Microphone Control and
Integrated Headphone
Amplifier System
Version 1.2
DM Engineering
2174 Chandler St.
Camarillo, CA 91345-4611
805-987-7881 800-249-0487
The “Audio-Pod System” is a microprocessor controlled Microphone On-Off control
system along with an integrated headphone amplifier which is ideal for remote and talk
studio applications. The Microphone circuit is available with a high quality, low noise
pre-amplifier with switched phantom power as an option. The Audio-Pod system
consists up to four Audio-Pod modules and a Power Supply. One Power Supply will
supply power for up to four Audio-Pod modules, and the modules may include any of
the available variety of options. 10 foot Power Supply cables, Velcro mounting pads
and a trimpot adjustment tool are supplied.
Optional permanent table top tilt mounting brackets and recessed flush mounting bezels
for permanent flush mount solutions for the Audio-Pod modules are also available.
The Microphone circuit and Mic on-off control portion includes the following features:
Large LED differentially lighted Mic-On and Mic-Off long life reed type
silent push buttons
Cough-mute function integrated with Mic-On button (Operational with
local control mode enabled)
Local Mic On-Off feature may be disabled and controlled remotely
Remote control of Mic on-off function with a logic low or contact closure
may be accomplished with either local control enabled or disabled
LED Mic On status indication on the top of the enclosure for status
check by control room operator or others
Microphone XLR in and XLR out connectors as well as Eurostyle screw
terminal termination of Mic out connection for permanent installations
SSR output voltage, continuous or flashing, to drive a DME Solid State
Relay Pack or customers own solid state relay for ON-AIR lamps or for
external LED indicator (multiple Audio-Pod SSR outputs may be
connected in parallel in the continuous mode only)
Precision metal film resistors used throughout audio chain for low noise
The optional Mic pre-amp portion includes the following features:
Quality low noise mic preamp with user adjustable rear panel variable
gain control with output ranging from mic to line level
Phantom power with rear panel switch and LED indicator
The integrated headphone amplifier section includes the following features:
Voltage Controlled Amplifier (VCA) circuitry employed (no “dirty” pots)
Rear panel high/low impedance headphone switch covering the range
from 8 to 400 ohm headsets
Rear panel output phase switch (0-180O) to address bone conduction
cancellation issues sometimes experienced by users
ESD protected front panel 3.5mm and ¼” stereo headphone output
Rear panel maximum headphone gain set control to restrict the
maximum headset output to prevent possible hearing damage and
liability issue avoidance
Single ended L&R inputs via a rear panel 3.5mm jack for quick connect
applications and on Eurostyle screw terminal connectors for permanent
Precision metal film resistors used throughout the audio chain for low
Mount the Power Supply within 10’ of the Audio-Pod location. Mounting may
be table top or under the desk mounting using the supplied mounting screws
and the “keyhole” slots located on the bottom of the power supply cabinet.
(2 ¾” center to center mounting holes) Orientation may be in two different axes
depending upon user preference.
The Audio-Pod modules are normally desk top mounted using the supplied
rubber feet and/or the supplied Velcro strips for a more secure installation. It is
not necessary to remove the rubber feet when using the Velcro strips.
Cleaning the mounting surface with alcohol is recommended before applying
the Velcro. Allow the alcohol to dry completely before applying. If the optional
table top or flush mounting brackets are used, refer to the installation
instructions that accompany them
Fig. 1
Connect the Power Supply to the Audio-Pods using the supplied 10ft. 8 pin
Mini-Din cables. The orientation of the connector has the flat side facing the
top of the enclosures. IMPORTANT: Assure that the Mini-Din connectors are
fully engaged with the sockets. Insert, wiggle and press firmly! Failure to
completely insert the power cables will result in hum or non-operation of the
Audio-Pod module.
Connect the microphone XLR in and out connectors to the respective
receptacles. A more permanent wire output connection, balanced or
unbalanced, may be made using the Eurostyle screw terminal connector “MIC
OUT +”, “MIC GND”, and “MIC OUT –“ terminals.
