Topic: dpa 5.1

[chronictonicbear]

yet another option to drool over ...........

http://news.harmony-central.com/Newp/2008/DPA-5100-Mobile-Surround-Microphone-.html

[H₂O]

Better put a sign on it, saying "Not a Chair!! - Do not Sit!!!"

[Gutbucket]

1st thought is that it seems sized for cameras & convenience rather than optimal sound. We need some sound samples.

The interesting bits-

DPA's proprietary DiPMic™ (Directional Pressure Microphone) technology, which mounts interference tubes on the L/C/R capsules, and the use of acoustic baffles that further preserve the accuracy of levels between the discrete analogue output channels.

The 5100's three front microphones are time coincident to eliminate comb filtering and ensure paramount frequency consistency when downmixing to stereo or mono. In contrast, the rear microphones, which feature standard omnidirectional patterns, are optimally spaced from both each other and the front array to simulate natural time arrival differences.

DiPMIC? Hmmm.  Checking the DPA site..

[boojum]

Verrrrry interesting.    But no price.  Good thing, too.  I am not yet scared off.  Downside: six channels to do ambient sound.  Upside: these guys at DPA are good.  I think the six channel requirement is going to make it all but a lustful dream for the likes of us.  Hot shit setup, though.  And it does look like the drummer's chair.  Look out!   

[Dede2002]

Better put a sign on it, saying "Not a Chair!! - Do not Sit!!!"

Good point. 

[Gutbucket]

it does look like the drummer's chair.  Look out!   

Truth.

We can at least discard the 6th (.1) video oriented channel that is just a [120hz low-passed] sum of L+R -10db.  That still leaves 5, one more than a 4-channel machine can handle.  So when are we going to see the 5-track flash recorders? OK, I guess it will have to be 6 to target the video market.

DPA's surround angle until now has all been widely spaced.  See their 5-armed Decca tree.  The 4015 subcards on their surround demo disc sound phenomenal.

I've been running four baffled 4060s for some surround recording experiments (L,C,R,S) and it is very encouraging.  Looks like this thing isn't too far off from what I've been doing.  That's a big reason why I'm curious to lean more about the DiPMic technology.  Please post here if anyone finds out what that is other than a marketing word.

[edited to specify the low pass corner frequency of the LFE channel]

[aaronji]

Just got an e-mail from DPA that links to some more information on the 5100 and DiPMic technology:

http://www.dpamicrophones.com/en/Microphone-University/Surround-Techniques/5100.aspx and http://www.dpamicrophones.com/en/News/Archive/The%20Press%20Wrote/Line-Up-5100.aspx.

My apologies if this has been previously posted somewhere (although I didn't see it when I searched)...

[notlance]

Verrrrry interesting.    But no price.  Good thing, too.  I am not yet scared off.  Downside: six channels to do ambient sound.  Upside: these guys at DPA are good.  I think the six channel requirement is going to make it all but a lustful dream for the likes of us.  Hot shit setup, though.  And it does look like the drummer's chair.  Look out!   

As you probably know, it's possible to get 5.1 playback channels from 3 recorded channels using the Double MS technique:
http://www.schoeps.de/E-2004/double-ms.html
You don't have to use Schoeps mics, of course, but if you did I'm sure it would sound fine.  Nobody will mistake a Double MS setup for a stool.

Using 4 cardioid mics each 90 degrees apart you can get 5.1 playback channels from 4 recorded channels with the ability to have a stereo pair of any mic pattern facing any direction in a plane.

Then if you arrange the cards mics in a tetrahedron you can get a stereo pair facing any direction (including up and down) so you can get height information.  This is what is done with the Soundfield microphone and the TetraMic.

[Gutbucket]

There are two fundamental differences between the DPA 5100 and Double M/S or a tetrahedral mic: 1) pressure omni capsules are used instead of pressure gradient directional mics and 2) the rear surround capsules are spaced from each other and from the coincident front triplet.

I'd really like to see the baffle arrangement and the interference tubes used on the capsules inside this thing.  It's probably safe to assume they use 4060 capsules. The interference tubes probably fit on the capsules like the soft and high boost grids we're familiar with. I'd guess they look like extended grid tubes with slots along their length, typical of interference tubes on shotgun mics.  Unfortunately I doubt the tubes will be made available, similar to the 4090 flat response grid which fits the same capsules but is not available to purchase for the 406x.

