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SPECIFICATIONS AND SPECIAL FEATURES OF THE
JBR MICROCASSETTE PLAYBACK/TRANSCRIBER UNIT


Tape Format: 4-track stereo microcassette.
Number of Channels: Standard: Three compensated channels (Side A 1/4-track stereo plus Side B right channel backwards)
Optional: Four compensated & four uncompensated channels (Side A 1/4-track stereo plus Side B 1/4-track stereo backwards).
Playback Capability: Plays all microcassettes (1/4-track stereo and -track monaural).
Variable Speed:
  • Continuously variable (not discrete digital steps) from 0.63 cm/sec to over 7.2 cm/sec.
  • Three digit LED speed display to 1/100 cm/sec.
Number of Heads:
  • Two 1/4-track stereo play heads.
  • One head is located to play approximately 3/4" of virgin tape, the record head start transient, then the erase head transient and permits the measurement of the "warm-up" time of the electronics of the recorder used to make this recording.
  • Head azimuth is adjustable by operator.
  • Custom heads are available (see accessories).
Number & type of Motors:
  • Three direct drive motors. (No belts, gears, or pulleys to wear or generate vibration and noise).
Cross talk:
  • -60 dB (between left and right channels, 1 kHz @ -10 dB).
Speed Change BOT to EOT:
  • Less than 1/2% (less than 15 Hz change in the frequency of a 3 kHz tone from BOT to EOT @ 2.4 cm/sec).
Signal-to-Noise:
  • Better than 62 dBA (Referred to 250 nW/m).
Distortion:
  • Less than 1.5% (312 Hz @ 0 dB 2nd, 3rd and 4th harmonics).
Tape Drag Display:
  • "High" and "Normal" LED display. Provides an alert that the tape being played is binding inside the microcassette housing or sticking to itself from wrap-to-wrap.
Audio Outputs:
Front of Unit:
  • Four fully isolated, unbalanced stereo line/headphone outputs on front of unit with limiter for hearing protection. 1/8" stereo mini-phone jacks with switchable 0, +6 or +12 dB gain to improve listener's ability to hear quiet passages.
  • One headphone output on front of unit. 1/4" stereo phone jack with left, right, and stereo selector switch and volume and tone controls.
Rear of Unit:
  • 3-Channel Unit: 3 unbalanced RCA phono jacks on rear of Unit. 0 dB = 0.775V.
  • 4-Channel Unit: 8 unbalanced RCA phono jacks on rear of Unit. 0 dB - 0.775V.
Audio Level Bargraph:
  • Stereo -60 to +9 dB LED bargraph. Selectable average or peak hold with reset.
Tape Counter:
  • 4-digit LED display with "return to zero" and "Go to" functions.
Sequential Timers for Controlling Copying Recorders:
  • Four fully isolated remote control timer circuits to sequentially start up to four recorders with an overlap of one minute between consecutive tapes.
Transcription Capability:
  • Foot switch control of play, backspace, and stop plus keyboard backspace key.
Performance Documentation:
  • Complete documentation of frequency response, wow & flutter, 2nd and 3rd harmonic distortion, signal-to-noise, cross talk, hold back and take-up tension measurements are provided.
Size:
  • 16-1/2" x 12" x 5-3/4", 19" mountable with optional shelf or ears.
Warranty:
  • One year parts & labor.
    (Shipping & insurance paid by customer).

JBR MICROCASSETTE PLAYBACK/TRANSCRIBER UNIT OPTIONS

3-Channel JBR Microcassette Playback/Transcriber Unit.

  • Frequency response compensated at 2.4 cm/sec. The 2.4 cm/sec compensation is used for the five fixed speeds and in the variable speed mode. Frequency response is flat only at 2.4 cm/sec.
  • Three compensated outputs (Side A left and right and Side B right (backwards)). 2.4 cm/sec compensation used. No natural frequency response (uncompensated) outputs.
  • Frequency response specifications at five-fixed speeds. See 3-channel unit frequency response on page 1.
  • All other specifications for the 3 and 4 channel units are the same.
  • With standard accessories.

    1 each Operator's Manual
    1 each AC Power Cord for Country of Use
    1 each Foot Switch with 8-pin DIN plug
    1 each manual tape winding tool
    1 each 1.5 mm ball head hex driver
    2 each spare fuses
    1 each cleaning kit

4-Channel JBR Microcassette Playback/Transcriber Unit.

  • Frequency response compensated at the five-fixed speeds and from 0.63 to 4.80 cm/sec in variable speed mode. Frequency response is flat ( 2.5 dB) at all speeds.
  • Four frequency compensated and four natural frequency response (uncompensated) outputs.
  • Frequency response specifications at five-fixed speeds. See 4-channel unit frequency response on page 1.
  • All other specifications for the 3 and 4 channel unit are the same.
  • With standard accessories.

Custom playback heads (for forensic applications):

One of the following Custom playback heads may be installed in place of the standard 1/4-track stereo head that plays Side B as Side A is being played:

  1. Plays the Side A/B Guard Band (plays the part of original erase head marks that extend up into the Guard Band above the audio recording that are usually recorded on the tape when the tape is stopped) and if installed in a 4-channel unit, also plays the Side B right channel. Used to determine if an erase head magnetic mark is an original or a copy by playing the tape and to determine if a recording is present on Side B while playing Side A.

  2. Plays the Side A/B Guard Band (plays the part of original erase head marks that extend up into the Guard Band above the audio recording that are usually recorded on the tape when the tape is stopped) and if installed in a 4-channel unit, also plays the right channel of Side A. Used to determine if an erase head magnetic mark is an original or a copy by playing the tape and to verify that a transient is in the recording by redundantly playing the right channel of Side A on separate heads that are displaced by 0.825 inches.

  3. Plays the Side A left channel and if installed in a 4-channel unit, also plays the right channel. (Same as the left head but redundantly plays the tape 0.825-inch to the right which allows transients to be verified as being on the tape by playing the Side A audio on separate heads that are displaced by 0.825 inches). In addition, this head plays the record head off mark that is placed on the recording when the tape runs out.

Custom black 19-inch rackmount ears for mounting the JBR Microcassette Playback Unit in a 19-inch wide metal rack. Standard rack space high with all mounting hardware.

Custom external table-top Power Supply and internal triple DC-to-DC converter that reduces 60 Hertz and harmonics from -70dB to below -80dB.

8-Channel Balanced line output pre-amplifier in place of 3-Channel Unbalanced pre-amplifier used to eliminate ground loops and reduce Cable noise pick-up.

Call for pricing

(Specifications Subject to Change Without Notice)

JBR Technology, Inc.
1971 Keswick Mews
Woodbridge, VA 22192
Voice: 703-625-2763
Email: info@jbrtech.com