This is a review and detailed measurements of the Dayton Audio APA 150 power (speaker) amplifier. It is on kind loan from a member. It costs USD $168 from Parts Express including free shipping. If the specs of 75 watts/channel are true, you are getting a stereo amplifier for about $1 per watt! Amazing how cheap these amplifiers have gotten.
The APA 150 is a chunky unit, departing from the typical wide cabinet format:
As you see, there is a volume control so you can skip a preamplifier if all you have is one input. In the back, there are switches for bridging to mono, filtering and auto on.
The unit is fan cooled but it is temperature controlled and quiet.
The design is the classic class AB with a linear power supply which makes the unit heavy and inefficient. So good to see the fan there to keep things cool.
There are serious looking ETL/CE safety and regulatory markings on the unit which I take to be genuine and provide peace of mind.
Let's get into measurements and see how the APA 150 performs.
Measurements
Let's start with our dashboard view while the input is adjusted to produce 5 watts into both channels:
We get typical performance of budget amplifiers. SINAD (signal over distortion and noise) is in the 70s with lots of harmonic distortion and power supply noise apparent. No awards will be won at this rate.
Channel mismatch as far as distortion is fairly large which shows up in warm-up sequence just the same:
Stability is really good though so you don't need to leave the unit on. It is as good or bad as when it first turns on.
As noted the fan was on during this test and blew a lot of air that was barely warm.
Frequency response is very good and typical of class AB amplifiers (which don't need filtering as switching amplifiers do):
Response is down just half a dB at 40 kHz limit of the test.
Likewise output impedance is negligible:
Impedance is 1 ohm or less at 20 Hz and averages 0.4 ohm above that. In other words, there will be no trouble running any impedance speaker with respect to impacting its frequency response.
Let's look at all important power versus distortion measurement:
Compared to our previous budget amplifiers, the Dayton Audio APA 150 beats them slightly on power, producing nearly 90 watts into 4 ohms. And it does that with lower distortion to boot.
Distortion+noise versus frequency at a few power levels is ugly though:
At 50 millivolts of input, the graph is dominated by noise especially in high frequencies (red). As we increase the input levels, we get two clusters of lines, one for good channel and not so good channel. All show much increased distortion with frequency, rising to as much as 0.1%. Between 2 and 5 Khz where our hearing is most sensitive, we are looking at 0.02 to 0.03% or about 50 times worse than most DACs.
Conclusions
The Dayton Audio APA 150 performs along the lines that we have sunk into in budget amplifiers. Lot of cheap power with cringe-worthy distortions and noise. Fortunately when it comes to non-linear distortions, our hearing is fairly poor so likely people are satisfied with the great value they are getting.
I like the fact that the APA 150 is safety rated given the high voltages and currents running around in power amplifiers. The fan with its high air flow gives me comfort that it will run cool and likely reliable even under max load.
No doubt with good speakers and content, the APA 150 will provide an enjoyable experience. But if you are after the best as I am, this is not it. Our hunt for reasonably priced amplifier but with high performance continues....
------------
As always, questions, comments, recommendations, etc. are welcome.
They say you should save money for a rainy day. It rains for about 6 months here so I need plenty of money!!! Please consider donating funds using:
Patreon: https://www.patreon.com/audiosciencereview), or
upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).
The APA 150 is a chunky unit, departing from the typical wide cabinet format:
As you see, there is a volume control so you can skip a preamplifier if all you have is one input. In the back, there are switches for bridging to mono, filtering and auto on.
The unit is fan cooled but it is temperature controlled and quiet.
The design is the classic class AB with a linear power supply which makes the unit heavy and inefficient. So good to see the fan there to keep things cool.
There are serious looking ETL/CE safety and regulatory markings on the unit which I take to be genuine and provide peace of mind.
Let's get into measurements and see how the APA 150 performs.
Measurements
Let's start with our dashboard view while the input is adjusted to produce 5 watts into both channels:
We get typical performance of budget amplifiers. SINAD (signal over distortion and noise) is in the 70s with lots of harmonic distortion and power supply noise apparent. No awards will be won at this rate.
Channel mismatch as far as distortion is fairly large which shows up in warm-up sequence just the same:
Stability is really good though so you don't need to leave the unit on. It is as good or bad as when it first turns on.
As noted the fan was on during this test and blew a lot of air that was barely warm.
Frequency response is very good and typical of class AB amplifiers (which don't need filtering as switching amplifiers do):
Response is down just half a dB at 40 kHz limit of the test.
Likewise output impedance is negligible:
Impedance is 1 ohm or less at 20 Hz and averages 0.4 ohm above that. In other words, there will be no trouble running any impedance speaker with respect to impacting its frequency response.
Let's look at all important power versus distortion measurement:
Compared to our previous budget amplifiers, the Dayton Audio APA 150 beats them slightly on power, producing nearly 90 watts into 4 ohms. And it does that with lower distortion to boot.
Distortion+noise versus frequency at a few power levels is ugly though:
At 50 millivolts of input, the graph is dominated by noise especially in high frequencies (red). As we increase the input levels, we get two clusters of lines, one for good channel and not so good channel. All show much increased distortion with frequency, rising to as much as 0.1%. Between 2 and 5 Khz where our hearing is most sensitive, we are looking at 0.02 to 0.03% or about 50 times worse than most DACs.
Conclusions
The Dayton Audio APA 150 performs along the lines that we have sunk into in budget amplifiers. Lot of cheap power with cringe-worthy distortions and noise. Fortunately when it comes to non-linear distortions, our hearing is fairly poor so likely people are satisfied with the great value they are getting.
I like the fact that the APA 150 is safety rated given the high voltages and currents running around in power amplifiers. The fan with its high air flow gives me comfort that it will run cool and likely reliable even under max load.
No doubt with good speakers and content, the APA 150 will provide an enjoyable experience. But if you are after the best as I am, this is not it. Our hunt for reasonably priced amplifier but with high performance continues....
------------
As always, questions, comments, recommendations, etc. are welcome.
They say you should save money for a rainy day. It rains for about 6 months here so I need plenty of money!!! Please consider donating funds using:
Patreon: https://www.patreon.com/audiosciencereview), or
upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).