TN1019 - Instructions for Lectrosonics Headset Microphones

Phantom Power

These microphones use an electret type pickup that operates from 5 Volt “phantom power.” This is a DC voltage present on the input jack of Lectrosonics transmitters, and also on the input jack of various portable sound systems. This eliminates having to use a separate battery for the microphone and keeps the size and weight of the headset at a minimum, while preserving the excellent tone quality of the electret pickup element. Some portable PA systems do not have “phantom powered” inputs. The headset will not operate with these units without a special adapter. Call the factory for details on older models or for information regarding which Lectrosonics products are compatible.

hdset2The Volume Control 

An integral volume control built into the headset provides control over feedback when the headset is used with high output PA systems. It is very important to set this control at maximum before making adjustments to either the wireless system or setting the volume of the sound system.

Follow these steps in the order shown:

  1. Rotate the white control knob on the headset fully clockwise to set it at maximum.
  2. Adjust the gain of your wireless transmitter if you are using a wireless system.
  3. Adjust the volume of your sound system.

This volume control is really an attenuator, or “reducer” of the volume. It should not be used in the same manner as the regular volume control. Most of the time the control should be left in the maximum position. Set it at maximum to start out, and then use it only to temporarily reduce the volume of your sound system to control feedback.

Wearing the headset

The headset is designed to be worn over the head, but can also be worn around the neck. Adjust the headband for a comfortable fit with the mic tube to the left side of your head. The microphone pickup element should be just to the side of your mouth. Do not position the pickup directly in front of your mouth as this may cause noise from breath pops as you speak.

It is possible to rotate the mic tube such that the connecting wires inside can become twisted and may even break. The mic tube has been designed to allow for normal use and movement, however, if the tube is continuously rotated the wires will eventually break.


The headsets are available with either a locking micro plug or a standard mini plug for use with any Lectrosonics wireless system or portable PA system.

Locking Micro Plug

To attach the locking micro plug, insert it into the jack and then rotate it clockwise. Do not over-tighten. Rotate it counter-clockwise to release it before pulling it out of the jack.

Standard Mini Plug

The standard mini plug is simply inserted into the jack on either the wireless transmitter, or into the jack on the portable PA system.


TN1018 - Battery Box Polarity Protection Installation

This Tech Note explains how to install the polarity protectors into the UCR210D battery box. This should be done on all units up to serial number 1145. Units numbered 1146 and up already have these installed.

Tools Needed:

  • Phillips head screwdriver size 00
  • Phillips head screwdriver size 0
  • Small needle nose pliers

Figure 1

Kit number BP210AABATTKIT consists of two metal and plastic inserts and three screws. (Dime not included)


TN1018-fig2Installing the Polarity Protection Devices

1. Remove the battery box from the receiver

2. Remove the three Phillips-head screws which hold the latch and spring mechanism to the battery box housing. See Figure 2. Don't remove any other screws.

3. Remove the end-cap assembly from the housing (See Figure 3).

4. Using needle-nose pliers, press a polarity protector into the end of one of the springs (See Figure 4). It will snap into place lightly. Pinch all the way around the edge with the pliers to be sure it is firmly in place.

5. Repeat step 4 using the second polarity protector and the other spring

6. Insert the end-cap back into the housing. be sure to line up all three holes. Be sure the contact tines are visible from outside the housing after re-assembly as shown in Figure 5.

7. Replace the three original screws with the new ones provided in the kit. Tighten firmly but do not over-tighten as the small screws may be damaged.



TN1017 - IFB R1 Audio Jack Replacement

Contents of Preassembled Kit


CAUTION: Installation of this kit should be performed by a qualified technician. Malfunctions or damage as a result of improper installation of this kit are not covered by warranty.

1. Remove the receiver from the enclosure.
Remove the 2 black Phillips screws on the enclosure side nearest the front panel (Fig. 1) and carefully slide the receiver out of the enclosure. (Fig. 2)


2. Remove the knob.

Using the small Allen wrench loosen the two knob setscrews (Fig.3), remove the knob being careful not to lose the spacer washer inside the knob hole (some knobs do not have the washer inside).


3. Remove the knob guard.

Unscrew and remove the knob guard and the domed Bellville washer under the guard. (Fig. 4)


4. Remove the front panel.

Remove 4 stainless Phillips head screws retaining the 2 PC boards to the front panel (Fig. 5 & 6). Separate the PC boards being careful not to bend the connecting pins. (Fig. 7)


5. Remove the obsolete jack.

Unsolder the obsolete phone jack from the RF PC board and remove solder from the holes using solder wick or a solder sucker. (Fig. 8)


6. Install the audio PC board to the new pre-assembled front panel.

Use 2 stainless Phillips head screws to assemble the “L” shaped audio board to the front panel. (Fig. 9)


7. Install the RF board.

Dress the three jack leads vertical from the connector spacer insulator and feed each lead into it’s respective hole in the RF PC board. Mate the connector pins into the audio board connector strips, and install 2 stainless Phillips screws to attach the RF PC board to the panel. (Fig. 10)


8. Solder the leads.

Dress and pull on the stereo jack leads to remove excess wire loops between the jack and the PC board, solder and trim the leads. (Be careful not to damage the 3 tiny inductor coils in the same area on the PC board). (Fig. 11)


9. Install the knob/guard.

Place the domed Bellville washer over the knob shaft and bushing then screw on the knob guard, align the flats on the guard parallel with the length of the front panel, turn the shaft to the full CCW “OFF” position, place the tiny spacer washer inside the knob hole if it had one and put the knob on the shaft. Align the knob mark with the “OFF” position on the panel and tighten the exposed setscrew, rotate the knob and tighten the second setscrew. (Fig. 12)

Note: With the knob pushed in make sure the switch has a tactile “click” feel and that the knob does not bottom against the guard base. If it does, loosen both knob setscrews and readjust the knob slightly higher on the shaft then retighten.


