cleaning...choose your preferred analogy !) to more extended musical bandwidth. However, it also places more onus upon you to locate them precisely, as they wont filter out lower bass material like standing wave reinforcement ....sometimes called "mud"

It's easy to get an extended frequency range organ recoding which simultaneously sounds slow, bloated, obese...listening to it played back can appear as if you have a head cold. All this means is that the mics are giving you an accurate depiction of the sound at the place they're located. The implication is thus >>> find the right place to locate them ! This is likely to take quite an amount of trial and error.

By contrast the inbuilt mics of your Zoom recorder very likely roll off below 100Hz...which can neatly filter out some of those same problematic bass frequencies your Neumanns are faithfully capturing. For this reason, the H6 is apparently giving you a faster, lighter, more nimble sound...albeit perhaps lacking in solid bass foundation and contrasts.

I'd recommend spending several days absorbing (via subject search) the numerous 'organ recording' threads already existing on the Remote Possibilities forum here....there's a goldmine of valuable advice and guidance awaiting your discovery. This will set you up with some extremely helpful startup techniques....as you're on the bottom of a very tall learning ladder.

Even after this research , you still have a lot of trial and error experimentation to do, within parameters such as mic spacing, mic stand height, and location of mics within the church/hall. Fortunately, these organ recording threads are populated with plenty of audio samples, to illustrate what you could expect from a given configuration.

Make sure you have good quality, full range monitor speakers (speakers and/or headphones) to fully reveal what your various experiments are revealing !
Old 25th April 2020
  #7
Gear Nut
 

Quote:
Originally Posted by Falcon1 View Post
Today the H6 was closer to the organ but this happened also the other day when it was almost on the same place as the Neumanns.

What is likely error on my part?
The XY cardioid mics on the H6 are unidirectional; the KM183 is omnidirectional. So, for a given placement, their ratios of direct to indirect sound pickup are different. See the attached table.

If a cardioid mic is in a position you like (distance "1.7"), an omni would need to be much closer (distance "1") for a similar ratio of direct vs reverberant sound.

AB omnis can be a very nice way to depict the expanse and full frequency range of an organ and the building of which it is part -
- but this depends on being able to get the mics close enough. In larger buildings this can often involve very tall stands, or flying. If this is not possible/convenient/realistic, then omnis are no longer the best choice.

Currently, your Neumanns are too far away.
Attached Thumbnails
AB spaced pair - loss of high frequency?-polar-patterns.gif  
Old 25th April 2020
  #8
Gear Nut
 

Also, an XY coincident pickup inherently gives a stronger centre image and localisation (you mentioned 'in your face' above) than AB omnis.

The opposite is exaggerated by AB omnis, where above a certain excess width the centre disappears entirely.

Experiment with mic positioning and AB width. Ideally, have someone else play the organ while you move the mics around and listen live via the H6.
Old 25th April 2020
  #9
Lives for gear
Quote:
Originally Posted by Falcon1 View Post
Here's something for you to listen to, if it helps pinpointing the possible problem.

It's unedited except I panned the two Neumann channels in hard Righ/Left.
Well, immediately I'm thinking you've provided 2 audio files which aren't level matched, in other words the xy mics sample is significantly louder than the KM183. So the louder one is going to appear with more midrange and HF energy, just because of that imbalance, which is why it sounds quite strident and megaphone-like. See if you can level the samples up, so we're hearing equal loudness from each.

The real reference point is:"which of the 2 mic pairs sounds to you closest to the actual sound of the organ in the church" ? My guess is that neither of them do, but perhaps the 183s are more rounded and less shouty ? All that is really indicating is that you've got to go back and run some more mic placement experiments, and then listen rigorously to your recordings...always using the sound in the church as your verification reference.

Another tip....you'll notice that this thread relies heavily on measurements: how wide is your AB bar, are the mics angled or facing forward, how high is the stand, how far from the organ is the stand located, what is the size of the church, is it old or modern, what is it built from, what type of ceiling (flat or arched). All these things have a bearing and influence....as you'll discover when you start excavating the existing organ recording threads !!

