Topic: The AKG Active Project - 2

[johnw]

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

Chris - check out my post from page 7. This is the same point I brought up.

Here's the deal:
AKG offers 3 options to separate the capsule from the body:

A61 - an angle adapter that uses no circuit to make the separation. This is the least expensive ($175) and appears easy to disassemble. There are pictures of the disassembled parts on page 7. I would think it would be fairly easy to disassemble this, desolder the 3 solder points and use 3 wires of varying lengths to connect the capsule to the body via the hacked A61. If successful, an active cable could easily be made with a Dremel tool, heat-shrink tubing and wire.

VR61 - this is a 14 inch tube that is fairly pricy unless you get real lucky on Ebay. It is no longer in production AFAIK. Nobody has seen a disassembled one on this board and no technical service document has surfaced so it may contain a buffer/circuit. This is what Marc Nutter hacked and the result was a signal with lots of humming or buzzing that I would guess was a poor ground although this has never been established. This would be slight more ideal IMHO for use to hack into a cable as it already has straight tubing coming out of the connectors that could be cut to run wires through.

VR62 - this is a 3 foot tube that appears identical to the VR61 only longer and is also fairly pricy (>$500) and again nobody has seen the inside of this so we don't know if there is a buffer/circuit.

I wish I had the soldering skills to hack up my A61, but I don't want to run the risk of ruining one and can't afford to replace one now. Again, I could def throw in $20....
 

[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

Chris - check out my post from page 7. This is the same point I brought up.

Here's the deal:
AKG offers 3 options to separate the capsule from the body:

A61 - an angle adapter that uses no circuit to make the separation. This is the least expensive ($175) and appears easy to disassemble. There are pictures of the disassembled parts on page 7. I would think it would be fairly easy to disassemble this, desolder the 3 solder points and use 3 wires of varying lengths to connect the capsule to the body via the hacked A61. If successful, an active cable could easily be made with a Dremel tool, heat-shrink tubing and wire.

VR61 - this is a 14 inch tube that is fairly pricy unless you get real lucky on Ebay. It is no longer in production AFAIK. Nobody has seen a disassembled one on this board and no technical service document has surfaced so it may contain a buffer/circuit. This is what Marc Nutter hacked and the result was a signal with lots of humming or buzzing that I would guess was a poor ground although this has never been established. This would be slight more ideal IMHO for use to hack into a cable as it already has straight tubing coming out of the connectors that could be cut to run wires through.

VR62 - this is a 3 foot tube that appears identical to the VR61 only longer and is also fairly pricy (>$500) and again nobody has seen the inside of this so we don't know if there is a buffer/circuit.

I wish I had the soldering skills to hack up my A61, but I don't want to run the risk of ruining one and can't afford to replace one now. Again, I could def throw in $20....
 

I suspect that the 3 foot tube does not have a buffer in it.. I think before you guys go building circuits try the cable if someone has a set of tubes I would be more then happy to hack them up and make the cables for you guys for FREE if someone will supply me with the cable you guys want to use..

Chris Church

[johnw]

Not sure why I didn't think of this earlier, but an easy way to test if a buffer is needed would be to use 3 wires with alligator clips on each end and connect them to the capsule and body similar to what poorlyconditioned did when he tested the capsule for his circuit.

EDIT: If that works, then we could talk about hacking the A61 or VR tubes to use for the connections.

[Church-Audio]

Not sure why I didn't think of this earlier, but an easy way to test if a buffer is needed would be to use 3 wires with alligator clips on each end and connect them to the capsule and body similar to what poorlyconditioned did when he tested the capsule for his circuit.

EDIT: If that works, then we could talk about hacking the A61 or VR tubes to use for the connections.

You cant really do that because you need a shield in the back of that capsule so you can see if they are quiet. Also you have to watch the polarization voltage.... Its not a good idea to use alligator clips I think the best way is to hack a pair of wands.

