Lovely little unit, the Audiolab 8000Q preamplifier. Unfortunately, it’s let down by poor quality factory-fitted parts, particularly the capacitors. In this article, I repair this very nice pre-amp.
This Audiolab 8000Q preamplifier came to me with a fault which would see it sometimes take a long time to turn on. I’m talking a really long time – it would sometimes take up to 30 minutes to become operational after turn-on.
In this case, I found one definite and one possible fault. A couple of the small electrolytic capacitors in the multiple regulated power supply sections showed signs of poor aging. One was bulging and clearly suffering, exhibiting low C and high ESR. I removed all of them.
Specifications, as always, from HiFi Engine:
Frequency response: 10Hz to 20kHz
Total harmonic distortion: 0.007%
Gain: 15dB (line)
Input sensitivity: 100mV (line)
Signal to noise ratio: 97dB (line)
Channel separation: 100dB (line)
Output: 100mV (line), 0.5V (Pre out), 7.7V (Pre out Max)
Dimensions: 445 x 74 x 335mm
The small capacitors used in the 8000Q are from a particularly shitful Chinese brand called Capxon. Capxon caps feature in some spectacularly cheap and awful gear. This preamp wasn’t cheap, but the accountants saved a few cents by fitting the world’s worst capacitors. Nice work Audiolab.
I replaced all the small capacitors in the power supply, given that they were all so awful. It’s likely they were all stressed due to ripple current, heat and age. Naturally, I used premium 105 degree, low ESR parts as replacements.
The second possible fault might be that one of the owner’s sources is feeding DC into the preamp. The control module inside the 8000Q senses DC offsets and sends the unit into standby until the fault clears. I will have a better idea if that’s an issue when the owner tests the unit again in his system.
In the meantime, I’ve repaired the Audiolab and she is working perfectly again. A side benefit is that it now sounds even better than when it came to me!