Finally, a picture is worth 1000 words, so please take several photos, as these are very helpful in conveying information about your recording situation.

However, in terms of simply providing you with a reference for your own playing performance, even what you have here (as compromised as it is, likely by being too far from the instrument) will do the job. I'm guessing that you'd prefer something a little closer akin to what a typical listener would hear seated in the church ?

Last edited by studer58; 25th April 2020 at 12:27 PM..
Old 25th April 2020
  #10
I d test putting the pair halfway the church 8 meters wide and compensating the lost HF with a shelf eq +10dB starting at 1000Hz
Old 25th April 2020
  #11
Lives for gear
Quote:
Originally Posted by monitor View Post
I d test putting the pair halfway the church 8 meters wide and compensating the lost HF with a shelf eq +10dB starting at 1000Hz
Note to Falcon 1: see what I meant... about the importance of measurements & specifications in this forum ?
Old 25th April 2020
  #12
The Neumann omni's sound much better to my ears. No competition!
Old 25th April 2020
  #13
Gear Nut
 

Quote:
Originally Posted by studer58 View Post
Well, immediately I'm thinking you've provided 2 audio files which aren't level matched, in other words the xy mics sample is significantly louder than the KM183. So the louder one is going to appear with more midrange and HF energy, just because of that imbalance, which is why it sounds quite strident and megaphone-like. See if you can level the samples up, so we're hearing equal loudness from each.
What is the best way to level them so they match? Just to look at the green indicators in my software? Or can I let the software (I'm using Reaper) do it automatically for me? Normalize?
Old 25th April 2020
  #14
Gear Nut
 

Here's the same clips but I tried my best to match them visually and by ear.
Attached Files

Neumann-km183-solo_leveled.mp3 (1.70 MB, 993 views)

Zoom-H6--solo_leveled.mp3 (1.70 MB, 967 views)

Old 25th April 2020
  #15
Best not to mess around with them - the Neumann 183's as recorded sounded by far the best.
Old 25th April 2020
  #16
Gear Nut
 

Quote:
Originally Posted by Lurcher_lover View Post
Best not to mess around with them - the Neumann 183's as recorded sounded by far the best.
So you think the placement was ok? Maybe the reason for my original question is that because the Neumanns was placed about 3-4 meters from the organ that it sounds too distant and I'm interpreting that as a loss of high frequency in the organ? If I will place them little bit closer to the organ then it would appear like I get more of the higher frequencies of the high stops of the organ.

Another way of saying what I'm trying to blurb out of me is that I think the higher stops come out little bit too soft in the Neumann. It's very nice though but I would like maybe more "bite" in the higher range. :D
Old 25th April 2020
  #17
Lives for gear
You've done a pretty good job of matching the levels by ear, it doesn't change the result in this case, as the Neumanns still render a truer picture of the acoustic. I don't find there's an absence of HF, nor an over abundance of wooly Lf either.

I agree with previous comments that the mics are too far back in the church, as there's a lot of wall reflections making it sound boxy. Did you have the mics in the centre aisle, or off to one side ? Notice also that the 183's have a wider more spacious feel to the stereo image, while the xy pair collapse the image into the centre..this is typical of the method, and entirely to be expected.

Stick with the Neumanns, do a thorough search and study of all the church organ recording threads here, start experimenting with variations in the width of the AB spacing (what is it currently ?) ...height of the stand ( what is it now ?) ...distance from the organ (ditto ?)

Ask a patient friend or assistant, while you're playing and the recorder's running, to move the mic stand (and adjust mic spacing width) along all of the above dimensions, all the while writing down distance measurements and correlating these with the recording time counter (and taking lots of photos)...and then analyse at home at your leisure and try to discern some patterns and trends. Forget about the xy mics altogether and focus on the KM183's only....recalibrate your ears to the natural un-hyped sound !!
Old 25th April 2020
  #18
Gear Nut
 

Here's the final mix of that clip I was quite happy with but probably messed it all up haha...

