CK Series (CK75.4 Shiny Black with lines surface) Test Report


Model number: CK75.4 Class AB 75Wattsx4CH
4X75Wrms Class-AB amplifier.
2 ohm load stable.
Double Side PCB and SMD components.
Adjustable Input level, LPF, HPF.
Advanced short circuit, overload, over heat and low voltage protection.
Gold-plated isolation terminals.
3 Detailed specs:
3.1 Test Condition.
All the specs were tested with following condition unless noted.
1. Power supply: 14.4V DC power supply
2. Test signal: 1KHz sine wave.
3. Loads: Resistor dummy load.
4. Environment: 25 degree C, open air.
5. Relative humidity: 70%.
6. Test Instruments: Audio Precision SYS-2322A.


1.1Output power performance.

Following table is the RMS output power with THD+N value at 5%, 3% and 1%.
RMS power (4ohm) RMS power (2ohm) Bridged RMS power
Left Right Left Right 8ohm 4ohm
THD+N=5% 77W 77W 121W 122W 156W 245W
THD+N=3% 72W 72W 114W 115W 145W 230W
THD+N=1% 65W 65W 105W 106W 131W 210W
Table 1Output Power with THD+N
Following charts show the output power with THD curve at 4ohm load, 2ohm load stereo and bridged power at 8ohm, 4ohm.

Chat 1. RMS output power @4ohm with THD+N

Chat 2. RMS output power @2ohm with THD+N

Chat 3. Bridged RMS power @8ohm with THD+N

Chat 4. Bridged RMS power @4ohm with THD+N

3.3 Frequency Response

  1. -3dB frequency response: 10Hz~65KHz.

Chat 5.Frequency Response

3.4 LPF & HPF Filter feature

  1. A-HPF adjustable from 17Hz~210Hz.
  2. B-LPF adjustable from 60Hz~800Hz.
  3. B-HPF adjustable from 50Hz~700Hz.

Chat 6.A-HPF Filter response

Chat 7.B-LPF Filter response

Chat 8.B-HPF Filter response

3.5 Total Harmonic Distortion
THD+N=0.016%(A-weighted) @ 16W with 4ohm load.
3.6 Protection System
1. Overload: 
   Protect at 1.3Ohm load at full rated output power.
2. Short Circuit:
   Full rated power short circuit protect test: passed.
   Full rated power long last short circuit test: 10 minutes passed.
3. Over temperature:
   Protect while heat sink temperature over 81 degree C.
4. Low voltage:
Protect while power supply voltage lower than 8.3V.
3.7 Idle current and Efficiency:
1. Idle current: 0.6A.
2. Efficiency: 65% at 61W 4ohm load (stereo).
3.8 Dimension
This amplifier’s size is at 140mmX255.5mmX54mm(W,L,H).