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Left/Right Balance

Alu -  
baladur13 Posted messages 47322 Registration date   Status Moderator Last intervention   -
Hello,
I have a Marantz PM-35 mkII amplifier. The problem is that the sound is not equal between the left and right channels. This happens on the speakers and also on a headset.

To achieve an equal level, I have to set the balance significantly to the right. Additionally, there are fewer highs on the right than on the left.

Alternatively, I can activate the TONE DEFEAT button on the amplifier, which perfectly equalizes the level of both speakers and their sound with the balance set to 0.

To ensure that the speakers were not the problem, I connected both of them to the left side of the amplifier, one to the MAIN channel and the other to the SUB. And there were no issues there.

I also tried all available RCA inputs, but the problem persists.

So I would like to know what might be wrong with my amplifier that prevents it from equalizing the sound.

3 answers

  1.
    baladur13 Posted messages 47322 Registration date   Status Moderator Last intervention   14 387
     
    Good evening,
    If it works normally with the TONE DEFEAT button pressed, then the issue lies in the tone and/or Loudness settings.
    How are these two buttons positioned?

    -- 
     It's very difficult to catch a black cat in a dark room.
     Especially when it's not there...
    0
    1. Alu
       
      Loudness is activated and the bass/treble are both centered. If I turn them both all the way up, the problem remains the same. I'm afraid it might be an issue with the amplification and that, for example, capacitors need to be replaced...
      0
  2. baladur13 Posted messages 47322 Registration date   Status Moderator Last intervention   14 387
     
    Certainly a problem in the tone adjustment part...
    I can't find the schematic for this amp, but generally, they are filters (resistor-capacitor) added or removed in the circuit via the tone potentiometer.
    I suspect more of a dirty tone potentiometer or false contacts in the tone defeat switch that activates or deactivates them...
    A spray of contact cleaner on it might, who knows, improve things.

    -- 
     Very difficult to catch a black cat in a dark room.
                                  Especially when it's not there...
    0
    1. Alu
       
      Indeed, the diagram is hard to find, it's down on the server where I downloaded it.
      But I had saved it and here it is:
      https://www.cjoint.com/c/IBjmYGEFin1

      If it can help...
      I've already tried the compressed air bomb, but without disassembling anything.
      0
  3. baladur13 Posted messages 47322 Registration date   Status Moderator Last intervention   14 387
     
    Tone filters are represented in PE01, the "Tone Defeat" switch in PE51

    There are 4 electrolytic capacitors CE05 CE06 and CE09 CE10 that may have aged poorly. (check that they are not deformed)

    Note that an air duster is not enough, a contact spray should be used if possible, the SE51 switch may cause issues.
    -- 
    It is very difficult to catch a black cat in a dark room.
     Especially when it isn't there...
    0