Bottlehead Kits > Crack-a-two-a

New developing issues

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Hello all,

I've been using my C2A for quite a few months with no problems at all. There have been a few issues rising recently and I want to address them before starting the stepped attenuator upgrade.

For a few weeks now, there has been intermittent static anytime the headphone cable moves. I've had plenty of cables wear out at this point before, so I thought nothing of it. However, a few nights back, when I turned the amp off (volume pot all the way down first), there was a large pop through the headphones. I have also recently changed my DAC and noticed that the volume pot is now incredibly sensitive... it was not like this before. Time for the manual again and on to resistance/voltage checks.

All resistance check passed with a few oddities...

Left side:
Terminal 4: 3.358K

Right side:
Terminal 12: 2.137K

Terminal 22: Open (both switch positions)

Voltages are stranger. I did this check again in January after using the amp for a month or so just to check. The values have changed since then...

Low Current:
IA: 148.8
OA: 65 (was 73 at previous check)
kRegA: 5.8
bRegA: 148.8

IB: 149.7
OB: 92 (was 73 at previous check)
kRegB: 4.16 (was 5.3 at previous check)
bRegB: 149.7

High Current (L/R):

IA: 192.5 / 192.3
OA: 148.8 / 149.7
bA: 0 / 0

IB: 0 / 0
OB: 88.92 / 109.6 (was 97.05 / 93.83 at previous check)
bB: 148.8 / 149.7

Tip: .002
Ring: .002

Any help is greatly appreciated!


Paul Birkeland:
Noise when moving the headphone cable means you have a wire that's not well soldered in the amp.

Thanks for the quick reply Paul! Would a poorly soldered wire cause the pop at power off too?

Paul Birkeland:
That is also somewhat of a possibility.

Would it be in the audio path or could it be anywhere?


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