Author Topic: Homebrew Jecklin and results (Read 7881 times)

boojum · « **on:** March 22, 2007, 03:47:18 PM »

I have made this Jecklin disk from an old LP, foam plastic, fake lambs wool, a 12" long 1/4 threaded rod, nuts, washers and heavy wire. The heavy wire was formed to stick the Velcro hooks onto to hold the mics which have a fabric backinig on them which acts as an isolation medium. It is as ugly as homemade soap but seems to work.

Let me know what you think of the tracks from a Monday night bluegrass jam at a local saloon. The jam has been there on Monday nights for ~20 years. Some of the crowd has been, too. The musicians are pretty good. The Dobro and mandolin players are quite good. The guitar players are, too. The bass player is good, but a little soft. And the washboard guy is kind of funny and talented.

I am not so much interested in what you think of bluegrass but solicit your criticism on the quality of recording, and, how I can improve it.

Thanks all!

here are links to three files.

http://download.yousendit.com/9EFD6C952E2DA16D
http://download.yousendit.com/A6FC3CD4509DA16F
http://download.yousendit.com/89BB465B66E54055

SmokinJoe · « **Reply #1 on:** March 23, 2007, 12:57:15 AM »

I'm listening to the first track. Nice and crisp, good separation, or at least it sounds spacious. What did you use for mics?

I've thought about building one of these... I wonder if I can use a pair of Nak300's with Omni caps. Kinda big, but it's what I've got. What are the design rules for a J card? I assume there are ratios and proportions for spacing, etc.

boojum · « **Reply #2 on:** March 23, 2007, 02:21:35 AM »

Jecklin's latest iteration on this specifies 35cm diameter disc and 36cm separation between the mics. An old LP is close enough to 35cm and a 12" rod with attachements on the ends are 36cm. I used a 12" threaded 1/4 rod, nuts and washers. I laid plastic foam on the disc, each side and 1/2' thick. I ran a 1/2' strip around the outside edge. When assembled I used the foamed disc to mark the fake lamb's wool using it folded over on one side so I would have one less side to attach together. I inverted the lamb's wool so the smooth side was out and stapled the edge. I cannot sew. It works fine. I turned it right side out, dragged it over the foamed disc, pushed the rod through the lamb's wool and center hole of the LP, locked it in place with washers and nuts and then attached the ever-so-ugly bent wire on the ends. Voila! El Cheapo but effective J-disc, not to be confused with J-Lo. ;o) The bent wire elevates the mics about 1/4 - 1/2 inch above the center line as Jecklin describes.

Using larger mics would require a larger rod through the middle or through a spot better suited. As long as it is locked in place by washers and nuts, strong enough, and the mics are of equal weight [they are] there is no reason you cannot have fun with this for $5 or $10. I used the base end of a mic clamp to attach to the disc so I could stick it on the end of a mic stand. Give it a shot. The mics must point at the sound and be omnis according to Jecklin. I am not going to argue with a Swiss Ph D in audio engineering as I think he knows a tad more than I.

I will post a step-by-step in the next day or so for the chronically ungifted at construction like myself. My whole point is to not get lost in all the technicalities or the "my mic is better than yours" stuff but to have fun, record some good sound and try to learn, learn, learn.

I hope what I have done has helped encourage you some.

OK, how did you like the recording? What can I do to make it better?

Yes, it was in a spacious room: the Cannon Beach, OR, American Legion hall where this jam has been for a long time. $5 for a burger with the greasy trimmings and a couple of hours of free music, but it is a good idea to put a couple of buck in the tip pitcher. ;o) The core of this group plays at Bill's Tavern on Thursdays and when I get the mic placement right in that place I will post a few tracks.

Let's have some fun!

Brian Skalinder · « **Reply #3 on:** March 23, 2007, 07:37:06 PM »

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.flac

Sample 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.flac

First 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.

boojum · « **Reply #4 on:** March 23, 2007, 10:01:12 PM »

Now that is a real professional looking rig. The faux fur reminds me of a gal I used to date. ;o)

I will put togther a step-by-step on my creation. It is really for the ungifted with tools, as I am. But the disc does work and that is all I care. This is a medium about hearing, not seeing. You just have to promise not to laugh at ethe step-by-step. ;o)

Cheers B)

CQBert · « **Reply #5 on:** March 23, 2007, 10:23:20 PM »

Congrats on the work....

