Capsule Drawings/Designs for Large Diaphragms

[Scrappersa]

Hi There,

There has been so much incredible information posted on this forum over the years from the likes of Tim Campbell, Jakob, Dale, Marik, Gus, Ricardo, Kingkorg, and more. It's been amazing reading through the meta and through all of the posts that date back to 2005. I've learned a ton about capsule design working through different patents and articles like the Debenham, Robinson, and Stebbings capsule.

However, I have not been able to find drawings or designs of any older large-diaphragm capsules outside of the DRS and Williamson articles. At some point, I saw that Dale had posted the drawings for an M7 but they no longer seem to exist anywhere on the internet.

I'd love to try tackling some different capsule designs so I was wondering if anybody has or would be willing to post any backplate drawings/designs from some different mics. Anything from an M7, K47, to the incredibly complicated CK12 or something more obscure like a Lomo. Just seeing what's out there and hoping something exists.

Or if anybody has an older capsule with a broken diaphragm or a capsule they'd be willing to sacrifice (or sell), I'd be happy to draw up the designs and post them for the community.

 

[wlinart]

There's also the Schulein capsule (also an article), and in the micbuilders group Ricardo posted a fig-8 capsule.
Dale also posted some instructions https://groupdiy.com/index.php?topic=6790.msg83118#msg83118

 

[gyraf]

..the very-first capsules we did around here in last century were estimated from images.. was it saturnsound.com that had the nice images?

worked reasonably well for what it was. I've lost the files unfortunately

/Jakob E.

 

[Scrappersa]

..the very-first capsules we did around here in last century were estimated from images.. was it saturnsound.com that had the nice images?

worked reasonably well for what it was. I've lost the files unfortunately

/Jakob E.

Yeah, Saturnsound is a great resource! Makes perfect sense you'd estimate from images and go from there.

There's also the Schulein capsule (also an article), and in the micbuilders group Ricardo posted a fig-8 capsule.
Dale also posted some instructions https://groupdiy.com/index.php?topic=6790.msg83118#msg83118

That thread is a great resource.

Thanks!

 

[kingkorg]

A lot of people who have knowledge  about this stuff are pretty shy sharing it. I am afraid a lot of it could be lost in future.

If you do a bit of advanced Google search you should be able to find detailed CK12 patent, Neumann kk84, Audio Technica capsules etc. Start with Google patent search.

 

[jarvis]

A lot of people who have knowledge  about this stuff are pretty shy sharing it. I am afraid a lot of it could be lost in future.

If you do a bit of advanced Google search you should be able to find detailed CK12 patent, Neumann kk84, Audio Technica capsules etc. Start with Google patent search.

Hey KingKorg,

I'm very interested in that topic as well, especially in small diaphragm capsules like the KK84 but my searches came up blank. Could kindly point me in the right direction? So far I've only found the drawings of the KK50 on Saturn-Sound.

Best
Jannis

 

[kingkorg]

https://patents.google.com/patent/US3418436?oq=neumann+georg

 

[gyraf]

..but note that ALL patent illustrations and descriptions are purposefully generic and unspecific, you won't ever find any to-scale information in there - or even information of HOW to scale it yourself. This is the secret sauce.

Other than in the two original DIY-articles, I have never, ever seen actual drawings and dimensions published.

As mentioned, pictures plus a lot of experimentation can get you there. It's an interesting journey alright.

/Jakob E.

 

[Scrappersa]

Hi Jakob,

Yes, that makes perfect sense.

Also, I remember that Dale created M7 drawings that he had uploaded back in 2005. Those were around for a while but I cannot seem to find them anywhere. Does anybody have them and would they be willing to share?

 

[gyraf]

You're looking for the M7CapsuleDirections.pdf from Dale's site 10000cows.com - a file that does not exist anymore, was not web-archived either. Sorry, didn't save it. Have you looked through his site? There is still some good tricks to be learned there..

/Jakob E.

 

[Paul-o]

I saved that file.

 

[12afael]

and Paul-O receive the ball, shoot! it is GOOOOOOOOOOOOOOOOOOOAAAL!  ;D

 

[jarvis]

Guys,

I've said it before and I will say it again: your rock!
Thank you so much for the information, the patent, the capsule model and the pdf. All of it is extremely helpful to get me started and heading into the right direction!

