recordings be in width center-to-center spacing tracks for four record - PDF document

recordings be in width center-to-center spacing tracks for four recordings shall shall be The four tracks Track Stereophonic Recordings stereophonic recordings, left-hand channel ing for stereophonic recordings, shall be equipment so two channel for four track shall be Track Sterephonic shall be be standard left-hand chan- stereophonic recordings and Tracks shall be recorded be phased produces in-phase signals shall be reels shall plastic reels shall conform to the be standard include all SPECIFICATIONS FOR STANDARD SYSTEMS high quality magnetic superior performance be standard speed be shall apply Supplementary Tape shall be in use measured by described in level on shall be program material flection on a Tape shall be tolerance shall be exceeded beyond frequency limits. Tape shall shown in tolerance shall be exceeded beyond Tape shall tolerance shall exceeded beyond that the be within shown in 4a, b The NAB normal general purpose output, sensitivity cps recording imply a with the magnetic recording process. Since the tape nor the measurement Standard Test the NAB margin is wave load handling capacity a system and the program material measured by (ASA Standard response roll db per frequency limits Reproducing Characteristics defined in and the listed in measuring and calibrating reproducer calibrated these methods and meeting all NAB Standard Test Tapes full width tape, per quency boost the test tape is full track in consistently shall be that the record reproduce harmonic distortion shall be shall not flutter content shall measured over 200 cps. measuring system 200 cps, shall indicate The indicating a full-wave shall be calibrated shall be tape, noting peak readings, random peaks flutter content when repro- in use 200 cps. frequencies where shall indicate ing meter shall have dal frequency shall be peak readings, excluding random peaks 10-second period. four track amplifier should with high frequency to the recording high frequency output. Distortion type is not detected by distortion measurements. Bias leakage a source flutter measurement employs a frequency response similar to the ear more useful These measurements frequency response and must these measurements, shall not be applied with stereophonic 100 cps be applied magnetic recorders presents what performance requirements intelligibility and fidelity recording and shall measured by method described in shall not content shall be measured of 0.5 The response and fall- db per frequencies, respectively. frequencies where The indicating full-wave rectified average measurement a sinusoidal frequency variation. random periods tape, noting peak readings, random peaks than three program material produced by Tape shall in Figure be recognized on stereophonic equipment a stereophonic system and therefore a system Indicator (ASA Standard This is certain types program material a lower Reproducing Characteristics without distortion. is, however, improved speech intelligibility. Recorded Response shall be reproduce response NAB Standard Standard Test operating bias be used. that the in order uation above in order shall be that the shall be Track 43 measuring system 15,000 cps. cps shall be 3 least 12 db per above 20 measurement shall be made previously recorded reference signal cps NAB shall have measuring system average measurement TEST TAPES equipment shall be designated Tape shall contain as that corresponding frequency azimuth shall be cps sine following level frequency response indicated re- corded levels. Each tone shall be approximately seconds in The signal these tapes constant output Ideal Reproducing on a method described cps sine cps sine (See Section this Standard a definition and the frequency response curves with constant Ideal Head curve in terms constants remains unchanged practical reproduce Reproducing System. cps tone Test Tapes recorded such ideal head the Primary shall be by applying stroboscope disc surface. Tests be made to the power line thickness and speed checks should under normal tape the to the base tape. suggested design practical stroboscope a pulley is attached lamp operating supply flashes rate. The speeds, respectively. ips operation, in series with a neon required so stroboscope disc no more dots per minute shall a fixed per minute for the calibrating Standard Tapes shall following specifications: Electrical-Apparent core loss shall not amplifier deviation shall not curve shall not deviate db from frequency response system output quency in Magnetic losses and measurements by which be measured to determine losses independ- and consider Electrical Measurements curves shall each octave increase) measured head and amplifier response applying a small voltage proportional across a response measured with a reproduce head. can be wire over firmly in place, flux distribution is not tory for ideal because head resonance core losses. Resonance effects mined by core losses identified by comparing curves frequency shall be calculated calculated (180") (d/h) ] Gap loss null wavelength loss is by finding reaches a maximum output. and with a tuned voltmeter with a one-third octave Standard Reproducing not fulfill the requirements Calibrated Reproduc- described in FOR NAB CENTER HOLE 0.462 0.020 See Note Not applicable Not applicable NOTES FOR shall have shown in Flanges may cut outs random shape. shall not between flanges and shall not vary hub surface center diameter A) within indicator reading be concentric inches TIR. mounting surfaces both sides reel shall machinist's flats contact with machinist's flats have a greater than shall mount not protrude mounting surface. for the FOR NAB See note however, flange area must not center axis fall within ribs or other but they is rotated Threading slots shall not center diameter shall be concentric center diameter within inches TIR. to either shall mount mounting surface. plastic reels dimension between es and of' 0.243 n Z 8 W II) I?! W a V) W U 5: Z I G z W 3 E I?! L NAB STANDARD REPRODUCING CHARACTERISTIC Constant Flux Reproducing Head TERMS AND See Magnetic Biasing. or shaft reproducing head wavelengths due Distortion characterized by Harmonic Distortion system or component, numerically equal root-mean-square voltages harmonic frequencies, to the root-mean-square voltage amplitude-frequency response signal handling in order audible signal-to-noise amplitude-frequency response results in non-uniform motion The term refers to a once-per-revolution reproducing sys- presented in curve plotted ordinate and LENGTH, PHYSICAL. adjacent surfaces head measured null point. than the both theoretical their gaps LEVEL, RECORDED. on a recording by superposing general, magnetic biasing is sustantially linear relationship Engineering Department National Association N.W. Washington,