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Jecklin Disk construction? Condenser Microphones
Old 25th November 2009
  #61
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Quote:
Originally Posted by boojum View Post
I loved what my hokey attempt at a Jecklin did for me. The big downside is what it looks like. People are quite used to seeing tube-like things with wires coming from them on stands. Small furry discs are another story. I do have to get that four inch extension so that my Oral Roberts Jecklin will work with the 4006 TL's and try some more recording. I think that is what Juerg had in mind. The mics, not Oral Roberts.
I built mine using a 1/4 inch piece of plywood and fancy convoluted acoustic foam. It can look cool if you want...
Old 25th November 2009
  #62
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Here's my version. I am trying it out on a solo piano early next month and I'll try and post a clip.
Attached Thumbnails
Jecklin Disk construction?-img_1244.jpg  
Old 25th November 2009
  #63
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Quote:
Originally Posted by tourtelot View Post
Here's my version. I am trying it out on a solo piano early next month and I'll try and post a clip.
Nice construction job. If it works as well as it looks you have the winner. ;o)
Old 17th June 2010
  #64
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I'm going to build a disc of my own. i'm contemplating using some old 12' vinyl records. would this work or is plexi glass recommended? I'm also wondering if bass frequencies are trying to keep separated in L and R channels, if so i had an idea to put an air trap between two discs. any ideas or suggestions?
Old 17th June 2010
  #65
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I used an old LP which I sprayed with contact cement and glued foam to that. I then sprayed the edge of the disc and wrapped it with a strip of foam. I covered the whole thing with fake lambs wool. I cannot sew, so in turned the wool inside out, stapled the seam and then turned it right side out and dropped it over the disc. Perfect. I would recommend gray. White just sticks out too much.
Old 17th June 2010
  #66
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alright. i was thinking of putting an air gap between two LP's and then covering each side with underlay which is a rubber kind of material used for soundproofing homes and stuff and then putting some fake fur on the outside of that. i think that would cover all my bases frequency wise.
Old 18th June 2010
  #67
Agreed...

Quote:
Originally Posted by Remoteness View Post
...Various types of material can be used. What do you have laying around? ...Even a couple of mouse pads can be glued to the above mentioned material instead of foam. It's all good. Try it out and see (hear) what works the best for you.
...
The Jecklin disc approach relies upon two main elements in acoustics - a barrier (the disc) and an absorber (the foam / material affixed to the disc faces).

One thing you might want to try (an acquaintence of mine has done this) is to find a few different types of foam as well as a lossy absorptive material (something akin to fiberglass, but with continuous fibers to minimize the 'nastiness' factor) and treat their backs with Velcro. Likewise, treat the face with the complementary part of the Velcro.

That way, you can use the disc with a variety of absorptive materials for a given set of microphones; those materials with the lowest reflection coefficient (provided by many NVH material specialists, usually per ASTM E1050-98 or sometimes ASTM C-423) will obviously absorb more of the high frequencies. I am not sure what's in the original specification for the Jecklin's materials (whether the absoprtion vs frequency is called out, or if the material proper is called out), but clearly, if you knew that you could emulate the 'reference' design, and then experiment with other materials in terms of their absorptive (lossy) properties (and of course, with different mic elements).

If you wanted to take the experiment further, I suppose you could make the disc proper (the barrier) with a hole pattern that could also be covered (as needed) with another material to allow more (when uncovered) or less (when covered) to pass between the two mics. In essence, you would be controlling the barrier portion whereas the materials used on the sides of the disc act as absorbers.

Lots and lots of possible combinations to the approach, and definitely, worth trying with different materials...but like I said, the Velcro approach, with various absoprtive discs seemed a like a clever approach to me.

Last edited by Mark A. Jay; 18th June 2010 at 06:28 PM.. Reason: typos
Old 18th June 2010
  #68
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I wonder if any of you have heard of, or experimented with alternate Schneider disk shapes/sizes.

When I first read about binaural (fake head) techniques, my first thought was maybe a poor mans version (not true binaural by any means) would simply be a sphere, with mics on either side (perhaps a medicine ball covered in a sound absorber).

Then I read about the Jecklin disk, which made perfect sense to me. And now after reading about the Schneider disk, and why it is supposed to be a further improvement to the Jecklin... I'm now wondering why use the Jecklin disk with two smaller 1/3 spheres glued to the center? What a strange shape for the purpose. Why not use a simpler shape to achieve the same disk diameter, and round central width- Find a sphere, which is more elliptical than perfectly spherical, cut it in two, and place a rigid disk in between the two halves. Attached is a rough diagram to better illustrate the idea, small circles indicate mic placment-

So this "Hybrid Disc" could be quite easy to make- take a rigid disc of your preferred material, sew a slightly larger "pillow case" for it out of some fabric, and stuff it with some inexpensive sound absorber (I'm thinking cellulose insulation, not the nasty fiberglass stuff). Then after making sure it was nice and taught, and evenly stuffed on both sides, sew it shut.

