Topic: Nak cm300 active mod?

[Chuck]

Jeez, I'm just not getting it...
So after the mod is done, do you end up with an active/ phantom pair and have the (2) old bodies left over?
So you really have two pairs of microphones?

[aberg]

Jeez, I'm just not getting it...
So after the mod is done, do you end up with an active/ phantom pair and have the (2) old bodies left over?
So you really have two pairs of microphones?

Nope, the leftover "bodies" are useless i think because part of the "bodies" are used for the actives...

[Patrick]

Jeez, I'm just not getting it...
So after the mod is done, do you end up with an active/ phantom pair and have the (2) old bodies left over?
So you really have two pairs of microphones?

There are three parts to a stock cm300.  

1) A Capsule (cp1,2,3 or 4)
2) An Attenuator Barrel.  The capsule is screwed into the top of the barrel, and the bottom of the barrel is screwed into the...
3) Body.  All this really does is hold the required battery in place.  No electronics besides for the on/off/lo cut switch.

The mod eliminates the need for the battery body.  The cable on the actives exits out of the back of the attenuator housing.  It is held tight using zip ties on either side to keep it secure.

So yes, I now have my actives, and I have the bodies left over.  I use the bodies for the cp4 (shotgun) capsules, which is a whole different story.

Let me know if this makes no sense.

[Patrick]

here's  a picture of what i was talking about....you lose the third part, keep the first two.

also, check this link out as well: http://taperssection.com/index.php?topic=27307.0

[Chuck]

OK, that makes sense... So the upper part of the main body is part of the active set-up...
I see it now  

Maybe a handy person could make a whole other microphone out of that left over body...

Why am I obsessed with these things?   Maybe all the Nak300 Grateful Dead recordings I used to have? I dunno...

[Chuck]

OK, that makes sense... So the upper part of the main body is part of the active set-up...
I see it now  

Maybe a handy person could make a whole other microphone out of that left over body...

Why am I obsessed with these things?   Maybe all the Nak300 Grateful Dead recordings I used to have? I dunno...

Thank you very much Patrick... +T guys...

[Chuck]

OK, now more questions...
It looks like the rest of the body is there just to hold the 9v battery.
Is it possible to just build a simple voltage step-down circuit into the part with the vents. Say, using a 9v DC zener diode or another regulation circuit? Zener might introduce noise... Then you wouldn't need the Samson P4 right? This would be very cheap and seemingly simple to do.

[poorlyconditioned]

OK, now more questions...
It looks like the rest of the body is there just to hold the 9v battery.
Is it possible to just build a simple voltage step-down circuit into the part with the vents. Say, using a 9v DC zener diode or another regulation circuit? Zener might introduce noise... Then you wouldn't need the Samson P4 right? This would be very cheap and seemingly simple to do.

The simplest circuit is just use the (electret) capsule with a 9v battery box!  That is what I've done.  Rewire the capsule + FET so three wires are sticking out and wire it according to the three wire circuit I posted earlier.  Or, put  a 4.7k resistor between source and ground and run it with a standard battery box.

The only reason to use "phantom adapters" is when you need to run off 48V phantom power.  Or, when it is more convenient not to have an extra battery box hanging around (eg., for permanent installation in a club).

  Richard

[Chuck]

OK, now more questions...
It looks like the rest of the body is there just to hold the 9v battery.
Is it possible to just build a simple voltage step-down circuit into the part with the vents. Say, using a 9v DC zener diode or another regulation circuit? Zener might introduce noise... Then you wouldn't need the Samson P4 right? This would be very cheap and seemingly simple to do.

The simplest circuit is just use the (electret) capsule with a 9v battery box!  That is what I've done.  Rewire the capsule + FET so three wires are sticking out and wire it according to the three wire circuit I posted earlier.  Or, put  a 4.7k resistor between source and ground and run it with a standard battery box.

The only reason to use "phantom adapters" is when you need to run off 48V phantom power.  Or, when it is more convenient not to have an extra battery box hanging around (eg., for permanent installation in a club).

  Richard

Yeah, Richard, I was just thinking about using phantom power. I saw a post where leegeddy talked about how simple it was to do the phantom power mod, but he didn't mention the details... Anyway... I really need to get my hands on a pair of these to tinker with. Are those electret capsules still manufactured?

[aberg]

OK, now more questions...
It looks like the rest of the body is there just to hold the 9v battery.
Is it possible to just build a simple voltage step-down circuit into the part with the vents. Say, using a 9v DC zener diode or another regulation circuit? Zener might introduce noise... Then you wouldn't need the Samson P4 right? This would be very cheap and seemingly simple to do.

