Topic: The AKG Active Project - 2

[poorlyconditioned]

Found some parts that might work well for the pin contact problem.. I wish my lathe wasn't in storage..

The MG2000 body doesn't use a socket, it uses a spring loaded contact pad. The pad contacts just the rounded tip of the capsule pin. Maybe something like this:

http://www.mill-max.com/pin_rec_catalog/productInfo.cfm?webpartnumber=0907&start=1&leaddiameterrange=&pin_or_rec=pin&Part_Description=Spring%2DLoaded%20Pin&taildiameter=&tailtype=&mountingfeature=&mountinghole=&bodylength=&search=&pr=pin

Though I'm wondering if the signal path is via the spring or via a sliding contact?  I'd really want to solder directly to the socket and not have the path via the spring, etc.

For sockets, maybe:

http://www.mill-max.com/pin_rec_catalog/productInfo.cfm?webpartnumber=0490&start=1&leaddiameterrange=%2E065%2D%2E082&pin_or_rec=rec&Part_Description=Receptacle%20with%20a%20Standard%20Tail&taildiameter=showall&tailtype=Soldertail&mountingfeature=&mountinghole=&bodylength=&search=&pr=rec

I like the idea of tip contact over a socket. Seems like less wear and tear on the pin. But I guess it depends on how tight the socket is.

Nice, I like where this is going... Richard, what do you think?

Good research!

The second one (socket) looks better.  That center pin is pretty thin.  I don't want anything just pushing up against it.  It could bend or just make poor contact.

I notice that the A61 has a socket with flexible diameter (slots going down).  I think that is what you need.  If you look at any commercial connectors (XLR, banana plugs, whatever), you either have an expandable socket and a fixed pin, or a squeezable pin and a fixed socket.  So, we need a socket that is just a bit too small, but expands just a bit when the pin is inserted.

  Richard

[MarkF]

More brainstorming, and running with freelunch's idea

I dont know if these DIP sockets come in different size socket openings. 
The socket can be at some determined height/depth in the collette and you would just screw the capsule down until it reaches the socket and bottoms out making a tight connection between the capsule pin and socket.

In these pictures the single DIP socket is just resting on top of the capsule pin.  The socket I had isnt big enough to push over the pin.

[it-goes-to-eleven]

The second one (socket) looks better.  That center pin is pretty thin.  I don't want anything just pushing up against it.  It could bend or just make poor contact.

My feeling on the sprung pad is that the pin clearance would be setup so contact is not even made until the cap is screwed on 80-90% of the way. That is another way in which rotational friction and wear and tear is reduced. So I don't think there would be much chance of misalignment..

I notice that the A61 has a socket with flexible diameter (slots going down).  I think that is what you need.

I think that is what this is.. The one I linked has 4 contact fingers; others have 6. It looks like the contact fingers press into the socket.  I saw an insertion force spec for one and two insertions but no data on 10, 40, 100.. That's where a sprung contact pad would likely excel over a socket.

It would be nice to get some samples for testing.. Some things just have to be tried...  FWIW, the MG pin is .078" dia.  They might be able to rec a better part or another mfg if they don't have a suitable off the shelf.

[willndmb]

+T
So it is possible to separate the capsule from the body by at least 2-3cm using only a wire and grounding the other 2 connectors. Wonder what the maximum distance is? Thanks for doing this!

yes big +t

john the vr62 is 3 ft so we know at least that far, assuming it is basically the same guts
do you think it is?

So what does three feet get you though?    Can you really see taping your bodies to a stand because you only have 3 feet to play with?

Remember eye on the prize here.  It seems to me that many generations of tapers have tried knocking down the door of the extension cables.  Maybe we need to focus on other means. 

Again I continue to go back to the thought that you need to figure out your goal and work back from that. 

sure 3 ft doesn't do anything for open taping but it does for stealth

really though i was just helping to answer his question

i agree though, the goal imo is for open taping and so i think you would want at least 10 ft, 15 would be sweeeeet

[carlbeck]

I would be willing to kick in some cash to help fund the research. What if everyone kicked in $20.00 or so? I know I can spend that in a bar in a few minutes, I don't think it is an unfair donation to help fund this? I would also easily pay $1000 or so to purchase this with or without the bodies. I would prefer to keep the bodies & just have cables but would take what I could get.

[poorlyconditioned]

I would be willing to kick in some cash to help fund the research. What if everyone kicked in $20.00 or so? I know I can spend that in a bar in a few minutes, I don't think it is an unfair donation to help fund this? I would also easily pay $1000 or so to purchase this with or without the bodies. I would prefer to keep the bodies & just have cables but would take what I could get.

