Dead Optema OS-110 Capsule Use?
« on: December 18, 2019, 08:33:57 AM »
Howdy folks. I just had to have the capsule replaced in a CAD E350 that I bought on craigslist, (thanks a lot random guy >:( )
It was acting up, randomly cutting out etc. So I sent it to CAD who told me the capsule had gone bad, and replaced it. They returned the mic with the old capsule, so I was wondering if there was anything that could be done with this dead capsule?

Could it be rebuilt, repaired? Would anyone be interested in taking it apart to see the design? Or is it just a paperweight?

Thanks!
« Last Edit: December 20, 2019, 08:04:07 AM by Icegoldnixon »


Khron

Re: Dead Optema OS-110 Capsule Use?
« Reply #1 on: December 18, 2019, 11:04:43 AM »
Photos?
Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

Re: Dead Optema OS-110 Capsule Use?
« Reply #2 on: December 18, 2019, 01:05:06 PM »
Should be this one. Looks sweet. Guys who re skin capsules should have no issue fixing it. Not sure about diaphragm material though.

Have they replaced it with the original capsule, or some other type?

http://recordinghacks.com/microphones/tag/optema

Re: Dead Optema OS-110 Capsule Use?
« Reply #3 on: December 20, 2019, 08:04:52 AM »
Photo attached to first post, another angle here. Looks like a nice capsule to me.

Re: Dead Optema OS-110 Capsule Use?
« Reply #4 on: December 20, 2019, 08:05:44 AM »
Should be this one. Looks sweet. Guys who re skin capsules should have no issue fixing it. Not sure about diaphragm material though.

Have they replaced it with the original capsule, or some other type?

http://recordinghacks.com/microphones/tag/optema

I'm glad to say they replaced it with another Optema, they have a small old stock still apparently.

Re: Dead Optema OS-110 Capsule Use?
« Reply #5 on: December 20, 2019, 12:05:20 PM »
Photo attached to first post, another angle here. Looks like a nice capsule to me.

Mylar membrane?  Agree, the capsule looks like a good one and may not be difficult to reskin...it would be interesting to know the tension on the membrane before the membrane is clamped down.  The membrane tension is set to resonate at 1500 Hz or some other frequency to account for acoustic properties behind the membrane, especially since the capsule is double membrane, the membrane tension for each capsule must be correct and match.. (those holes in the backplate are there for a reason...)

I personally like using sub micron nickel membrane material...saw some 1 micron nickel on sale a while back, but getting that gold sputtered mylar is difficult and expensive...

ln76d

Re: Dead Optema OS-110 Capsule Use?
« Reply #6 on: December 20, 2019, 01:50:01 PM »
Ok, maybe i'm blind, but don't see anything suspicious on the pics, except dirty diaphragms.
Looks k67/k87 variant.  If diaphragms aren't  colapsed, then i would just clean it and try in some other mic. Some diy built? Some U87 project? Backplates looks like connected internally, so for example cardioid U87. Just a thought.
Anyway, i believe it cut off the signal due to too big polarisation voltage and dirt. This is common in many modern mics.
Good example here is Rode NT1a, this was common fault in these mics, more common with center terminated k67 than edge terminated version. After clean mic worked without cutting off the signal until diaphragms didn't get dirty again. Overall pretty sensitive for humidity. Reduction 10V down from 75V for polarisation voltage solved the issue., working even with dirty diaphragm.

Re: Dead Optema OS-110 Capsule Use?
« Reply #7 on: December 20, 2019, 07:51:04 PM »
Ok, maybe i'm blind, but don't see anything suspicious on the pics, except dirty diaphragms.
Looks k67/k87 variant.  If diaphragms aren't  colapsed, then i would just clean it and try in some other mic. Some diy built? Some U87 project? Backplates looks like connected internally, so for example cardioid U87. Just a thought.
Anyway, i believe it cut off the signal due to too big polarisation voltage and dirt. This is common in many modern mics.
Good example here is Rode NT1a, this was common fault in these mics, more common with center terminated k67 than edge terminated version. After clean mic worked without cutting off the signal until diaphragms didn't get dirty again. Overall pretty sensitive for humidity. Reduction 10V down from 75V for polarisation voltage solved the issue., working even with dirty diaphragm.

I feel like mic capsules are pretty over my head DIY-wise, is there anyone I could send it to? I'd love to have a capsule lined up for a U87 project or something!

Recording Engineer

Re: Dead Optema OS-110 Capsule Use?
« Reply #8 on: December 20, 2019, 08:16:11 PM »
I’ve used our Dany here and Allen Luke of Luke Audio. Both excellent work!

ln76d

Re: Dead Optema OS-110 Capsule Use?
« Reply #9 on: December 20, 2019, 09:53:24 PM »
I feel like mic capsules are pretty over my head DIY-wise, is there anyone I could send it to? I'd love to have a capsule lined up for a U87 project or something!

There's few people, all depends which continet you live. Anyway if you are considering reskinning, then worth consider first more diy spirit and clean it. Not a rocket science, there's a lot of info over groupdiy, if you need few tips how to do it and what use for, PM me here. 
If you have any other mic than CAD, where's known polarisation voltage value, worth first try it with current condition. Also compare the sides for the front diaphragm choice - if there's second side sputtered with gold ;)
I would definately pack it well if not using to not get more dust.
If you truly considering reskinning, then find someone who will use at least 6um - this only have sense to spend money on whole process in case of CAD capsule.

Just spot manual for E350, there's  partial schematic included. Amount of diodes at the converter output looks to me like high polarisation voltage we can expect inside. Best just would be measure. Besides that with 2Gohm input impedance we can also expect more problems due to little dirt on diaphragm.

http://recordinghacks.com/pdf/cad/E350-manual.pdf

Another edit :D

Just spot full schematic :D

http://recordinghacks.com/images/mic_extras/cad/E300-schematic.png
« Last Edit: December 20, 2019, 10:09:59 PM by ln76d »


Re: Dead Optema OS-110 Capsule Use?
« Reply #10 on: December 28, 2019, 08:53:48 AM »
There's few people, all depends which continet you live.
http://recordinghacks.com/images/mic_extras/cad/E300-schematic.png

Is there anyone in Europe I should consider? I'll be going to Germany soon, and would be happy to bring the capsule with me. Whoever is best!

ln76d

Re: Dead Optema OS-110 Capsule Use?
« Reply #11 on: December 28, 2019, 02:44:39 PM »
Definately Siegfried Thiersch, but i'm not sure he would even consider work on this transducer. Probably he will tell you that he don't know proper tension for it... Anyway try if you would have luck then you will get excellent transducer.

iturnknobs

Re: Dead Optema OS-110 Capsule Use?
« Reply #12 on: May 05, 2020, 11:05:41 AM »
https://youtu.be/i9eYpWY675g

Old post, I know. Figured I'd post this link anyway. Just had a CAD e350 given to me by a Broadway sound designer exhibiting the same issues.  I was not confident when cleaning the "faulty/intermittent" side, but afterwards it had more extended high end which caused me to follow through and clean the other side. Sounds great now. Thought this info and link might give others the confidence to go through with a cleaning. I've got a late 60s u87 that I'll be less afraid to service when the time comes.
Election 2020.  For the people, not the money.


 

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