Single Ended Tube Audio Amplifier Audio Lot SE-833MX Challenge

Single Ended Tube Audio Amplifier

Audio Lot SE-833MX Challenge

Built around a vacuum tube triode GU-48 (similar to 833)

Amplifier Description:

The amplifier is combined of two independent monoblocks for the left and for the right channels.

The circuit of each consists of a signal amplifier on a 6SN7 (6N8S) tube and a follower on 6N30P,

which supplies the grid current to GU-48 output triode, allowing it to operate in a wider voltage range, which in turn boosts the output power (class A2).

Each monoblock has one RCA input with volume control. Amplifier sensitivity is enough to operate directly from the output of a playback devices or a pre-amplifier.

On the rear panel there are two sockets for monitoring the current through the output tube (I=120mA).

To adjust the currents, two multi-turn potentiometers are installed, which are accessed through round windows using a flat screwdriver. Measurements must be made with a millivoltmeter at the minimum voltage setting.

A reading of 120 mV will correspond to a current of 120 mA.

The power supply of the device ensures a normal operation with a line voltage in the range of 170 to 265 V. At a higher voltage, an emergency shutdown of the entire amplifier occurs. Such wide supply voltage range is possible due to the use of an automatic microcontroller based control system. Depending on the line voltage, the automatic system controls the relays, which connect the appropriate tap on the power transformer to the line. This assures the most optimum matching of the transformer to the AC line.

Specifications: monoblock

Type: single-ended , class A2

Load power (Watts): 4 ohms - 82

6 ohm - 65

8 ohm - 58

Frequency range (Hz÷kHz): 16 - 50

Output impedance (ohm): 1.9

Input impedance (L-type regulator) (kΩ): ​​18 - 32 (depending on the angle of rotation)

Power Consumption (Continuous)(Watts): 400

Supply voltage (V): 170÷265

Dimensions (mm; L \ W \ H): 430 x 500 x 320

Weight (kg): 46

Precautionary measures

Since the Gu-48 vacuum tube installed on monoblocks has an increased temperature and is powered by high voltage, it is necessary not to allow humans or pets next to the tubes.

The Gu-48 tube is installed into the socket so that, looking at the amplifier from the front, the anode ,,A,, is on the left of the glass container, and the grid ,,C,, is on the right.

Disconnecting high-voltage wires from the tubes should be done no sooner than 15 minutes after turning the amplifier off.

It is not allowed to turn the amplifier on without tunes installed, as well as to replace them during operation.