Scott LK 48 Schematic

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H. H. SCOTT, INC.
111 Powder Mill Road
Maynard, Muss.

SERVICE BULLETIN
For
MODEL LK-48 STEREO AMPLIFIER

SPECIFICATIONS
Maximum power output each channel at 1000 cycles: Music waveforms... 24 watts
Steady state ...... 20 watts
Maximum.total harmonic distortion at rated output ....... .. .......... 0.8% '
Frequency response for 20 watts steady state at less than 1.5%
total distortion ...................... .................... ............ 20 to 20,000 cycles *
Maximum usable power output at 20 cycles: Music waveforms... 28 watts
Steady state...... 24 watts
Power bandwidth at rated distortion (IHFM method).......... .......... below 19 cycles to
above 20,000 cycles
(limits of test equip)
Intermodulation distortion.. ...... ... . ........... ..... ............. below 0.5%
Signal for rated output -- NAB (NARTB) tape at 1 kc .............. .... 3.0 mv.
Signal for rated output -- RIAA equalization at l kc ................. 3.0 mv. (MAG LOW)
Signal for rated output -- RIAA equalization at l kc........ ......... 9.0 my. (MAG HIGH)
Signal for rated output -- Tuner, Extra, and Playback ................ 0.50 volts
Hum and noise -- high level inputs ..... . ..... ... ....... ... ..... . ..... 80 db. below rated
power
Hum and noise -- low level inputs................... ................ . 10 microvolts equiva-
lent
Scratch filter ............ . ......... .................... Above 5 kc.
Treble boost and Treble cut (at 10 kc. ).. ..... ..... . ..... . ........ 15 db. :12 db.
Bass boost and cut (at 50 cycles)...... ...... ...... ........... . ...... 15 db. 12 db.

(These characteristics are measured at a line voltage of 117 volts rms and line frequency of
60 cycles per second. No significant changes of characteristics should be experienced for
normal variations of line voltages or a line frequency of 50 cycles per second).

_ Input impedance -- low level inputs (MAG LOW)................ ........ 47 k. ohms
Input impedance -- low level inputs (MAG HIGH)................ ....... 150 k. ohms
Input impedance -- high level inputs.... ..... ........... ....... ...... 500 k. ohms
Minimum recommended load resistance on tape outputs.......... ..... ... 200 k. ohms
Maximum recommended cable capacitance on tape outputs........ ..... ... 200 mmfds.
Range of line voltage and frequency.... ..... . ..... ............. ...... 105-125 volts,

50-60 cycles
Power consumption -- 117 volts at 60 eps (A.C. only) 170 watts

* All H. H. Scott amplifiers and preamplifiers incorporate a low frequency rolloff

which becomes fully operative below 20 cycles. This is designed to pre-
vent overload of the output stage and the loudspeaker due to subsonic rumble frequencies and
record eccentricity. This means that the full power of the amplifier can be concentrated into

the audible range.

D-LK-48-2 ' (Continued on reverse)