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Jecklin Disk construction?
Old 12th November 2012 | Show parent
  #151
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🎧 10 years
Quote:
Originally Posted by Rolo 46 ➡️
I borrowed the Neumann Dummy head and chest,found it quite resonant in comparison to DPA 4060s spaced outside a head on HD 25 cans.
It's interesting to use a 4060 pair gaff taped temporarily to a wooden sphere. They can be remounted easily on wooden spheres of different
sizes depending on the particular recording.

Otherwise, the distance at which a sphere based mic is placed from a source is overly determined by the fixed size of the sphere.
Old 1st June 2013 | Show parent
  #152
Gear Nut
 
🎧 10 years
Very interesting post Nikolay,

I made my own Jecklin Disk to be used with a pair of KSM141 along with a pair of large APE spheres I made to fit the 141s. The disc I made is 35cm, mics spaced 36cm (mics parallel to each other) as I followed Jecklin's most recent specs- Jecklin Disk - Wikipedia, the free encyclopedia.

I was very pleased with the results and used this setup to record a piano CD/DVD released a couple years back (you can just make out the disk at the tail end of the piano in the opening shot of this video)- Images (9 of 10) St Catherine - Nathan Shirley - YouTube (sound compressed severely on youtube)

However, I believe I've noticed a similar effect as what you describe. When comparing the test recordings for this CD, the disk did seem to cut HF to a slight extent. It was actually helpful in my case as the piano was a bit overly bright, but it also had the effect of slightly muddying the bass. When I added the APE spheres with the JD it improved things all the way around, and I was very happy with the result, but it wasn't quite what I would consider perfect.

After doing some research and talking to people I decided it might have to do with the amount of padding I used on the disk- foam AND lambswool-like material, likely overkill.

Perhaps the exact attributes of the foam covering the disk are critical.

I've also wondered if slimming the disk down might help. I used plywood, but perhaps Plexiglas might be better, along with less padding?

I'd love to hear what you've found now that it's been over a year.
Old 1st June 2013 | Show parent
  #153
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boojum's Avatar
 
1 Review written
🎧 10 years
I used an old LP for my Jecklin disc. It was an Oral Roberts LP that I got somewhere. A good use for it.
Old 1st June 2013 | Show parent
  #154
Gear Nut
 
🎧 10 years
I've heard of using LPs, that would certainly be slim... and about what, 30cm diameter?

Have you noticed any subtle HF cut?

BTW, here is Nikolay's post I was responding to- https://www.gearslutz.com/board/7785018-post143.html

Last edited by NathanShirley; 1st June 2013 at 05:16 AM.. Reason: Added link to OP sited
Old 1st June 2013
  #155
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boojum's Avatar
 
1 Review written
🎧 10 years
Nathan, I used contact cement to attach some cheap foam and then covered the whole thing with fake lambswool. HF cut was beneficial for the app, a not too polished chorale.
Old 1st June 2013 | Show parent
  #156
Gear Addict
 
🎧 10 years
Quote:
Originally Posted by boojum ➡️
I used an old LP for my Jecklin disc. It was an Oral Roberts LP that I got somewhere. A good use for it.
Several stacked LP's is better. A friend got very gratifying results by repurposing a bunch of Barry Manilow LP's :-)
Old 18th November 2013
  #157
Gear Head
 
2 Reviews written
🎧 5 years
I have run listening tests on putting a sound-absorbent material between two spaced omnis and what I found is that the lower and mid frequencies are louder because some sound reflects off the material. It doesn't matter what you use, it will reflect a bit and cause a few db rise in volume in the lower registers. This will make the sound punchier but also less smooth, and more grating on the ears. I record classical music and smoothness is a must, esp. since typical commercial classical CDs are way to harsh and bright. A first generation Digital recording can be magically smooth if you do it right, but the minor reflections from adding an absorbing material ruin what would otherwise be a great concept.
Old 5th June 2019 | Show parent
  #158
Here for the gear
 
Mounting mics on Jecklindisc

Hey everybody !

I am new on the forum, and ok, the theme is already many
years old.
But I am busy now to build a Jecklindisc, and want to keep it
a bit universal. So that I can use any mic that I want to try.

That means that the mounting of the microphones must be
possible in 3D !!
Only THAN you can be sure to be able to use any mic.
If it ain't difficult, I will make it difficult ! HAHA

I have seen different methodes, but I am not sure yet.
Maybe there is someone with a nice idea, not publicised in
the forum yet ?

Oh, and maybe someone knows what it would do, when I use
cardioids, instead of omni ?
It seems to be a bit difficult to find a payable omni...


Many thanks in advance.

Kind regards,

Evert
Old 5th June 2019
  #159
Lives for gear
 
🎧 10 years
Why not try it the other way? Have the Jeckling disk made so that it is mountable between any 2mic setup?
Old 5th June 2019 | Show parent
  #160
Gear Head
 
al_net77's Avatar
I recently builded a Jecklin using a "configurable" list of items. On the disk I used a couple of Adam Hall D 921 Base Plates on which I can mount different extensions. If you need a pseudo-3d positioning I can suggest a goose (I used this: https://www.thomann.de/it/millenium_goose_s.htm) with a K&M 19695 Universal Mount at the end.
Usually I use it with the Gravity MS QC 1B because it does have the right lenght to get the 35cm distance.