So the Neumanns are the main sound in the mix but I added tiny bit of H6 to blend into it - to get little bit of that "bite" I was talking about. Also my brother on the trumpet was using Sennheiser E908b which I also blended just a bit into the mix.

Thank you all for your helpful comments, I've lot of exploring and trial and errors to do - I know.
Attached Files
Old 25th April 2020
  #19
Gear Nut
 

Quote:
Originally Posted by studer58 View Post
You've done a pretty good job of matching the levels by ear, it doesn't change the result in this case, as the Neumanns still render a truer picture of the acoustic. I don't find there's an absence of HF, nor an over abundance of wooly Lf either.

I agree with previous comments that the mics are too far back in the church, as there's a lot of wall reflections making it sound boxy. Did you have the mics in the centre aisle, or off to one side ? Notice also that the 183's have a wider more spacious feel to the stereo image, while the xy pair collapse the image into the centre..this is typical of the method, and entirely to be expected.
Thanks. :D Yes, I agree that Neumanns gives quite a good picture of the acoustics in the church. Long reverb etc.
Maybe that's what is bothering me, too boxy sound? :D

I attached some photos (needed to blur out the people) to try to give you idea of what the room looks like and the placement of the organ as well as approx position of mics.

Green = Neumann Red = H6
Attached Thumbnails
AB spaced pair - loss of high frequency?-mic-placement.jpg   AB spaced pair - loss of high frequency?-mic-placement_organ.jpg  
Old 25th April 2020
  #20
Gear Nut
 

I will take some photos next time I record. :D
Old 25th April 2020
  #21
Lives for gear
Quote:
Originally Posted by Falcon1 View Post
Here's the final mix of that clip I was quite happy with but probably messed it all up haha...

So the Neumanns are the main sound in the mix but I added tiny bit of H6 to blend into it - to get little bit of that "bite" I was talking about. Also my brother on the trumpet was using Sennheiser E908b which I also blended just a bit into the mix.

Thank you all for your helpful comments, I've lot of exploring and trial and errors to do - I know.
Sounds not too bad, but I think by going closer to the organ with your AB pair you could perhaps leave out the xy altogether and still have got that closer, less reverberant sound with the Neumanns alone...same for the spot mic on the trumpet. It's a trap to record an overly ambient main sound, and to then try to 'repair' it by adding spots. Always try to get the main pair sounding as good as possible via careful placement, and then add spots only to the instruments which remain indisinct.

How close was your 183AB pair to the xy pair ?

EDIT: you probably added the photos just as I was posting this. Assuming you won't be recording during a church service (?) I'd suggest placing the AB pair closer to the organ, about halfway along the row of seating, and possibly even as close as the first people seated closest to the organ. AB spacing could anything from 1-3 metres (the latter would require 2 stands)

From your drawn in lines, I'm guessing your mics are on regular stage mic stands (1.6-1.8 metres high) ? Trying going up to 3 or 4 metres....that will likely give you more of the HF you think you're missing. If it all sounds a bit dry, with mics that high, try moving them back towards the middle of the seating area, to bring a little of the hall back into the sound.

I'm not sure if you're intending to record concerts or not...if not you'll have freedom to experiment with mic placement
Old 25th April 2020
  #22
Gear Nut
 

Quote:
Originally Posted by studer58 View Post
Sounds not too bad, but I think by going closer to the organ with your AB pair you could perhaps leave out the xy altogether and still have got that closer, less reverberant sound with the Neumanns alone...same for the spot mic on the trumpet. It's a trap to record an overly ambient main sound, and to then try to 'repair' it by adding spots. Always try to get the main pair sounding as good as possible via careful placement, and then add spots only to the instruments which remain indisinct.

How close was your 183AB pair to the xy pair ?
The 183AB was about 3,5 meters from the organ so the xy pair was probably around 1-1,5 meters closer.