[johnw]

I understand now - thanks. See my PM. I'm interested if you think it might work. Let me know.

[Church-Audio]

I want to make it clear by doing this mod I am not looking to get into modding AKG mics for a living. I am doing this mod for free. And I will not be doing it for anyone else. I will however take pictures "if it works" and show you guys what I did and how I did it, so others can do it them selves. I want to help you guys 100% free of charge..

Chris

[leehookem]

nice Chris

[willndmb]

i thought the biggest challanges were the center pin
as well as fitting everything into the small space

taking the center pin out of the problem, how much room is needed to fit everything inside the collette?
couldn't the collette be longer, kinda a mini body?

i guess it depends how much needs to fit and how big the "typical" collette is in size
but if it had to be a little longer i don't see why that would be a big deal

[Church-Audio]

i thought the biggest challanges were the center pin
as well as fitting everything into the small space

taking the center pin out of the problem, how much room is needed to fit everything inside the collette?
couldn't the collette be longer, kinda a mini body?

i guess it depends how much needs to fit and how big the "typical" collette is in size
but if it had to be a little longer i don't see why that would be a big deal

I think you have to figure out what the max distance is that you can run between the capsule and the mic body first. Then if you need a driver to drive the capsule you can look at what size you need the Collette to be. I think you might be able to get away with 3 feet between the mic body and the capsule but I will not know until I get the mic in my hands and try it... If that's the case making the Collette is easy and the center pin problem is very easy too.. Its a matter of a spring loaded contact. That's not a huge deal first thing is to figure out the max distance. I think 3 feet would be good for most users here? But I dont know.

Chris

[OFOTD]

I think 3 feet would be good for most users here? But I dont know.

Three does no one any good.  Well maybe a small handful but not many.  While it would be great to have an active cable most folks would want 6-10 feet.   Remember that active caps are not just for stealthing they are also for open taping.

Thanks for the input Chris.

[fozzy]

I think 3 feet would be good for most users here? But I dont know.

Three does no one any good.  Well maybe a small handful but not many.  While it would be great to have an active cable most folks would want 6-10 feet.   Remember that active caps are not just for stealthing they are also for open taping.

Thanks for the input Chris.

the jklabs box I speced had 25' cables

[T.J.]

I think 3 feet would be good for most users here? But I dont know.

Three does no one any good.  Well maybe a small handful but not many.  While it would be great to have an active cable most folks would want 6-10 feet.   Remember that active caps are not just for stealthing they are also for open taping.

Thanks for the input Chris.

i would have to agree. while i'm sure 3 feet would be a huge accomplishment and a great step forward for this project, i don't see the use in an open taping situation. a three foot seperation b/w caps and bodies would not be beneficial. jk labs had 25 ft cables  that's insane!

i do want to say again i am very appreciative for everyone who is contributing to this project. thanks to all and +T's all around. i would being willing to contribute some money into a paypal account for R&D.

[spreadheadtom]

I think 3 feet would be good for most users here? But I dont know.

Three does no one any good.  Well maybe a small handful but not many.  While it would be great to have an active cable most folks would want 6-10 feet.   Remember that active caps are not just for stealthing they are also for open taping.

Thanks for the input Chris.

the jklabs box I speced had 25' cables

my cables are about 12' I think.....Todd made extension cables for them also.

[johnw]

Another idea would be to machine a brass tube that is 20cm long with threads to fit A61s on either end. Remove the boards from 2 480 bodies and mount them inside the tube with the cables soldered directly to the terminations on the board and exiting in the middle of the tube. Then the tube could be mounted similar to a Kwon bar or placed in a hat. Of course you'd have a fixed distance, but the angle could be varied with the A61s. Give me a minute and I'll post a photoshop mock up. Only problem is the inner diameter of the tube would have to accomodate both boards.

Sort of like this..

[T.J.]

wow, that is really thinking outside the box. +T

i like it!