New diaphragms and voice coils for vintage German mics?

[frans]

Maybe it helps: some coils are wound on a round hard, polished surface and the wire is coated so a little heat bakes it all together so after the heat is done, you can pull off the -now one piece- coil. It is glued to the exact center of a membrane thats manufactured with heat and pressure from the right kind of plastic material. A very large magnifying glass is helpful to center the coil, you have to be veeery precise.
Even for a company that has all the knowhow and access to materials it can be hard to re-create things they did a few decades ago. Or even worse: that demand would be in such low numbers that they would lose quite some money in the process. The AKG D12 (and it's variants that started with a 2 or 3) had a lot of change over the decades and if you ever have seen how the capsule is built you understand why nowbody cloned it. It simply would be so expensive that only a few people could afford it. Remember, in the days of old the D12 was close to half a months salary for a worker and these high prices weren't unusual for good mics of the time.

 

[David König]

Hi David,
Nice to meet you.
It’s great to know more people that fix dynamic mic capsules.

How can we know more about your work?

Thanks
Best regards

Hi, my way is to buy mic, repair and sell it. I do service only to my long term custommers. I don´t have any websites because I simply don´t need it. So you may only check my 100% feedback history on Reverb (nick smichoff AT centrum DOT cz, which is also my email address). Or you may buy any of my mics and listen

 

[David König]

Maybe it helps: some coils are wound on a round hard, polished surface and the wire is coated so a little heat bakes it all together so after the heat is done, you can pull off the -now one piece- coil. It is glued to the exact center of a membrane thats manufactured with heat and pressure from the right kind of plastic material. A very large magnifying glass is helpful to center the coil, you have to be veeery precise.
Even for a company that has all the knowhow and access to materials it can be hard to re-create things they did a few decades ago. Or even worse: that demand would be in such low numbers that they would lose quite some money in the process. The AKG D12 (and it's variants that started with a 2 or 3) had a lot of change over the decades and if you ever have seen how the capsule is built you understand why nowbody cloned it. It simply would be so expensive that only a few people could afford it. Remember, in the days of old the D12 was close to half a months salary for a worker and these high prices weren't unusual for good mics of the time.

True. And the coil is wound in 4 layers of tiny wire. I cannot imagine how to do it without proper machinery.

 

[Whoops]

Hi, my way is to buy mic, repair and sell it. I do service only to my long term custommers.

Thanks for your Reply David.
I’m personally more interested in repair services for my own mics and also mics from many friends/colleagues.
There’s not many people doing this work (dynamic mics repair), and even fewer doing it properly.

So you may only check my 100% feedback history on Reverb (nick smichoff AT centrum DOT cz, which is also my email address). Or you may buy any of my mics and listen

I went on Reverb trying to find you to check what mics do you for sale there but I can’t seem to find how I search for a user.
Can you post a link to your Reverb store page?

 

[David König]

Thanks for your Reply David.
I’m personally more interested in repair services for my own mics and also mics from many friends/colleagues.
There’s not many people doing this work (dynamic mics repair), and even fewer doing it properly.

So you may only check my 100% feedback history on Reverb (nick smichoff AT centrum DOT cz, which is also my email address). Or you may buy any of my mics and listen

I went on Reverb trying to find you to check what mics do you for sale there but I can’t seem to find how I search for a user.
Can you post a link to your Reverb store page?

https://reverb.com/shop/smichoff-at-centrumIf you´d email me a list of what you have I may be interested in some of your mics (because I am a collector, too) and we may trade repair service for some of your faulty mic(s).

 

[snor]

Jan, 2023, work-in-progress on my thought project: 50+ hours attempting to fabricate hand-made replacement AKG D12 diaphragm(s?) in the USA.

Lo-Fi tooling and proof-of-concepts seem promising, but zero-budget "fail, learn, repeat" is my technique. Probably months from a working prototype, and at least a year away from anything repeatable... If repeatability is even possible!

This looks really promising. I was wondering what kind material you are using and how you are forming them.
I've been toying with the idea of 3D printing the shape of the diaphragm (I've already measured the thing and made the model) and then vacuum forming thin sheet mylar over it. Wonder if you ever got it to work!