Connect the single ended headphone inputs to the 3.5mm “PHONES IN”
connector, (lft=tip, r=ring, com=sleeve) or the “PH IN LFT”, “PH IN RT”, and
“PH COM” (headphone common or ground) terminals.
If desired, connect the “SSR/LED out” and the “GND” terminals to your DM
Engineering Studio Solid State Relay or users’ solid state relay (5-15VDC input)
for lighting incandescent ON AIR or RECORDING lights. Outputs may be
connected in parallel for multiple Audio-Pods driving one SSR if all modules are
set for constant SSR operation. IMPORTANT: Maintain SSR output polarity
considerations between the Audio-Pods or damage may result. If multiple
Audio-Pod SSR outputs are used for driving a single LED indicator, a 220 ohm
series resistor between the + outputs and the LED is recommended.
If desired, connect the remote control wiring to the “RMT CONT ON/OFF” and
“GND” terminals. Either a logic low or contact closure will turn the microphone
on. A logic high or open contact will turn the microphone off unless local
control has it locked on. It is recommended that an “open collector” logic
interface be used.
The “LOC CONT ENABLE” jumper that is connected to “GND” with the factory
installed jumper enables the front panel push buttons and “COUGH” function.
To disable the local microphone on-off switch and cough functions, remove the
jumper between the “LOC CONT ENABLE” and “GND” terminals. The Mic ONOFF function will now only work using the remote control input.
If the preamplifier option has been selected and phantom powered
microphones are to be used, set the “PHANTOM POWER” switch to the “ON”
position. (switch to the left position) This switch setting may be changed at any
time without causing a damaging “thump” in the output.
Connect the AC power cord to an 115VAC outlet. The LED indicator on the power
supply should light as well as the “MIC OFF” buttons on the Audio Pods.
Microphone Section with the mic pre-amplifier option only:
1. The Audio-Pod microphone gain is factory preset for the average dynamic
microphone and there may not be need for any adjustment. If the gain is set
too high or a Condenser or an Electret type of microphone is used, the rear
panel “MIC GAIN” control setting will need to be reduced.
A. If a Condenser or Electret type of microphone is being used turn the
Phantom Power switch to ON. The LED indicator will light when the
switch is in the ON position. It is advisable to disable the phantom power
supplied by the mixing console unless other such microphones are being
used directly connected to the console. The presence of up to 48 volts on
the output of the Audio-Pod will do no damage.
B. Set your mixing console for normal input and output, press the Audio-Pod
“MIC ON” button. Adjust the “MIC GAIN” control counter-clockwise (less
gain) for the proper VU indication on your console. Use the trimpot tool
provided for this adjustment. Note that the “MIC GAIN” control is very
sensitive to adjustment at the most clockwise end of its range.
C. IMPORTANT: Due to the large amount of gain in the Mic pre-amp section
it is possible to overpower the FET Mic On-Off switching circuit if the “MIC
GAIN” control is set for excessive gain. To assure that you have not
exceeded the capabilities of the switch, press the “MIC OFF” switch and
speak loudly into the microphone. If modulation peaks cause an output
you have the gain set too high and it should be reduced accordingly.
Microphone section with NO microphone pre-amplifier option:
There is no user setup required. External phantom power may be supplied to
the “MIC OUT” connector or terminals from the users console or mixing board
for powering condenser or electret microphones used with the Audio-Pod
Headphone Section:
1. Select the type of headset desired and insert the jack into the appropriate
“Phones” receptacle. Select “LOW” impedance for headphones below 60 ohms
and select “HI” impedance for headphones above 60 ohms. The rear panel
“PHONES MAX GAIN SET” is factory pre-set to maximum and must be
adjusted to the users desired maximum level.
2. To reset the maximum headset level, have the headset audio input source
active, adjust the front panel “GAIN” control to maximum, and using the trimpot
adjusting tool, set the rear panel “PHONES MAX GAIN SET” to the maximum
level that you feel is safe for the user. This feature is included to protect the
user from possible damaging volume levels to their hearing which may lead to
possible litigation in the future.