Has anyone heard of anything like this? Bad idea?? It would be a piece of cake to make, and depending on your taste in fabric (and sewing skills), look quite elegant.
Attached Thumbnails
Jecklin Disk construction?-hybrid-disc.jpg  
Old 18th June 2010
  #69
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Remoteness's Avatar
Man, what a cool thread...

The ideas are flowing strong!
Old 19th June 2010
  #70
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Pfhuck's Avatar
 

Not a Jecklin Disc, I know, but....

Been using this to intimidate drummers!

Please and THANK YOU,
Pfhuck
Attached Thumbnails
Jecklin Disk construction?-p_004021.jpg  
Old 20th June 2010
  #71
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Pfhuck that. its too scary. heh
Old 20th June 2010
  #72
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John Willett's Avatar
 

Re: Jecklin Disk construction?

Quote:
Originally Posted by Pfhuck
Not a Jecklin Disc, I know, but....

Been using this to intimidate drummers!
LOL - wonderful - love it.

Posted via the Gearslutz iPhone app
Old 21st June 2010
  #73
Great Idea

Quote:
Originally Posted by Pfhuck View Post
Not a Jecklin Disc, I know, but....

Been using this to intimidate drummers!

Please and THANK YOU,
Pfhuck
...makes me wonder if a whole Spinal Tap set of surrogate binaural microphones could be issued. Of course, for their drummers, the look would have to change. Constantly, as there is the never-ending threat of spontaneous combustion for a 'Tap drummer...

Still, a "Nigel Tufnel" or "Derek Smalls" a "David St, Hubbins" or a "Peter James Bond" signature model could work...of course, they would require retrofit such that any and all gain indictaors go 'to 11'.
Old 21st June 2010
  #74
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My pseudo-schneider disk:

- 12" 1/4' plywood disk
- about 4' diameter 1/2' thick cell foam disks glued to both sides, centered
- 12' foam disks glued on top of this
- covered with grey fleece.
- Manfrotto light stand spigot epoxied into a cut in the plywood for mic stand attachment with Manfrotto knee joint.
- Proper size machine screws epoxied slightly to one side for mic holders.

Makes a professional sounding and looking contraption. Slightly but smoothly thicker in the middle.

My second version is larger (35 cm) and has two inside layers of foam which makes it thicker in the middle. I covered it with fluffy fleece, but I do not like it as much as this one; makes the sound too bass heavy. I think it blocks the highs too efficiently. I have to try it with the balls (after I get around making them).

Mic suspensions are K-Tek K-SSM shock mounts.
Attached Thumbnails
Jecklin Disk construction?-jeck_side.jpg   Jecklin Disk construction?-jeck_side_2.jpg   Jecklin Disk construction?-jeck_front.jpg  
Old 21st June 2010
  #75
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Jecklin freaks, out of the closet and unite! I had no idea so many were tinkering with this mode of arraying mics. Is there a separate thread here for results??
Old 22nd June 2010
  #76
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Quote:
Originally Posted by Petrus View Post
My pseudo-schneider disk:

- 12" 1/4' plywood disk
- about 4' diameter 1/2' thick cell foam disks glued to both sides, centered
- 12' foam disks glued on top of this
- covered with grey fleece.
- Manfrotto light stand spigot epoxied into a cut in the plywood for mic stand attachment with Manfrotto knee joint.
- Proper size machine screws epoxied slightly to one side for mic holders.

Makes a professional sounding and looking contraption. Slightly but smoothly thicker in the middle.

My second version is larger (35 cm) and has two inside layers of foam which makes it thicker in the middle. I covered it with fluffy fleece, but I do not like it as much as this one; makes the sound too bass heavy. I think it blocks the highs too efficiently. I have to try it with the balls (after I get around making them).

Mic suspensions are K-Tek K-SSM shock mounts.
where did you get the hardware for mounting the disc to a mic stand? are there any good online sources i can order from?
Old 22nd June 2010
  #77
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Quote:
Originally Posted by zoso2 View Post
where did you get the hardware for mounting the disc to a mic stand? are there any good online sources i can order from?
Manfrotto - 026 Swivel Umbrella Adapter (Lite-Tite) - 026 - B&H

$29.50 from B&H. Just screw the spigots together and you get a connector where there is a right size hole for a straight mic stand attachement if you do not need/want the knee joint. Epoxy the top spigot with screws with smaller screw down (or the double-female spigot with the larger hole down if you want a more compact disk with nothing sticking out) in a right size cut in the plywood, and glue smaller pieces of plywood on both sides to cover.

