LUXMAN L-505V

Commentary

This pre-main amplifier is one of the V Series products and is the fifth generation from the SQ505 released in 1968.

The circuit quality has been improved by introducing technology developed for the power amplifier M-6000 and the control amplifier C-1000.

The main amplifier section uses a pure complimentary service OCL system directly connected to all stages of 2-stage differential-amplification with two positive and negative power supplies.
Like the M-6000, the emitter follower circuit is installed after the pre-driver stage to improve the load condition in the high-frequency range of the pre-driver stage and to obtain excellent distortion factor characteristics. This emitter follower circuit electrically insulates the pre-driver stage for class B operation from the output stage for class A operation, and prevents the pre-driver stage from receiving impedance changes caused by the speaker load.

The equalizer circuit of the preamp section combines carefully selected operational amplifier ICs with the output stage of a class A inverted Darlington push-pull circuit applied with high voltage to obtain excellent distortion factor characteristics as well as excellent input resistance characteristics.

The intermediate amplifier circuit is a 2-stage direct connection type combining NPN-PNP transistors, and the tone control circuit is a LUX system NF type. The tone control circuit has three bending point frequencies in the low and high range for finer adjustment. Tone feedback is also possible.

The filter circuit uses CR type for low-cut and NF type for high-cut.
The low-boost circuit is of the NF type so that it operates only in the heavy and low frequency range.

Two large-capacity electrolytic capacitors of 10,000 μ F are used for the filter circuit of the power supply section, which is combined with a well-regulated power transformer to supply a stable power supply.

Model Rating

Type	Pre-main amplifier
Continuous effective output	55W + 55W (8 Ω, both channel operation, 20 hz to 20 khz) 72W + 72W (4 Ω, double-channel operation, 20 hz to 20 khz)
Total harmonic distortion factor	0.03% or Less (8 Ω, 55W)
Cross modulation distortion factor	0.03% or Less (8 Ω, 55W, 60 hz : 7 khz = 4 : 1)
Output bandwidth	5 Hz to 50 kHz -3dB (0.1%)
Input Sensitivity / Impedance	Phono1 : 2.5mV/30k ~ 50k ~ 100k Ω (continuously variable) Phono2 : 2.5mV/50k Ω Tuner, Aux1/2 : 150mV/50k Ω
Signal-to-noise ratio	Phono1/2 : 62 dB or more Tuner, Aux1/2 : 80 dB or more
Maximum allowable input	Phono : 300 mV or more (RMS, 1 kHz)
Residual noise	0.5 mV or less
Damping factor	40 (8 Ω Load)
Tone control	LUX System NF Type with Bending Point Frequency Switching Low-range bending point : 150 Hz, 300 Hz, 600 Hz, defeat High-frequency curved point : 1.5 kHz, 3 kHz, 6 kHz, Defeat
Low-cut : 30 Hz (-6dB/oct.) High Cut : 8 kHz (-6dB/oct.)
Low boost	70Hz(+6dB/oct)
Attachment	Input impedance adjustment for Phono1 Tape dubbing circuit Attenuator (-18dB)
Semiconductor used	Transistor : 47 IC : 1 Diode : 20 pcs Zener diode : 4 pcs Varistor : 4 pcs
Power consumption	200W (8 Ω, both channel operation, at rated output)
External dimensions	Width 450x Height 160x Depth 268 mm
Weight	11.5kg