WARNING: Listening to earphones too loudly may cause hearing loss. To prevent
hearing loss, adjust the volume to comfortable levels and avoid prolonged use.
The Audio-Pod front panel control functions are as follows:
MIC ON (COUGH): Turns on the microphone function and displays a brighter switch
illumination on the active button. Depressing and holding this button while in the
“ON” position will mute the microphone output.
MIC OFF: Turns off the microphone function.
GAIN: Sets the headset gain and is adjusted by the user to a comfortable volume
PHONE JACKS: Both ¼” and 3.5mm stereo headphone jacks are supplied. The
jacks are connected in parallel and employ ESD protection from static build-up on an
earphone plug that is being connected.
The Audio-Pod rear panel control adjustments are as follows: (refer to Fig. 1)
Z (impedance switch): Depressed for high impedance headsets (>60 ohms) and left
in the outermost position for low impedance headsets (8-60 ohms).
PHASE: Depressed for 180° phase shift in the headphone output to correct for pone
conduction issues that may arise, and left in the outermost position for 0° phase
PHONES MAX GAIN SET: Factory pre-set to maximum and must be adjusted to
the users desired maximum level. (Refer to headphone section setup instructions on
page 4.)
All other rear panel connections and functions are discussed in the INSTALLATION
section starting on page 3.
Warranty Information:
The DM Engineering Audio-Pod system is warranted for a period of one year from the
date of purchase. This warranty covers materials and workmanship only. Any
misapplication, physical or electrical damage from outside sources or by the customer is
not covered. For factory warranty repairs, the customer must pay shipping costs to the
factory, and DME will pay standard ground transportation shipping costs to return the
warranted equipment to the customer. “Loaner” units, if available, will have shipping
paid both ways by the customer, and must be returned within 20 days after return
shipment of the repaired unit. Failure to do so will result in billing to the customer for the
full retail amount. Any priority shipping costs are to be the responsibility of the customer
as ground service is standard. Please contact the factory for an RMA number prior to
any returns. Items returned without an RMA may be sent back to the customer
Technical Support
If you have questions, experience difficulties with the product or require further
information please contact DME at: 805-987-7881, toll free 800-249-0487, or E-mail
technical support at:, or visit
for the latest User Guide.
Case dimensions: Audio-Pod module and Power Supply: 5.09" W X 5.95" L X 2.2" H
Case material and color: ABS flame retardant plastic, black
Power supply to Audio-Pod DC power connection method: 8 pin mini-din connector
AC input operating voltage: 105-125 VAC
Solid State Relay drive output voltage: 5VDC current limited by 330 ohms
Microphone buttons: Silent long life reed type with differential LED illumination
Microphone input impedance: 150-250Ω
Microphone pre-amplifier output impedance: 600Ω (balanced)
Microphone user gain adjustment: > 43dBm (overall gain=58dBm)
Microphone pre-amplifier maximum output level: +20dBu
Headphone gain control circuitry: VCA (voltage controlled amplifier)
Headphone amplifier input level: Stereo L & R, -20dBu to +4dBu
Headphone amplifier input impedance: 10KΩ
Headphone output: (ESD protected) Low Z; 8-60Ω (160MW per channel), Hi Z; 60400Ω (22VP-P max per channel). THD <.5%
Power supply AC cord length: approx. 6 ft. total
Power interface cables: 10 ft. 8 pin mini-din M-M
Mounting method: Power supply and Audio-Pod modules are supplied with rubber feet.
Screws for “key hole” type mounting of the power supply and hook & loop fastener
material (Velcro) for more secure desk top mounting of the Audio-Pod modules is
supplied. Desk-top mounting brackets for mounting the module at an angle and
flush mounting bezels for recessed module mounting are available.
Operating temperature: 32 to 110F
Humidity: 0 to 95% non-condensing