Best
Jannis

 

[MS Vienna]

I´m sure Neumann/Sennheiser has kept all the original drawings and manufacturing directions for all of their capsules. I visited Neumann headquarters in Berlin this February and was shown the mechanical prototyping workshop, service department, measuring room, ect. Pretty amazing. But the most lovely thing that I spotted there was an old drilling template/jig for the M7 capsule.

As for the brass-CK12 blueprints I can tell you that detailed large scale drawings with measurements and tolerance ranges of all versions still exist and are kept safely here in Vienna.

Be aware that even the most detailed drawings and measurements alone won´t enable you to fully recreate a given classic capsule. Additional know how is needed such as manufacturing processes ect. Especially correct diaphragm manufacturing is very tricky. Apart from the basic processes you need to know how to handle the variations in specific film properties per supplied individual production lot to get constant long term end results.
These things cannot be reverse engineered from the finished product.

All the best,
Markus

 

[Scrappersa]

Paul-o!!! You're a hero! Thank you. This will be a fun one to try out after the Debenham capsule.

If anybody uses the model I posted and has good results, let me know! I'd love to see how it turns out. I'll post the M7 model as well once I model it up. Is .step format good for everybody?

 

[Scrappersa]

I had some time tonight and modeled up the M7 capsule from Dale's drawings. His drawings do not specify the edges which are important because there is a channel for the glue to sit in. And there is also a space between the section of the backplate with the holes and that channel which presumably directly impacts the acoustics of the design.

I looked at some of the pictures on Dale's website as well as some other M7 capsule pictures and created my own idea for a glue channel and guessed for how deep to bring the channels. I have that as a separate file as well. Let me know if anybody has any specifics for the edge and I can upload an updated model.

One aspect I found really interesting about this capsule is how thin it is! Unless I'm mistaken, it's barely thinner than 6mm– partially because there are no retainer rings. But this is still super interesting. I do wonder if I could add retainer rings to the design while keeping the dimensions as close as possible and use screws to hold down the retainer rings with mylar instead of only gluing the mylar directly to the backplate. I think I'll model this up for fun unless anybody thinks there is a reason that this would not work.

Dale's M7: https://www.dropbox.com/s/lc44jzht15gg0gm/M7%20Capsules%20%28Dale%29.step?dl=0
Dale's M7 with Edges: https://www.dropbox.com/s/e3um7rwbyjaesvj/M7%20Capsules%20%28Dale%29%20-%20Guessed%20Edges%20-%2010-3-20.step?dl=0

Also, if anybody else has any other drawings or super nice pictures, I'd be happy to take a swing at some other capsules and model them up.

 

[kingkorg]

If it's of any use, here are some images of Dale's M7 which i DIY reskined. Have in mind this one is made by Cathedral Pipes after Dale's instructions.

https://groupdiy.com/index.php?topic=67303.0

This one as well
https://groupdiy.com/index.php?topic=66382.0

I am not sure what was the issue, if it has anything to do with Dale, but a lot of those CP M7 capsules had issue with sticking to the backplate. Some say Chuck didn't clean backplates properly, i doubt that, to me it seems like tensioning, glue, or mylar "baking in" issue where mylar loses tension over time.

 

[Tim Campbell]

I would chime in here to say that the people with the knowledge in this area put in every bit of the hard work. Beyond the articles mentioned there are almost no real technical explanations and breakdown about the actual workings of capsules. All of us purchased many capsules, dissected them, did in some cases years of testing and measuring using only empirical methods.

When Dale Ulan and I started it was almost impossible to purchase capsules and everyone said laymen were incapable of building them.

This journey is so interesting and rewarding there is no reason to shortcut it.

 

[Scrappersa]

Hi Everybody,

I built a couple of the Debenham capsules. They sound really great! Overall, I'm super impressed with the sound.

Below are some pictures.

I first followed the directions and had the distance between the mylar and the backplate at 2 thou. I reduced it to 1 thou and lowered the tension of the mylar, and the output went up by about 20db. Does anybody know if the was the distance or tension that caused the change in output?

I'm going to experiment with different weights for the tuning. I'm surprised by how nice this capsule sounds.

Question for you all- do you have any ideas on how I could modify the holes or backplate design to change the sound? Just interested to know if anybody has played around with this at all.

 

[gyraf]

both distance and tension will result in output level variation like that - tension probably less so, but still