10. Install the receiver into the enclosure.

Carefully slide the unit into the case, open the battery door and with one finger move the battery partition to clear the contact assembly on the PC boards to allow the unit to slide all the way in. Install the 2 black Phillips head screws.


11. Test the receiver.

Using a T1 or T2 transmitter test the unit with a stereo headset and a mono headset placing the mono-stereo switch on the side of the unit in the respective position for each test. If audio is not present in one or more earphones accordingly then the jack wiring should be checked.



TN1016 - Transmitter Audio Gain vs Signal to Noise Ratio

The transmitter input gain is the single most important adjustment on any wireless mic system to insure an optimum signal to noise ratio.

The audio signal to noise ratio will never be any better than it is at the transmitter input. If the input signal is noisy at the transmitter, there is nothing else that can be done later to restore it to its original quality. The audio level is adjusted with the gain control on the transmitter, with some sort of level metering on either the transmitter or receiver.

txgainThe most difficult problem with properly adjusting the transmitter input gain involves duplicating the user's voice level in advance of the actual performance or use. Obviously, you need some sort of metering in order to correctly set the transmitter input gain. The metering must indicate the modulation level of the radio signal and also limiting in the transmitter. Pro Series Lectrosonics transmitters provide LED level metering for this purpose. Metering is also provided on the receivers, but often times the transmitter metering is easier to use, since the receiver may not be accessible or visible from the transmitter location during setup.

The following is an excerpt from the Lectrosonics UM195 Transmitter manual. Although the details may differ depending on what transmitter is being used, the general procedure is valid for most transmitters.

  1. Position the microphone in the location you will use in actual operation.
  2. While speaking or singing at the same voice level that will actually be used, observe the MOD LEVEL LEDs. Adjust the MIC LEVEL control knob until the LEDs begin to light. Start at a low setting where neither LED lights as you speak. Gradually, turn the gain up until one LED lights, then the other.
  3. The LEVEL (or -20) LED lights when the audio level is about 12dB below full modulation. The LIMIT (or 0dB) LED lights when the limiter begins to operate. There is over 40dB of limiting range without overload above the LIMIT LED, so it is normal that the LIMIT LED light up 5% to 10% of the time during use.
  4. Once the gain has been adjusted, the transmitter audio can be turned on to make sound system level adjustments. Set the power switch to the ON position and adjust the receiver and/or sound system level as required. Please note, there will be a delay between the moment the switch is thrown and the time when audio will actually pass through to the amplifier. This intentional delay eliminates turn on thumps, and is controlled by the pilot tone squelch control.


The MIC LEVEL control knob should not be used to control the volume of your sound system or recorder levels. This gain adjustment matches the transmitter gain with the user’s voice level and microphone positioning.

If the mic level is too high -- both LEDs will light frequently or stay lit. This condition may reduce the dynamic range of the audio signal.

If the mic level is too low -- neither LED will light, or the LEVEL LED will light dimly. This condition may cause hiss and noise in the audio.

The first LED turns on 12dB below full deviation. The limiting LED turns on at full deviation and indicates that the input shunt compressor is operating. The input limiter will handle peaks over 40dB above full modulation, regardless of the gain control setting. The limiter uses a true absolute value circuit to detect both positive and negative peaks. The attack time is 5 milliseconds and the release time is 200 milliseconds. Occasional limiting is desirable, indicating that the gain is correctly set and the transmitter is fully modulated for optimum signal to noise ratio.

Different voices will usually require different settings of the MIC LEVEL control, so check this adjustment as each new person uses the system. 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.


TN1013 - H Series Microphone Latch Assembly Wiring (SKHCONN/A9042)



The Lectrosonics SKHCONN service kit is provided to allow replacement of a damaged XLR connector in the head assembly of Lectrosonics H series plug-on transmitters.

Replacement of the XLR connector requires disassembly and reassembly of the head assembly. A special holding fixture is required to perform these operations successfully.

Before attempting to install a new XLR connector, it is
recommended that a photograph or sketch be made of the old head/PC board assembly. This will allow the wires from the new XLR connector to be twisted, routed and soldered to the PC board exactly like the wires from the connector being replaced.

* Head assemblies for older transmitters have a black plastic molded wire clamp that holds the wires from the XLR connector in position. Later plug-on models do not have the wire clamp. These later models CANNOT be disassembled in the field.

Consult Lectrosonics Customer Service for instructions.


The blue wire from the old A9042 Mic Latch Assembly now connects to a solder lug on the new A9042 insulator block.