IBF-Akustik IBF-MP-B-USB User manual

Microphone Preamplifier
IBF-MP-B-USB
with microphone BIAS supply and USB-sound port
( IBF-MP-B-USB KIT includes MM8 cal microphone )
User Guide
Draft 2, January 2007
(C) IBF-Akustik e.K. olfgang Frank
Alexanderstr. 66 ● 68519 Viernheim ● Germany
Fon. [phone] ● Fax. [phone]
[e-mail] www.ibf-akustik.de
Design and specifications are subject to change without notice. Ask factory for technical specifications
before purchase and/or use. Whenever a doubt about safety issues arises from this product, please
inform us immediately for technical consultation.
MP-B-USB-manual_r03.sxw Microsoft, Windows and Windows XP are registered trademarks of Microsoft Corporation page 1

Contents
·Quick Guide to using the MIC-Amp
·Introduction
·General Description
·Installation
·Locating the unit
·Signal connections
·Operational Notes
·Power Switch
·Bias Supply
·Clipping Indicator
·Batteries and external Voltage supplies
·
·Appendices
·Controls, Connectors and Indicators
·GAIN Control
·MIC IN / LINE IN
·LINE OUT
·PO ER LED
·Low Battery Indicator
·CLIPPING INDICATOR LED
·PO ER Switch
·BATTERY Compartment
·Specification
·USB-Option
·CE Conformity Statement
·Limited arranty
·Safety Clause And Unauthorized Applications
MP-B-USB-manual_r03.sxw Microsoft, Windows and Windows XP are registered trademarks of Microsoft Corporation page 2

Quick Guide to using the MIC-Amp
All of us get in a hurry to use a new device. e want you to fully understand how to use the mic amp and
avoiding user faults.
Step 1
Open the battery compartment and connect the battery, accumulator or external voltage supply unit.
Note: The mic-amp has a build in reverse polarity protection avoiding damages caused by voltage supplies with
wrong configurated ouput voltage polarity .
ITH USB OPTION: connect your computer to the microphone preamplifier
using the enclosed miniUSB-USB cable. The USB sound adapter is automatically powered while
connected with an USB port. The gain switch doesn't control the USB adapter while the preamplifier is
powered when the gain switch is not at the off-state.
Step 2
Check the rotary switch (gain setting) and make sure it is in the off state.
Step 3
Using shielded microphone cable, connect a microphone to the microphone input channel on the front panel.
Step 4
Connect the USB line output
to the line input of the next device. If you're using the preamplifier section only you have
to make the following connections:
Left channel Loopback (left channel output connected to left channel input)
Right channel output to audio amplifier of your HiFi equipment.
Microphone to MP-B's MICin.
Step 5
Set the gain switch to 20dB gain. Turning power switch on or off, can produce a voltage spike in the
line and/or power output. Protect your ears, speakers and equipment by being careful while the mic-
amp line output is connected to the next device.
Step 6
Adjust the gain control with signal going into the microphone to give the desired output level. The indicator LED's
can provide help in setting the right level. The Clip-LED has a characteristic somewhat between that of a peak
and VU control (short attack and enlarged release time). It is a quasi reference and should force you into a lower
gain setting if necessary. If you do not find an adequate gain setting, try out the most left VAR position and adjust
your gain setting using a small srew driver. You get access to the associated trimmin potentiometer through the
small front panel hole.
Step 7
Be Careful and watch the gain setting! Is it realistic!
Most equipment connected to the mic-amp will clip before the mic-amp will. Your soundcard may be distorting on
peak signals even though the mic-amp isn't. This is because the soundcard line inputs being overloaded with too
much signal coming from the mic amp's line output. Turn down the mic-amps gain control until distortion stops.
MP-B-USB-manual_r03.sxw Microsoft, Windows and Windows XP are registered trademarks of Microsoft Corporation page 3

Introduction
General Description
The IBF-MP-B-USB is a portable, battery-powered microphone preamplifier with BIAS power for electret
microphones and designed for the 20Hz to 20kHz audio bandwidth. This quality mic pre is ideal for audio
recording and acoustic measurement purposes such as speaker and roomacoustic measurements.
ith its rugged mechanical and electrical construction, compact size and high-quality components, the
IBF-MP-B-USB is extremely durable and easy to use. This highly reliable mic preamp will provide years of superb
audio performance under regular conditions.
Installation
Locating the unit: Keep the mic-amp physically separated from other electronic equipment that
produce electrical fields. As a high gain device, hum and noise pickup is possible through chassis and
associated cable. Placing the unit away from transformers, power amplifiers, etc. will help to avoid
pickup of those unwanted signals.
Signal and supply connections
All necessary connections on the
mic-amp are made via RF phono
jacks. Both the microphone
preamplifer input and output
connectors as well as line output
connector are female. In addition a
DC-IN (1.3mm connector) jack can
be found on the right side of the
device. ith the USB option
installed the associated mini-USB
connector is located next to the DC-
IN jack.
MP-B-USB-manual_r03.sxw Microsoft, Windows and Windows XP are registered trademarks of Microsoft Corporation page 4

