Great thread, boojum. Prompted me to post my DIY, something I've forgotten to do for a while now...
I built a Jecklin disc in December for recording an a cappella performance. I based it on the 300mm (11.8") disc diameter spec from the
Josephson OSS/Jecklin disc page.
I used a 12" flat cut-off disc,
like this, and two smaller discs epoxied to either side of the disc - with the outer edge of the smaller discs lining up with the outer edge of the larger disc at the "bottom" of the disc - to cover up the hole in the middle. (see attached diagram) I cut out two channels on the bottom of the disc to fit a 5/8" female barrel for easy mounting and epoxied it in place. I then picked up some foam (~0.5" thick) and faux fur at the local craft store, cut to size, epoxied the foam to the disc and then the faux fur to the foam.
I didn't affix any mic mounts to the disc itself because I couldn't figure out how to do so in such a way that would allow me to mount either my Schoeps MK5s (actives) or AKG C414s depending on my preference. So, I mount either pair of mics in their stock shockmounts on a K&M 235 mic mount bar on the stand, use a "c"-type clamp and posi-lok to mount and orient the disc, and control the spacing/angle of the mics with the mount bar and shockmounts.
Future improvements planned: replace fairly porous/thick foam with more dense/narrow foam, replace faux fur with less offending color faux fur / lambs wool.
I've only used it once so far, at an a cappella performance. During pre-performance rehearsal, I started off using the mic spacing as recommended on the
Josephson OSS/Jecklin disc page: 165mm (6.5"), or ~3" from my ~1" thick disc. After listening, I pretty quickly decided to reduce the spacing to achieve better L/R separation. Looks like I neglected to capture the precise spacing in my notes (dumb), but it was probably in the neighborhood of 1.5"-2". In hindsight, and while I'm pleased with the recording, I think I reduced the spacing too far.
Two 16-bit FLAC samples from
Coriolis, Dec 2006 at
St. Luke's Church, Evanston IL:
Sample 1: E'en So, Lord Jesus, Quickly Come..............................Paul O. Manz (1927-)
ftp://bskalinderfriends:fbsf947F@tapers.org/coriolis2006-12-16_samples/coriolis2006-12-16d1-mk5_04.flacSample 2: Joy To The World...........................Lowell Mason (1792-1872) / Arr. Don Hart
ftp://bskalinderfriends:fbsf947F@tapers.org/coriolis2006-12-16_samples/coriolis2006-12-16d2-mk5_03.flacFirst sample is the full group. Second sample is just the men. Surprising to me, and different than the previous week's performance, they arranged themselves in front of the risers ~5' closer to the mics than I expected. While I find the 1st sample has pretty good blending, individual voices come out more than I'd like in the 2nd sample. Live & learn.
And now...I'm itching to try it on-stage or FOB in a couple of my local venues! Major slump lately, unfortunately, seems I always have something going on, work or personal, that keeps me from recording as much as I'd like. Hopefully, I'll get to it soon.