Omnicron Electronics - Professional Voice Logging Recorders and Accessories - since 1975 
 Professional Voice Logging Recorders  and  Accessories


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Omnicron Electronics - Professional Voice Logging Recorders and Accessories - since 1975


(Click here for VLR Owners Manual in pdf format)

Standard speed models VLR-1 and VLR-1CT
One quarter speed models VLR-4 and VLR-4CT
One eighth speed models VLR-8 and VLR-8CT

Line Drawing of VLR Recorder with Call-outs

This condensed recorder manual does not include all drawings and schematics that are in the manual supplied with each recorder. Only version three VLR recorders with a serial number starting with a 3 are covered by this manual (e.g. S/N V-300000). If you have an older  VLR recorder with a S/N starting with either 1 or 2 (e.g. S/N K-100000 or P-200000), operation is essentially the same. However some controls and function keys will not be in the same location.


The Omnicron VLR recorder is a versatile solid-state unit featuring voice-activated recording. This feature permits you to record conversations without having to turn the recorder on and off manually. You can make recordings directly from the built-in microphone, or you can use an optional interface coupler or cable to connect the recorder to telephone or radio circuits. Other important features include an end-of-tape alarm, review and cue capability, digital tape counter, and monitor while recording. The VLR-4 and VLR-8 recorders include slow speed drive circuitry. The VLR-4 provides up to four hours of recording time on each side of a tape. The VLR-8 provides up to 8 hours per side. Automatic level control recording assures the best performance with reduced back-ground noise and distortion. A second recording channel for use with the Omnicron Talking Clock can be found on models VLR-1CT, VLR-4CT, and VLR-8CT. The clock provides documentation of the time and date each recording takes place.

When you reach the end of tape in either play, record, fast-forward, or fast-rewind, the function keys will pop up turning the power off. If the End-Of-Tape Alarm switch is ON, the recorder will emit a continuous beep tone from its speaker whenever all function keys (Play, Review, and Cue) are up.



The recorder uses standard 120-volt 60 Hz AC power. On the bottom of your recorder you will find the AC power cord storage compartment. Remove the cord and plug it into an AC outlet.

The recorder uses six C-size cells. To install batteries, remove the lid of the battery compartment which is on the bottom of the recorder. Insert the six batteries to match the polarity of the "+" and "-" symbols shown inside of the battery compartment. After the batteries are installed and seated correctly, replace the battery compartment lid.

Incorrectly inserted batteries will not work and could cause damage to the batteries and the recorder. The recorder will trickle charge rechargeable batteries and a built-in relay will automatically switch over to battery power whenever AC power is lost. Non rechargeable batteries should be removed prior to operating the recorder on AC power. Batteries are not required for operation on AC power.

Open the cover of the cassette compartment by depressing the STOP-EJECT key. Insert the cassette with the tape edge toward you and the full reel to the left. Now close the cover and the recorder is ready to operate.


You control all tape mechanism functions with the push buttons. The tape will stop, and power is off  when all buttons are up.

Depressing one of the PLAY, REVIEW (rewind), or CUE (fast-forward) buttons turns on the power and places the tape recorder into the selected mode. You can stop the tape by pushing the STOP-EJECT key. Depress this key again to eject the cassette. The recorder has an automatic power-off circuit. When you reach the end of tape, the buttons will pop-up and power will turn off. A tape COUNTER helps you quickly locate recorded material for playback. Depress the button next to the counter to reset the numerals to "000".

When recording, the tape drive motor will run only when audio is present at one of the recorder's audio input sources. You can use either the built-in microphone, an external microphone, or an auxiliary audio source. You will automatically turn off the built-in microphone when you use either the external microphone jack (MIC), or the auxiliary input jack (AUX). Audio fed into the CLOCK jack on recorders with the CT option goes directly to the time track on the recording head and will not start the recorder's voice activation circuit. You must depress both the RECORD and the PLAY keys for the recorder to be in the RECORD mode.