Coming form photography background I often use Manfrotto lightstands for mics, as I have closets full of them. The umbrella adapter fits them perfectly, but it also fits most mic stands. Two adapters are needed if the disk is hanging form a boom and you need to angle it down.
Old 23rd June 2010
  #78
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Quote:
Originally Posted by Petrus View Post
Manfrotto - 026 Swivel Umbrella Adapter (Lite-Tite) - 026 - B&H

$29.50 from B&H. Just screw the spigots together and you get a connector where there is a right size hole for a straight mic stand attachement if you do not need/want the knee joint. Epoxy the top spigot with screws with smaller screw down (or the double-female spigot with the larger hole down if you want a more compact disk with nothing sticking out) in a right size cut in the plywood, and glue smaller pieces of plywood on both sides to cover.

Coming form photography background I often use Manfrotto lightstands for mics, as I have closets full of them. The umbrella adapter fits them perfectly, but it also fits most mic stands. Two adapters are needed if the disk is hanging form a boom and you need to angle it down.
judging from your location your mic stands are likely the european kind with the smaller and more coarse threading. I think i can fashion most of the bits myself all i need are the threaded parts for attaching to a mic stand and attaching mic clips to
Old 23rd June 2010
  #79
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Quote:
Originally Posted by zoso2 View Post
judging from your location your mic stands are likely the european kind with the smaller and more coarse threading. I think i can fashion most of the bits myself all i need are the threaded parts for attaching to a mic stand and attaching mic clips to
If you use the knee/swivel adapter you really need not worry about the threads, as long as the bottom end fits around the top of the mic stand you plan to use. Just thread the spigots together and epoxy them to the J-disk which ever way. That goes inside the top part of the joint, mic stand inside the bottom.
Old 24th June 2010
  #80
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so what is the general rule for mic spacing. do you space them as far apart as the disc is wide?
Old 24th June 2010
  #81
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If my memory serves the original OSS spacing for 12"/30 cm disk was 16.5 cm or 6.5". I do not follow that strictly, between 17 and 20 cm with the smaller disk. Version 2 which is 14"/35cm in diameter mr Jeclin recommends 35 cm spacing. Like I said at least my version of the larger disk kills too much HF to my taste.
Old 24th June 2010
  #82
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Quote:
Originally Posted by Petrus View Post
If my memory serves the original OSS spacing for 12"/30 cm disk was 16.5 cm or 6.5". I do not follow that strictly, between 17 and 20 cm with the smaller disk. Version 2 which is 14"/35cm in diameter mr Jeclin recommends 35 cm spacing. Like I said at least my version of the larger disk kills too much HF to my taste.
That is interesting that it seems to cut too much HF. Have you tried this 35cm disc with mics that have a HF boost, like some of the diffuse field omnis have?

This makes me wonder how much of the HF cut is due to the larger diameter of the disc vs. the extra sound absorption of the foam/fleece. I've noticed the manufactured OSS discs seem to have a fairly thin layer of foam, which might not cut HF to such a degree? And I have read that all Jecklin/Schneider discs cut HF to some extent.

Overlooking the HF issue, did you notice an improvement in stereo spacing with the larger disc?

I've been wondering how the standard Schneider disc compares to the new Jecklin disc, and if a larger Schneider would be superior in any respect (similar to what you have experimented with).

This makes me realize my own idea for an elliptical-sphere disc would most likely cut HF way too much.
Old 22nd September 2010
  #83
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Regarding the new Jecklin Disk specs-

Wikipedia has a link to the German document which contains a little information on this OSS technique.

Now, my German is poor, so I did a google translation, here.

I find this very interesting for a few reasons, and maybe someone with more knowledge and/or fluency in German could shed some light on a few things.

First, it is interesting that he recommends the 4006 specifically, but that isn't too surprising right? But he also recommends some sort of accessory for this microphone. Is he referring to a nose cone, or maybe an APE sphere?

Next, the brief translation given on Wikipedia suggests Jecklin recommends placing the microphones parallel to each other. However, later in the original document there is mention of a 60 degree angle, which makes me wonder if Jecklin is actually recommending the mics be placed at a fairly wide angle... similar to the old specs??? or maybe this 60 degree angle refers to something else?

