34mm dual diaphragm capsule dissection

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alk509

Well-known member
Joined
Sep 3, 2004
Messages
1,207
Location
MA, US
I put this little thing together for you guys. Enjoy!

http://home.comcast.net/%7Ealkoury/34mm/34mm.html

Peace,
Al.
 
Hi Al,

You said:

I haven't yet tested them in a microphone (quite frankly, I don't expect much from them)...

I'm just curious, why shouldn't you expect much from these capsules?
 
Very cool - though I must make my usual suggestion to try a flatbed scanner for better lighting and resolution.

Any plans for capsule mods, like fooling with the thru-holes?
 
nice pics!!! al .the ak78 it´s working ?.i have old hitachi 6au6 and work fine.it`s interesting tube for mic?it`s beter than ef86?
 
[quote author="dale116dot7"]A wierd hybrid, though. Edge terminated but with a K67 style hole pattern otherwise.[/quote]

Isn't there another capsule that looks like this? I could've sworn I saw a pic posted here somewhere that looked similar...

Peace,
Al.
 
Very nice work, Al..!

The capsule you've seen that looks like this may have been Tim C's CK12 experiment.

A thing that would be very interesting to know is what distance there was between the two backplates (that is, the size of the chamber between the halves). And, if possible, the thickness of the backplates..?

Any guesses on the thickness of the diagphragme spacers (nylon+copper)?

These parameters has a lot of influence on capsule sonics - at least if they're CK12-variants..

Jakob E.
 
The backplates are about 4mm thick. I don't have any way to measure the thickness of the spacers... but I just realized something: There's only one spacer between backplate and diaphragm, not a copper and a plastic one. The confusion arose from the fact that one side had a plastic spacer and the other had a copper one! Now, I can definitely feel a difference in the thickness of the plastic spacer (thin) and the copper one (thicker)... Doesn't that fuck with the off-axis response????

So that's:

===== brass ring
_______ diaphragm
---------- plastic washer
[IIIIIIII] backplate
---------- copper washer
[IIIIIIII] backplate
---------- copper washer
_______ diaphragm
===== brass ring

I'll update the website later in the day.

Peace,
Al.
 
So one side of the capsule must have had a significantly higher distance between membrane and backplate - meaning lower capacitance and thus lower level...? Yes, this would disturb pickup pattern seriously..

Ant guesses as to the thickness of the inner copper washer?

JAkob E.
 
[quote author="gyraf"]Ant guesses as to the thickness of the inner copper washer?[/quote]

It looks and feels exactly the same as the one between one of the diaphragms and its backplate. If I put them together and measure them with my caliper, I can "guesstimate" their thickness to about .004" for both of them. That's .002", or about 50um each.

Remember, I'm just eyeing it, though... It could be a little less, but definitely not more.

Peace,
Al.
 
[quote author="dbock"]the Peluso "CK12" has the same dual k67 backplate construction. False advertising![/quote]

Where did you get this information?
-Scott
 
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