Topic: Experimental 'umbilical cable' for C460 to CKxx capsules

[Todd R]

I would only ask that if you know as much about all this that you say, that you share your wealth of information.  That and that you acknowledge that others have tried to be helpful and that it would be nice to appreciative and not antagonistic.

I've been here long enough to know that it is hard to find someone like mshilarious, a professional microphone and mic preamp builder, impart their knowledge freely and openly.  And as is gets harder and harder for them to keep with their open exchange when over time people challenge and attack them, they eventually stop posting as much or not at all.

Not saying you're doing all this groovon, just saying it is nice to create an atmosphere that encourages an open exchange of ideas.

And to jon -- much appreciation for your willingness to share your wealth of knowledge!

[groovon]

Appreciate your input, Todd. I can only say that I never attacked or challenged anyone here, and certainly not mshilarious, either personally or professionally.
I don't know why what I wrote was taken personally.
I was merely making an observation that I thought the project would probably not be as easy to accomplish as some appear to think, especially given that, presumably, AKG itself had not thought it either worthwhile or, perhaps, achievable to an acceptable standard.

Again, I made no personal attack, and I certainly wish anyone working on the AKG active cap project the best.

Cheers
Dave

[Todd R]

Right on Dave, thanks.  Just hoping to keep the good ideas flowing!

[groovon]

No problem!

[Chuck]

I'm just happy that there is some interest in the AKG Actives project again. 

[Walstib62]

A buddy of mine in Tampa had a set for his AKG's that sounded great. I don't remember what model mics/caps they were. But I'm reasonably sure the actives were made by the Oades, but this was 16 yrs. ago. If Doug Oade has made them, but does not now, perhaps he could be persuadd to part with the info.(?)

[Walstib62]

Small-diameter cable is often ~100pF/ft, which will be not good for an unbuffered capsule.

So...Jon, is this something you would be interested in tackling?

[Chuck]

Awesome

[groovon]

If it will help, later today I can try to set up a CK61 cap on a surface plate and get you the depth measurements. Distance from top of pin to bottom of male threads I think is what you need, right? PS - and length of threaded section too, from shoulder to edge. (I think dia. is 19mm x pitch 0.75mm.)

Do you think if you do the CAD and find a machinist who can do these in brass, that they will eventually be available for us to buy in pairs to experiment with?

Looking good. I like the idea of compact built-in connector.

Cheers
Dave

[illconditioned]

Price for the coupling with mini-XLR jack and single PFA terminated in mini-XLR plug would be about $100.

I would be happy to see you take this on.

By the way, even if you built just the board and battery box (with polarization), I would purchase a setup for my capsules (by hard wiring them).

  Richard

[johnw]

This might be a minor point, but instead of a mini-xlr, would it be possible to hard wire the cable to the PCB in the housing? The reason being that MBHO has a similar design and the stiff mini_XLR sticks out so far that it makes these harder to stealth compared to Schoeps or Neumann. The hard wired cable more like the Schoeps KC connector or CMR is softer and easier to work with. Also, if you machined the connector to have a collar the same size as the schoeps KC connector or CMR, it would work with already existing accessories.

[groovon]

If it will help, later today I can try to set up a CK61 cap on a surface plate and get you the depth measurements. Distance from top of pin to bottom of male threads I think is what you need, right? PS - and length of threaded section too, from shoulder to edge. (I think dia. is 19mm x pitch 0.75mm.)

For any machinists, here's the dimensions from one of my CK61 caps, relevant to mounting it in a threaded adaptor:

Length of the threaded portion, from shoulder to bottom edge, is 0.143"

Inside depth, from surface of plastic spacer (effectively level with the base of the center pin) to bottom edge, is 0.195"

Tip of center pin protrudes from bottom edge by 0.012"

Thread appears to be nominally 19mm x 0.75mm pitch. Actual O.D. measures 18.85mm.

(Measurements are from CK61 cap serial no. 8158. Other caps may vary slightly.)

[groovon]

PCB design, I still might need to cram a couple more components on the head amp (round PCB), but the goal there is to keep stuff away from the input so as to avoid stray capacitance . . . I'll be testing the head amp circuit later today, see if I can dial in the right gain/current/noise/distortion sweet spot.

Somebody wanna measure a capsule's capacitance for me    I'm going with 22pF, should be close enough.

Hi ms - I would be happy to, but don't have the setup for it at the moment as most of my test gear is in storage. It's probably in AKG specs somewhere.
 
BTW, I measured 13.55 volts (w/ Fluke 8050A) on the bias ring with the mic body powered from a DA-P1, if that helps any.

PCBs looking good.

Cheers

[Chuck]

I can donate a malfunctioning AKG CK-61 capsule if needed.

[NOLAfishwater]

I can contact the machine shop I dealt with in the past regarding making the connectors out of brass. Once you get all the measurements for the threading, I think tonedeaf made a cad drawing of housing with no threads.