Keep experimenting and posting your result...

+T To you and Skalinder for DIY !

CQBert

CQBert · « **Reply #6 on:** March 23, 2007, 10:33:15 PM »

The picture below is of the Disk I built for Sleepypedro in use at Langarado earlier this month.

What I did was a little more involved but seemed to work...

I had a 12" disk cut from 3/8 Birch Plywood (light)

Drilled a 1.5" hole dead center and used a thin walled PVC pipe approx 4" in length... put small screws at 4 points on either end and used O-rings to create a shock mount that ran through the center of the disk... slip in a Kwon bar and away you go...

For foam I purchased some from a dealer on line that charged me a couple of bucks to cut into 12" circles...

To mount to a stand I put the bottom part of a mic holder in a narrowed area of the wood and that is it...

http://i3.photobucket.com/albums/y52/clarkeart/misc/article%20photos/IMGP7587.jpg
http://i3.photobucket.com/albums/y52/clarkeart/misc/article%20photos/IMGP7585.jpg
http://taperssection.com/index.php?action=dlattach;topic=81193.0;attach=60135;image

CQBert

boojum · « **Reply #7 on:** March 24, 2007, 10:41:33 AM »

CQB - now that looks professional. Even the color is right. How did the recordings turn out?

I have only recorded inside so far. The J-disc likes to be close, about half the distance of a cardioid. I can get the sound recorded fine at a distance but while my ear compensate the recording does not: it sounds far away. And applying gain does ot help as the acoustics do not change, of course. I just wind up with a track sounding far away and loud. Imagine that! ;o)

OK, back to the sawing board. B)

CQBert · « **Reply #8 on:** March 24, 2007, 12:27:08 PM »

I recoreded with my u89 only 10 ft from the source... I used a sub-card pattern and the recording was great...

http://taperssection.com/index.php?action=dlattach;topic=80717.0;attach=59440;image

Sleepypedro and crew were using at Langarado.... I have not hear the tapes but they were very happy.

Check Kickdown to see if any of those have been posted..

CQBert

fasteddy · « **Reply #9 on:** March 24, 2007, 01:24:52 PM »

very cool

has anyone tried this separation technique with other mics then omni?

would it be a waste?

boojum · « **Reply #10 on:** March 24, 2007, 02:38:16 PM »

Quote from: fasteddy on March 24, 2007, 01:24:52 PM

very cool

has anyone tried this separation technique with other mics then omni?

would it be a waste?

I do not know if it would be a waste or not. But I would give some considerable weight to what Jecklin has come up with. He is knowledgeable and did quite a bit of research to come up with this. He is more than a seat-of-your-pants shade tree mechanic type. He went to school for this and understands the theory and practice as he was the head of Radio Switzerland. He has to know something! It is worth playing around with, though, so go for it and let us know what you come up with.

Cheers B)

CQBert · « **Reply #11 on:** March 24, 2007, 04:46:40 PM »

I run my u89's in sub-card with the disk...

Good Results...

CQBert

SmokinJoe · « **Reply #12 on:** March 28, 2007, 08:32:40 PM »

I can appeciate the hidden beauty of a well designed contraption as well as the next geek, but Brian... dude... it looks like you filleted the green monster from Sesame Street and stuck it up on a pole

Sorry, I just had to say that.

Gutbucket · « **Reply #13 on:** March 29, 2007, 02:28:07 PM »

Posting to track this thread.

Did some Jecklin disk-ish & spaced omni experimentation last weekend at Suwannee Springfest using plenty of ideas collected from the forum. Details and thoughts after I get film processed and have a chance to listen critically. John R posted a photo of my makeshift baffle with TV antenna adjustable bar in his Suwannee Springfest thread.

boojum · « **Reply #14 on:** March 31, 2007, 07:15:53 PM »

GBG -

That TV antenna setup is killer. What a stroke of genius. I guess we should not be allowed to the dump unescorted! LOL I will try to do something like that. It is damned clever. I'd give you a + but am too young.

