Topic: The AKG Actives Project

[Chuck]

Richard, are you using the famous Schoeps circuit or a variant, like one of the Dorsey circuits?

[poorlyconditioned]

Richard, are you using the famous Schoeps circuit or a variant, like one of the Dorsey circuits?

I'm using a very simple "battery box" circuit.  The Scheops circuit has a balanced output with a pair of transistors.  I'm not using that, although it is certainly possible.

My schematic is here:
   www.cs.uwaterloo.ca/~mannr/AKG/ck63_schematic.jpg
The "prototype" is here:
   www.cs.uwaterloo.ca/~mannr/AKG/ck63_prototype.jpg
(the big black parcel is six 9V batteries in series to generate the polarization voltage!)

I have not made any more progress on this, due to busy times at work and a lot of shows to tape!  I experimented with some collettes, but decided I need to make a "hard" attachment to the mic capsule for a reliable connection.

  Richard

[fozzy]

I searched high and low at digi key and could not come up with that value.  Any chance you have a part # available?

try 1000M

[Chuck]

I searched high and low at digi key and could not come up with that value.  Any chance you have a part # available?

try 1000M

Yeah, when I Dorsey moded Oktava MC012's, that's what I used.

[Church-Audio]

I searched high and low at digi key and could not come up with that value.  Any chance you have a part # available?

try 1000M

Yeah, when I Dorsey moded Oktava MC012's, that's what I used.

1 gigaohm is the best value for that resistor thats what they all use. Dale makes that part they are about $5.50 each in a 1% metal film
and Digikey does sell them.

Chris Church

[aberg]

bump... any progress updates from the nbox camp?

[musicsherlock]

bump... any progress updates from the nbox camp?

would love to hear about positive results as well...Last I spoke with Nick (via PM's) around Thanksgiving time, he was hoping to have a solution by the end of the year.

[aberg]

bump... any progress updates from the nbox camp?

would love to hear about positive results as well...Last I spoke with Nick (via PM's) around Thanksgiving time, he was hoping to have a solution by the end of the year.

I've been talking to Richard about getting his prototype going (mostly mechanical issues dealing with the cap/collette connection at this point), but if Nick is nearly ready and will be offering these up in the near future, maybe it's not worth the trouble... although it would be fun to get running.

[musicsherlock]

I'm pretty electronically inept here...but I do have an AKG C 451 that I can pull the insides of the mic out too readily...I'll see if I can post a picture later but it appears that the section where the cap connects with the body is only connected by one or two copper wires to the PCB board...couldn't one extend these copper wires? or do we loose too much juice doing that?

attached is a picture I found on the net...the capsule attaches to the board by just a couple of copper wires...

[aberg]

I think the 480 is a very different beast ...

[musicsherlock]

I think the 480 is a very different beast ...

perhaps...but I'm sure the answer lies in the 460's....

[poorlyconditioned]

I think the 480 is a very different beast ...

perhaps...but I'm sure the answer lies in the 460's....

The "answer" is just what I (and others) have shown in schematics, innards, parts lists, etc.

There should be one or two FETs (transistors) inside the "collette" that joins the capsule, then a wire to a remote "battery box" that somehow provides 60V to polarize the capsule.

My preliminary schematic is at:
  www.cs.uwaterloo.ca/~mannr/AKG/ck63_schematic.jpg

The difficult part (for me) is getting a good mechanical and electrical contact at the capsule.  A second issue is getting a 60V power source.  I've cheated for now and just used a bunch of 9V batteries in series.  The proper thing is an oscillator/transformer pair, which is shown in the AKG service schematics for AKG 460 and 480 mics.

Oh yeah, I checked with MBHO, they sell a collette+cable for $175 each.  This should have FETs in it, and fit their (relatively) inexpensive caps.  Hmm.  I wonder, would it fit the AKGs?  Anyone have specs on the MBHO caps?

  Richard

[terrapinj]

I think the 480 is a very different beast ...

perhaps...but I'm sure the answer lies in the 460's....

The "answer" is just what I (and others) have shown in schematics, innards, parts lists, etc.

There should be one or two FETs (transistors) inside the "collette" that joins the capsule, then a wire to a remote "battery box" that somehow provides 60V to polarize the capsule.

My preliminary schematic is at:
  www.cs.uwaterloo.ca/~mannr/AKG/ck63_schematic.jpg

The difficult part (for me) is getting a good mechanical and electrical contact at the capsule.  A second issue is getting a 60V power source.  I've cheated for now and just used a bunch of 9V batteries in series.  The proper thing is an oscillator/transformer pair, which is shown in the AKG service schematics for AKG 460 and 480 mics.

Oh yeah, I checked with MBHO, they sell a collette+cable for $175 each.  This should have FETs in it, and fit their (relatively) inexpensive caps.  Hmm.  I wonder, would it fit the AKGs?  Anyone have specs on the MBHO caps?

  Richard

i think the MBHO actives connect via lemo connector

[aberg]

I think the 480 is a very different beast ...

perhaps...but I'm sure the answer lies in the 460's....

The "answer" is just what I (and others) have shown in schematics, innards, parts lists, etc.

There should be one or two FETs (transistors) inside the "collette" that joins the capsule, then a wire to a remote "battery box" that somehow provides 60V to polarize the capsule.

My preliminary schematic is at:
  www.cs.uwaterloo.ca/~mannr/AKG/ck63_schematic.jpg

The difficult part (for me) is getting a good mechanical and electrical contact at the capsule.  A second issue is getting a 60V power source.  I've cheated for now and just used a bunch of 9V batteries in series.  The proper thing is an oscillator/transformer pair, which is shown in the AKG service schematics for AKG 460 and 480 mics.

Oh yeah, I checked with MBHO, they sell a collette+cable for $175 each.  This should have FETs in it, and fit their (relatively) inexpensive caps.  Hmm.  I wonder, would it fit the AKGs?  Anyone have specs on the MBHO caps?

  Richard

i think the MBHO actives connect via lemo connector

Yup, they do, but maybe their cables could be hacked.... a lot of money to spend to hack shit apart though.

[Sanjay]

i think the MBHO actives connect via lemo connector

4 pin mini xlr to be exact.

and i dont think that akg caps would fit on a mbho collette....