Friday, April 09, 2010

Errata - Exotic Positions

I just read Paul Stamler's Exotic Positions, and here are some necessary corrections:

3 out of 4 ways of recording in stereo...

Let me start with (the old master) Alan Dower Blumlein. While it is certainly correct that "he did most of the theoretical analysis necessary for the development of stereo recording" he was also very much into exploring the practical aspects of recording. And while "he developed a stereo miking system [the Blumlein setup] that solves many of the problems inherent in XY and ORTF techniques" it is important to note that not only ORTF came 30 years later, but that Mr. Blumlein invented all three coincident setups, including XY and M/S. The latter is listed under the "true exotica" section although it is the de facto standard of stereo in moving picture sound.


Back to the start of the post. XY creates a stereo image strictly by differences in sound pressure level. The term "volume differences" is not accurate. And while often arranged at an angle of +-45, resulting in a huge recording angle of 196°, any angle can be used. It is important to note that the size of the inter-capsule-angle is inversely proportional to the size of the recording angle. Point the capsules father apart for a smaller soundstage!

Visit Eberhard Sengpiel's stereophonic playground for some experimentation.

Rather than saying that "typically, XY recording produces a narrow soundstage" I'd explain that using an XY pair with an inter-capsule-angle of 90° results in a semicircular pickup range. I use this configuration when I have to mike very close to an ensemble and don't want to go for AB, perhaps because I want to reduce the influence of the room or attenuate audience noise.

"Getting fancy: ORTF"

I'd personally place the near-coincident pair stereo technique after XY, Blumlein and M/S. Or, if I were to sort the approaches by their practical relevance to me it would be at the top.

The very nice stereo image that ORTF (and other near-concident techniques: NOS, DIN, EBS, ...) can produce relies on a combination of differences in sound pressure level volume and time of arrival cues. The reason that "sources are rendered in correct spatial perspective rather than in the narrow soundstage endemic to XY recording" is due to the fact that the recording angle is 98°, a little more than half that of XY (at +-45°).

"The old master: Blumlein"

I consider Blumlein to be a special case of XY, using bidirectional capsules / ribbon transducers angled at +-45°. While it is true that "Figure-8s tend to maintain their pattern at all frequencies" the statement that "at least some of them have excellent bass response" is doubtful. Look at the frequency charts of all bidirectional capsules for a pronounced proximity effect / LF-attenuation. As an example please compare the charts on the cardioid Schoeps MK 4 with that of the fig-8 Schoeps MK 8. David Royer has argued that this does not hold for ribbons (see the Royerlabs SF-1) and I have done a few one-point Blumlein recordings that seem to justify the assessment, but I am as yet uncertain on this point.

I don't agree with the statement that "because the pickup pattern is bidirectional the microphones will pick up lots of room sound, leading to a very wet recording." AB gives me much more spaciousness, but since AB (with two parallel omnis spaced at a distance of 51.5 cm) results in a recording angle of 180° I place it much closer to the ensemble than a Blumlen setup with it's recording angle of 76°. Therefore it is definitely true that the sonics of the recording space matter a lot when using a Blumlein setup.

"True exotica"

Read all about Tony Faulkner's Phased Array here: Part-1, Part-2, Part-3.

The Jecklin disk uses "a pair of omnidirectional mics spaced a foot or so apart with a large plastic disc between them." That much I can follow. The statement that "this creates the equivalent of a pair of cardioids pointed outward at 180˚" sounds wrong as (in the case of coincident capsules) this would result in a recording angle of 102°.

Regarding M/S the post states that "what’s most useful about this is a high degree of mono compatibility". In fact M/S is completely mono compatible: Use only the central channel...

Interesting to me: the "Swedien technique"--although in theory coincident yet angled true omnidirectional microphones can not generate differences in sound pressure level. Paul Stamler does say the setup pertains to the use of large diaphragm condensers though. I'll give it a try when I get the chance.

"Step up to the bar"

The sturdy yet inexpensive K&M 23550 stereo bar does a good job for XY & ORTF. Don't forget one or two K&M 218 thread adapters to be able position one mic above the other without undue vertical angling.

