This is a review and detailed measurements of the Starke Sound AD4.320 four channel amplifier. It was kindly purchased by a member new and drop shipped to me. It costs US $1,499 but they have had sales with prices as low as US $900.
The Ad4.320 looks a bit industrial and is quite heavy for a class D amplifier:
The reason for heavy weight is dual linear transformers and power supply on the right side. Usually class D amplifiers use switching power supplies which keeps the unit light. My own switching amplifier also uses a linear power supply with its weight and size penalty.
I was pleased to see balanced inputs and triggers for remote on and off:
As you can see, you can bridge two channels together and get double the power. Unlike other amps that require funky connections, you have two dedicated terminals with a slide switch to select the mode (which need to be activated when power is off). When I powered on the unit, I could not get output out of one channel. I switched the bridge mode left and right (when off) and it got both working. For bulk of my testing I tested channels 1 and 2.
Starke Sound AD4.320 Measurements
We start with our usual dashboard of 1 kHz tone with a load of 4 ohm with power of 5 watts:
Gain is atypically low at 21 dB (usually it is in 28 to 32 dB). Not a problem with our dedicated DACs as they can easily provide the voltage the unit needs.
Sadly we have high 2nd and 3rd harmonics that cause SINAD to droop down to 73 dB. This is well below average of all amplifiers tested:
We are talking chip-amp performance level here not anything that would come at this price range.
Signal to noise ratio is better but not exciting:
Multitone test shows rapid rise in distortion with frequency:
The class D amplifier filter is not inside the feedback loop so shows high sensitivity to load:
This means the tonality you get may depend on the actual impedance of the speaker you use.
Crosstalk between channels 1 and 2 is very good:
Key performance metric for any amplifier is powered and I was very surprised to see far less power than specified:
We are not even in the same planet with 104 watts vs spec of 320! I switched channel 2 to 3 just in case there is a power supply limit but it almost made no difference. We are still way short of the company specs:
Story repeated with 8 ohm load:
Forgetting about lack of power, we also have very early rise in distortion and rising before clipping.
I thought maybe they had used peak power to rate the amplifier but that is not in the same vicinity either:
We do see the benefit of the linear amplifier in the way it allows higher burst power than tightly regulated switching power supplies.
Sweeping the frequency and measuring power and THD+N, shows smooth lines which is good but they are quite elevated at higher frequencies:
Conclusions
The AD4.320 underperforms in so many categories. You can argue about audibility of this and that measurements but not the lack of power. That, you will hear. Is the unit broken? Could be but it doesn't perform like it is broken. I thought maybe it is set to 240 volts but it is clearly marked as being a 120 volt unit (see the back panel picture). And at any rate, if they shipped the amp this way to a US customer, then that is what they are going to get.
I can't recommend the Starke Audio AD4.320. Getting four channels with so much power would have been a good value if they had delivered. But when they don't, there is no reason to buy it.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
The Ad4.320 looks a bit industrial and is quite heavy for a class D amplifier:
The reason for heavy weight is dual linear transformers and power supply on the right side. Usually class D amplifiers use switching power supplies which keeps the unit light. My own switching amplifier also uses a linear power supply with its weight and size penalty.
I was pleased to see balanced inputs and triggers for remote on and off:
As you can see, you can bridge two channels together and get double the power. Unlike other amps that require funky connections, you have two dedicated terminals with a slide switch to select the mode (which need to be activated when power is off). When I powered on the unit, I could not get output out of one channel. I switched the bridge mode left and right (when off) and it got both working. For bulk of my testing I tested channels 1 and 2.
Starke Sound AD4.320 Measurements
We start with our usual dashboard of 1 kHz tone with a load of 4 ohm with power of 5 watts:
Gain is atypically low at 21 dB (usually it is in 28 to 32 dB). Not a problem with our dedicated DACs as they can easily provide the voltage the unit needs.
Sadly we have high 2nd and 3rd harmonics that cause SINAD to droop down to 73 dB. This is well below average of all amplifiers tested:
We are talking chip-amp performance level here not anything that would come at this price range.
Signal to noise ratio is better but not exciting:
Multitone test shows rapid rise in distortion with frequency:
The class D amplifier filter is not inside the feedback loop so shows high sensitivity to load:
This means the tonality you get may depend on the actual impedance of the speaker you use.
Crosstalk between channels 1 and 2 is very good:
Key performance metric for any amplifier is powered and I was very surprised to see far less power than specified:
We are not even in the same planet with 104 watts vs spec of 320! I switched channel 2 to 3 just in case there is a power supply limit but it almost made no difference. We are still way short of the company specs:
Story repeated with 8 ohm load:
Forgetting about lack of power, we also have very early rise in distortion and rising before clipping.
I thought maybe they had used peak power to rate the amplifier but that is not in the same vicinity either:
We do see the benefit of the linear amplifier in the way it allows higher burst power than tightly regulated switching power supplies.
Sweeping the frequency and measuring power and THD+N, shows smooth lines which is good but they are quite elevated at higher frequencies:
Conclusions
The AD4.320 underperforms in so many categories. You can argue about audibility of this and that measurements but not the lack of power. That, you will hear. Is the unit broken? Could be but it doesn't perform like it is broken. I thought maybe it is set to 240 volts but it is clearly marked as being a 120 volt unit (see the back panel picture). And at any rate, if they shipped the amp this way to a US customer, then that is what they are going to get.
I can't recommend the Starke Audio AD4.320. Getting four channels with so much power would have been a good value if they had delivered. But when they don't, there is no reason to buy it.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
