Prokofiev Piano Sonata No. 6

Posted: Tue May 23, 2006 10:40 am

Thank you David.

I have some questions about things that I see as inconsistencies in your replies. I hope you don't take this is as nitpicking, but I'm eally confused and eager to learn from you.

1) Up here you said the main pair should be 3-4 m away, but in the last post you said 2-3. My main pair was 8' away, which is 2.44 m, right in the middle of your 2-3 m range.

Here, on the other thread (point 6), you said that you like the Blumlein pair to be behind the omnis such that they get the same direct to reverb balance, but here you said the Blum should be much closer than the omnis.

Now, this has nothing to do with ears, but I decided to check out the angles graphically. See this scale drawing. One set of lines represents teh extent of the sound source for a 90 degree sweep and the other pair represents the extent of the sound source for a 72 degree sweep (the correct SRA as calculated here, which is based on M. Williams's The Stereophonic Zoom. I find that you should be this far away for each case:

90 degrees - 1.168 m
72 degrees - 1.76 m

Like I said, no ears involved, but if the soundboard is the extent of the sound source, then this should be right.

Also, it seems like getting the piano to fill the stereo field in the blum array and getting the correct direct to reverb ratio will usually be mutually exclusive.

Did I mention no sound check? Cool

Posted: Tue May 23, 2006 11:02 am

Monkey's Audio did 2.1% better than FLAC at 24 bit and 4.3% better than FLAC at 16 bit. Thanks ptr!

Posted: Tue May 23, 2006 1:22 pm

David French wrote:

Monkey's Audio did 2.1% better than FLAC at 24 bit and 4.3% better than FLAC at 16 bit.

You're welcome! - Small procentages but if You're dealing with big files small amounts to big!

Quite an interesting discussion om positioning at the grand you have here...

/ptr

Posted: Tue May 23, 2006 1:47 pm

Nice playing!

First, I'd be happy if I could catch a piano like you did. You heard my results in an earlier thread... I hope you don't mind my questions. I make them in order to learn from the dialog. The Schoeps pair sounds quite nice, but it puzzles me a bit. Some sounds in it seems close and others not so close. The softer and lower register sounds full and smooth, but the forte right hand playing sounds has a different character. There is plenty of room in the Schoeps pair too, isn't there? Should one have more? Could you perhaps add your mic positions to the drawing you made earlier?

best regards
Lars

Posted: Tue May 23, 2006 2:57 pm

Piano mic positioning graphic, JPEG, 52.6 KB

Posted: Tue May 23, 2006 3:09 pm

Thanks for the illustration! If you rotated the pairs around the piano, constant radius, how would that alter the recorded sound?

best regards
Lars

Posted: Tue May 23, 2006 3:17 pm

Yes, I have been a little inconsistent. Sorry about that. Operating from memory. Lets get the notebook out.

Looking at my notes from the last piano recording I did with the SF24 and Omni outriggers, here are the dimensions.

1. SF24, 2770mm from front leg, piano skewed with tail around so that the tail leg is 440mm further back than the near front leg.

2. SF24 2070mm high

3. 4003's, 2140mm away from near front leg, 740mm out each side of centre line where SF24 was, and 2370mm high.

So in summary, the omnis were a little nearer than the SF24, spaced 1.5m apart, and 2.4m high, whereas the SF24 was further out and lower.

Now I think I said that the omnis should be nearer based on theory, due to the directivity accent from the SF24, but that you should use your ears.

I also said to START with the mics in these sorts of positions but move them as required as I cannot possibly understand what your hall is like. Unfortunately I have been too specific about my case and you have taken me too literally without a sound check. Our rooms are obviously very different and one should always listen and adjust.

I know you said you didn't have a sound check, and from your dimensions and sound of your omni pr, your room is smaller than the one I am in. Is this true? I am in a chamber concert hall that seats 1200. Ceiling height at the stage is some 17m. What is your room like.

