Topic: Any of you Jecklin disc users ever try a spherical baffle?

[Gutbucket]

Curious about how a spherical baffle compares to a Jecklin disc in playback as well as any differences in use (set-up vs. other stereo techniques, critical distance, variations of sphere size, typical applications, etc.).  If anyone here has experience with using or building these things I'd love to hear about it.


Stan Linkwitz mentions using a homebrewed version (image above) for his own recordings http://www.linkwitzlab.com/sound_picture_cd.htm
Examples of complete comercial sphere baffle stereo mics are the T.H.E. BS-3D wooden sphere http://www.audiochocolate.com.au/products_t.h.e_binaural.htm & the Schoeps KFM6http://www.schoeps.de/E-2004/kfm6.html.

[pfife]

I tried this once.... I used a styrofoam ball.... I can't say exactly what the cause was, but it sounded very tinny/shrill.   It could have been a number of other factors, such as shitty venue, mics too high, and what I think it was, which was that my sphere didn't have some kind of dampening fabric on it - it was just painted styrofoam.

[Gutbucket]

Thanks for the links.  When I heard of people using Nerf ball baffles I assumed 'Nerf' ball meant the old-school open cell orange balls that are more like big wind protection foams that would probably block a little high end at most.  The heavy 'skinned' closed cell foam balls used in the links above would seem effective to much lower frequencies (cutoff determined at that point by the diameter of the ball I'd think, much like the diameter of the J-disc).  Talking casually to another guy who also tried a styrofoam ball awhile back, he mentioned that styrofoam didn't work very well and often had a nasty ringing resonant frequency.

I can understand that a 'ball on a stand' would block sightlines sigificantly more than a J-disk from behind and that's a vailid concern of course, but mostly I'm wondering if the end result sounds significantly different.  Potential differences that I can forsee would be: 

• The commercial sphere mics have their caps mounted flush to the surface of the sphere, pointing directly to the sides (90 deg off axis) so the directional nature of the highest frequencies may be more like a pair of Healy 'critically spaced omnis' oriented 180 degrees apart. Whereas Jecklin disc setups orient the capsules more forwards than sideways, towards the sound source.  This could affect reach and room balance somewhat.
• I'd think omnicaps mounted flush to the surface of the sphere operate under boundry layer effects that would cause somewhat of a rising high end response (due to the small size of the boundry) sort of like a Neumann M50 with a bigger sphere & lower point at which the frequency rise starts.
• The placement of mics a few inches away from a Jecklin disc allows for some adjustment of the amount of isolation provided by moving the capsules closer or farther from the disc (& also puts space around the capsules).
• The constant curvature of the sphere surface could possibly make for a more smooth pan across the stereo soundfield since the frequencies affected defract smoothly around the barrier instead of the shadowing effect of a flat disc with an edge

Just some inital thoughts, curious what you all think and especially the experience of any that have compaired both.

[BayTaynt3d]

I wouldn't use that ball in the picture provided personally because it looks like it'd reflect sound waves way too much. Yeah it'll block waves from the other sides, but it'll also pick up more reflections wouldn't it? Seems like it should be made of sound absorbing material shouldn't it?

[WiFiJeff]

with the Schneider Sphere being the true hybrid between them.

I've done a ton of HRTF recordings with my head as baffle, a few Jecklin recordings and will be going in with a Schneider Disk tomorrow and the new Sanken omnis (CO 100Ks).  I find it really takes getting used to a change in a setup I'm familiar with, at first any change sounds worse but people seem to like the Jecklin disk recordings.  I listen a lot on headphones, where the HRTF seem unbeatable, but on monitors the results are not so clear to me.  Have you done any piano (concert grand) recordings with s Schneider disk, any hints?

Jeff

[Gutbucket]

I wouldn't use that ball in the picture provided personally because it looks like it'd reflect sound waves way too much. Yeah it'll block waves from the other sides, but it'll also pick up more reflections wouldn't it? Seems like it should be made of sound absorbing material shouldn't it?

If the capsules are flush with the surface they should not be picking up reflections off the sphere and should act just like a PZM on a surface. That is the case with the THE hard wooden ball. Linkwitz's sphere pictured above does have his Panny capsules next to the surface of the sphere but I doubt they're far away enough to have significant comb filtering issues.  I'd be more concerned with damping the resonace of that plastic-looking shinny ball.

[Gutbucket]

Styrofoam just has this high tensionness thing going on about it, period. You touch it, and it lets out that skin-crawling screeech noise.

Ha ha. I know exacly what you mean, I despise that screeech 

All of these baffled omni/quasi-binaural techniques are so similar that were splitting hairs in these details.

Probably so.. Thanks much for sharing your experience & insights m0k3.  You've mostly confirmed my suspicions with your experience.  Always a good step before going too far with the wires and glue searching for experimental confimation of what others have already found out.
Cheers!

[poorlyconditioned]

Always a good step before going too far with the wires and glue searching for experimental confimation of what
                                           ^^^^^^^^^^^^^^^^^^^^^^
others have already found out.
Cheers!

I say go for the glue and wires.  Give it a try yourself!  That is how you learn, and have fun too.  Oh yeah, don't forget the duct tape...

  Richard

[WiFiJeff]

Jeff,

My speculative concern with the sphere/disc, is the lack of inward mobility in mic adjustment (again, total speculation). But, that inward adjustability with the mics is really nice!

The Schneider disk I have, from Core Sound. has the mic mount just like a Jecklin disk, so the mic will point towards the sound source (in fact, you can move the tripod mount to have it point down at various angles as well as horizontally, I intend to aim it into the lid of the piano from the front right).  I do not intend to have the mic flush with the surface, though the two inch gap Len suggests strikes me as perhaps a bit too far off the spherical bump and away from the disk part of the baffle.  I'll try to get a picture of it (the Sanken mics look like mini-missiless to me, giving the setup the look of an anti-aircraft battery).  A piano is not the best way to test stereo separation, though.

Jeff

[WiFiJeff]

Okay, here is the setup I used (direct to a 722 at 24/96), I REALLY like the sound I got from the piano:

[SonicSound]

Okay, here is the setup I used (direct to a 722 at 24/96), I REALLY like the sound I got from the piano:

What mic's were you using?

[WiFiJeff]

Okay, here is the setup I used (direct to a 722 at 24/96), I REALLY like the sound I got from the piano:

What mic's were you using?

These are the newish Sanken CO 100Ks, I can't hear if they go up to 100 kH as claimed (and I was taping at 24/96 on the 722 anyway), but they sure sound great on a Steinway.

Jeff