Apex 460 ELA M250/251 Style Headbasket Mod?

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dfer

Well-known member
Joined
Dec 13, 2008
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Location
Galway, Ireland
Recently stumbled across the JJ Audio Dutch site and was really amazed by the headbasket mod. I'd really like to try somthing like that on my Dave Thomas AA C12 Peluso CEK-12, Cinemag TX.


I've never attemped a Mic Mod before so I'm a bit nervous about starting somthing like this, so could prob do with some advice from you dudes.


Link - http://bspade.com/UM25Mic.htm


Any info on the ELA M Headbasket would be great! Like size/diameter of Mesh used? Materials used in original? Caps/resistors in orig?








 

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One of the biggest difference between a C12 and an ElaM is precisely the head-basket.
As seen on the pictures, the C12 (and JJ audio) head basket is a single layer of grill, while the ElaM is a multi layered one, which conduce to different sonic characteristics.

The former is more 'transparent' but provides less shielding which may lead to a noisier mic.
A multi layered grill provides more shielding, and can tame the 'harshness' of many capsules.

Bottom line: If your capsule sounds very 'sweet' and your mic is dead silent, you may gain something from a C12 type head-basket...
Otherwise, it may just worsen things...

Axel
 
dfer

Why do you want to remove the inner layer?
Is it because you read/saw something on the web? 

Sometimes removing a layer can make a microphone worse.  Plus the capsule has less protection from dirt.

One should ask why do some of the classics have two or more layers.

Have you heard the microphones in person you have posted about?
 
Gus said:
Sometimes removing a layer can make a microphone worse.  Plus the capsule has less protection from dirt.

I fell into this trap for awhile, then I some significant RF rejection issues on an oktava. If you want to try it, I'd be sure you can easily replace if the result is less than desirable. I believe JJ offers replacement headbaskets, so you you might be just fine. If it were me, I'd be more interested in getting the headbasket profile as close to the original as possible.
 
True, Dave Thomas sells spare headbaskets for 35USD so it can be replaced relatively cheaply if things go south. Last time I check JJ's price for the headbasket mod was 110USD but I think the price has gone up a bit.

Either way for the price of the mesh and solderpaste i think its worth a shot in the DIY department. : )
 
Really interesting Link - http://www.treblebooster.com/m251e/telefunken_ela_m251e_circuit.htm


Anyone have any info on the size of mesh used in the Ela 250? I assume the outer mesh would be the same as the C12.

Mabey - 10 x 10 mesh....?


Unsure about what size the 250's additional inner finer mesh, that's not part of the C12 single mesh design
 
In my experience, taking out the thin inner mesh brings out rather unwanted sibilance, depending on the capsule, of course.

Multiple layers of mesh smooth out the high end nicely, but if it can be restored back by buying a replacement, try it out and use your ears.
 
Another good link - http://recforums.prosoundweb.com/index.php/t/28951/0/


Still unsure about getting authentic mesh diamentions - 10 x 10 outer, 30 x 30 inner fine mesh?
 
After searching google images for HQ pics I'm estimating around 65-70mm for the Headbasket which is accounting for the first ring/groove on the headbasket.

If someone has access to a real C12 its would be a great help if you could mesure the headbasket lenght, or if you already have info please chime in as I think it plays a big part of the character of this mic.


The offical PDF manual was great for overall diamentions - 258mm Body Shell (Not inc mic connector), Width - 42mm


 
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