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



Standard Speed Model CR-1

Slow Speed Model CR-4

This condensed conference recorder manual does not include all drawings and schematics that are in the manual supplied with each recorder.

Omnicron CR-1 and CR-4 recorders are designed to provide excellent recordings of meetings and conferences with the PZ-2L microphone. They are also useful for many security and surveillance applications. If you ordered the CR-1PZ recorder and microphone package, your recorder was shipped with one of the Omnicron PZ-2L conference microphone.

Conventional microphones are hindered by interference between sound coming directly from the source and reflected sounds. The PZ-2L design minimizes this interference by using sound waves, which reinforce themselves near a flat surface, to achieve amazing sound reproduction from distant audio sources. A low noise amplifier is built into the PZ-2L microphone housing. It provides a high level output that permits long cable runs and maintains the high signal to noise ratio. Follow the instructions provided with the PZ-2L microphone for its installation and operation.

The CR recorders has both a fast response automatic level control circuit and manual record level control. With the recorder and PZ-2L microphone, the resulting recordings are vastly superior to recordings made with standard microphones and consumer recorders. The recorders use standard audio cassette tapes. The CR-1 records at the standard 1-7/8 ips (inches per second) cassette speed. the CR-4 records and plays at a slower 15/32 ips (1/4) speed. Tapes recorded at the standard 1-7/8 ips speed can also be played back on any standard speed cassette player. Tapes recorded at the slower speed provide four times the record time per tape, four hours per side on an MLC-120 tape.

Tapes recorded in the CR-4 at the slow speed must be played back either in the recorder that made the recording, or another unit that plays at 1/4 speed. You will not be able to understand tapes recorded at 1/4 speed if you play them in a standard speed cassette tape player. Other features of both recorders include an end-of-tape alarm, review and cue capability, digital tape counter, and the ability to monitor external audio sources in all modes

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1.  Volume control — Adjusts sound level of tapes being played. Controls the record level when recording.

2.  Tone control — To adjust tone on playback.

3.  Condenser microphone — Built-in to allow convenient recording.

4.  Tape counter and reset button — Provides method for indexing tape selections and locating parts of tape when desired. Button resets counter to "000". Conforms to 2X ANSI standards.

5.  Alarm switch — Enables or disables a beep tone to indicate when the tape is at its end, or that the recorder has been left in the off mode.

6.  LED record level indicator — A red light emitting diode shows audio strength when recording.

7.  Carrying handle — Pulls out for easy and safe carrying. Slides back into unit when not in use.

8.  AC line cord storage — Located in bottom of unit. Holds AC cord when unit is being operated on batteries.

9.  Raised symbol keyboard — Provides added assistance to the visually handicapped. Symbols used are those approved by the Library of Congress.

10.  Record key — Switches recorder into record mode when depressed simultaneously with Play key. NOTE: The cassette must have "knock-out" tabs intact to permit Record key to be pressed down.

11.  Play key — Turns on the unit and starts the tape transport in motion for playing and, when used simultaneously with the Record key, for recording.

12.  Review key — Pressing key while tape is playing permits quick back up of tape for reviewing a previously played portion. When other keys are not depressed, this key locks down and rapidly rewinds tape back to the start.

13.  Cue key — Pressing this key while the tape is playing permits quick forward movement of the tape to a different selection. This key also locks down for fast forward when other keys are not depressed.

14.  Stop/Eject key — When other keys are depressed (except Pause key), this key acts as a Stop key and returns the other keys to up positions. When keys are up, pressing this key opens cassette chamber cover and ejects cassette.

15.  Pause key — When depressed, this key stops the tape transport instantly if Play or Play and Record keys are down.

16.  Cassette chamber — Holds tape cassette during playing and recording. Pop-up cover allows easy loading and unloading.

17.  Built-in speaker — Provides excellent sound reproduction. Is muted automatically when the External Speaker Jack is used in record or either Headphone Jack is used in record or play.

18.  PZ-2L Microphone jack — Provides connection for special PZ-2L microphone. Supplies power to its amplifier and connects its audio to the recorder.