On the bottom of the recorder you will find the record level control. You may increase the record level and make weak sounds louder by turning this control clockwise. If you set the control too high, your recordings could be distorted and the recorder will boost background noise excessively. Line up the blade of a small screwdriver with the slot in the control. Adjust it up or down as required for the best sound quality. DO NOT FORCE THE CONTROL. To set the level correctly, watch the Record Level indicator light. When you are recording, set the record level adjustment only as high as required to cause the red light to come on during voice peaks. If the light does not flash during conversations, the record level is too low. If it is on continuously, the record level is too high.
Before inserting a cassette, take up any slack in the tape by inserting a pencil into the hub of the cassette and turning it a few times. Press the STOP/EJECT key to open the cassette door. Insert the cassette into the chamber with the exposed edge of the tape facing you and the full reel to your left. Close the door by pressing downward until it latches shut.

To remove a cassette, press the STOP/EJECT button once to stop the recorder. Press the button a second time to open the cassette door.

Insert a tape and simultaneously depress both the RECORD and PLAY keys. The tape will begin to move, and the machine will be recording. The recorder will continue to record as long as there is sufficient audio in the amplifier to trigger the voice-activation circuit. It stops after it is quiet for a few seconds and starts recording when you speak within a few feet of the microphone.

The volume control is inoperative in the record mode. The MONITOR function should be off (MONITOR key UP) to prevent feedback during microphone recording. To end the recording, depress the STOP/ EJECT key. Depress this key a second time to EJECT the cassette. If you reach the end of the tape while recording, the recorder will shut off and the PLAY and RECORD buttons will pop up.

Plug a suitable microphone (such as the OMNICRON RMC-8 or PZ-2LA) into the MIC or MIC and REM jacks on the left side of the recorder. The large jack (MIC) is the microphone circuit. It is also used to connect other low level audio sources to the recorder.

The small jack next to the MIC jack is the remote switch circuit (REM). When the remote jack is used, the tape will not move in the RECORD mode unless the external remote switching circuit is on. The voice activation circuit also must have sufficient audio to start the motor. Operate the recorder as described in the instructions for built-in microphone recording. Increase or decrease the record level as necessary.

Your recorder receives audio either by placing a microphone near the speaker of your audio source, or by connecting directly to the speaker or audio output of the device you wish to monitor. If possible, use a direct connection to prevent unnecessary noise pickup. A direct connection also will produce clearer recordings.

Most telephone and some two-way radio installations require the use of an interface coupler or adapter (such as the TSA-3, LIC-390, or LIC-100) between the recorder and the audio circuit. Couplers provide isolation and a balanced line input. They also help to prevent the noise on telephone lines from reaching the recorder between conversations. Check with your Omnicron dealer or telephone company to see if you require a coupler for your application. Do not connect the recorder directly to telephone lines without a coupler. Improper operation of both your recorder and the telephone circuit could result. The recorder could also be damaged.

An accessory patch cord is available (AUX-6S) for use if you will be connecting the recorder to your audio source without a coupler. It has a miniature phone plug on one end to match the auxiliary audio input jack on the recorder (AUX) and spade lugs on the other end. It is six feet long. You can shorten or lengthen it if necessary. The spade lugs can be changed, if required, to match the audio connections on your signal source (two-way radio, tone alert receiver, scanner, tape recorder, pocket pager, etc.). The cable may be special ordered to match your specific application.

If the recorder does not record weak conversations properly after adjusting the RECORD LEVEL, you can adjust the recorder so it will be more sensitive and start recording with weaker sound levels by turning the ACTIVATE SENSITIVITY control clockwise. You will find this screw driver adjustment on the bottom of the recorder. You can also adjust this control to make the recorder less sensitive if it runs with noise that is weaker than the normal conversation level. To make the voice activation less sensitive, turn the control counter-clockwise with a small screwdriver.

Adjusting the ACTIVATE SENSITIVITY control too far in the clockwise direction can turn off the voice activation circuit. This will cause the unit to run continuously when it is in the record mode. Adjusting the control too far in the counter-clockwise direction will cause the recorder to remain stopped in the record mode even if there are loud sounds in the amplifier. DO NOT FORCE THE CONTROL.