"What, when, and where"

Much of this is a matter of taste, but I'd usually not recommend using "a pair of good condensers overhead in ORTF formation (panned hard left and right) [...]" for recording drums. True, a stereo overhead and two mics, one for the snare (or a central position) and one for the kick is all you'll need, but if you don't use a coincident overhead you can not reduce the spread of the image in post without introducing comb filtering!

"Try a few true-stereo single pair recordings just to hear what the technique can do. And if you have the tracks, try using stereo miking techniques on multitracked projects. You won’t be sorry." I am happy to say that I wholeheartedly agree with that final statement. "Happy pairing" to you as well :-)

[Please check out Eberhard Sengpiel's website for detailed insights into various stereophonic configurations, recording angles etc.]

Thursday, April 08, 2010

Do we need 24 bit audio for sonic nirvana?

"The noise level in the avarage residence is about 43 decibels" [Harry Ferdinand Olson (1967): Music, physics and engineering], whereas a house in the country can be as quiet as 35 dB. Let's deduct 6 dB from that number as it is quite possible to discern musical content that level-wise lies within and seemingly should be masked by the noise floor.

16 bit audio has a theoretical dynamic range of 96 dB, which, if you add that onto the baseline 29 dB amounts to a peak of 128 dB, slightly below the threshold of pain. It seems to me that that span should suffice to adequately present the finest dynamics inherent in music, especially since the range I usually experience recording very high dynamic range avant-garde music lies at 54 dB, and many real-life concert venues have a noise floor at -60 dB FS. Of course less is highly preferable, but then it is also dependent on the quality of the ambient noise.

Note the use of the word "suffice". Clearly, having a theoretically usable resolution of 144 dB when working with (real) 24 bit audio is even better. It is tantamount when recording music while leaving adequate headroom--with no manual gain riding required and no need to use a compressor while tracking--, and during mixing to avoid introducing distortion while processing.

But once you are done, dithering carefully to 16 bit will be OK.


John Watkinson in Resolution, March-2010 (p. 59): CD "[...] was put together by a skilled group of people who knew what they were doing, and it has stood the test of time. It's not broken and it doesn't need fixing."

Thursday, January 14, 2010

Q&A: When Do I Normalize?

Happy new year :-)

Please check out my latest post, and the 1st one with Ask a Sound Guy: Q&A: When Do I Normalize?

Friday, October 30, 2009

Andrew Levine's DAW-history

In 1995, while in the process of obtaining my M.A. (in Computational Linguistics & Cognitive Psychology) I started developing multimedia applications. Being a dedicated Macromedia user I did all sound editing in SoundEdit 16 that came as part of the Director bundle. At some point DECK II joined the fray, originally developed by OSC for Digidesign, later sold to Macromedia and finally dropped by BIAS.

DECK was originally used for four track hard disk recording with synchronous MIDI recording and playback. Original DECK also offered moving fader automation, digital mix-to-disk, and unlimited, non-degrading track bounce. Among other awards, DECK (and DECK II) won the 1990 and 1993 MacUser Eddy awards for best music and sound software. [Link]

When in 2002 I got serious about "sound" I first delved into Protools LE that came with the 2ch MBox. While I liked the ergonomics of that GUI I quickly realized that
  • I wanted to move to OSX now that a UNIX-kernel had (finally) become the basis of the Mac OS
    (I used to be a fan of the BeOS; the Wikipedia article states that "iZ Technology sells the RADAR 24, a hard disc-based, 24-track professional audio recorder based on BeOS 5."--amazing!)
  • I'd want to record more than two channels
  • Using a Protools system kept you locked to one hard-&software combination
In any case, I returned the MBox and after researching my options ordered a 2882+DSP by Metric Halo and Digital Performer by MOTU, which (as version 4.0) was the first OSX-based DAW on the market.

As with most complex programs it took me a while to get fluent in DP. I stayed with it for several years / iterations (DP 3.x, 4.x, 5.x, 6.0--that one I returned) until I ran into some serious issues, the worst being that with complex projects the engine would not play back the pieces of audio I saw on screen. You can imagine that it made editing quite painful, and I was in the middle of an editing-intense project (Debussy Préludes).

