Topic: Nakamichi CM300 Active mod (aka "Franken-Nak")

[leegeddy]

hi all;

i purchased Andy's (dwonk) CM300 pair last month and after few discussions with Audio Technica's tech about the specs of the AT8533 9-52v power modules, i decided to make the Nak cm300s a wee bit smaller for stealthing and run it on phantom power from my Beyerdynamic MV-100. my taping is mostly stealth, so i want to give the cm300s a run.

*Original Nakamich CM300 mics. it's internally powered by an AA-sized 9v battery. it has a switch for Off/On/Rolloff (-10dB/100Hz)


*this shows the mic disassembled.


*this shows the capsule assembly. the mini-xlr (TA3M) will be added later.


*schematic for the modification.


*this shows a temporary mod for testing.  once the mod has been tested, the TA3M mini-xlr will be mounted to the end of the capsule assembly and all the wires will be gone.


i've already tested one of the mics and it worked great. i'll do the other one later tonight for some testing tomorrow.

i'll record some sound samples with the temporary setup and the same samples with the mics back in their original state powered by their internal batteries.. let's see which setup yield better results.

*final modification. i didn't use the mini-xlr (TA3M) due to space limitations.  cabling is AT (same ones for AT853) and terminates to miniXLRF (TA3F).


marc

[caymanreview]

can you take a pic with the last one with maybe a quarter or something for size reference?

that is VERY cool!

[shaggy]

I-ya!  What the heck have you done to my little ones?

Quick question, are you gonna come out of an AT8533 power module (voltage step down) or you going straight into the phantom source, b/c it seems like you'd fry the mic if you did the latter.

Seriously, I am glad you took the initiative to do the stealthing mod.  It is a dream that I have had about using those mics for years.  I had no idea that you were gonna shorten them up!  If this is sucessful, would you consider doing mods for cash?

ANDY

[junkbondking]

yeah, i'll second that.  the only issue keeping me from buying the naks is the power issue. 

[leegeddy]

Nakamichi CM300 modification samples.

Recording Equipment list. 

Modified:     Nakamichi CP-2 (omni) > Passive cable > AT8533 (9-52v phantom module) > Beyerdynamic MV-100 (48V phantom, +20dB gain) > Sony M1

Unmodified:  Nakamichi CP-2/CM300 > Beyerdynamic MV-100 (dynamic, +20dB gain) > Sony M1

Sound Source: Sony SACD player > Sunfire pre > Audio Research amp > B&W CDM-7SE

Tracks:

01. sample1-mod
02. sample1-mod-normalized
03. sample1-unmod
04. sample1-unmod-normalized
05. sample2-mod
06. sample2-mod-normalized
07. sample2-unmod
08. sample2-unmod-normalized
09. sample3-mod
10. sample3-mod-normalized
11. sample3-unmod
12. sample3-unmod-normalized

both FLAC and 320kbps MP3 are included.

Notes:

Gain on the mv100 was kept at +20dB. Record level dial on the m1 was set at 7. 
Volume on the stereo was same for both playbacks.

Sample songs are from an Alpine Test Disc:

Sample1: Jennifer Warnes "Bird on a Wire"
Sample2: David Benoit "Re Bach"
Sample3: Billy Cobham "The Juggler"

-leegeddy (AUG '04)

[super-phat-al]

very intersted in this, downloading now.  +t

[jhirte]

bad ass!! I miss my naks all of a sudden!!!
Very nice! gonna download the sample when I get home!

-Jim

[super-phat-al]

the mod sounds really good.  very well done.  the presentation of the data is awesome.

[shaggy]

Marc,

Can you include your AT853s for reference?  Post it up on bt.etree.org if you decide to to it and make a new torrent file.

ANDY

[Kindguy]

I-ya!  What the heck have you done to my little ones?

T+ great job!

[leegeddy]

few things about the mod that i'm still trying to work out. 1. i hear a hum louder in the mod vs. the unmod.  i messed around with my getto cabling and it's the culprit. the handling noise is present as well.  hopefully when i do the final cabling with shielded ones, it will be fixed.

2nd. the bass in the unmod is sounds a *wee* bit better, but less punch.  also, i get a much lower signal with the unmod. (see the difference in the unmod vs. unmod-normalized).

now, i'm looking to taking these into a venue and running them with PA level sounds. 

marc

[LeftoverSammy]

This is almost exactly how my CM-700's were modified by Mark Severson many moons ago (back in the 80's)! The main body of the mics, which contained the special 6V cell, switch, low-cut, etc, was removed from the FET & caps. I had a new, updated PS built by Luminous Audio with updated components (high end resistors and caps) along with all being hard wired with solid silver wire to replace the older mini supply Mark made back in the day. It had issues with shorting out, noisy and only used 6V to power the mics which is not the most efficient manner to power them with.

So we stepped up the operating voltage from 6V to 9V which reduced the noise level down AND allowed me to use standard 9V cells! This was a suggestion at the time from Steven Sank (Nak guru who does the 48V phantom mods to 100's, 300's, 700's and 1000's), at the time we were designing the PS with Luminous folks. Sank told me that the CP-701 caps could actually handle up to 30V DC before you fry them. The hotter voltage you run them on the less self noise they will introduce into the incoming signal.

Basically my mod 700's are the same arrangement: FETw/capsules (very short and small) with a small machined brass fitting that screws into the back of the FET (common to the mic body/batt source). Then a BNC connector was mounted in the back of that brass plug. From that I run very thin solid silver unbalanced cables from the connector in the FET to my external PS that sits in my bag. Basically pretty much the same design, although this 300 mod looks as if the balanced connector is being taken advantage of!! I wish mine were still balanced although I am yet to have any interference issues as a result of running unbalanced. To make them balanced again would require a new machined brass plug and would make the interface common to the FET much larger. As it is now the 700's are very small compaired to their little brother the 300's.

Nice job! Let me know if you wish to see what the mod 700's look like or what the PS looks like!
+t for the Nak mods! Right on man!! 

Peace,
LoS

[jessedscott]

What the hell DID YOU DO BATMAN?!!!! OH MY GOD!

[Big Muff]

that's some nice work...
It's a dream come true for me, hope for active Nak 300's after all.
Would you consider doing this on a contract basis Marc?
Still trying to do something with my CP-701 caps too,  any ideas?

Sammy? Marc?

+T to all you Nak guys!

later,
-Mike


added something below for the JB3 / Nakamichi users 

[leegeddy]

i'm going to test the mics in the field before i commit to keeping the mod. they worked great recording my speakers' output, but i really want to see how they do in a live PA setting.

marc