Introduction:

In 2018, I began to listen to the DIY EAR834 phono preamp. After a few years, the 834's atmosphere, balance, and dynamic dynamics are convincing; but it also has shortcomings, which are also innate design problems, singular tubes (3 tubes), dual channel It is unavoidable to share at least one electronic tube, and the separation of the two channels will become the biggest bug; if you like this kind of sound and have the ability to eliminate the bug, then it will be a big change;

 

EAR834-C is compared with ordinary imitations or replicas of EAR834, and has the following differences (features);

 

◆ High voltage power supply:

Two-stage step-down voltage regulator filter, power low-pass filter cut-off FC=1.6Hz, providing a purer power supply (close to battery level);

The high-voltage power supply adjustment tube uses N-MOS, which has a certain odor and noise of rectification and voltage regulation of the bile;

With high-voltage power supply soft-start function, it reaches the design voltage value in about 3 seconds, no voltage shock will occur, and the electronic tube is protected;

 

◆ Filament Power:

DC filament power supply, with filament voltage soft start function, about 5 seconds to reach the design voltage 12.6V, protect the filament and prolong the life of the tube;

 

◆ Core amplifier circuit:

The input stages are connected in parallel, and the current parameters are newly set according to the needs of sound calibration;

The parallel input stage can enhance the sense of detail, and at the same time add an electronic tube to solve the problem of two-channel sharing

 

◆ Electronic tubes;

Independent tubes for left and right channels, avoid dual channel co-management, further improve separation and reduce crosstalk;

Mirror the filament pin position, replace the tube every six months or so, reduce the magnetization phenomenon, and further prolong the life of the tube;

 

◆ Materials:

The entire line of coupling capacitors uses licensed German-Mondolfo MCAP-EVO series capacitors.

The main filter capacitor uses the licensed German-Mondolfo 450V-220uF high-voltage electrolytic capacitor.

High voltage decoupling uses BC hydrolyzed blue electrolytic capacitors. Class A PCB.

 

Works voltage;

High voltage: AC 0---220V/50mA, 0---220V/50mA

Filament voltage: AC 0---14V/0.8A, 0---14V/0.8A

(We also have E834-C transformer for sale. If you need it, please enter my store to search and buy).

PCB Size: 221mm*161mm

Applicable electronic tube model: 4 PCS 12AX7 (ECC83)

 

NOTE: This is a finished board that is welded and tested OK. We do not include electronic tubes.