Sorry to have confused you.

Posted: Tue May 23, 2006 3:25 pm

Quote:

Also, it seems like getting the piano to fill the stereo field in the blum array and getting the correct direct to reverb ratio will usually be mutually exclusive.

Yes a little. Again these are starting positions before repositioning after careful listening and balance.

I find the big problem with Blumlein is that on its own it can sound mono and too far away if a very quick balance is done in headphones without proper listening. So if I am setting up without decent sound check, I start by placing it closer than one would like, to spread the image and I can usually do something with it later with a little reverb. If its too far away there is nothing that can be done.

Posted: Tue May 23, 2006 5:24 pm

Interesting.

2770 mm is about 9 feet, and my Blumlein pair was about 8 feet away. Yours was about 6.8 feet high, while mine was only about 4 feet high. So, you were about 1.8 feet (54 cm) farther away. Yours presumably was not too far, but mine was way too far, yet mine was closer. Yes, differeny halls. Mine at 600 seats is smaller. Greater sound density at the same distance? Here's a picture of the hall, and here's a stereo impulse I made of the hall. The speaker was a Genelec 1037C. It was resting back on a chair aimed up and out into the hall. The mics (4007 spaced 30 cm and 250 cm high) were about 2/3rds of the hall's length back (at FOH). That should give you a very good idea of what I'm dealing with.

Our omnis were the same distance away, yours are twice as wide, and your were just a little bit higher.

We have the same setup except for four major factors: Your SF-24 was twice as high, your omnis are brighter, , your omnis were twice as wide, and your hall is bigger. All in all, It still seems odd to me that my recording is so very much worse. I really want to get to the bottom of this. I woudl be very happy to be able to make piano recordings as good as yours. Could you post a little of this recording you've been speaking of?

Posted: Tue May 23, 2006 8:28 pm

David (Spearritt), I'm surprised that you recomend placing the outriggers 4 meters apart, which seems far apart, but I take your word for it based on the high quality of your recordings. Would you recomend a similar
placement as a starting point, if the main mic is a AKG c426b and the
outriggers are Sennheiser 800's ?

Posted: Wed May 24, 2006 4:57 am

Yes omnis at 4m because the centre is filled by the Blumlein pair. Its a great way to start the positioning.

Posted: Wed May 24, 2006 6:05 am

Quote:

We have the same setup except for four major factors: Your SF-24 was twice as high, your omnis are brighter, , your omnis were twice as wide, and your hall is bigger. All in all, It still seems odd to me that my recording is so very much worse. I really want to get to the bottom of this. I woudl be very happy to be able to make piano recordings as good as yours. Could you post a little of this recording you've been speaking of?

The hall is the big factor of difference here. I will try to post something when and if I get permission from the artist.

Posted: Wed May 24, 2006 7:16 am

When you have your omnis so wide apart, do you usually have
them pointing (downward and) straight ahead or inward?

Posted: Wed May 24, 2006 10:19 am

Outriggers spaced 4m is perfectly acceptable when using such a strong center as blumlein/ortf/XY. For piano, I certainly wouldn't go MUCH further, but 4m is fine. The purpose of the omni outriggers really is to capture the sound of the instrument in the space, not the sound of the instruments mechanics. Leave that to the center pair.

As for direction - aim them how you'd like. With more directional omnis (such as M50s or M296s), I would bring them slightly towards center and angled down slightly towards the instrument. For less directional ones (Schoeps, Earthworks, DPA), it's all a matter of personal preference.

Posted: Wed May 24, 2006 10:50 am

Very interesting. The one thing I don't understand is, if the goal of
the outriggers is to capture the sound of the instrument(s) in the
space, why not have them much further back in the hall. David
Spearritt suggested that having the main pair closer would produce
a wider and dryer stereo image, so why not have the outriggers
much further back to capture more ambience. I guess it would depend
on the acoustics of the particular hall.

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