Making a LDC Capsule - Videos

[Tim Campbell]

 

[craigmorris74]

I have an idea to throw your way.
There is real lack of true kk84 type capsules. However mxl603 type capsules can easily be modded by just manufacturing the right backplate and replacing the existing one in 603 model. They cost comething like 10$... can be found everywhere.

Have you made the right backplate? I would love to have a few of those!

 

[Whoops]

As diaphragm collapsing as been talked here, I’m posting a photo of a K47 capsule that I own that has the back diaphragm collapsed (front is good), I have no idea why this happened

 

[soliloqueen]

As diaphragm collapsing as been talked here, I’m posting a photo of a K47 capsule that I own that has the back diaphragm collapsed (front is good), I have no idea why this happened

View attachment 87957

loss of tension from the right side. I think. The trace is shifted away from the right side, left side is closer and folded. Weird. Anyone have any clue on how this could happen to a finished capsule? How old is it? did it just pull itself out from under the clamping ring due to age?

 

[Recording Engineer]

Interesting… I’m curious what you might have been doing when this happened. I know it’s a thing, but after over 25-years of being a studio owner and engineer, and owning at least 100 LDC mics over the years from all sorts of manufacturers, I’ve never once experienced this.

 

[soliloqueen]

Yeah, this is truly weird. Is it possible that one of the screws corroded and broke, or was too short and slipped out? This has to be the result of a small defect from the factory aging somehow.

 

[Tim Campbell]

Obviously not a glued diaphram

 

[soliloqueen]

Was the capsule subjected to any blunt force that might have jostled the screws far enough out of set to unscrew due to back force over time?

 

[Whoops]

How old is it? did it just pull itself out from under the clamping ring due to age?

I can't be certain but it doesn't have more than 10 years

I’m curious what you might have been doing when this happened.

The mic was inside it's box for 1 year without being used, when I used it again it had Low End loss.
I opened the microphone to troubleshoot it and noticed the back diaphragm was collapsed.
It did it on it's own, it was not user error

Is it possible that one of the screws corroded and broke, or was too short and slipped out? This has to be the result of a small defect from the factory aging somehow.

3x Maybe

Was the capsule subjected to any blunt force that might have jostled the screws far enough out of set to unscrew due to back force over time?

No. No blunt force or any force used

 

[kingkorg]

Have you made the right backplate? I would love to have a few of those!

Unfortunately nothing we could use for serial production. The reason i was hoping someone might make a 3d model eventually. Maybe @soliloqueen could chime in. Machining this one might be tricky due to sharp 90° angles at the base of the backplate.

 

[soliloqueen]

Unfortunately nothing we could use for serial production. The reason i was hoping someone might make a 3d model eventually. Maybe @soliloqueen could chime in. Machining this one might be tricky due to sharp 90° angles at the base of the backplate.

I'd be happy to make a 3d model if someone could get me some good ref pics and a sense of scale, or better yet send one here.

I am happy to make a 3d model of any capsule sent to me

 

[craigmorris74]

I'd be happy to make a 3d model if someone could get me some good ref pics and a sense of scale, or better yet send one here.

I am happy to make a 3d model of any capsule sent to me

I'd be happy to contribute in any way to this project.

 

[soliloqueen]

I'd be happy to contribute in any way to this project.

Send me anything you got! For vintage capsules they MUST be broken or at least have one diaphragm out of service because obviously it needs to be disassembled to see all the parts. If the back plate is removable without compromising the function of the capsule, please just send the back plate. Please do not send me any working capsules unless you are very confident in your ability to reskin them. For you and anyone else reading this, if you've got a capsule or backplate you want documented, drop me a PM. We can work out the logistics and maybe if you want some kind of insurance. When it's done I'll drop it the paper and model here just like I did with the k47. Not sure if I'm comfortable doing this and not releasing the result publicly, but willing to talk about it.

I don't really have the equipment to measure threads precisely so threaded elements like screw holes I'll need some kind of reference for. I'll do my best to get the hole depth right in general for non screw holes but you might need to experiment slightly.

 

[craigmorris74]

I do have the Warm WA -84 omni capsule if anyone tho is they copied the backplate.

 

[Marik]

With all due respect i see this comment as misleading. There is no way one can account for that tiny of a difference in volume of air between 800 grit vs 400 vs polished, and claim it makes a difference in diaphragm damping = difference in sound.