And last, it is interesting to see the 4 mic technique with a disk. Not that I could tell how this would work, other than using two omni mics and two cardioid mics?
Old 22nd September 2010
  #84
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referring to a dual x/y with disk in between?
far left, left, right, far right?
Old 24th September 2010
  #85
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x/y, could be I suppose. I'm thinking "ball" is the poor translation for what should have been omni, but then ball is mentioned with cardioid, so who knows.

I'm especially wondering about what this 60 degree angle is in reference to.

The "accessory" might just be another poor translation?
Old 24th September 2010
  #86
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^^^^^^ Kugel is ball or sphere which describes the pattern that the mic hears in. In the case of the DPA 4006/4006 TL's there are 30mm, 40mm and 50mm which slip onto the omni mic and affect how the sound is "heard" by the omni mic. It adds a HF bump and makes it a sort of wide cardioid. The old Neumann U50 (?) had the same 50mm sphere. This is the DPA link: http://www.dpamicrophones.com/en/pro...146&item=24250
Old 24th September 2010
  #87
Old 24th September 2010
  #88
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Quote:
Originally Posted by boojum View Post
^^^^^^ Kugel is ball or sphere which describes the pattern that the mic hears in. In the case of the DPA 4006/4006 TL's there are 30mm, 40mm and 50mm which slip onto the omni mic and affect how the sound is "heard" by the omni mic. It adds a HF bump and makes it a sort of wide cardioid. The old Neumann U50 (?) had the same 50mm sphere. This is the DPA link: DPA Microphones :: Products
Not really,
I wish people would stop spreading disinformation on m50 type omni capsules.
You call it a U50 which is a designation Neumann has never used.

The ball makes the pattern go from full omni in the bass to very directional in the highs. If you use one you will hear this. The high lift is entirely dependant on the capsule, but it is in no way uniform around the capsule. From the rear,the sphere capsule would have rather the opposite effect. The sphere mount greatly colours the sound.
Old 24th September 2010
  #89
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>>>Kugel is ball or sphere which describes the pattern that the mic hears in.

Right, that's why I was assuming omni, which is also why with the 4 mic technique it gets confusing when it mentions ball and cardioid. I wondered if it meant two omnis in normal position, and two rear facing cardioids (with capsules as close to the omni capsules as possible- to pick up purely reflected sound).

>>>im so over OSS

Yes, I remember seeing this, pretty insane! But for me, not being a trained/professional engineer (just a musician), the simple, single disc OSS with two omni mics alone should actually simplify the recording process for me.

>>>The ball makes the pattern go from full omni in the bass to very directional in the highs.

Right. But is this (APE sphere) what Jecklin is talking about in this document?
Old 24th September 2010
  #90
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Let me post the text in question here-

Quote:
The two microphones must have a diffuse linear response. Optimally suited for this arrangement, the microphone 4006 of B + K with diffuse attachment
(Black). The angular aperture is about 60 degrees (due to superelevation of the frequency response in
the microphone axis)
And the original German-

Quote:
Die zwei Mikrofone müssen einen linearen Diffusfeld-Frequenzgang haben. Optimal für diese Anordnung geeignet ist das Mikrofon 4006 von B+K mit Diffusfeld-Aufsatz
(schwarz). Der Oeffnungswinkel beträgt rund 60° (Grund: Ueberhöhung des Frequenzgangs in
der Mikrofonachse)
I'm trying to clarify these points because I'm going to build a disc today/tomorrow for use at a concert the day after tomorrow.

For those of you interested in the 4 mic technique (I wouldn't personally have a use for it), here is the text regarding that-

Quote:
OSS4 - Engineering (Jecklin disc with four microphones)

In addition to the two microphones, two ball
used rear-facing cardioid microphones, the
must be placed as possible to the same places as the balls (to achieve optimal only with
Microphones with side inlet)
The lateral view angle becomes wider. and
while more room sound has been recorded.
This arrangement allows for a more detailed definition and
better coverage of large ensembles
(Symphony).
And the German-

Quote:
OSS4 - Technik (Jecklin-Scheibe mit vier Mikrofonen)

Zusätzlich zu den zwei Kugelmikrofone werden zwei
nach hinten gerichtete Nierenmikrofone verwendet, die
möglichst an den gleichen Orten wie die Kugeln plaziert werden müssen (optimal zu realisieren nur mit
Mikrofonen mit seitlicher Einsprache)
Der seitliche Aufnahmewinkel wird so verbreitert. und
gleichzeitig werden mehr Raumschallanteile aufgenommen.
Diese Anordnung erlaubt eine nähere Aufstellung und
eine bessere Abdeckung von breiten Klangkörpern
(Sinfonieorchester).
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