 

[AustinMics]

This looks really promising. I was wondering what kind material you are using and how you are forming them.
I've been toying with the idea of 3D printing the shape of the diaphragm (I've already measured the thing and made the model) and then vacuum forming thin sheet mylar over it. Wonder if you ever got it to work!

I put it away in January, in favor of revenue-producing builds for www.AustinMics.com. I have not continued on the D12 project for more than a year now. Forming and varnishing the voice-coil appears to require special tooling, as well as accurately cutting the circumference of the diaphragm. My intent is to get something that simply "works" - not something that replaces the diaphragm with the same specifications.

 

[ElSmurf]

I put it away in January, in favor of revenue-producing builds for www.AustinMics.com.

Totally unrelated, but those Hot Holders are absolute genius!

 

[christopantz]

reviving an old thread, curious if there's been any new developments here. i've got an EV RE-20 with a mangled voice coil and a new capsule costs about as much as the mic itself. kind of curious about sourcing a tweeter voice coil with the same coil and diaphragm dimensions (coil is about 19.5mm, entire diaphragm is about 32mm), and seeing if i can attach it.

 

[Whoops]

kind of curious about sourcing a tweeter voice coil with the same coil and diaphragm dimensions (coil is about 19.5mm, entire diaphragm is about 32mm), and seeing if i can attach it.

You will not be able to source that

 

[christopantz]

I’ve already found a source with the same dimensions, haven’t yet pulled the trigger yet because I’m seeing if I can source a headphone driver that has a similar impedance to the original (I believe 150 ohm)

 

[Whoops]

I’ve already found a source with the same dimensions

share that source with us

 

[christopantz]

share that source with us

Don’t have it handy as I’m not at my computer, but there’s plenty of voice coils with the proper dimensions on AliExpress, but like I said tracking down the proper impedance is harder

 

[Whoops]

I don't see any voice coils in Aliexpress with the same coil and diaphragm dimensions as the RE-20 capsule voice coil.

You said you already found a source,
so please share that source with us because that would be very useful for many people.

 

[christopantz]

Ended up winding a replacement voice coil for this RE-20, and it works, but there's additional damage to the mylar diaphragm that I'm not equipped to fix —

This looks really promising. I was wondering what kind material you are using and how you are forming them.
I've been toying with the idea of 3D printing the shape of the diaphragm (I've already measured the thing and made the model) and then vacuum forming thin sheet mylar over it. Wonder if you ever got it to work!

Did you ever try doing this? I'm not sure what the proper mylar thickness is or where to find it, and also never done vacuum forming… any tips?

 

[MicMaven]

Ended up winding a replacement voice coil...

Hmmm ... First, you said you found a source ... now you say you wound your own. Please clarify. And, if you have a source, please identify same. James

 

[christopantz]

Hmmm ... First, you said you found a source ... now you say you wound your own. Please clarify. And, if you have a source, please identify same. James

Like I said I wound my own coil. The sources I found were all for speaker drivers where the thickness of the Mylar and wire gauge was too heavy. Hope that helps.

 

[MicMaven]

Like I said I wound my own coil. The sources I found were all for speaker drivers

Curious. While it may not suit your project, it may suite mine! I enjoy repurposing materials - a frequent feature of many DIY solutions. So I press for the source you said you found.

In Message #29 you express a desire to source "a tweeter voice coil with the same coil and diaphragm dimensions (coil is about 19.5mm, entire diaphragm is about 32mm), and seeing if i can attach it."​

​

In Message #30 Mr. @Whoops said you could not source that. (referring to what you describe in Message #29)​

​

In Message $31 - you said your had already sourced that. (still referring to what you describe in Messag4 #29)​

Please indicate the source you mention in Message #31 as it may help me solve my issue. Thanks loads. James

 

[Whoops]

The sources I found were all for speaker drivers where the thickness of the Mylar and wire gauge was too heavy.

So you didn't found any source.

Bummer, if you did found like you stated that would be very useful

 

[christopantz]

So you didn't found any source.

Bummer, if you did found like you stated that would be very useful

Agreed.