Thanks to a new output limiter and analog-style metering, the ART Tube MP
Studio is a worthy upgrade to the original compact ART Tube Mic Pre.
Ease of Use: 5
Applied Research and Technology (a.k.a. ART) is at it again. The original
Tube MP put a tube microphone preamplifier in the hands of musicians
everywhere. And I mean that literally: this little unit, not much larger
than a guitar stompbox, fits right in your palm. Just make sure to keep it
on your desktop and not under foot! But size was only part of the MP's
appeal: a 12AX7A dual triode vacuum tube helped shape the little pre's
unique sound, and its price was in reach of even the most modest studio
Like the original MP, the MP Studio is a one-channel microphone
preamplifier with both XLR and 1/4" input and output connections. Powered
by a nine-volt AC wall-wart, the MP Studio is all you'll need to record
any microphone or instrument directly to your tape deck or hard-disk
computer recording system.
The Tube MP Studio adds two new features to the original design. There's a
lighted VU meter, which monitors output level. The meter also tracks the
action of the second new feature, the Output Peak Limiter circuit (or
The MP Studio's control layout is pretty basic. Input Level sets gain from
+6dB to +40dB. The Gain switch adds a 20dB boost, bringing the input range
up to +26dB through +60dB. It's good to know that there is up to 60dB of
gain for boosting low-output mics and recording very quiet sounds. The
Equivalent Input Noise (EIN) is -129dBu (A-weighted). Additional controls include +48volt phantom power (required for powering condenser mics and some direct boxes) and a Phase-Reverse switch. The latter, a common feature on "pro-level" devices, can come in handy when using the Tube MP Studio in a multi-miking setup.
The OPL uses an FET (Field-Effect Transistor) -based circuit to guarantee
full control over output peak levels. This is an insurance policy against
overloading and clipping your recorder's inputs with a signal that's too
hot. When the OPL push-button is engaged, the output level is limited to
0dBu at the unbalanced 1/4" output jack, and +6dBu at the balanced XLR
out. Attack time is program-dependent, ranging from less than 1ms up to
30ms. Release time is also variable with the shortest time set to 200ms.
These presets work well for most situations.
The bi-colored LED helps you find optimal levels. It glows green when the
unit is powered up and when it receives a low-level signal. (This "signal
present" indicator is very helpful when trouble-shooting a studio setup.)
When OPL is not active, the LED turns red if the tube's output is
near or over the point of clipping. When that happens, you have the
option of turning down the Input Level or activating the OPL. When OPL is
engaged, a red LED indicates that the signal has exceeded the OPL's
threshold level and that gain reduction (limiting) has begun.
The VU meter indicates output level and not gain reduction of the limiter.
When the meter reads 0dB, it corresponds to a +6dBu output level at the
1/4" jack (into an impedance of 300 ohms), and a +12dBu level at the XLR
jack (into a 600 ohm load). The maximum output level for the unit is an
I was surprised that the MP Studio offered an Output control; many pro
units costing thousands of dollars do not. The Output control is great for
setting the final level going to your recorder. And if you want to pump up
the input to overdrive the Tube MP's tube, you can use the output control
The MP Studio offers two input connections:
1/4" unbalanced, for instrument and line-level signals such as
synthesizers, with an impedance of about 1kOhm and handling levels up to
+22dBu and XLR balanced, designed for studio microphones but able to handle levels
up to +14dBu. Both inputs can be active at the same time, but I don't recommend using
them this way, since the level drops on both inputs as they mix together.
In The Studio
I ran a Neumann U-87 microphone through the MP Studio, which performed
well with this demanding microphone. I was also happy with the results of
plugging an an electric guitar into the 1/4" jack, and found the MP Studio
to be a great sounding direct box.
Using the OPL is about as easy as it gets. As you crank up the Input
control, you'll see the red LED light up more and more. The limiter action
is very affirmative: an absolute peak stopper. I actually used it as an
effect on one recording and loved it. This is called "brick wall"
limiting, and the sound of it proves out the slang.
The Tube MP Studio is small enough to be set next to your computer
keyboard for easy access, but be warned: I noticed increased noise and
interference in the sound when I had it too close to my computer. It
turned out to be my computer monitor radiating into the MP, causing a
buzzing sound whenever I used the higher gain position. After I moved the
MP Studio a little further away, all noise stopped.
Compact and affordable, the ART MP Studio is a great, user-friendly
microphone preamplifier that anybody can use. It's just the tool for quick
and foolproof recording.
The Tube MP carries a three-year warranty and sells for $159 MSRP. Applied Research & Technology at 215 Tremont St., Rochester, NY 14608. Telephone: 716-436-2720 or Fax: 716-436-3942. Web to: www.artproaudio.com