Luxman M-4000

Luxman M-4000A

1 9 7 5 july 1975
October   1 9 7 9 october 1979
1 9 8 1 1981

The M-4000 is the smaller version of the M-6000 masterpiece, somewhat more affordable, but circuit-wise fully identical so it also is a Tim de Paravinci design.

Pioneer at the same time, 1974, also called on a non-japanese designer for its upcoming HPM series while, in 1973, Marantz was doing the very opposite with the Model 1060, a fully Marantz-Japan (aka SRC) designed amplifier with no US roots.

The M-4000 was launched a few months after the original M-6000, also celebrating the 50th anniversary of the brand's foundation as radio amateur shop in a supermarket in 1925.

The circuit of the M-4000 is a 2-stage constant current differential amp ending in triple push-pull pure complementary OCL output with an emitter-follower in between the differential driver stage in Class A and the output stage in Class B.

The dual power-supply, the very big power-supply, feeds the circuits with two 400VA transformers and four 15,000µF / 100V caps and separate windings used for the driver and output stages.

Protection schemes were particularily cared for - there are four !
DC-drift sensing when ± 3V are detected at the speaker terminals, power transistor failure sensing shuts everything down, high temp sensing shuts everything down again when heatsink temp rises above 100°C and over-current sensing when DC current appears with the signal and is detected by the comparator.

Meters are doubled-up with the average levels handled by the VU and the peak spots by the six added red LEDs. If you see the +3dB light up, you'll know you've just hit 1,2kW but you won't hear anything anymore.
These peaky LEDs can be switched to x10 scale or be turned off completely and this flashy addition was, visually, done very intelligently.

Input level "setters" allow to balance respective levels in optimal ranges for both preamplifier and amplifier between -20dB and 0dB in 1dB steps. This is done with stepped metalized film precision pots.

The M-4000, visually, is simply stunning and its design is on par with the circuit, perhaps even better - that says a lot.

Before vanishing in favor of the M-300, the M-4000 briefly saw an updated M-4000A version made for the C-5000A master preamplifier.
The M-4000A sported MOS-FETs, Lux's Duo-Beta scheme, a pair of XLR plugs (as speaker terminals), a better s/n ratio by 2dB and 2 more kilos on the balance. Also changed : the LED meters' diffusion plate (smaller and much less diffused) and the addition of the Duo-ß logo south-west of the L meter.

If the original M-4000 is already excellent and sold in sizeable quantities, the M-4000A is a true gem that is unfortunately very rare due to a very limited availabilty.

A real M-4000 at hifi-do's and an M-4000A there too.

Luxman M-4000, image 1 Luxman M-4000, image 2 Luxman M-4000, image 3
Luxman M-4000 specifications
Title Value
Power output : 2x 180W
(continuous, 20Hz...20Khz, 8 Ohm, 0,05% THD)
IM : no more than 0,05%
(8 Ohm, 120W/ch, 60Hz:7Khz = 4:1)
Frequency response : 3Hz... 100Khz (-1dB)
Input sensitivity : 1V
Input impedance : 50kOhm
Residual hum & noise : -108dB
Crosstalk : better than 90dB (vol. max, 1Khz)
better than 70dB (vol. max, 20Khz)
Damping factor : 100 (8 Ohm)
PC : 800VA max (JP)
Dimensions : 48,5 x 39 x 17,5cm
Weight : 28kg.
Listprice : 350,000¥ (M-4000, 1975)
395,000¥ (M-4000A, 1980)
Luxman M-4000 : 0 topic
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page online since : june 2005
page updated : august 2010
page type : LGT / KNB
page weight : 276.47 Kb / 0 b

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