Topic: Anyone using the Schoeps Sphere Attachment KA 40?

[0vu]

I've used the KA attachments with MK5 capsules and they work fine.

Here's a pic of a KA (actually a KA50 but the idea's the same) in use on a small early music choral recording session. (It's the mic way up on the long boom coming in from the right.)

[H₂O]

Now that is a Boom! 


You could have your gear in a tapers section behind the board and have your mics FOB extended of the mixing area with a boom that long! 

[NOLAfishwater]

I wonder if you can make some out of something like these:

http://www.amazon.com/Spin-Table-Tennis-Uncoated-Balls/dp/B0042SUR40/ref=sr_1_8?s=sporting-goods&ie=UTF8&qid=1300982047&sr=1-8

or these:

http://cgi.ebay.com/40mm-STYROFOAM-Polystyrene-Foam-Christmas-Craft-Balls-/290515166445?pt=LH_DefaultDomain_0&hash=item43a40da4ed

[Gutbucket]

If they are relatively hard and dense foam, the yellow ones you've linked to seem similar to the green Nerf Balistic Balls spheres I've used:- http://www.amazon.com/Nerf-Blaster-Ballistic-Ball-Refill/dp/B0007VZVHY.  They don't seem to have a resonance issue, which keeps me away from styrofoam/polystyrene.  To me styrofoam always seems horribly 'screechy' and 'hollow sounding' with a sort of tension in it so I avoid it.  The yellow or green balls seem far more acousticly damped.  I had a yellow ball around here somewhere which was similar looking to those in the link you posted which I think was a ping pong ball.  It was slightly smaller in diameter than the Nerfs but the same material. The light weight of these is attractive for me in keeping weight down on the ends of the telescopic TV antenna aerials I use for adjustable mic bars with them, otherwise I'd prefer a smooth, hard surface of a dense plastic like Delrin or a wooden ball simply on acoustic priniciples.  But as long as they don't resonate or ring, I figure the dense foam is probably similarly effective in the mid and high frequency range where sphere attachments are effective.

BTW, the big head of a heavy nail heated red hot in a propane flame melts a nice and clean smooth hole through the middle of that foam.  That hole is the perfect size for the very small diameter 4060 capsules I use them with. You may be able to do something similar for mics with a bigger diameter by heaing the end of a short section of pipe secured in a vice as a makeshift hot cutting die- something like a piece of electrical conduit might work well.

[NOLAfishwater]

what if you put fur around your styrofoam sphere? or fur plus a high density foam disk in the middle?

talk about dense. check out this wooden sphere: http://www.premierwood.com/8-wood-ball-p38419.htm

If they are relatively hard and dense foam, the yellow ones you've linked to seem similar to the green Nerf Balistic Balls spheres I've used:- http://www.amazon.com/Nerf-Blaster-Ballistic-Ball-Refill/dp/B0007VZVHY.  They don't seem to have a resonance issue, which keeps me away from styrofoam/polystyrene.  To me styrofoam always seems horribly 'screechy' and 'hollow sounding' with a sort of tension in it so I avoid it.  The yellow or green balls seem far more acousticly damped.  I had a yellow ball around here somewhere which was similar looking to those in the link you posted which I think was a ping pong ball.  It was slightly smaller in diameter than the Nerfs but the same material. The light weight of these is attractive for me in keeping weight down on the ends of the telescopic TV antenna aerials I use for adjustable mic bars with them, otherwise I'd prefer a smooth, hard surface of a dense plastic like Delrin or UMHWPE or a wooden ball simply on acoustic priniciples.  But as long as they don't resonate or ring, I figure the dense foam is probably similarly effective in the mid and high frequency range where sphere attachments are effective.

BTW, the big head of a heavy nail heated red hot in a propane flame melts a nice and clean smooth hole through the middle of that foam.  That hole is the perfect size for the very small diameter 4060 capsules I use them with. You may be able to do something similar for mics with a bigger diameter by heaing the end of a short section of pipe secured in a vice as a makeshift hot cutting die- something like a piece of electrical conduit might work well.

[Gutbucket]

what if you put fur around your styrofoam sphere? or fur plus a high density foam disk in the middle?

