Saturday, 26 February 2011

Some Crack Measurements and a Surprise!

Took the time to do some measurements on the Crack, and following are the results.

B+ is 166.3 V at the 6080 tube socket pin.
AC Hum at the headphone jack; Right is 0.005 Vac,  Left is 0.013 Vac
85 mA through the first PSU Filter resistor.

After doing this, I thought I give the HD650 a crack before I send them away, and lo and behold, the left channel works again!

However, in the two sessions with the DT880 and the HD650, I found that the right channel is significantly softer then the left channel. I think some is amiss here. Also measuring the voltage across the the large 2W resistor in the driver CCS, there was a big different between the left and right channels, something is not quite right in the amp, that is for sure. Maybe this also has something to do with the imbalance in Vac across the output.

On another note, it might be the HD650 connectors on the left side may be loose, and hence it worked again since I unplugged the cable ready for shipping, and then re-plugged it in after. Again, something is amiss.

I also took the time to plug back in my MiniMax Millet (MMM) and make sure the HD650 were working well and to test out the DT880 on them. I must say, they don't have the life, or the engagement with the music as the Crack. A little dry or lifeless when compared to the crack. The bass is probably better through the MMM than the Crack. However, there was no hum. Dead silence. There was however, noise, which is proportional to the volume, which would suggest that it was source, as this was also present on the Crack. Well, more testing and debugging ahead.

No comments:

Post a Comment