You are a knowledgeable man, with great resources, setup... and i am sure you can provide for once some empirical measurements and proof for claims of any of your products. Either capsule which has very unique features not available in any other capsule i am aware of. Or your acoustic lens capsule holders for example.

If anything, you as a manufacturer, can provide some resource material or video about capsule manufacturing process, not revealing proprietary secrets off course. This thread is about that. This forum i hope is still about DIY, not just advertisement and product placement.

Kingkorg,

I think there is some misunderstanding here. I never claimed the 400 grit makes any sonic difference vs 800. What I clearly stated was 400 grit is not working in OUR capsules because they have tighter spacing. That is, 400 grit translates into 22um, which becomes dangerously close to the size of spacing, so occasional burrs start touching diaphragm (I am sure, most here know how it looks). This and only this is the reason for finishing it with 800 grit (which is 11um).

In general, that was my answer to Tim, who asked specific question, which I answered with ‘how we do it’, giving information to the DIY community (which I’ve been trying to contribute for over 20 years on this board). If you see it as ‘advertising our products’ you can report my post to moderators and they will delete it, if decide there is any infringement.

Best, M

 

[Marik]

Unfortunately nothing we could use for serial production. The reason i was hoping someone might make a 3d model eventually. Maybe @soliloqueen could chime in. Machining this one might be tricky due to sharp 90° angles at the base of the backplate.

Machining those with slitting saw of correct thickness would be the easiest—one pass for a slit—done! You will need to mount the backplate vertically, though, unless there is an accsess to horizontal mill.

You could also do it with an end mill. Since it will be pretty small one your cuts should be shallow, as you are slitting here, little by little building the depth. I’d take a slightly undersized tool and then once you get through entire depth make a 0.002” finishing climb pass in all axises, climbing to every wall. That will leave very presize and repeatable dimensions and excellent finish. Assuming it is 360 brass carbide high helix 3 flute would work the best for fast material removal and good finish. Make sure you get a stubby tool for this job. You could also do the roughing with ball nose end mill and then finish with sharp corners.

Make sure to get correct speeds and feeds (and perhaps go conservative) here. There are some excellent apps for those.

Best, M

 

[kingkorg]

Machining those with slitting saw of correct thickness would be the easiest—one pass for a slit—done! You will need to mount the backplate vertically, though, unless there is an accsess to horizontal mill.

You could also do it with an end mill. Since it will be pretty small one your cuts should be shallow, as you are slitting here, little by little building the depth. I’d take a slightly undersized tool and then once you get through entire depth make a 0.002” finishing climb pass in all axises, climbing to every wall. That will leave very presize and repeatable dimensions and excellent finish. Assuming it is 360 brass carbide high helix 3 flute would work the best for fast material removal and good finish. Make sure you get a stubby tool for this job. You could also do the roughing with ball nose end mill and then finish with sharp corners.

Make sure to get correct speeds and feeds (and perhaps go conservative) here. There are some excellent apps for those.

Best, M

Thank you

 

[Whoops]

I do have the Warm WA -84 omni capsule if anyone tho is they copied the backplate.

I don’t know for sure, but I think they didn’t copy the capsule.
I’ve tried those Warm 84 mics side by side with 2x Neumann KM84 and they don’t sound in any was similar to the KM84. Im not even saying they don’t sound the same, it’s much further away, they don’t even sound similar.

The WA-84 is bass heavy when compared to the KM84 mics, it has more low mids, bass and bass extension, something that I’m not used to in SDC mics. The high mids and the high end are also quite different. The WA-84 lacked those regions and the KM84 had plenty of definition there.

My assumption after we tried it was that they didn’t got a very good capsule or were not able to get an exact replica of the KM84 capsule.

 

[craigmorris74]

I don’t know for sure, but I think they didn’t copy the capsule.
I’ve tried those Warm 84 mics side by side with 2x Neumann KM84 and they don’t sound in any was similar to the KM84. Im not even saying they don’t sound the same, it’s much further away, they don’t even sound similar.

The WA-84 is bass heavy when compared to the KM84 mics, it has more low mids, bass and bass extension, something that I’m not used to in SDC mics. The high mids and the high end are also quite different. The WA-84 lacked those regions and the KM84 had plenty of definition there.

My assumption after we tried it was that they didn’t got a very good capsule or were not able to get an exact replica of the KM84 capsule.

I have had the opposite experience, with the Warm and KM84 being extremely close.

 

[kingkorg]

Kk84 can be crazy inconsistent, especially if vintage. They are insanely sensitive to ring and pin tension variation. Even temperature difference can throw the response off.