Since the sensitivity of the voice activation circuit is also affected by the setting of the record level adjustment, you should adjust the record level for best sound quality. Then adjust the ACTIVATE SENSITIVITY if necessary to insure that the recorder does not run when it should be stopped, or if it stops when it should be recording.

You can adjust the length of time between the end of a conversation and the moment when the recorder stops with the TURN-OFF-DELAY control. This screw driver adjustment is on the bottom of the recorder. Adjust this control by inserting a small screwdriver in the hole indicated. If the recorder turns off too quickly during pauses, turn the control clockwise to increase the turn-off-delay.

If the recorder runs too long after a conversation is over, adjust the control counter-clockwise to decrease the turn-off-delay. When you are recording room conversations, it is advisable to set this control for a long turn-off-delay. This will help to prevent the recorder from stopping during low level conversations. DO NOT FORCE THE CONTROL.

Insert a recorded cassette with the full reel to the left and the side you wish to play up. If the cassette you are playing was just recorded and is still in the recorder, rewind it to the beginning of the recording. Press the PLAY key. Then set the volume for the desired listening level from the speaker. To end the playback, press the STOP/EJECT key. Depress this key a second time to eject the cassette.

You can use the TONE control to limit the frequency response when the recorder is in the play mode. With this control set to the low position, it will cut down on the level of high frequency sounds. Turning it to a higher position produces more high frequency sounds. Adjust the TONE control for best sound quality.

The monitor circuit lets you listen to conversations while you are recording. To activate the monitor function, depress the MONITOR key. Depress this key a second time to turn off the monitor feature. Feedback or an echo could pre-vent you from using this feature if your sound source is a microphone in the same room as the recorder.

During playback, you use the VOLUME control to adjust for a comfortable listening level. The VOLUME control has no effect while recording. You can also connect an external speaker to the recorder's speaker jack. Two headphone jacks are also available for private listening. When you use either headphone jack, the built-in speaker will be disconnected.

The end-of-tape alarm switch is also located behind a hole on the bottom of your recorder. When this switch is in the ON position, a beep tone will automatically start whenever all function keys are up. It will also beep if you do not place the unit back into the auto-record mode after reviewing a recording. To deactivate the alarm, use a small screwdriver to place the switch into the OFF position. DO NOT FORCE THE SWITCH.

The CUE (fast-forward) key is a dual function key. When you depress this key while the unit is in the play mode, the tape will run forward at high speed. When you remove pressure on the key, the recorder will return to the play mode. If you depress the CUE key when the recorder is not in the play mode, the key will lock down and the tape will run forward at high speed until it reaches the end of tape, or you press the STOP key. To prevent possible tape damage, you should always depress the STOP key after locked in fast winding prior to going into the PLAY, RECORD, or REWIND modes.

The REVIEW (rewind) key is also a dual function key. To repeat something that was just played, depress the REVIEW key. The recorder will rewind the tape. Removing pressure from the key will return the recorder to playback.If you depress the REVIEW key when the recorder is off, the key will lock down, and the tape will rewind until either you press the STOP/EJECT key or you reach the beginning of the tape.

The tape counter is helpful in finding certain portions of the tape or in determining how much tape you have left. You can set it to "000" at any time by depressing the small button to the right of the counter.

On recorders that do not have the CT option (Clock Track) there is a switch to turn off the Automatic Level Control. You should normally set this switch to the ON position. If you set it to the OFF position, the internal ALC circuit will be off and the recorder will not automatically adjust for sounds that are too loud. Use the record level adjustment on the bottom of the recorder to set the recording level.

When the ALC switch is on, you must still turn the record level up if the sound is too weak and the record level light does not flash while recording. The ALC circuit will prevent sounds that are too loud from over driving the recorder. On recorders with the Clock Track option, this switch is used to select the time track during playback.

On recorders that have the CT Clock Track option (VLR-1CT, VLR-4CT, or VLR-8CT), there is a jack on the side for connecting to a talking clock and a switch on top for selecting either conversation (VOICE), or time and date (TIME) playback.