Eh, styrofoam sucks, I just can't see making it good without more effort than starting with something better.  I made some hemispherical foam windscreens for my spheres that are simply cut-down Shure SM58 screens that slip over them and secure directly to the green foam ball with two sewing pins along the 'equator'.   Since they are for omnis I don't think they need anymore wind protection than that for most situations I'm recording in.  I've used them outdoors at the BearCreek festival for the last 3 years, usually without the wind screens and had no wind problems.

An Ebay search turns up lots of inexpenive hardwood balls about the right size.  I've also heard of people drilling holes through billiard balls.

talk about dense. check out this wooden sphere: http://www.premierwood.com/8-wood-ball-p38419.htm

That looks like the base for the T.H.E. BS-3D microphone, similar to the Schoeps KFM 6 but made from hardwood-

I hope it sounds better than it's name seems to imply. 

Of course those are much bigger and designed as stereo microphones so they have two omnis on opposing sides, yet the acoustic principles of reflection, diffraction and flush mounting of the capsules is the same.

[0vu]

what if you put fur around your styrofoam sphere? or fur plus a high density foam disk in the middle?

Then you have a totally different concept at work. The idea of the ball is that it is diffractive, not absorptive. I'm not sure that a lump of localised absorption centred so closely to a capsule would be very useful - it certainly won't do what a hard diffraction attachment does - but I guess it's an experiment someone could do. To be predictable, the spheres (and other shaped diffraction attachments need to be hard, reflective and smooth. Non resonant is also good. A critical aspect of these is getting the seal between the capsule and the surface of the ball (or whatever shape) properly airtight  or all sorts of nasty sounding and unpredictable things can happen. It's also important that the surface of the diffraction shape is smooth or the diffraction effect varies unpredictably with angle and can produce some strange frequency response and phase anomalies.

Wieslaw Woszczyk's paper detailing his research on different shapes and sizes of Acoustic Pressure Equalizer (as DPA calls them) used to be available from DPA's website but now seems to have been taken down. You should be able to get it from the AES.

Also, Martin Schneider from Neumann wrote a paper, about spheres only, available here: http://www.neumann.com/download.php?download=lect0043.PDF

I've tried using Jecklin and Schneider discs between mics with various shapes and sizes of diffraction attachments and the results generally weren't terribly useful. Sticking with smaller spheres - 30 - 40mm - was variably useful but the larger 50mm attachments didn't really work for me, neither did other shapes. My main problem with them all was to do with changes in the way the stereo imaging worked (or didn't) around the disc.

talk about dense. check out this wooden sphere: http://www.premierwood.com/8-wood-ball-p38419.htm

At 8" in diameter, you're getting into the realms of the stereo 'sphere' mics such as those made by Schoeps Neumann, Josephson and others. These are quite interesting and, in the right circumstances, can produce some extraordinary recordings but they're not by any means a universal tool and do take some getting used to. Ime they don't do what you at first expect them to and it takes some time to get the hang of them but they can be interesting. For me, they're more interesting experimental toys rather than day to day tools but I do have one of these for occasional fun and games: http://www.schoeps.de/en/products/kfm6.

[Gutbucket]

Thanks 0vu for sharing your experience with the actual sphere attachments.  I want to emphasize the point made about a good fit between the microphone and the sphere, both in the tightness of fit and in how flush the capsule is to the sphere surface.  Any gaps of significance will create a ragged high frequency response from cavity resonances and surface reflections.. I know that simply by listening while playing with my DIY versions, not from measuring them.  I second the papers cited to anyone interested in what is going on acoustically with these things.. and with diffraction around mics in general.

I realize the dense foam balls I'm using are less than ideal from a hard diffractive surface standpoint, yet they fit my other design criteria (low cost, low weight, correct diameter, easy to machine into the form I need, effective acoustic shadowing for far off axis sources) while being effective enough at the diffractive and boundary layer thing directly on and just off-axis.  They effectively convert the DPA 4060 from being almost perfectly omni up to something ridiculous like 15kHz into one with a smoothly directional high frequency response with a small presence rise.  No question that they are special use accessories which I only use in certain situations, but I have found them advantageous and interesting.  I've had better results using them than Jecklin disks.