Lectrosonics HMA-941 Series User manual

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Guide
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This guide is intended to assist with
initial setup and operation of your
Lectrosonics product.
For a detailed user manual, down-
load the most current
version at:
www.lectrosonics.com/manuals
HMa-941
Plug-On Transmitter
30 November 2018
Digital Hybrid Wireless®
U.S. Patent 7,225,135
For FCC Part 74 licensed operators

LECTROSONICS, INC.2
LCD Screen
Backlit for easy viewing in bright or dimly lit conditions.
Pwr (power) LED
Indicates power status and battery strength.
XLR Input Jack
Standard 3‑pin Switchcraft XLR type. Coupler is spring‑loaded to maintain a
snug fit and to prevent noise.
Modulation LEDs
Provides a visual indication of the audio input signal level ‑ either red or green
to indicate modulation levels.
AUDIO Button
Used to display the view and adjust the audio gain setting (0 dB to 44 dB).
FREQ Button
Used to set the operating frequency and toggle the LCD between the operating
frequency in MHz and a two‑digit hexadecimal frequency code.
UP/DOWN Arrows
Used to view and select parameters and values during setup and operation.
Battery Compartment Cover
Hinged to housing to prevent loss.
Antenna
An antenna is formed betiween the housing and the attached microphone,
operating much like a dipole. At UHF frequencies the length of the housing is
ismiliar to 1/4 wavelength of the operating frequency, so the antenna is supris‑
ingly efficient, which helps extend the operating range and suppress noise
and interference.
Controls and Functions
Battery
Compartment
Cover
XLR Input
Jack
AUDIO Button
LCD
Input
Coupler
FREQ Button
Modulation
LEDs
PWR LED
UP Arrow
DOWN Arrow

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The transmitter is powered by two AA batteries.
Note: Standard zinc‑carbon batteries marked “heavy-duty” or “long-
lasting” are not adequate.
To install new batteries:
1. Slide open the Battery Cover and remove any old batteries.
2. Insert the new batteries into the housing. One battery goes in positive
(+) end first, the other negative (‑) end first. Look into the battery com‑
partment to determine which end goes in which side. The side with the
plastic ring is the side which accepts the positive end of the battery.
Note: It is possible to install the batteries backward and close the
battery door, but the batteries will not make contact and the unit will not
work.
3. Slide the Battery Cover until it snaps securely shut.
Battery Installation
Battery
Compartment
Battery
Cover
positive (+)
terminal
negative (–)
terminal

LECTROSONICS, INC.4
Operating Instructions
Power Up and Boot Sequence
1) Ensure that good batteries are installed in the unit.
2) Simultaneously press and hold the AUDIO and FREQ buttons until the power
on boot sequence is initiated.
The count will progress from 1 through 3 and the unit
will then power up with the RF output turned on.
During this turn on sequence, the modulation and
power LEDs all glow red, then green, and then revert
to normal operation. If the buttons are released before the count is com‑
plete, the unit will boot up into the standby mode (see below).
The LCD displays the following information during the boot sequence:
Company Name: LECtro
Frequency Block: b 941
Firmware Version (rX.X): r1.01 (typical)
Compatibility Mode: CP Hbr (typical)
When the boot sequence is complete, the display will switch to the frequency
currently set.
Power Down
Initial Power Off
Timer Screen
1) Simultaneously press and hold the AUDIO and FREQ buttons while observ‑
ing that the word “Off” appears in the LCD along with a counter.
2) When the counter reaches “0”, the unit turns off.
Note: If the AUDIO and FREQ buttons are released before the LCD
goes blank at the end of the countdown, the unit will not turn off.
Instead, it will stay energized and the display will return to the previous
screen.
Standby Mode
Standby Screen
With the power turned off, pressing the AUDIO
and FREQ buttons briefly places the unit in
Standby Mode.
In this mode the RF output is turned off so all
setup adjustments can be made without interfering with other systems operat‑
ing in the same location. The screen displays “rf OFF” to remind the user that
the unit is not transmitting.
While the unit is in the standby mode, access the setup screens using the
AUDIO and FREQ buttons and make adjustments using the UP and DOWN
arrows.