Connect the audio from the clock (Omnicron TCC-14 or equivalent) to the CLOCK jack on the recorder and adjust the clock's output level following the instructions supplied with the clock. When you have the clock properly connected to the recorder, the time and date announcements from the clock will be recorded on the time track whenever you are recording. When you play back the tapes, you must switch the PLAYBACK switch to the TIME position to listen to recorded time announcements. If you did not have the clock connected to the recorder when you made the recording, no time announcements will be on the time track. It will be silent.

When recording, you will erase the previous recording on the tape and replace it with the new recording. Only the sections of the tape where you made new recordings will be erased. Your old recordings will remain on the other sections.

Every time you make a recording, you will erase previously recorded portions of the tape. To prevent you from accidentally erasing recordings, the cassette and the recorder have interlock devices. On the back of each cassette are two little flaps. If you want to be sure that the recorder will not erase a previously recorded tape, break out these flaps with a small screwdriver or key. You cannot depress the RECORD key unless there is a cassette in place that has an intact record interlock flap.

With use, the record/playback head, erase head, capstan, and rubber pinch roller in your recorder will gather dirt and material transferred from the tapes as they pass through. This could reduce the reliability of the recorder and result in weak or distorted sound.

To expose the heads and tape drive components for cleaning, press the STOP/EJECT key to open the cassette door. If there is a tape in the unit, remove the tape. With the door open, press the PLAY button to expose the parts that need cleaning.

Use a cotton swab and a commercial tape head cleaning agent to clean the heads and rollers. Follow the instructions on the cleaner container. DO NOT try to install a cassette with the heads in the forward position. If the recordings are still distorted or weak after cleaning, you could have a badly worn or damaged head that will require replacement.

You can clean the cabinet with a soft cloth. If necessary, dampen the cloth with water. Never use polish, solvents, abrasives, or strong detergents since these can damage the finish.The recorder is designed to be trouble free in normal use. If problems do occur, contact a qualified service technician or call Omnicron Electronics for help.

DO NOT push the RECORD button if you do not have a cassette in the recorder, or if the knockout tabs on the cassette are missing. DO NOT use excessive pressure on the function keys or adjustments.

DO NOT touch the recording head with metal or magnetic objects such as a screwdriver. Remove all batteries if the recorder is not in use for an extended period. Leaking batteries could damage the recorder.

Remove the AC line cord from the wall outlet if you are not going to use the recorder for an extended period.

1. If the recorder does not play back your messages properly, check to see that the following switches are in the correct position: PLAYBACK switch (recorders with CT option only) should be in the VOICE position to hear recorded conversations. Switch to the TIME position to hear recorded time announcements. The TIME TRACK will be silent if you did not have a talking clock connected to the recorder when you made the recording.

The MONITOR key should be up if you do not wish to listen to what you are recording when you are recording. If the MONITOR key is down when recording from a microphone that is within a few feet of the recorder, there will be a feedback squeal or echo. If the speaker squeals in record, turn the MONITOR switch OFF.

The VOLUME control should be turned to a point between "MAX" and "MIN" during playback. If it is all the way down at the minimum position, there will be no sound. If it is all of the way up to the maximum position, it could be too loud or distorted.

2. If the sound gets weak or muffled after many hours of use, check to see that the record/playback head is not dirty or badly worn. Clean or replace as necessary.Recorded tapes must be played at the same speed at which that they were recorded. You can play tapes recorded on the standard speed VLR-1 recorder in standard cassette players. You must play tapes recorded with the 1/4 speed VLR-4 recorder or 1/8 speed VLR-8 recorder either on the recorder that made the tape, or a recorder that runs at the same speed as the recorder that made the tape.

3. The recorder has calibration controls that allow you to adjust the unit for your particular installation. Check your manual for a more detailed explanation of the calibration procedure. All adjustments are normally set to mid range at the factory. After adjusting the RECORD LEVEL control to its optimum position, the other controls normally do not need to be adjusted.

Weak audio - increase RECORD LEVEL adjustment.

Audio too loud or distorted - decrease RECORD LEVEL adjustment.