OK, let's get concrete here.

If someone would machine the collette (brass) and get a connecting center pin, then I will build one prototype (for myself only!) and disclose all plans to others.

So, for the cost/work/effort of solving the mechanical problems, I will help.

That said, my motivation for doing this has decreased substantially.  I've been doing more and more binaural recording (various capsules) and digging that much more than other tapes.

So, any closet machinists out there?  Show yourselves and let's get rolling!

  Richard

[leehookem]

these last two posts interest me.  I am willing to kick in some money as well.  I also have no mechanical expertise to do this project myself.  where I commend richard for taking this on and sharing info, I have no way to take his knowledge and do it myself.  if someone has the knowledge to take this public, I will donate (to Richard?) as well as for a final product.

I want to keep the bodies as well.  I still want my sound that I have now.

[johnw]

Also willing to go in $20...

[carlbeck]

Also willing to go in $20...

See that is my thought, if everyone kicks in $20.00 & we deposit it into a paypal account as a slush fund it will add up quick. We can use the money to pay for the machining of the collettes or to buy an extension tube to experiment with?

[Church-Audio]

I have a question... If you can buy extension arms for these mics I assume they are about 1.5 feet long. I wonder what the max distance a mic cable can be between the mic body and the mic capsule does anyone really know for sure?

Chris

[carlbeck]

My thought has always been why can't an extension tube be used but I know Marc Nutter tried it way back when & the outside of the tube is the ground. Why can't a wire be used as a ground instead of the tube & just lengthen the tube? Obviously there has to be more to it then that.

[it-goes-to-eleven]

Did any of it work for Marc?

The schoeps extension tube has a buffer circuit, ala KC5 actives.  The AKG extension does not (based on pics).
I'd say that either means the AKG cap does not need the buffer circuit (because the FET can drive that cable) or it means the akg tube is not sonically on-par with the normal cap+body.  I think you'll need a buffer circuit to preserve fidelity.

Regardless, the circuit is the easy part.  Everyone needs to repeat that a thousand times.. or re-read the previous thread

Packaging all the guts into the machined collette and having it be servicable so the cable can be replaced is the hard part.  There will need to be at least one manufactured insert for the collette guts and for cable strain relief and anchoring. I'd expect one base plate for cable retention, a circuit assembly and then another interface component for the capsule.

Schoeps mounts the smd circuit on a small board:

[Church-Audio]

Did any of it work for Marc?

The schoeps extension tube has a buffer circuit, ala KC5 actives.  The AKG extension does not (based on pics).
I'd say that either means the AKG cap does not need the buffer circuit (because the FET can drive that cable) or it means the akg tube is not sonically on-par with the normal cap+body.  I think you'll need a buffer circuit to preserve fidelity.

Regardless, the circuit is the easy part.  Everyone needs to repeat that a thousand times.. or re-read the previous thread

Packaging all the guts into the machined collette and having it be servicable so the cable can be replaced is the hard part.  There will need to be at least one manufactured insert for the collette guts and for cable strain relief and anchoring. I'd expect one base plate for cable retention, a circuit assembly and then another interface component for the capsule.

Schoeps mounts the smd circuit on a small board:

Here is a question...

Why not hack a extension tube apart and connect cables to it and experiment with different lengths and do a comparison with the same cap and body and have listening tests to see if anyone can hear the difference. I am sure one of the only things to happen with increasing distance would be increasing noise floor. But that's pretty easy to hear. So why not try a series of experiments? That way you guys can just by extension tubes and hack them. Hell I could do that very easily if I had a tube.

Chris

[Colin Liston]

Set up the paypal account, I'm in for at least $20.

[poorlyconditioned]

Did any of it work for Marc?

The schoeps extension tube has a buffer circuit, ala KC5 actives.  The AKG extension does not (based on pics).
I'd say that either means the AKG cap does not need the buffer circuit (because the FET can drive that cable) or it means the akg tube is not sonically on-par with the normal cap+body.  I think you'll need a buffer circuit to preserve fidelity.

Regardless, the circuit is the easy part.  Everyone needs to repeat that a thousand times.. or re-read the previous thread

The circuit was not the easy part (until I published my solution here, well that solution adapted from various AKG tech docs).  We still have to test it too.  Packaging is a mechanical problem, but we know what has to be inside the collette.

  Richard