19.  Headphone jacks — Two jacks are provided for private listening during playback and record.

20.  Auxiliary input jack — (AUX) With an accessory connecting cord, this jack allows recording directly from another recorder or radio.

21.  External speaker jack — For using a speaker at a location away from the cassette player/recorder. Built-in speaker is disconnected automatically when external speaker is used in record.

22.  Microphone/remote jacks —(MIC and REM) Provide connections for dual-plug standard microphones. Remote jack provides connection for the microphone on/off switch and also is used for accessory remote switch devices.

23.  Monitor switch — When the switch is ON in the record mode, you will hear the sound being recorded through the recorders built-in speaker.  The monitor circuit can be used at all times. You do not have to be in record or play to monitor the audio source. In playback, the audio source will mix with the sound from the tape you are playing. To prevent feedback, do not switch the monitor ON when using a microphone that is located close to the recorder.

24.  N/A

25.  Battery compartment — Located on the bottom of the recorder. Use six C size batteries for portable operation. Batteries are not required for AC operation.


The recorder uses standard 120-volt 50/60 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.

Six C-size batteries can also power the recorder. To install batteries, remove the lid of the battery compartment that is located on the bottom of your recorder. Insert the cells to match the polarity of the "+" and "-" signs shown in the battery compartment. After installing the batteries, replace the battery compartment lid.

Incorrectly inserted batteries will not work and could cause damage to the batteries and the recorder. Batteries are not required for operation on AC power. Batteries should be removed if the recorder is not to be used for an extended period of time.

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. 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.


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.

Your recorder has three external audio input jacks. One is for the special Omnicron "PZ-2L" room monitoring microphone, one is for a standard microphone (MIC), and one is for an auxiliary input source (AUX). If required, you can use the special "PZ-2L" jack and either the "MIC" jack or "AUX" jack simultaneously. This permits you to mix signals from more than one source. Audio cassettes have two sides. You can record on both sides of audio cassette tapes.

You can use either the built-in microphone, the PZ-2L microphone, a standard external microphone, or an auxiliary audio source. The built-in microphone will be automatically turned off when you use an external audio source. You must depress both the RECORD and the PLAY keys for the recorder to be in the RECORD mode.

When recording, the volume control is used to adjust the record level. You may increase the record level and make weak sounds louder by setting this control to a higher position. If you set the control too high, your recordings could be distorted, and the recorder will boost back-ground noise excessively. Adjust it up or down as required for the best sound quality.

To set the level correctly, watch the recording level indicator light. When you are recording, set the record level adjustment only as high as required to cause the light to flicker. If the light stays lit, the recording level is too high. If the light does not flicker during audio peaks, record volume is too low. Experiment by making test recordings to determine the best setting to match your application. Too high a setting will increase the amount of background noise picked up when no one is speaking.

This recorder is also equipped with Automatic Level Control circuitry that helps to prevent overload by strong audio levels. If the recorder receives a sound which is much too loud to be properly recorded, the ALC circuit will automatically decrease the record level to prevent distortion. After the sound level re-turns to normal, the record level will automatically return to the record level set by the Volume Control.

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 until you either depress the pause or stop keys, or it reaches the end of the tape.

The volume control is used to set the record level. If it is set too low there will be no audio or weak audio on the tape. If it is set too high, the recordings could be distorted or have excessive background noise.

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.

The Omnicron PZ-2L microphone will work only if it is plugged into the jack on the side of your recorder labeled "PZ-2L MIC-IN". This jack connects to circuitry in the recorder that provides power for the microphones built-in amplifier and connects its output to the recorders amplifier.

When you use an external audio source, the built-in microphone is automatically turned-off. Operate the recorder as described for built-in microphone recording.

The PZ-2L is designed to look like a switch, not a microphone, so as not to draw attention. It uses a miniature microphone capsule mounted near a sound reflecting plate or boundary, in what is called the pressure zone. In this zone, direct sound from the audio source combines with the reflected sound off of the boundary. The benefits are many: 6 dB more sensitivity, 6 dB less noise, a wide smooth frequency response free of phase interference, excellent clarity and consistent pickup from anywhere around the microphone.