Cheers

2amuse · « **Reply #15 on:** April 08, 2007, 08:04:08 PM »

I am finding omnis to be quite forgiving. I have CSBs and attach them to the front of a waist pack a few inches apart and angled outward. The middle of the waist back "pooches" out a little creating a slight barrier between the mics but not anything like with the disc. The results are quite pleasing plus the setup is very fast and discrete.

Perhaps I could get even better imaging with a disc but my setup is incredibly stealth. The only thing visible are two very tiny mics. Everything else is in the waist pack.
CSB>bat box>R09. Ultra simple.

Also I am finding you don't need to record so hot. Give yourself plenty of room for percussion hits. It is nice to have those hits be very clear with no distortion. Ray

saxophoner · « **Reply #16 on:** April 10, 2007, 07:07:54 PM »

what does this jecklin disc achieve? it looks cool, esp. the green faux fur one, but i've got no clue what its doing. anyone care to explain to me.

thanks

goodcooker · « **Reply #17 on:** April 10, 2007, 07:50:41 PM »

Quote from: CQBert on March 24, 2007, 04:46:40 PM

I run my u89's in sub-card with the disk...

Good Results...

CQBert

i'll bet you get good results with a pair of U89's

I did a first run at a disc with the record album(scratched Duane Allman)+foam+hairy fabric+epoxy+mic clip approach......but it's pretty janky.......does anyone know if the density of the foam or the actual thickness of the disc has anything to do with the "sound" of the baffle.

The discs I've seen for sale do not have any sort of fabric or lambswool or anything....and they are a couple hundred bucks!

I want to use this contraption to record stage lip for Tortoise..........any thoughts???
The room sound in the club is questionable........

Brian Skalinder · « **Reply #18 on:** April 11, 2007, 01:42:25 AM »

Quote from: goodcooker on April 10, 2007, 07:50:41 PM

I want to use this contraption to record stage lip for Tortoise..........any thoughts???
The room sound in the club is questionable........

I think recording Tortoise with a J-disc would work quite well. At least around here, they play smallish venues and put out a lot of sound from the stage. The only caveat I'd add: don't get too close. Since they have both drum kits up front & center, you need to get some space between you and the kits to keep the drums from overwhelming the sound and achieve proper blending between the kits and the rest of the instruments. I've run subcards NOS ~15' back and that worked quite well - nice up-front sound from the drums, but didn't overwhelm everything. I'd be hesitant to go closer than 10'. Also...not sure the keyboards go through an on-stage amp, so you still want to catch some of the PA. But...each venue / stage setup is different. $0.02

boojum · « **Reply #19 on:** April 11, 2007, 01:47:51 AM »

Re foam: it should be acoustically dead. That is it should not allow sound to pass through it. I like the layer of fake lambswool to help. The Japanese first used this techinque if I remember correctly. Someone correct me if I am wrong.

From what I have read the OSS/Jecklin follows the same rules as other omnidirectionals: 1/2 to 1/3 the distance of a cardioid. So I would suggest getting as close as you can without overloading your mics. Only your experience with the mics and the band can guide you. Good luck. And let us know how it went.

china_rider · « **Reply #20 on:** April 11, 2007, 02:11:59 AM »

At Joshua Tree Roots fest last year one of the acts had their home made Jecklin head. I believe it was the Ditty Bops. I was quite surprised when I saw them with their own home made setup. Talked to them a little bit about it. They had a mannequins head with bolts coming out of the ears to mount the shocks on. The head was first wrapped with foam, then something like a cotton ball layer. Then a dead rat type of material layer wrapping it all. So the bolt stood out through all that. I think they were running AKG462s. I've never seen the source circulate but it looked like a pretty decent solution. I asked how they got the head and they said they had to buy the entire mannequin at good will.

boojum · « **Reply #21 on:** April 11, 2007, 01:30:00 PM »

Did you ever find out how it worked? The disc is so easy to make, and proven, so I wonder why folks try to reinvent the wheel. The "head" is a good way to do binaural with the mics in the "ears." I wonder how well it does as a psuedo OSS.