[[AUDIO AMPLIFIER]] KONZERT AV302 -- ONE CHANNEL BROKEN

[ActiveRegion]

One channel is playing at max volume compared to the other. The volume control works on the other one. So the speaker output is imbalanced one being always at full volume the other depends on my volume knob.

 I just want to understand why is there a pair of power transistors for the left and right channel. So there are total of 4 power transistors in this device. One pair of PNP and NPN per channel. Can you point me where i can read about the design concept of audio amplifiers. Is my understanding correct that it caters both positive and negative side of the audio waveform so it needs two transistors?


Thanks 

[ambrosia heart]

 Can you point me where i can read about the design concept of audio amplifier. Books are written by 鈴木雅臣 in japanese translated to chinese. For foreigners, only a crappy book called audio amplifier design by self Dxxxxx.鈴木雅臣accuphase designer and of course my teacher. China Mainlanders salute to him, LOL.

 Is my understanding correct that it caters both positive and negative side of the audio waveform so it needs two transistors? Yes, you are correct. They‘re emitter follower to amplify current. The preceding stage is pre-amp to amplify voltage by 1 or 2 differential amp connected to a constant current source, CCS, formed by a npn transistor and a zener(high end with mirror image) connected to voltage amp(driver stage) then to idlng current adjust. P = V x I. They are also called power amp. No matter how much they are, design has these 2 stages.  voltage amp will have DC Servo circuit to monitor DC offset OR have a VR to adjust.  In some high end amp, an isolation stage will be found in pre-amp to keep white noise as low as possible and emitter follower will have several power transistors connected in parallel to increase current output stage such as Accuphase and Mclntosh. If pre-amp include an op-amp for voltage amplification, OH DEAR, it is a nightmare for a C FU(師傅)[a technician] to repair.

[Kim Christensen]

One channel is playing at max volume compared to the other. The volume control works on the other one. So the speaker output is imbalanced one being always at full volume the other depends on my volume knob.

This sounds like a faulty volume control. These pots are dual gang. (Two pots controlled by the same shaft)
Probably the lower leg of one of the pots is open or it has a bad solder joint between the lower leg and ground.