Review of Nakamichi CM300 mikes

I bought three of these microphones (CP1 & CP2 capsules with CM300
backends), and two CP4 shotgun capsules, way back when I started video
production in the early 1990s, and have been using them ever since.
They cost me $1800 at the time, and have proved to be dependable and do a
very good job.

Before I started working for myself, I'd worked in other people's
studios and had really grown to hate the lack of interest in good sound
equipment. From using awful mikes, trying to use a group of mikes
with radically different audio characteristics together, only having one
mike to cover everything, mikes with very short leads ending in phone
jacks, horrible noises getting into unbalanced lines, etc. And when
I bought my first camera, it came with a truly dreadful mike. So
purchasing decent microphones was at the top of the “to do” list.
Fortunately one of the local audio/video dealers understood what I
wanted, and sold me these.

What I ended up with was three virtually identical mikes, with omni-
and uni-directional capsules, and a couple of super-directional shotgun
capsules. With these mikes, the interchangeable capsules screw into
the backend, giving you a kit that can be assembled for the type of
pick-up pattern you need.

They were only battery powered, but that didn't bother me at the time,
since my camera had no phantom power supply, though having to deal with
batteries was a nuisance. More recently, I modified the CM300 mike
backends to run off phantom power, to carry on using them with other
equipment, rather than replace the mikes. I've never really cared
for phantom power (with any connection gremlins you get horrible crackles
and crunches, some mixers produce nasty hums when their phantom power is
used, few mixers let you switch phantom power to each input individually,
etc.), but it is a useful thing to have (when it's working well).

Technical specifications

CP-1 (cardioid)

CP-2 (omni)

CP-3 (super omni)

CP-4 (super directional)

Frequency response

30–18,000 Hz
± 3.5 dB

20–16,000 Hz
± 3.5 dB

20–18,000 Hz
± 3.5 dB

30–20,000 Hz
± 3.5 dB

Output impedance (1 kHz)

200 Ω balanced ±20%

Sensitivity
(1 kHz 0 dB = 1 V/μ bar)

−76 dB ± 2.5 dB

−74 dB ± 2.5 dB

−76 dB ± 2.5 dB

Signal to Noise Ratio (weighted)

> 50 dB

> 46 dB

> 50 dB

Maximum SPL at 3% distortion
CM-300
CM-100

138 dB
118 dB

138 dB
120 dB

118 dB
118 dB

Dynamic range
CM-300
CM-100

> 114 dB
> 94 dB

> 107 dB
> 92 dB

> 94 dB
> 94 dB

Current consumption

< 1 mA

< 0.5 mA

One might comment about the frequency response being a bit limited,
and the odd ±3.5 dB points instead of the standard 3 dB limits,
but… At the time, 15 kHz was the standard bandwidth for
television and radio, and mike frequency response charts are notoriously
bumpy.

The good

I've always liked the sound quality of the mikes, and they've proved
good at being used for close-up and distant-miking. The three mikes
have virtually the same audio characteristics, so using them for stereo
or group recordings means that you don't notice sonic oddities between
them.

Being tube-shaped rather than conical mike meant that the mikes could
be clamped in any direction without it sliding out of the mike
holder.

Having a low-impedance transformer-coupled output is good for noise
immunity over long lines, and has been compatible with everything I've
used them with.

Being self-powered has meant that I could use them with any equipment
with a mike input.

The windscreen/pop-filters for the omni and uni capsules is a coarse
wiremesh backed by a fine wiremesh screen, so there's no decaying foam to
worry about.

Having a built-in low-cut filter means that you can compensate for
proximity effect, acoustic rumble, and windnoise at the mike, and use
them with equipment that had no low-cut feature in itself. And use
them with ease with equipment that buries such controls inside cumbersome
menus.

They have a switchable 10 dB pad in the head, before the preamp,
so you use them in some extremely loud situations with distortion
occurring. Though having to unscrew the capsule to reach the switch
is a bit of an inconvenience.

The bad

The use of a special battery was a bit annoying, at first. They
weren't cheap, though did last for a very long time. Later, the
battery became unavailable, so even more annoying, and I had to make up
batteries by taping button cells together. Not being phantom
powerable is a bit limiting, but it was very easy to convert them.

The windscreen/pop-filters soon became loose, and were prone to
sliding off. I've had to glue the plastic framework back together a
few times, but the rubber grippy strips that's supposed to hold them on
don't grip tightly enough, and are too slippery. The foam
windscreen cover for the shotgun mike eventually deteriorated after about
twenty years, so I've got to find a replacement for it. I was
fortunate to discover this before it dissolved into goo and got into the
mikes. So if you've got boxed up shotgun capsules, you want to
carefully inspect them.

The box they come in wasn't set up very conveniently. You have
to remove the wind/pop filter to put the mike away, leading to the filter
becoming sloppy very quickly. It would have been better to be able
to put the mike away still fully assembled. These days I keep them
in a plastic toolbox that is big enough for that, and to hold various
accessories.

The shotgun mike is very long, much longer than the usual mike blimp
windcages, so I've never bought one for it. I'm in two minds as to
whether to try and find a super-long one, or buy a newer mike that fits
the usual windcages. I've had to use them on a few occasions where
the original foam windsock just wasn't good enough to stop wind
noise.

The mikes are quite narrow, so need a special clamp to hold them, or
need packing around them to fit larger ones.

The mikes have no anti-shock mounting, so handling noise is very
noticeable (although they're not meant to be hand-held mikes).
Likewise for noise mechanically transmitted through the stand. I've
made shockmounts,
and bought third-party generic
ones to deal with that issue.

If you have to move a directional mike around, such as one mounted on
a camera, or using a roving mike, you do hear the accoustics of the
background sound change quite noticeably. All directional mikes
suffer from that, but it was surprisingly prominent with these mikes.

When I first bought my mikes, I tested one mike first, bought three
when I was happy with it, and bought a couple of shotgun capsules.
One of the shotgun capsules was a bit naff, so I sent it back for a
replacement. The supplier sent me back my original mike as the
replacement (there was a telltale internal scratch, and it came back in a
box with my gaffer tape on it). I wasn't pleased by the attitude of
returned rejected goods being fobbed off unto another customer (the same
customer, in this instance).

Summary

I suppose the ultimate comment about them is that I've used them for
almost thirty years, and not wanted to replace them. Over that time
I've compared them with other mikes, and have never been displeased by
mine's sound.