Fukada Tree - Boundary Microphone Array

[BLP]

Originally Posted by JEGG

The liability in the past was the terrible sound from the Crown mic's. Perhaps they've improved them...

Yeah, that's my only experience with the SASS. My response was, "Seriously? It costs how much?!?" Just not the sound quality one would expect from such a sleek and snazzy device...

Originally Posted by leddy

I've heard some omnis work better than others when taped to the wall or floor.

I've had good luck with the Schoeps mk2H (and the 2S in the studio), and the 130's worked out the one time I tried them. I heard from a trusted colleague that 183's and 4003's aren't so hot in this application, though.

[boojum]

Originally Posted by tenor39

Hmmm... it loads into Windows Media Player just fine. You can download it first by right clicking and selecting "save target as" into a folder on your computer, and then use any player you wish.

It does not DL in FF or Chrome. I got it fine in IE.

BTW, the reference page on Fukuda, Geoff Martin's book, is incredible. Check out his book!

This board is just one master class after another for me.

[David Rick]

Originally Posted by digitalolive

OK, I've read through the posts a few times. James M. Mastracco may have used boundary mics set up in a Fukada tree pattern but Akira uses cardioids and omnis (DPA cards and Sanken omnis I think). Akira's english is very limited but I believe I understood him correctly. Here is a page that talks a bit about it. I went to a lecture by him at AES a few years ago where he went IN DEPTH about his experiences with different mic patterns and the listener's responses. I'll see if I can find the photos I took of his slides.
Steve

Hey Steve,

I was at the same lecture, and got the same impression. I was really wishing I spoke Japanese, so I could ask Akira-san more questions in the hallway. But it was a fascinating talk, even with the language barrier. Japanese broadcasters are about fifteen years ahead of their American counterparts when it comes to surround. I think I first learned about the Hamasaki square during the same presentation. It helps to solve the lack of front-rear correlation that Geoff Martin writes about, and I've used it a lot over the last several years.

I've made one or two recordings with something very similar to a Fukada tree. I start with an OCT triple, add rear-facing cardioids per Theile's recommendation, and then DPA omni's (black grids, aimed upward) spaced as wide as the bar will allow. Used carefully (in light of the comb-filtering potential), the omni's add a great sense of spaciousness. I'll definately put them up on the tree anytime I have mics and input channels to spare.

David L. Rick
Seventh String Recording

[BLP]

Not to get too off topic, but while we're on the topic of Fukada's various AES presentations... The 2007 AES in New York, Fukada and some of the other NHK guys presented their massive multi-array surround comparison work. There was talk of sound examples (and possibly a CD at some point), all handled through a site setup for that particular project. Does anyone have the url of said site? Please?

[digitalolive]

The website they posted at that lecture is dead now. I'm going to look for the rest of my notes/pics from that weekend today.

Steve

[digitalolive]

OK, Here is the report of the tests they did with different arrays. Quite an interesting read.

http://www.aes-japan.org/surround_dv...eport_1_en.pdf

[BLP]

Originally Posted by digitalolive

OK, Here is the report of the tests they did with different arrays. Quite an interesting read.

http://www.aes-japan.org/surround_dv...eport_1_en.pdf

Steve, many thanks! Now I've got some thing interesting/productive to read on the plane...

[NorseHorse]

Remarks from Jim Mastracco, engineer of the Washington Collegium recording linked in the original post, who is not currently a member of this forum. Info sent via email:

First I'm happy to read that my application of boundary micrphones to surround sound recording sparked some discussion with this group. I've come across Gearslutz in the past, via searches, but have reached a point - unfortuantely, where I can't seem to join another listserver or group. "Norsehorse" has graciously offered to post a response/follow-up to the points and questions that were raised. I will try to address them all and give some background about the recording.

To begin, sometimes names, as much as we want to credit the source of our inspiration or idea, can lead to more confusion. The idea of using boundary micrphones in a surround context was first planted by a friend and former colleague at WRPI-FM, Aaron Heller. He's currently contributing to work on ambisonics, and you'll find him easily by searching Google and that subject. The use of these mics was also driven by my previous work in concert hall acoustics, where I examined the role of microphone choice and placement in determining various quantities that parameterize a music hall or opera house's sound, e.g. tradiotional Reverbeation Time, or other temporal energy ratios such as Reverberance or Definition. (I'll cite some souces at the end of this note.) My own work revealed real, quantifiable differences in how the reveberant energy in a concert was distributed across the audio range. I've attached a bar graph illustrating this.

As to the comments and questions about what one is hears in a boundary microphone recording, or PZM recording, or going back to the days when traditional condener micropones were placed near archiectural surfaces, in short - it is all real and audible. Those who have observed that comb filtering effects are reduced, and/or that one is actually hearing the effects of architecture, are spot on - and it was that aspect of the PZM that prompted me to make concert hall measurements with it. Indeed, if one is looking the effects of the architecure, measuring sound or sampling sound near the boundary makes sense to more, than placing microphones in free space, in halls that are over the order of hundreds of thousands of cubic feet. 'And yet, it is the omnidirectional pressure transducer in the so called freefield that dominates such measurements, even today. I recently heard such a prodedure described during a tour of the new Strathmore Concert Hall (MD).