Operational Notes
Power Switch
The power switch is a built in function of the gain switch. hen power is switched on or off, high level audio
"pops" on the microphone preamplifier output are likely.
This is a function of DC voltage turning on or off to the circuitry and can also be seen on the indicator LED's.
Care must be taken to ensure that these "pops" do not damage equipment or ears associated with the
mic preamp ouputs. It is a good idea to lower the sound level of the associated equipment.
Clipping Indicator
The Mic-Amp has a build in clipping indicator that can provide assistance in setting the gain control.
It has a characteristic somewhat between that of a peak and VU control (short attack and long release time). It is
a quasi reference and should force you into a lower gain setting if necessary.
Batteries and external Voltage supplies
The IBF-MP-B is designed to operate on one 9 V battery or accumulator or external 6 to 12V power supply (It
contains a reverse polarity protection device). Due to the power consumption of approximately 15 mA and supply
by battery power dictates applying power only as required or using a plug-in power supply.
e recommend using plug-in power supplies with a stabilized output voltage. Types without that feature normally
have a higher voltage output at low current consumption. This can damage the preamp or parts of it. Using
„unstabilized" plug-in power supplies also can cause additional noise in the signal path. Use a connector with a
1.3mm hole.
Note: The audio performance, respectively the maximum output voltage swing doesn't depend on the battery
voltage which drops down during it's life-time. End of life-time is indicated by flashing Power-LED.
The microphone preamplifier with USB option installed can be USB powered as well. The USB sound
adapter is automatically powered while being connected with an USB port of your computer (Yellow
LED lights up). The gain switch controls the microphone preamplifier only. In case of USB power the
use of a battery or plug in power supply is not necessary but recommended for better noise
performance at higher gain settings . All power supplies are decoupled from each other. USB power overrides
LO bat control while any battery power or 6..12Vdc plugin-power overrides the USB power for the amplifier
section only.
MP-B-USB-manual_r03.sxw Microsoft, Windows and Windows XP are registered trademarks of Microsoft Corporation page 5
Hole: + Vcc
Sleeve: GND

Appendices
Controls, Connectors and Indicators
GAIN & POW R CONTROL
Selects the amount of gain from input to output. Fixed gain positions (clockwise) 0dB, 20dB, 34dB, 40dB.
Additional variable gain position (VAR) left from the OFF position – The associated trimming potentiometer (gain
adjustment 0...40dB) is accessible through the small opening underneath the gain switch.
MIC IN
unbalanced MIC-Input accepts microphone level signals, The input channel uses a RCA Phono jacks which is
recommended for semi permanent connections in audio applications.
MIC OUT
unbalanced line level signal via RCA Phono jack. (Normally not used with the USB version amplifier.)
USB OUT (Line output / TF test signal output)
unbalanced & buffered analog signal output supplied from your choice of measurement software (e.g. ETF)
POW R L D / Low Batt indicator
LED illuminates green when the unit is powered. Same LED flashes when Battery voltage is too low for proper
operation. USB power overrides LowBat indication.
CLIPPING INDICATOR L D
LED illuminates red at clipping
POW R Switch
The power switch is part of the gain controlswitch. Powers the unit when the switch is moved from the its OFF-
position. Doesn't control the USB power.
MP-B-USB-manual_r03.sxw Microsoft, Windows and Windows XP are registered trademarks of Microsoft Corporation page 6

