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  • Headphones
    AKG K701 Westone 2
  • Headphone amplifiers
    iBasso D4
  1. andrelim

    CK2III help

    Sorry no offense meant. I was trying to see if anyone wanted to help me troubleshoot my amp either 1. out of kindness 2. as practise I have checked what I can but I used vishay dale CMF resistors which are brown and have no color bands. That was not really a smart move now that I think about it. The opamp is used to remove DC offset right? Since my DC offset is 0.5mV can I assume that it is working fine? I just downloaded trueRTA and I'm going to use the oscilloscope to check the signal. ALthough its not as good as a real oscilloscope I'm hoping its better than nothing. This is what I got in TrueRTA when playing a 1K hz sine wave, though my sound card isn't calibrated so I cant measure voltage properly. I was careful to heat each component for less than a second, so I'm hoping nothing is damaged. Yeah the image I uploaded is the schematic found on the AMB website, with the voltages I measured (in green) above the correct voltages. What I meant was that I removed the DC offset of 110mV I had previously, not that 0.5mV is bad. I checked it once, but I will go through it more carefully again. R2, R7 and R11 are correct. When I measure R16 in circuit it is 900K ohms. If I measure the resistors in circuit it wont be accurate will it? Thanks for your help
  2. andrelim

    CK2III help

    I have managed to get some sound on both channel after replacing the output transistors and resoldering all the solder joints. However it is still extremely distorted and intermittent. DC offset on both channels is around 0.5mV. However voltages across the board are still not the voltages they are supposed to be. I am at a loss as to what to do now. Any DIYer in Singapore looking to do a kind deed/for a challenge?
  3. andrelim

    CK2III help

    I recently built a CK2III. So far the +15V and -15V test pads measure 15.1V and -14.9V. But nothing else measures correctly. The green voltages are the voltages I measure, the white/red are the voltages they are supposed to be at. I cannot seem to get a constant voltage at resistors R23 and R47. They range form 0.5mV to 30mV. And I cannot hear anything when I hook up some cheap headphones to it. I get a DC offset of 0.4mV to 10mV on both left and right channels. Any help is greatly appreciated. Here is the circuit diagram from the AMB website.
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