In the PZ-2L, low frequencies below the voice range are rolled off to reduce rumble from trucks, machinery, and air conditioning. Because of its tailored response, it will pick up conversations with extra clarity. The box on the back of the microphone can be easily removed for custom installation in the ceiling or wall using a standard electrical outlet box. It can also be used without a box since its built-in line level amplifier is shielded in a metal housing.

The PZ-2L output is at a high level and is low impedance. This allows longer cable runs without excessive hum pickup or high-frequency loss.

Microphone placement is important to producing high quality recordings. To monitor an entire room, the PZ-2L should be placed in a central position in the room since it will pick up sound from all directions. To maximize the main speaker’s table and minimize background audience noise, the microphone should be placed on the speaker’s podium or table. By experimenting with different positions, you might find a spot, which will produce significantly improved recordings.

You can also use a suitable standard microphone such as the Omnicron RMC-8. Plug the microphone into the "MIC" and "REM" jacks on the side of the recorder. The large jack (MIC) is the standard microphone audio input 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 power switch circuit (REM). When the remote jack is used, the tape will not move unless the remote switching circuit is on. Operate the recorder as described in the instructions for built-in micro-phone recording.

Your recorder receives audio either by placing a microphone near the audio source, or by connecting directly to the speaker or audio output of the source you wish to record.

Most telephone and some two-way radio installations require the use of an interface coupler (such as the TSA-3, TSA-3S, LIC-390,  LIC-39M, LIC-100, or LIC-10M) between the recorder and the audio circuit. The couplers provide isolation, balanced line input, and help prevent noise on telephone circuits 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, and you could damage the recorder.

Accessory patch cords are available, such as the Omnicron AUX-6S, for use if you are going to connect the recorder to your audio source without a coupler. The AUX-6S 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 cables can be special ordered to match your specific application.

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.

If you are playing a cassette that was recorded with the recorders speed selection switch set at the slow speed and your recorder is set for standard speed play and record, it will play with a very high pitched sound and you will not understand the recorded voices.

You use the TONE control to either "cut" or "boost" high frequency response when the recorder is in the play mode. Adjust the TONE control for the best sound quality when you are playing tapes.

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 pres-sure on the key, the recorder will return to the play mode. If you de-press the CUE key when the recorder is not in the play mode, the key will lock down and the tape will run for-ward at high speed until you press the STOP key. If the recorder reaches the end of tape, it will automatically shut off after a few seconds. 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 a se-lection that you have just played, depress the REVIEW key. The recorder will rewind the tape. Removing pressure on the key will allow the unit to return to the play mode.

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 pause key is used to instantly stop the tape transport without releasing the play or play and record keys. Push this key once to stop the tape movement; push it again to restart the tape.

The pause key is especially useful when recording since it instantly stops the tape without turning the amplifier or motor off. To prevent unnecessary motor wear, do not leave the pause key down for excessive periods.

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.

CR-1 and CR-4 recorders have monitor circuitry that permits you to listen to external audio sources through the built-in speaker, an external speaker, or headphones. This feature can be used at all times. You do not have to be in play or record to listen your audio source. To prevent feedback, do not switch the monitor feature on when using the built-in microphone or an external microphone that is located close to the recorder.

The MONITOR switch is located on top of the recorder between the built-in Microphone and the tape counter. Slide this switch to the right, to turn the MONITOR function ON, or to the left to turn the MONITOR function OFF.

There are three ways to use the MONITOR function:

1. When RECORDING, switch the MONITOR to the ON position and you will hear what is being recorded through the unit’s built-in speaker. You can also use a speaker plugged into the external speaker jack or headphone sets plugged into the headphone jacks to monitor your audio source. Since the volume control determines both the record level and the monitor level, it should be left at the proper setting for recording.

2. If the MONITOR switch is ON during playback, the audio will blend with the sound from the tape at approximately the same volume.

3. If the MONITOR switch is ON when ALL FUNCTION KEYS ARE UP, you will still be able to monitor the audio even though you are not recording or playing a tape.