BATT RY Compartment, Power supply option
Requires one 9V battery, accumulator or plug-in power supply for operation. Due to the 15 mA Power
requirements we recommend the use of a accumulator or plugin-power supply instead of a battery. ith USB-
Option installed: The unit is powered from your computers USB voltage.
Note: Plug-in power supply. Use a type which can give you an electronically stabilized 6V to 12V supply
voltage. Unstabilized Power Packs can cause damages and/or hum and noise.
Specification
Number of preamplifier channels - 1 Mic
Connectors - RF phono jacks for both inputs and outputs
Mic Input - unbalanced, capacitor coupled,
Mic Output - unbalanced, capacitor coupled, short circuit protected, guaranteed output level without clipping 0,775Vrms
USB Input - internally connected with microphone output.
USB Output - Buffered right channel analog output from built-in USB soundcard adapter
DAC section - 32 – 44.1 – 48kHz / A-weighted S/N typ 96dB @1kHz
ADC section - 8 – 11.025 – 16 – 22.05 – 32 – 44.1 – 48kHz / A-weighted S/N typ 89dB @1kHz
Gain Range - up to 40 dB input to output (phase error <20deg)
Frequency Response - 20 Hz ... 20 kHz, +-0.4 dB (relative to 1 kHz)
Max. Output Level before clipping – typ. 3Vpp (preamplifier section)
Clipping indicator L D - Red indicates clipping short attack time, long release time. Bipolar detection (typ. 2.5Vpp)
THD 0.02% typical, THD 0.04% max, THD & Noise < 0.06% typical
Bias Supply - typ. 4V coupled via 6.8kOhm resistor (additionally low-pass-filtered for better noise performance)
Power - 1x 9V batterie or plug-in power supply connector or 5V-USB power
Power L D - Green indicates power ON, flashing LED indicates low batt. (Vbatt < 6.5V)
Polarity - Mic input to Mic output is non-inverting.
Operating Temperature Range
0 to 40 degrees Celsius (32 to 104 degrees F)
Power up delay – approx. 10 sec
Dimensions
34 mm x 68 mm x 120 mm (h x w x d) (1 11/32" x 2 11/16" x 4 23/32")
Weight (unit only)
120 grams (4 1/8 oz.) battery removed
Certification
C Conformity statement
RoHS category 9 compliant
MP-B-USB-manual_r03.sxw Microsoft, Windows and Windows XP are registered trademarks of Microsoft Corporation page 7

Amplifer with USB-Option only
While our amplifer has 1 analog Channel The USB-Option provides 2 analog inputs and outputs. The left analog
channel is internally looped for reference.
All in all, this interface is a complete audio solution for measuring the acoustic behaviour of your listening room
•High resolution up to 48kHz converter
•powered via USB bus
•miniUSB connector , USB cable included
•second left channel internally looped for reference
•The additional yellow L D next to the miniUSB jack gives you a quick check that the internal USB adapter is properly
connected to your computer
System requirements for USB operation: The USB-Option makes the MP-B or MP-CCP amplifier PC
compatible. Therefore no installation procedure or drivers are required.
PC: Intel® or AMD® CPU, 400Mhz or higher, min. 128MB RAM, USB1.1 compatible interface, Windows® XP or
2000
Hardware USB connection:Use the USB connecting cable supplied with your MP-B-USB amplifier to connect
the unit to your computer.
With this ultra-compact, bus-powered interface, you can link your Windows® computer with the IBF-Akustik
measurement amplifier. There is no setup or special drivers needed—simply plug the interface in a free USB
port. Your Windows 2000 or WindowsXP computer will detect the new device and install the original Windows
driver if needed.
Additional operating elements and connections:
WITH TH USB OPTION YOUR PR AMPLIFI R LOOKS LIK THIS:
and has the following additional elements compared to the non-USB MP-B Preamplifier
1) ANALOG USB OUTPUT on front panel (gn)
2) miniUSB jack located next to the DC-IN jack.
3) yellow USB power indicator (left from mini USB connector)
A USB-mini-USB cable is bundled with the amplifier
MP-B-USB-manual_r03.sxw Microsoft, Windows and Windows XP are registered trademarks of Microsoft Corporation page 8

Automated driver installation procedure Plug-n-Play)
Under a WIN2K environment you'll get the following or similar install screens (German install procedure shown).
The install procedure doesn't need your assistance it's plug and play at its best and all necessary drivers are
coming with your WIN2K or WINDOWS XP software.
After installation you have full access to you USB soundadapter using the original indows mixer sndvol32.exe.
German language version:
English language version
MP-B-USB-manual_r03.sxw Microsoft, Windows and Windows XP are registered trademarks of Microsoft Corporation page 9

Your hardware manager reports the installation of a USB Sound device as well as Human Interface Device (The
HID is not used by the MP-B-USB amplifier but is part of the original device driver)
MP-B-USB-manual_r03.sxw Microsoft, Windows and Windows XP are registered trademarks of Microsoft Corporation page 10