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Menus
Setup is accomplished using menus and setup screens accessed by holding
the UP and DOWN arrow buttons at turn on, and by pressing the AUDIO and
FREQ buttons when the unit is turned on.
Hold UP arrow at turn on.
Hold the UP arrow button in while pressing both AUDIO and FREQ buttons to
access the setup screens below. It’s easier if you lay the unit on a flat surface
and use two hands to press all three buttons at the same time. After the first
screen loads, press the AUDIO button repeatedly to switch between the set‑
tings. Press the UP and DOWN arrow buttons for the desired selection.
After the settings are made, press both AUDIO and FREQ buttons together to
exit and turn the power off.
CP (compatibility modes)
Allows the transmitter to be used with 941 Series receivers or IFB systems in
the 941 MHz band.
nHb Digital hybrid mode
IFb Lectrosonics IFB systems
Pr (power output)
Can be set at 250 for extended range or at 50 for longer battery life.
50 50 mW output and longer battery life when
maximum range is not necessary
100 100 mW for slightly increased range
NOTE: See battery life table in the specifications
AP (audio polarity)
The polarity of the audio input (sometimes referred to as “phase”) can be
reversed for compatibility with other microphones.
PDenotes positive polarity
nDenotes negative polarity
StP (Frequency step size)
Sets the increments of frequency adjustment.
100 100 kHz steps
25 25 kHz steps

LECTROSONICS, INC.6
Hold DOWN arrow at turn on.
Hold the DOWN arrow button in while pressing both AUDIO and FREQ but‑
tons to access the setup screens below. It’s easier if you lay the unit on a flat
surface and use two hands to press all three buttons at the same time. After
the first screen loads, press the AUDIO button repeatedly to switch between
the settings. Press the UP and DOWN arrow buttons for the desired selection.
After the settings are made, press both AUDIO and FREQ buttons together to
exit and turn the power off.
rc (remote control with mobile app)
Allows the transmitter to respond to remote control “dweedle” tones from a
mobile device, or from tones generated by the Lectrosonics RM and RM2
devices.
on Enables the remote function.
oFF Disables the remote function.
PbAc (auto power restore)
Sets the transmitter to automatically turn back on and return to the previous
state after a battery change or power interruption when it is in the operating
mode.
1 Restores power automatically
0 Does not restore power automatically
bL (backlight settings)
Adjusts how long the LCD stays lit after pressing buttons.
55 minutes
30 30 seconds
on Stays on

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AUDIO Button
When the unit is turned on in either the Standby or Operating Mode, pressing
the AUDIO button repeatedly switches between the available settings.
• LF (XX) adjusts the low frequency roll‑off of the audio signal.
• AUD (XX) adjusts the input gain
LF (XX) - Adjusting the Low Frequency Roll-off
Repeatedly press the AUDIO button until the LF roll‑off adjustment screen
appears. Then press and hold the AUDIO button while selecting the desired
roll‑off frequency with the UP and DOWN arrows.
The roll‑off frequency can be set to 35, 50, 70, 100, 120 and 150 Hz.

LECTROSONICS, INC.8
AUD (XX) - Adjusting Audio Level (Gain)
It’s generally a good idea to adjust the low frequency roll‑off before setting the
gain, since it could affect the gain adjustment. The control panel modulation
LEDs marked ‑10 and ‑20 indicate the audio level and limiter activity. Once
adjusted according to the following procedure, the transmitter’s audio level
setting should not be used to control the volume of your sound system or
recorder levels. This gain adjustment matches the transmitter gain with the
microphone’s output level, the user’s voice level and the position of the mi‑
crophone. The audio input level (gain) should be adjusted with the unit in the
Standby Mode while observing the LEDs.
It is generally best to set the LF roll‑off before adjusting the gain, since low
frequency energy can affect the input level to the transmitter.
It is desirable to to set the gain so that some limiting occurs on louder peaks.
The limiter is very transparent over a 43 dB range, and its effect is not audible
until the system is close to overload. In other words, don’t be shy about turn‑
ing up the gain.
It is actually a good idea to turn the gain up to maximum and listen for distor‑
tion or compression to get a feel for how much headroom is available.
Signal Level -20 LED -10 LED
Less than ‑20 dB Off Off
‑20 dB to ‑10 dB Green Off
‑10 dB to +0 dB Green Green
+0 dB to +10 dB Red Green
Greater than +10 dB Red Red
Note: If several different people will be using the transmitter and there is not
time to make the adjustment for each individual, adjust it for the loudest voice.
1) With the transmitter in the Standby Mode, plug in the microphone and make
sure the connector is firmly seated.
Warning: If the wireless system is powered up while connected
to a live sound system, be careful to turn the sound system level
down first or severe feedback can occur.
2) Position the microphone in the location where it will be used in actual op‑
eration.
3) Observe the modulation LEDs while speaking or singing into the micro‑
phone at the same voice level that will be used during operation. While
holding the AUDIO button, press the UP or DOWN arrow buttons until the
both the ‑20 and ‑10 LEDs glow green, with the ‑20 LED flickering red dur‑
ing louder peaks in the audio. This will maximize the signal to noise ratio of
the system with full modulation.
4) If the unit was set up in Standby Mode, it will be necessary to turn the trans‑
mitter off, then power it up again in normal operation so the RF output will
be on. Then the other components in the sound or recording system can be
adjusted.