Always keep the microphone and speaker apart, or a feedback squeal or howling sound will occur. Turning the volume down will reduce the feedback sound. If you are recording, this will also reduce the recording level. For the highest quality recordings, leave the monitor off if there is feedback with the monitor switch in the on position.

Play tapes through an accessory speaker by connecting the cord from the speaker to the External Speaker Jack that is located on the top of your recorder. You will find that the sound is further improved when a larger speaker is used.

Do not connect an external loud-speaker that is located close to the microphone while recording or a howling or whistling sound could spoil your recording.

Located on the top of the unit are two standard inch monaural headphone jacks. Headphone sets such as the Omnicron MHP-735 may be plugged into these jacks.

You can listen in privacy or monitor your recordings by connecting accessory headphones to the headphone jacks. When you play back a tape with one or two headphones plugged into the headphone jacks, the built-in speaker is automatically turned off.

When you record with headphones connected, you are able to hear your recordings as they are being made. This permits fully active monitoring of the recording.

NOTE: When using more than one headphone, be sure that all headphones are of the same impedance so that they will all reproduce at the same volume level. CAUTION:

To prevent the over driving of your headphones, do not plug them into the external speaker jack.

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

Recorded tapes can be erased by running them through the unit in the record mode. Be sure to turn the Volume Control, which functions as the record level control when recording, all the way down. A bulk tape eraser, such as the Omnicron # 90624, is the fastest, easiest and best way to erase recorded cassette tapes. These are available from your dealer.

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 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 will not be able to de-press the RECORD key unless there is a cassette in the recorder that has an intact record interlock flap in the left rear of the cassette tape chamber. If you wish to protect only one side of the tape, break out only the flap on the left rear of the cassette when it is in position to play.

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 will reduce the reliability of the recorder and could result in weak or distorted sound.

To expose the heads and tape drive components for inspection, press the STOP/EJECT key to open the cassette door. With the door open, press the PLAY button to expose the parts. Look at the front of the cassette chamber and see if the black rubber pinch roller, silver capstan shaft (in front of the pinch roller), or record/play head (center front of the chamber) have excessive tape oxide build-up and require cleaning.

If there is sufficient visible foreign matter, use a cotton swab and a commercial tape head-cleaning agent to clean the heads and rollers. Follow the instructions on the cleaner container. After cleaning, push the STOP/ EJECT key to return the parts to their normal position. 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 record interlock tabs on the cassette are missing (preventing you from recording on the tape). 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. Batteries may leak and damage the recorder.

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


POWER: 120 VAC 50/60 Hz, 10 Watts, or six "C" cell batteries
DIMENSIONS: 7"W x 11"D x 2"H
      Microphone: 2 K ohm, -70 dB
      Auxiliary: 150 K ohm, -20 dB
      PZ-2L MIC: 1 K ohm, 0 dB, 9 VDC phantom power
SIGNAL TO NOISE RATIO: A-Weighted,1-7/8 ips: 42 dB, 15/32 ips: 38 dB.
      CR-1 is Standard speed: 1-7/8 ips
      CR-4 is One-quarter speed: 15/32 ips
      CR-1 is 1-7/8 ips: 125 Hz to 10 kHz
      CR-4 is 15/32 ips: 125 Hz to 6 kHz
CASSETTE TAPE SIZE: Standard Compact Audio
RECORD SYSTEM: Half-Track, AC bias.
      Using a MLC-120 tape, 1-7/8 ips: 1 hour per side, 15/32 ips: 4 hours per side
      Using a MLC-90 tape, 1-7/8 ips: 45 minutes per side, 15/32 ips: 3 hours per side
      Using a C-60 tape, 1-7/8 ips: 30 minutes per side, 15/32 ips: 2 hours per side

Each CR-1 and CR-4 recorders come with one MLC-120 cassette tape, attached AC power cord, owner’s manual, and a one-year limited warranty. Specifications are subject to change without notice.


This Omnicron product is warranted against defects in materials and workmanship for one year from date of purchase. 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:

554 Liberty Highway Unit 2
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

Omnicron Electronics also offers assistance via the Internet:

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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