Ultimately, all of this still comes down to the physics, and that is that a TRUE PZM boundary microphone, including those mentioned in the thread that are the Radio Shack versions, the last incarnation of a PZM, as I understood - is that the capsule is only records scalar components of the sound - the acoustic pressure. Directional microphones of any kind respond to the particle velocity of the sound, including boundary microphones that are oriented at right angles to the architectural surface - such as the Crowns used in this recording. So even, when the distinction between a boundary microphone versus a PZM is made, and for sure a boundary microphone has far more scalar sound component than vector sound component, he orientation of the capsule relative to the boundary in of itself, introduces different physical quantities in the signal path.

Now - as to audible differences in the recording, one's taste, let alone the noise of a chorus stepping onto risers, or a piano's hammer noise, inexpensive electret boundary microphones bring their own set of issues. Two of these microphones were Crown PCC130s, which Crown sells as PA microphonse. The other two were modified Radio Shack boundary microphones, using a preamp circuit designed by Rick Chinn at Uneeda Audio. One of them actually has a high noise floor, so the recording was a good test run, to get that particular mic back into the garage so-to-speak, and I need to open up the hood and look around.

Ultimately, all of this is about the practical aspect of applying unabtrusive microphones, that can maximize frequency response by being placed in proximity to architectural surfaces, to create a boundary surround technique. As to whether this application is more Fudaka versus Decca Tree, or one of the other arrangements utilized in surround sound, it should be noted that Fudaka's requirement is that four cardoids placed near or at four points of a box or rectangle,similar to a Hamasaki. Square. The defination noted in the thread is an extended Fudaka Tree - where there are outriggers, and where there may be rear center microphone - depending on the shape of the venue. All of these are descendents of the Decca Tree, but where there is a need to have four uncorrelated channels of audio. Such a condition can be created with a stereo microphone used as the center mic - in a traditional Decca Tree arrangement. There are proponents of the use of a Soundfield microphone as part of a Decca Tree arrangement - Wes Dooley and Ron Streicher have written extensively on the implementation of that microphone, in that context. I've attached the model layout, that I applied for this recording, and wish to note the so-called "center microphone", is a virtual microphone with outputs derived from four microphones.

By using software that can matrix the various, traditional stereo configurations from the four signals, as was noted - one can compare the effects of using only two micrphones, both pairs, such as a "double ORTF" (attached), or perhaps deriving an MS Stereo or Blumlein result from the front mics. Ultimately, it was planned to generate a DTS surround sound recording from the arrangement. Currently - there are ambisonic samples of the concert posted at Ambisonia <http://www.ambinsonia.com>. The title of the web page, "birth of choir" - was intended to showcase how a concert was repared by a chorus that, literally, was performing for the first time that Sunday afternoon. I have, in the can, over 3 hours of rehearsal from the previous evening, also recorded with these microphones, but also by varying the boundaries, use of the boundaries, separation of the back pair with the front pair. Perhaps a series of podcasts discussing the results of the rehearsals is an idea.

Quite simply, there is a practical aspect of having all of this gear to comptely luggable on my shoulders, with possibly the use of a cab here and there, certainly public transportation. Thank you for Sanken reference. The literature is very interesting:
<http://www.plus24.net/dealers/pdf/sanken/CUB-01.pdf>

Also as for the observation about the soprano, that there was a pleasing choral sound, thank you. I thought the choir sang splendidly, but if I were to be my own worse critic, I would have backed up a bit given the church's acoustic, and tried to avoid the lip of the first step, which actually created a block for the sound. For sure, this is not the same as a having a good high quality condenser - on axis to an ensemble. But by we will only learn, by making more recordings, and experiment. Perhaps if I can get portions of the rehearsal up online, we can hear the effects of no Jecklin disc, or the effects of moving the rear mics back further.

Jim Mastracco

[Thomas W. Bethe]

I have used boundary layer microphones to record the Cleveland opera for years. My solution was to use good quality cardioid microphones placed on Sorbothane pads which completely deals with the foot fall problem while allowing you to use the small diaphragm microphone you want to use. More info on Sorbothane here Sorbothane

Using PZMs has been a mixed bag. Sometimes they sound great, sometimes not so great.

I used a pair of them taped to the wall of the Trinity Cathedral in Cleveland to do the chorus for Benjamin Brittan's Requiem in Time of War and they sounded fantastic and allowed me to do things I would not have had a way to do with out them. The recording was picked up by NPR and rebroadcast 13 times so I guess other people liked the recording as well. I also had two Plexiglas sheets made up and mounted the PZMs on them, flew them and used them to pick up a complete jazz ensemble drum set which also IMHO sounded GREAT! I tried using them in place of the cardioid microphones to record the opera but was not thrilled with the results and I had a lot more foot noise.

As to SASS. I had one for a couple of weeks on trial from our local Crown rep but could never get it to sound the way I wanted it to sound. I also have the recordings done with the SASS on a CD provided to me from Crown which I also did not like. There is a certain sound that the SASS has that makes it sound, for lack of a better word, plastic and unreal but maybe I had a bad one. I tried building my own SASS using guidelines I found on line out of plastic and two PZMs but that two proved not as good as what I normally used to record the same group.

Interesting discussion.

[phil.]

Originally Posted by digitalolive

OK, Here is the report of the tests they did with different arrays. Quite an interesting read.

http://www.aes-japan.org/surround_dv...eport_1_en.pdf

The DVD accompanying this paper can be found here.

ƒTƒ‰ƒEƒ“ƒhƒTƒEƒ“ƒhƒŠƒtƒ@ƒŒƒ“ƒXDVD

Best,

Phil.