ZPA 0.3 and 0.5 output testing
Posted: Sun Aug 18, 2013 3:09 pm
I did more testing with the ZPA's. The two that I tested are a v1 0.3 and 0.5. Both have had v2 upgrades and capacitor replacement. Both channels (one amplifier at a time) are measured at the same time (with only one channel driven output is higher, which would give a false two channel output test) with two 400W 4ohm non-inductive dummy load resistor banks. I also used two DMM to measure individual channel output and a DC clamp meter to measure DC input current. I used a 10v line driver on the rca input side. I did not test the output of the line driver although I did not have the gain adjusted to max.
My left channel resistor bank was about 1.17 ohms higher than the right during testing (after they warmed up). Even with a fan on both banks the left got much hotter. This caused the output for the left channel on both the 0.5 and 0.3 were slightly less than the right (at least I think that is why).
ACV and DC current is measured at max gain under clipping. The gains are adjusted higher at 14V testing. This gain setting at 12V will clip the output. Other amp I have tested showed the same gain setting gave non-clipped output at both 12V and 14V. Unique?
Testing was done with a 1Khz sine wave.
0.5
DCV battery 11.95
ACV(L)28.35 or 200.9wrms
ACV(R)27.6 or 190.44wrms
DC current 59.45A and 3.3A at idle
0.5
DCV battery 13.9
ACV(L)34.82 or 303.1wrms
ACV(R)35.11 o 308.18wrms
DC current 74.5A and 5.75A at idle
0.3
DCV battery 12.29
ACV(L)24.0 or 144wrms
ACV(R)23.43 o 137wrms
DC current 39.7A and 2.77A at idle
0.3
DCV battery 14.15
ACV(L)26.94 or 181.4wrms
ACV(R)28.42 or 201.9wrms
DC current 46.12A and 3.4A at idle
***I only did one short test per channel. Averaged multiple short testing bursts with cooler resistor banks might yield slightly different results but I doubt it will be a difference you could hear.
Both amps gave considerable more output at 12V then rated. Both amps measured the same as manufacturer specs at 14V. I also had to readjust the gain settings on the amplifiers for 12v and 14v testing. If I used the same gain setting at 12v that I used at 14v the amplifiers would clip hard, interesting. I would suspect 4ohm mono is rated. I will test this with my other two 0.5's when I get the back from being restored and upgraded.
**Note** When using an ipod touch (0.7v max output) as the source without a line driver I had very low output. I was not able to get either amp to clip and at max gain they had a max output under 5wrms per channel. Additional testing in the future will include a minimal input voltage required to drive these amplifiers to clipping.
My left channel resistor bank was about 1.17 ohms higher than the right during testing (after they warmed up). Even with a fan on both banks the left got much hotter. This caused the output for the left channel on both the 0.5 and 0.3 were slightly less than the right (at least I think that is why).
ACV and DC current is measured at max gain under clipping. The gains are adjusted higher at 14V testing. This gain setting at 12V will clip the output. Other amp I have tested showed the same gain setting gave non-clipped output at both 12V and 14V. Unique?
Testing was done with a 1Khz sine wave.
0.5
DCV battery 11.95
ACV(L)28.35 or 200.9wrms
ACV(R)27.6 or 190.44wrms
DC current 59.45A and 3.3A at idle
0.5
DCV battery 13.9
ACV(L)34.82 or 303.1wrms
ACV(R)35.11 o 308.18wrms
DC current 74.5A and 5.75A at idle
0.3
DCV battery 12.29
ACV(L)24.0 or 144wrms
ACV(R)23.43 o 137wrms
DC current 39.7A and 2.77A at idle
0.3
DCV battery 14.15
ACV(L)26.94 or 181.4wrms
ACV(R)28.42 or 201.9wrms
DC current 46.12A and 3.4A at idle
***I only did one short test per channel. Averaged multiple short testing bursts with cooler resistor banks might yield slightly different results but I doubt it will be a difference you could hear.
Both amps gave considerable more output at 12V then rated. Both amps measured the same as manufacturer specs at 14V. I also had to readjust the gain settings on the amplifiers for 12v and 14v testing. If I used the same gain setting at 12v that I used at 14v the amplifiers would clip hard, interesting. I would suspect 4ohm mono is rated. I will test this with my other two 0.5's when I get the back from being restored and upgraded.
**Note** When using an ipod touch (0.7v max output) as the source without a line driver I had very low output. I was not able to get either amp to clip and at max gain they had a max output under 5wrms per channel. Additional testing in the future will include a minimal input voltage required to drive these amplifiers to clipping.