They mention that the L/C/R mics are arranged coincidentally and that the baffle structure and interference tubes create the directionality. Looking at the response graphs, they get an impressive amount of level difference across the front of the array.  Check out the attenuation of the left mic for sources just 60 degrees to the right of center.  That is one of the aspects that could possibly stand improvement in my home-grown 4 channel baffled technique using 4060's- I have a spaced array for the front three mics with more distance between the capsules than is available in the 5100 'small drum throne' format, which probably helps reduce comb filtering plus the shadowing effect of the baffle creates good level differences between left and right, but the directionality isn't as sharply defined within the center 60 degrees for the high frequencies.  That is advantageous in getting a good center image when I use only the L/R pair.  It's also usually not a problem when using all three front mics in surround, but there are some sources that could use more L/C/R channel separation at times.

[guosh86]

just ran the 5.1 at the local conservatory last night

imo, the widely spaced surround kit definitely sounds more natural. the 5.1 sounds good still though, and since its really compact, its really handy.

more for outdoors stuff though, i'd reckon. could be perfect for video, but i won't really use it for recording indoors....

i'll try to get some clips up soon!

[aaronji]

^^^ I'd be curious to hear a sample or two!

And, speaking of size, how big is this thing?  I haven't really been able to find that information anywhere, but, from the description and photos, I am guessing it is roughly an equilateral triangle about 19 or 20 cm per side and maybe 4 cm thick?

[WiFiJeff]

^^^ I'd be curious to hear a sample or two!

And, speaking of size, how big is this thing?  I haven't really been able to find that information anywhere, but, from the description and photos, I am guessing it is roughly an equilateral triangle about 19 or 20 cm per side and maybe 4 cm thick?

And, can you fit it into a hat?  Looks like it might go into a colonial tri-cornered job.


Jeff

[boojum]

^^^ I'd be curious to hear a sample or two!

And, speaking of size, how big is this thing?  I haven't really been able to find that information anywhere, but, from the description and photos, I am guessing it is roughly an equilateral triangle about 19 or 20 cm per side and maybe 4 cm thick?

And, can you fit it into a hat?  Looks like it might go into a colonial tri-cornered job.


Jeff

I can see it now, the fife and drum corps, turned out in the new DPA mic setup.   LOL  The recordings would have a real "you are there" feel to them.

Has anyone seen a price on this getup?

[Gutbucket]

Very cool that you've gotten a chance to use this!  I'd also really like to hear some samples. 

Dimensions listed in the user manual are 7.7" x 9.4" x 5.5" (195 x 240 x 140mm) and just over a pound in weight.

I Played around a couple days ago with the published dimensions, the indicated spacing between the rear capsules and the polar plots of the thing to try and figure out the internal baffle structure.  See the attached image if interested in my best guess.  Here's what's going on-

Polar plots across the top are left surround, left and center, rotated so their primary axis is aligned towards the top of the page, to compare the differences in directionality imparted by the interference tubes and baffles for each mic. The polars on the left are just coincident overlays of those same rotated images to better see the differences by adjusting the opacity of the image (hard to see it in this image). The lower left is the left surround mic with black lines indicating the primary axis (and a line perpendicular to that) and colored lines indicating the angles at which frequencies are 5 db down on the polar plot.

The main part of interest is the plan view of the mic in the lower right.  The colored lines have been transferred to indicate the angles at which frequencies are 5 db down on the polar plots for the left surround and the center mic.  The center pattern is much tighter at these frequencies with the interference tube, but gets less smooth (notice that the 8kHz -5 db down angle is wider than the 4kHz angle).  The white lines indicate the probable baffle walls and the angle of those is determined by a line perpendicular to the primary sensitivity axis of each mic.  The yellow walls indicate possible additional baffling to impart more directionality to the surround omnis without interference tubes.

Overboard? perhaps. I had some time to waste and I like to build these kind of things so my interest was piqued.

Looks like it might go into a colonial tri-cornered job.

I thought exactly the same thing. 
No one would ever notice.

[WiFiJeff]

Dimensions listed in the user manual are 7.7" x 9.4" x 5.5" (195 x 240 x 140mm) and just over a pound in weight.

This is a little big for a colonial hat, but just about perfect for a standard-issue movie pirate hat.  How appropriate!

Jeff (Harhar mateys, methinks we could use such a hat)