I managed to trudge along for a while, but when a friend suggested I try out the newly revamped Logic 8 I went for it. Luckily for me I used the DAW mostly for editing and as a "tape machine". I used to mix, process & master all projects mainly within the MIO's (Metric Halo's MobileIO interfaces) DSP-matrix. With the advent of the 2d-architecture that became even easier, even when I started moving into the surround realm. But still, the paradigm and handling of Logic was so much different from the one of DP that I enjoyed going back to old (working!) DP-projects from time to time.

And then came Reaper by Cockos.

Floris van Manen, a longtime net-acquaintance and friend of mine had been suggesting I give Reaper a try for ages, and it had been growing to be more and more feature-complete on OSX as time passed. So I finally decided to give it a spin with several new, not especially time-critical projects--and I got hooked!

Reaper features...
  • a newly designed audio engine, that sounds so good I moved from realtime-bouncing to DAW-rendering for most projects
  • a very comfortable GUI, that is even skinnable
  • an editing paradigm that is very smooth and that I got used to in next to no time
  • amazing support, both from the user community and the developers
  • all at an unbeatable price
How can you go wrong? The last iteration since I registered has introduced Redbook-CD-rendering, yet again streamlining my workflow, and fixed some small bugs that I had came accross. You just don't get that level of responsiveness from any of the big DAW-companies.

So, if you have not already done so, give Reaper a spin. I see myself happily sticking to this platform for a long time to come :-)

Wednesday, October 28, 2009

Tracking festivals

I just noticed that it's been a while since my last blog entry. I guess there was too much "real" work to be done :-)

In any case, having just finished recording six 90 min concerts and one open podium event at the International Jewish Music Festival 2009 in Amsterdam I'll share some thoughts on covering festivals. In this case I was not only in charge of the recordings but also fed the guys handling the sound reinforcement all channels requested by the ensembles.
  • There has to be one, and only one person in charge of the overall procedure.
  • Organisation is key. The mikes have to be placed, patched to clearly documented lines & tested for functionality, the gain is determined for optimal signals, then the levels for the SR are set before running an overall soundcheck.
  • Prepare well in advance and still stay flexible.
  • Collect the ensembles' set lists right after each performance, make sure they are correct, and perhaps even ask for the musicians' opinions regarding which titles they felt especially good (or bad) about.
Always remember: the recording comes first--at least that's my take on things :-) The record of the music is the one thing that remains and can be re-listened (to), and as such it is always good practice to keep the FOH volume as low as possible and avoid stage monitor bleed in your main mic setup.

Sunday, July 19, 2009

Mini-DV-Cameras with 5.1 surround?

I have been seeing Mini-DV-cameras that are advertised as having a "5.1 channel surround sound microphone". The Sony ECM-HQP has been around as an add-on. SonyStyle says: "It features the capability to record up to four channels of high quality audio for clear, distinct voices and life-like sounds. [...] Offers 3 modes for recording: 5.1 channel Surround mode; 4ch MIC mode;" --mode 3 is sadly missing in the description.

Well, let me tell you it just won't work ;-)

Getting stereo "right" is not trivial, and achieving a soundstage that corresponds with the repertoire, ensemble & performance space gets even more complicated. This can not be achieved by any suit-all clip-on solution--and this goes even more for an enveloping surround soundstage. Recording music & ambience well requires accurate planning, based on plenty of experience, and adapted to the specific situation.

It's like the old joke about how to get to Carnegie Hall. The answer is _not_ to just grab an instrument & a map. Why, even a GPS will only do you so much good.

Monday, July 06, 2009

The C-trilogy (Part 2) - Center, where are you?

[Continued from Part 1]

Like I said before: "What you want to do is find a spot where you'd place the one microphone required for a monophonic recording."

There are collegues that insist that the center is reserved for instruments that can be heard from the middle of the ensemble, but this makes sense primarily with small groupings. As soon as the ensemble is wide and deep it becomes difficult to determine--without examining the music in depth.

One possible creative idea would be to enhance transparency by placing various spot-miked sources in the center, delayed to let the original impression (from the space between the two front speakers) come first and steer the perceived source in that direction utilizing the Haas effect.

The single microphone used to derive the center will most likely be placed not far off the central axis, and rather close to the ensemble. Since we are dealing with a discrete channel Lou Burroughs' "3:1-rule" must not be taken into account--except for the situation in which you might want to experiment with adding some of that signal to a stereo mix.