I can provide some photos if needed.
Old 5th June 2019 | Show parent
  #161
Gear Head
 
al_net77's Avatar
Quote:
Originally Posted by heva ➡️
Why not try it the other way? Have the Jeckling disk made so that it is mountable between any 2mic setup?

This was my second idea: take a Manfrotto 154 and build a disk with a slot.
Old 5th June 2019
  #162
Gear Addict
 
Mark A. Jay's Avatar
Well...

First, there's a lot of great material on this thread (and on the web), so study that well.

I can say that you should choose the most absorptive material that you can find that will also 'handle' well. One of the materials that I have found that works well (but is somewhat hard to find) is melamine foam. BASF manufactures it (they may hold the patent) and they sell it to any number of companies who then re-brand it. 25 mm thick Basotect (melamine) would work well...other materials can work equally well, again, provided that their alpha values are similar.

Anyway, the lossy (absorptive) material should have as high an absorption value (alpha) as possible. Reputable companies will list (usually) absorption versus frequency per ASTM E-1050-98 (normal incidence absorption) or its ISO equivalent. The higher the alpha value the better. The foam's job (or the cloth's job) is to act as a sink for acoustic energy - to minimize the reflections from the disc. In other words...the foam makes it 'look' like there's an open window to the outside...where the incident sound can pass through and leave. The reflections from an un-treated disc will set up some comb filtering effects.

The disc is there of course to act as a barrier for mid to high frequencies.

The universal mount sounds like a great idea.

As far as different patterns...there is another way to get there, but with way more complexity.

In theory, were you to mount a velocity mic and a pressure mic, you could (in post) create any first order pattern (omni, card, super-card, fig 8). Of course physically mounting four mics (two of each type on both sides) is a bit of a mounting nightmare, but the math works. If you are not familiar with the approach look up the paper (circa 1977 I think) written by Wes Dooley.

The advantage to this is that you could choose the pattern during post production...which can be handy.

Practically though, I can't think of any convenient mounting system - you'd have to come up with it - but there are some options, though a bit pricey.

You could, in theory, use something like an Avantone CK-40. Size is the issue here, but the idea would work. That is you would:

Place a CK-40 on either side.
Turn one capsule 90 degrees. Set THAT capsule to FIG 8 (so it points front / back)
Set the forward-facing capsule to omni

This gives you the pressure (omni) and velocity signals (fig 8) that you will need to alter the pattern.

So, with four channels you would have:

Left omni (pressure)
Left fig 8 (velocity

Right omni (pressure)
Right fig 8 (velocity)

This will NOT allow you to redirect the microphone pattern (i.e. the angle of it) but you would be able to control the pattern...but...you would have the option of creating specific patterns (any number of them, really).

The other way to do this would be to use a soundfield mic and convert the signal to B-format. This approach would likely be 3x the cost of the two dual diaphragm LDC mics, but it WOULD allow you to a) generate whatever pattern you wanted (first order) as well as 'steer' the pattern...but now you're working with eight channels just to get there. Still, theoretically this could work (because B-format comprises four signals - W (pressure), X velocity, Y velocity, and Z velocity)

Getting back to Planet Earth, I have to say that I've used omnis, I've used cards and have had great results with both. It's a nice mic configuration regardless, and the options that I mention are more to get you thinking about how you might manipulate signals to give you whatever mic you wanted at the time.

Mark
Old 6th June 2019 | Show parent
  #163
Here for the gear
 
Thanks !

Hey friends,

thank you all for the reactions.
Strange, that I did not got any mail that there were new reactions.

One of the ideas I have seen, is a long bolt through the disc, with
on both ends a micclamp.
I'm not critisizing that, don't misunderstand me, but with that idea
you cannot change the distance to the disc.

But by using two ... how are they called ? My English is a bit poor.
Stereobars:
I think a picture is attached, went so strange, I couldn't get it
right I think.
But by using two of those bars for each side it should be possible
to move the mics in 3D :-)
Look, if you take care that the screw in the micclamp lays hori-
zontally, you don't have to worry about the height of the mics.
They are than always 'above' the horizontal center line.

Well, let's try !

Many thanks again !

C you !

Evert
Attached Images
Jecklin Disk construction?-stereoschiene.jpg 
Old 6th June 2019 | Show parent
  #164
Here for the gear
 
The best idea ??

Sorry !

What about a long bolt through the disc, and than use at each
side two nuts, for clamming (?) the bar between.
In that way it is possible to move the bar closer to or further
away from the disc.
And if necessary you can shift the micclamp in the bar forward or
backwards.
Hmmm... I am still thinking of a little danger of hurting someone
or yourself, whith the bolt if it is too long.
So it would be a bit nicer to be able to rotate the bar on the bolt
with a kind of hinge.