So no mic on the trumpet?
Old 25th April 2020
  #23
Lives for gear
Quote:
Originally Posted by Falcon1 View Post
The 183AB was about 3,5 meters from the organ so the xy pair was probably around 1-1,5 meters closer.

So no mic on the trumpet?
I'm surprised all your mics are so close to the organ...the AB pair sounds much further away than that. You haven't added any computer reverb to the sound ? Try initially raising your stands higher, and making the AB distance (width) about 1.0-1.5 m....and bring the 183's to the same location as the xy pair now is...see if that gives you a better all-round sound, with the 183's alone ?
Old 25th April 2020
  #24
Gear Nut
 

Quote:
Originally Posted by studer58 View Post
I'm surprised all your mics are so close to the organ...the AB pair sounds much further away than that. You haven't added any computer reverb to the sound ? Try initially raising your stands higher, and making the AB distance (width) about 1.0-1.5 m....and bring the 183's to the same location as the xy pair now is...see if that gives you a better all-round sound, with the 183's alone ?
I will probably go later today to test more. :D I will try to take photos and take measure tape with me. :D
Old 25th April 2020
  #25
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Plush's Avatar
The differences I heard in your two files has to do with the presence of the recorded sound. This is solved with a different closer placement of the omni mics.

You need to move closer in with your omni pair.

Best to use a bar and space the omni mics at 67 cm. Go high up with your stand.

Omni mics need to be almost twice as close to the organ as your Zoom.

Experiment.

You cannot EQ the omni mics into position--they have to be moved closer.
Old 25th April 2020
  #26
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elektrovolt's Avatar
Getting the mics closer will help. The distance factor is important here: omnis should be placed much closer to get the same ratio of direct and reverberant sound.
And extending the mic stand height can do wonders. The AB sound is much smoother than the H6 XY mics which are a bit brittle to me but the 'directness' of the cardioids helps to 'zoom in' on the organ a bit. You could solve this by using a cardioid pair in the middle of the AB bar as long as the ABs are spaced apart far enough. Spot mics near the organ front and trumpet can work well too as long as you use a delay on the spot tracks to time align them to the main pair.

The church looks rather small to me, looking at the pics. Maybe you could practice your recording in the church some other time, for instace when the organ player is rehearsing? It can't hurt to ask.
Old 25th April 2020
  #27
Gear Nut
 

Testing 2m and 3m position

Ok, so I went to my church today to try out two positions. Sorry for not my best playing, I was too much thinking about the recording setups haha...

1) 2 meters from the organ and 1 meter between the (AB) mic pair
2) 3 meters from the organ and 1 meter between the (AB) mic pair

I included photos of the setup when the AB stands was at 3 meters (about 2,5-2,7 meters height), the H6 is on the middle tripod at 2 meters.

I needed to normalize about 12db because I had the mic gain little to low on my H6. I thought I would need lower gain because moved the mics closer so I lowered it from 5 to 4 but that was really a mistake.

Is this improvement in position and sound?

Ps. the chairs are moved out of the room because of this COVID-19 issue.
Attached Thumbnails
AB spaced pair - loss of high frequency?-prufa-25-april-2020-ytri-njardvikurkirkja_orgel-mics.jpg   AB spaced pair - loss of high frequency?-prufa-25-april-2020-ytri-njardvikurkirkja_orgel-mics2.jpg  
Attached Files
Old 25th April 2020
  #28
Gear Nut
 

Quote:
Originally Posted by studer58 View Post
I'm surprised all your mics are so close to the organ...the AB pair sounds much further away than that. You haven't added any computer reverb to the sound ? Try initially raising your stands higher, and making the AB distance (width) about 1.0-1.5 m....and bring the 183's to the same location as the xy pair now is...see if that gives you a better all-round sound, with the 183's alone ?
I measured it today and I was at about 6 meters with the AB pair in the first recording. So my memory was way off haha...
Old 25th April 2020
  #29
Gear Nut
 