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PH (phantom power supply)
The transmitter input jack can provide phantom power for the attached mi‑
crophone if needed, with voltages at 5, 15 or 48 or be turned off. Use the UP
and DOWN arrow buttons to select the desired setting. Phantom power will
consume a slight amount of battery power.
About the Phantom Power Supply
Three phantom voltages are selectable from the control panel.
The voltages are:
• 5 Volts for lavaliere microphones,
• 15 Volts for some professional mics requiring high current and for many
common stage mics that will operate over a wide phantom Voltage range of
12 to 48 Volts. With the proper adapter, this position can also be used with
T power microphones. See our web site for details on finding or making the
proper adapter.
• 48 Volts for microphones that do in fact require a supply greater than 18
Volts. (See below for a discussion of why 42 and not a “true” 48 Volts.)
For longest battery life use the minimum phantom voltage necessary for the
microphone. Many stage microphones regulate the 48 Volts down to 10 Volts
internally anyway, so you might as well use the 15 Volt setting and save some
battery power. If you are not using a microphone for the input device, or are
using a microphone that does not require phantom power, turn the phantom
power off.
Phantom power should only be used with a fully floating, balanced device
such as most microphones with a 3‑pin XLR connector. If you use the phan‑
tom power with an unbalanced device or if pins 2 or 3 are DC connected to
ground, then you will draw maximum current from the power supply. The HM
is fully protected against such shorts but the batteries will be drained at twice
the normal rate.
The transmitter can supply 4 mA at 42 Volts, 8 mA at 15 Volts, and 8 mA at 5
Volts. The 42 Volts setting actually supplies the same voltage to a 48 Volt mi‑
crophone as the DIN standard arrangement due to a dynamic biasing scheme
that does not have as much voltage drop as the DIN standard. The 48 Volt
DIN standard arrangement protects against shorts and high fault current with
high resistance in the power supply feeds to pins 2 and 3. This provides pro‑
tection if the supply current is accidentally shorted to ground and also keeps
the microphone from being attenuated by the power supply.
The HMa improves on those functions and is able to use less power from
the battery by using constant current sources and current limiters. With this
dynamic arrangement the HMa can also supply more than twice the current
of competing 48 Volt plug on units and provide four times the current for some
very high end 15 Volt microphones.

LECTROSONICS, INC.10
FREQ Button
The operating frequency can be adjusted according to the frequency in MHz
or a two‑digit hexadecimal code. Press the button repeatedly to switch be‑
tween the two displays. The display switches when the button is first pushed;
push and hold the button in the desired mode and use the UP and DOWN
arrow buttons to make the adjustment.
Hex code numbering came about years ago when the first synthesized wire‑
less equipment was introduced. Two 16‑position rotary switches were used
to set the frequency. 16 on one switch and 16 on the other switch yielded 256
frequencies (16x16=256). While there are no 941 band models that use these
switches, hex code numbering is easier way to remember than frequencies
expressed in MHz with six numerals.
In this example, the same frequency is displayed in MHz and the equivalent
hex code.
The hex code is a hexadecimal numbering sequence that progresses upward
from lowest to highest frequency using the numerals and letters from 0
through F. When the frequency is on a 100 kHz step, the hex code will display
two 00’s for the last two digits, which is easy to remember (3A in the example
above). When the step size is set to 25 kHz, the last two digits will be 00, 25,
50 or 75 (3A.25 in the example below), which is still easier to remember than
all six numerals of the frequency in MHz.