The simplest circuit is just use the (electret) capsule with a 9v battery box!  That is what I've done.  Rewire the capsule + FET so three wires are sticking out and wire it according to the three wire circuit I posted earlier.  Or, put  a 4.7k resistor between source and ground and run it with a standard battery box.

The only reason to use "phantom adapters" is when you need to run off 48V phantom power.  Or, when it is more convenient not to have an extra battery box hanging around (eg., for permanent installation in a club).

  Richard

Yeah, Richard, I was just thinking about using phantom power. I saw a post where leegeddy talked about how simple it was to do the phantom power mod, but he didn't mention the details... Anyway... I really need to get my hands on a pair of these to tinker with. Are those electret capsules still manufactured?

Yup, primo still makes them... $50 apeice I think. raoulduke had a link that i've since lost...

[Chuck]

I bet there are some transitor buffers in the vented piece? That makes it pretty slick, to be able to screw the capsules onto that piece. Is the reason most guys have to use the Samson phantom power adaptors because of the type of connector (mini-XLR) that is used in the active cable itself.  I assume the Samson unit just steps the 48v down to 9v and has the matching connector which makes everything nice and neat?

[poorlyconditioned]

I bet there are some transitor buffers in the vented piece? That makes it pretty slick, to be able to screw the capsules onto that piece. Is the reason most guys have to use the Samson phantom power adaptors because of the type of connector (mini-XLR) that is used in the active cable itself.  I assume the Samson unit just steps the 48v down to 9v and has the matching connector which makes everything nice and neat?

The vented place has one transistor only (the FET).  The body has a resistor and a transformer (I think).  Anyway, get rid of the body, and treat the vented part as "electret plus FET", the same as any other mic (AT853, DPA406x, etc).

The reason for the AT or Samson adapter is just to run on phantom voltage.  If you want battery power, skip the adapter and run directly as I said above...

  Richard

[Chuck]

I bet there are some transitor buffers in the vented piece? That makes it pretty slick, to be able to screw the capsules onto that piece. Is the reason most guys have to use the Samson phantom power adaptors because of the type of connector (mini-XLR) that is used in the active cable itself.  I assume the Samson unit just steps the 48v down to 9v and has the matching connector which makes everything nice and neat?

The vented place has one transistor only (the FET).  The body has a resistor and a transformer (I think).  Anyway, get rid of the body, and treat the vented part as "electret plus FET", the same as any other mic (AT853, DPA406x, etc).

The reason for the AT or Samson adapter is just to run on phantom voltage.  If you want battery power, skip the adapter and run directly as I said above...

  Richard

Yeah, I just looked at the Samson PM4 paperwork at the Samson site. There is an impedence matching transformer in there. I think you could do the same thing, much cleaner, using op-amps instead of a cheap transformer. Thanks for the info Richard... + another T in 12...

[Chuck]

Yup, that's why Marc's mod was so cheap. He just re-wired it, removing the transformer and the switches. The real cost is in the that AT or Samson phantom power module.

[poorlyconditioned]

I bet there are some transitor buffers in the vented piece? That makes it pretty slick, to be able to screw the capsules onto that piece. Is the reason most guys have to use the Samson phantom power adaptors because of the type of connector (mini-XLR) that is used in the active cable itself.  I assume the Samson unit just steps the 48v down to 9v and has the matching connector which makes everything nice and neat?

The vented place has one transistor only (the FET).  The body has a resistor and a transformer (I think).  Anyway, get rid of the body, and treat the vented part as "electret plus FET", the same as any other mic (AT853, DPA406x, etc).

The reason for the AT or Samson adapter is just to run on phantom voltage.  If you want battery power, skip the adapter and run directly as I said above...

  Richard

richard, if I understand correctly, nak 30x > 3 wire wiring > 9v battery box should sound exactly the same as nak 30x > samson pm4 / at8533 ?

is being powered with 9v of phantom power supply a "different power" than 9v from a battery box? 

They are *almost* the same.

For short wire runs and high impedance mic inputs they are identical.  For longer runs, the AT/Samson adapters provide "buffering" or strengthening of the signal (via a transistor driving an output transformer).  This provides a balanced and low impedance output.  Balanced is good for long runs (>50' or so) and low impedance means you can drive any kind of input.  Notably, you could put a step up tranformer there and drive a line input!

But for most of us, running a short five or ten foot cable into a preamp, the battery box is fine.  In fact, one may argue that removing the extra components, the transformer in particular, makes it sound better.  My experience is that the AT adapters are pretty good though.  I have not tried the Samson ones.

  Richard