Quote:
Originally Posted by elektrovolt View Post
Getting the mics closer will help. The distance factor is important here: omnis should be placed much closer to get the same ratio of direct and reverberant sound.
And extending the mic stand height can do wonders. The AB sound is much smoother than the H6 XY mics which are a bit brittle to me but the 'directness' of the cardioids helps to 'zoom in' on the organ a bit. You could solve this by using a cardioid pair in the middle of the AB bar as long as the ABs are spaced apart far enough. Spot mics near the organ front and trumpet can work well too as long as you use a delay on the spot tracks to time align them to the main pair.

The church looks rather small to me, looking at the pics. Maybe you could practice your recording in the church some other time, for instace when the organ player is rehearsing? It can't hurt to ask.
Well, I'm the organist of this church so I have free rein.

If I would try to use cardioid pair in the middle later, the H6 X/Y is my only cardioids, would I need to have them the further back than the omni pair?
Old 26th April 2020
  #30
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Quote:
Originally Posted by Falcon1 View Post
Well, I'm the organist of this church so I have free rein.

If I would try to use cardioid pair in the middle later, the H6 X/Y is my only cardioids, would I need to have them the further back than the omni pair?
Yes you would...the concept to grasp here is the direct sound to reverberant sound ratio. No matter which mic pair you use ( cardioid, fig8, Omni, hyper cardioid etc) you want to get a pleasing balance between the direct sound of an instrument and the contribution that the room/space makes to the sound by reflecting the instrument sound off its walls, floor and ceiling. There's pretty much just one spot ( or a very narrow range of locations) where your mics need to be to produce that pleasing balance of direct to reverberant sound.

Hence my insistence in the mic stand placement experiment phase. Record, move stand, measure ( or at least photograph) and write down...move stand, adjust height, AB spacing, record, photograph...repeat...you get the idea. This won't take days...you can do all this mic moving/adjusting with a helpful assistant over the course of an hour, maybe 2 at most. Make no assessments on site...take the recordings home and judge there, under best controlled monitoring conditions.

After that 1st trial session you'll come to a point where you can say confidently stuff like: "I really dig the sound of the organ when miked between 3.8 and 4.7 metres away, and between a height of 3.4 and 3.9 metres on the mic stand...and when the mics are spaced between 67cms and 120 cams apart" Just wild guesses on the numerics...but you get the general idea !

If you want to get really pedantic (and most folk here would encourage this...why stop when you're having such fun !) keep honing these parameters until you pretty much find "the spot" in the room where your mics sound best. Mark the floor with an X and you're set forever more....job complete !

What might change that is if you alternate between recording in an empty church vs with a congregation...their presence will 'dry up' the sound of the organ, making it sound closer and less reverberant. Also it's very likely to alter where you can practically locate your stand, without it getting kicked by audience feet....or worse ! With an audience present you'll likely need the stand further from the organ, to get the same direct:reverberant ratio as you obtained without the seated people. You might thus nominate a second floor X Mark, for such situations.

To get the same direct to reverberant ratio from a cardioid pair as an Omni, the cardioid pair needs to be located 1.7 times further away from the source than your Omni pair. So if your favourite Omni mic location ended up being 3 metres from the organ, to get the same direct/reverb ratio from your cardioid(xy) mics you'd locate them 5.1 metres from the organ (3x1.7=5.1). Stand height doesn't seem to factor in as much here as sheer distance from source.

So why not use this information to make simultaneous xy and AB recordings, using this 1.7 ratio to guide your placement of both mics ? I'll still predict you'll get a much more satisfying and extended and natural sound from the 183's....but if you prefer the narrower stereo image and 'peakier', more strident sound of the xy then at least your AB placement location will give the info about where the xy needs to go....the 1.7 ratio knowledge allows you to somewhat level the playing field between the 2 mic pairs. I hope this helps clarify things ?
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