Revox A740

Revox A500

March
1 9 7 6 march 1976
1 9 8 2 1982

Big serious powerhouse originally planned as A500, with confimation LEDs for power and overload.

Finally released as A740 with a supplementary subsonic position for input A, the LEDs replaced by speaker A / speaker B on/off switches and bulkier VU meters.
The chassis and specifications are seemingly identical for both.

Complementary (symmetrical) circuits from input to output, high local NFB loops and low global NFB amount, high idling current, six power transistors per channel, each with a Pc of 200W, two 30,000µF caps per channel.

Fully regulated power supply protected aginst AC short-circuits ; outputs are electronically protected - sans relays :

• power transistors' heat dissipation
(> current limiter)

• heatsinks+power-supply heat detector
(> power off)

• DC or lower than 3Hz current
(> output shutoff by "Crowbar" circuit)

Two 6-position input trim pots allow precise level matching while logarithmic meters show the result between -40dB and +3dB.
The front input attenuators are stepped by 5dB steps and accurate within 0,2dB.

Revox A740, image 1 Revox A740, image 2 Revox A740, image 3
Revox A740 specifications
Title Value
"Musical" power : 2x 300W (4 Ohm)
DIN 45500 power : 2x 200W (4 Ohm)
2x 125W (8 Ohm)
Nominal power : 2x 175W (4 Ohm)
2x 100W (8 Ohm)
Max power : 1x 250W (4 Ohm)
1x 150W (8 Ohm)
Damping factor : 76
250 (1Khz, 8 Ohm)
Frequency response : 20Hz...20Khz (+0 / -0,5dB)
THD : < 0,1% (any level at and below rated power)
S/N ratio : > 100dB (rated power)
Crosstalk : < 76dB (1Khz)
Inputs : 0,775mV / 50kOhm (RCA)
?? / ?? (XLR)
Speakers' outputs : A : screw plug (60A capacity)
B : DIN terminals
Back input pots : 30dB range (RCA terminals)
Front input pots : 5dB stepped attenuators
± 0,2dB precision
Meters : -40...+3dB range
10ms rise time (to reach -1dB)
1,7s (fall from 0dB to -20dB)
0dB = 200W / 4 Ohm
9,5 x 7,3cm frame
PC : 1000W max.
Dimensions : 45 x 15,1 x 35,6cm
Weight : 20kg.
page online since : 2005
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