And slowly 'we' come to the ideal way of mounting

Byyee !

Evert
Old 6th June 2019 | Show parent
  #165
Gear Head
 
al_net77's Avatar
If you need "infinite" positions consider my quote:

Quote:
Originally Posted by al_net77 ➡️
This was my second idea: take a Manfrotto 154 and build a disk with a slot.
Old 6th June 2019 | Show parent
  #166
Here for the gear
 
Yeah, I had seen that one, the Manfrotto, but very expensive.

In the mean time I got different ideas.
One of them:

Mount a bolt like M8 x 50, parallel to the disc.
Along that bolt you can move the 'stereo-bar' up and down, AND
the bar can rotate around that bolt for the distance to the disc.

I think that could be the easiest way.
If ready, I'll post a photo of it.

Kind regards, and thanks to the ideas, they bend my brain in the
right direction.

Evert
Old 10th June 2019 | Show parent
  #167
Gear Maniac
 
PuebloAudio's Avatar
 
🎧 5 years
Making Jecklin Discs are great weekend projects. I have built many over the years and have made some interesting recordings with them. The last round of discs I made were inspired by a stack of spent Lacquer Discs laying around the mastering studio. I constructed a few without being overly strict to proper specifications. Pictured below are two of them.

One is a straight forward, stand mounted disc. It is made from two 14" lacq's (lacquer coated aluminum) with 1/4" neoprene sheeting glued to the surface to damp resonances. On top of that are layers of poly-fill batting which is enveloped by a porous fabric skin for HF absorption. Standard mic mount flanges hold the mic clips.

The second is a crazy experiment which I call the "DiscaTree". This mounts three DPA 130HV omni's for LCR recording (like a Decca Tree). Two 4003's with bullets on either side for L/R, and one 4003 facing front with an API for C. Similar build to the above except I used a soft but dense 1/2" black batting instead of the poly-fill. The material is held together with removable clamps so that I can get underneath the material to mount the mics. DiscaTree is meant for hanging. It is visually ugly up close but once it is hung no one can tell.
Attached Thumbnails
Jecklin Disk construction?-img_0678.jpg   Jecklin Disk construction?-img_0679.jpg   Jecklin Disk construction?-img_0693.jpg   Jecklin Disk construction?-img_0696.jpg   Jecklin Disk construction?-img_0680.jpg  


Last edited by PuebloAudio; 10th June 2019 at 08:41 PM..
Old 10th June 2019 | Show parent
  #168
Here for the gear
 
Hello Scott, thanks for your reply.

They look very nice.

Suddenly, a few moments ago, I got a new idea,
for damping the discs.

Haha, why not use two carpet tiles ?
Very cheap to get.

I'm still waiting for some discmaterials. (Pertinax)

It will take a bit time, before my disc is ready, because
I cannot get out of the house, bcs of backproblems.
So, I have to order everything, and than have some moments
with less pain in the back.

When ready, I'll post the photos.

Byyee !

Evert
Old 10th June 2019 | Show parent
  #169
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boojum's Avatar
 
1 Review written
🎧 10 years
Built my Jecklin over an Oral Roberts LP. Covered it in fake lamb's wool. I did not use it much but it was fun to put Mr. Roberts to work.
Old 11th June 2019 | Show parent
  #170
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by boojum ➡️
Built my Jecklin over an Oral Roberts LP. Covered it in fake lamb's wool. I did not use it much but it was fun to put Mr. Roberts to work.
You re-baptised him as Aural Roberts !
Old 11th June 2019 | Show parent
  #171
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boojum's Avatar
 
1 Review written
🎧 10 years
Quote:
Originally Posted by studer58 ➡️
You re-baptised him as Aural Roberts !
Dr. Johnson says a pun is the lowest form of humor.
Old 11th June 2019 | Show parent
  #172
Gear Guru
 
1 Review written
🎧 5 years
Quote:
Originally Posted by boojum ➡️
Built my Jecklin over an Oral Roberts LP. Covered it in fake lamb's wool. I did not use it much but it was fun to put Mr. Roberts to work.
unfortunately, i don't remember which lp jürg used to build the first mic separation disk i saw - but i'm pretty much sure it was one he didn't like much (either); foam came off the control room's rear wall, from behind the studer a80/a800 :-)
Old 11th June 2019 | Show parent
  #173
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by boojum ➡️
Dr. Johnson says a pun is the lowest form of humor.
Descent to limbo and lower levels is a distinct possibility !
Old 11th June 2019 | Show parent
  #174
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boojum's Avatar
 
1 Review written
🎧 10 years
Quote:
Originally Posted by deedeeyeah ➡️
unfortunately, i don't remember which lp jürg used to build the first mic separation disk i saw - but i'm pretty much sure it was one he didn't like much (either); foam came off the control room's rear wall, from behind the studer a80/a800 :-)
Once again, by sheer luck, I was traveling with the angels. I'd have said "great minds think alike" but would be only half right.
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