Stops during weak conversations - increase ACTIVATE SENSITIVITY.

Runs with no conversation present - decrease ACTIVATE SENSITIVITY.

Turns off too quickly during pauses - increase TURN-OFF-DELAY.

Runs too long after a conversation ends - decrease TURN-OFF-DELAY.

4. Do not connect the recorder directly to a telephone line. You must use an interface coupler between the recorder and the phone line. The type of coupler and its installation will vary depending on your phone system and the type of recording you will be doing. Consult your Omnicron Electronics representative for help as required.


POWER: 120 VAC 50/60 Hz, 10 watts, six "C" cell batteries, or optional battery pack (RBC-6)
SIZE: 7-3/4"L x 11-1/2"W x 2-3/4"H, 4-1/2 lbs.
INPUTS: Microphone - 2 k ohms -70dB, Auxiliary - 200 k ohms -20 dB, Clock - 600 ohms -10 dB
SIGNAL TO NOISE RATIO (A-weighted): VLR-1 = 50 dB, VLR-4 = 42 dB, VLR-8 = 34 dB
TAPE SPEED: VLR-1 = 1-7/8 I.P.S., VLR-4 = 15/32 I.P.S., VLR-8 = 15/64 I.P.S.
FREQUENCY RESPONSE: VLR-1 = 125 Hz to 10 kHz, VLR-4 = 125 Hz to 6 kHz, VLR-8 = 125 Hz to 3 kHz
RECORD SYSTEM: Half Track (1/4 track with "CT" option), AC bias
           VLR-1 = 1 hour per side (MLC-120) at 1-7/8 I.P.S.
        VLR-4 = 4 hours per side (MLC-120) at 15/32 I.P.S.
        VLR-8 = 8 hours per side (MLC-120) at 15/64 I.P.S.
WARRANTY: Limited, 1 year parts and labor



Model # VLR-1  is for standard speed recording without the TCC-14 Time/Date source.
Model #
VLR-1CT  is for standard speed recording with the TCC-14 Time/Date source.
Model #
VLR-4  is for 1/4 speed recording without the TCC-14 Time/Date source.
Model #
VLR-4CT  is for 1/4 speed recording with the TCC-14 Time/Date source.
Model #
VLR-8  is for 1/8 speed recording without the TCC-14 Time/Date source.
Model #
VLR-8CT  is for 1/8 speed recording with the TCC-14 Time/Date source.

Each recorder comes with an MLC-120 cassette tape, attached AC power cord with built-in storage case, owner’s manual, and a limited one year warranty. All records will also play back their tapes. Specifications are subject to change without notice.

This Omnicron product is warranted against defects in materials and workmanship for one year from the date of shipment. Omnicron will, at its option, repair or replace products that prove to be defective during the warranty period provided they are returned to Omnicron Electronics. Repairs necessitated by misuse, accident, improper installation, unauthorized modifications, or use in violation of the operating instructions, are not covered by the factory warranty, nor are cases where the serial number has been removed, defaced, or changed.

No other warranties are expressed or implied, including but not limited to the implied warranties of merchantability and fitness for a particular purpose. Omnicron Electronics is not liable for consequential damages.

Should your recorder become defective within the warranty period, we will repair it without charge. Should it require service that is not covered by the warranty, Omnicron will repair it for a nominal service charge plus the cost of parts and transportation.

If factory service is required, pack securely and forward by United Parcel Service (UPS) or insured parcel post to:

OMNICRON ELECTRONICS, 581 Liberty Highway,
P.O. Box 623, Putnam, CT 06260-0623

Enclose a note explaining what is wrong. Include your name, address, and telephone number. Omnicron Electronics also offers telephone help:

VOICE: (860) 928-0377      FAX: (860) 928-6477
Electronic mail:     WEB Site:      WEB Site:


                          Prevent costly mistakes - record all important phone and two-way radio conversations. Compact, economical recorders that document every word of your important conversations.     
                                   OMNICRON ELECTRONICS
                        554 Liberty Highway Unit 2, Putnam, CT  06260   

(860) 928-0377

(860) 928-6477

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