This is a review and detailed measurements of the Denon PMA-50 Audio (speaker) amplifier with included DAC and Bluetooth. It is on kind loan from a member. It seems to be discontinued but when available, it cost US $599. I see it on ebay and such from $370 to $450.
The enclosure is more stout and nicer looking/feeling than a lot of products in this category:
The volume control is large and nice feeling. It works a bit odd though in that when you first turn it, it switches the display to volume level but doesn't do anything with respect to changing the level. You need to keep turning it to have it take effect.
There is a headphone amp which I did not test yet. May do that later.
Back panel shows a nice suite of digital and analog inputs but no line out for the DAC:
I performed all of my testing with USB and a bit with analog Aux input.
Included mains power supply gets rid of the tangle of wires that comes with external supplies.
Internally this is a "DDFA" design which means it accepts digital input and converts it to PWM for amplification.
Amplifier Audio Measurements
I started my initial test with USB input to the amplifier and got this:
While not state-of-the-art, performance is above average for amplifiers we have tested with respect to distortion:
Using analog input degrades performance fair bit:
We lose about 5 dB, mostly in elevated noise level. Note the channel mismatch when you use analog input as opposed to digital.
Frequency response using USB input and high sample rate of 192 kHz, shows the noise shaping/filtering of the digital amplifier:
Young people with good hearing may hear some elevated sharpness. Total bandwidth though is better than some other amps we have tested which truncate at 22 kHz and such.
Looking at the spectrum of 1 kHz tone, we see a very well behaved amplifier despite being class-D:
Ultrasonic noise is limited to -60 dB. Some other products have peaks as high as -20 dB here. There is a single spike at 840 kHz or so, which is likely the switching frequency.
Note that I did not have to use my AES filter as I usually do with class D amp. The analyzer was not confused by the ultrasonic noise as present.
Using USB input we get very clean signal until the amp stops producing power:
54 watts of power slightly beats the 50 watt specification into 4 ohm. Alas, this is not much power, relegating the unit to office, small room use.
As expected, power drops with 8 ohm load:
I suggest getting a 4 ohm speaker to extract the max power out of the unit.
Using analog input, we can compare the power at 4 ohm to other amps tested. Here again, the gain was strange as turning it up to 0 dB, caused elevated noise and very early clipping. So I dialed volume down and drove the unit to 2 volt input to get this:
As we see, its modern competitors all have tons more power.
The digital input though does better as we see in this IMD comparison:
If the PMA-50 had more power, it would be a real contender here.
Signal to noise ratio using USB input at nearly 5 watts and max power yielded this:
We barely miss the spec at max power. Even at 5 watt though, we are reasonably close to noise floor of CD/16-bit audio. So not bad.
Conclusions
The Denon PMA-50 seems to be competently designed. It has none of the performance quirks of cheap class-D amps. It has a solid cabinet and controls to go with that engineering.
The big knock against it is modest amount of power and high price relative to competition. And in this day and age, lack of streaming support.
I personally put huge value on power in amplifiers so can't recommend the PMA-50 on that front. But you have the data and can judge for yourself with your priorities.
------
Questions, comments, critique, etc. are welcome.
The weather has warmed up and we are having a glorious, dry spring which is unusual for us. The panthers have noticed the same and have been pestering me for a picnic lunch. They may seem small in pictures but they have voracious appetite so I need money for food and drinks for them. Please help with this cause by donating generously 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 enclosure is more stout and nicer looking/feeling than a lot of products in this category:
The volume control is large and nice feeling. It works a bit odd though in that when you first turn it, it switches the display to volume level but doesn't do anything with respect to changing the level. You need to keep turning it to have it take effect.
There is a headphone amp which I did not test yet. May do that later.
Back panel shows a nice suite of digital and analog inputs but no line out for the DAC:
I performed all of my testing with USB and a bit with analog Aux input.
Included mains power supply gets rid of the tangle of wires that comes with external supplies.
Internally this is a "DDFA" design which means it accepts digital input and converts it to PWM for amplification.
Amplifier Audio Measurements
I started my initial test with USB input to the amplifier and got this:
While not state-of-the-art, performance is above average for amplifiers we have tested with respect to distortion:
Using analog input degrades performance fair bit:
We lose about 5 dB, mostly in elevated noise level. Note the channel mismatch when you use analog input as opposed to digital.
Frequency response using USB input and high sample rate of 192 kHz, shows the noise shaping/filtering of the digital amplifier:
Young people with good hearing may hear some elevated sharpness. Total bandwidth though is better than some other amps we have tested which truncate at 22 kHz and such.
Looking at the spectrum of 1 kHz tone, we see a very well behaved amplifier despite being class-D:
Ultrasonic noise is limited to -60 dB. Some other products have peaks as high as -20 dB here. There is a single spike at 840 kHz or so, which is likely the switching frequency.
Note that I did not have to use my AES filter as I usually do with class D amp. The analyzer was not confused by the ultrasonic noise as present.
Using USB input we get very clean signal until the amp stops producing power:
54 watts of power slightly beats the 50 watt specification into 4 ohm. Alas, this is not much power, relegating the unit to office, small room use.
As expected, power drops with 8 ohm load:
I suggest getting a 4 ohm speaker to extract the max power out of the unit.
Using analog input, we can compare the power at 4 ohm to other amps tested. Here again, the gain was strange as turning it up to 0 dB, caused elevated noise and very early clipping. So I dialed volume down and drove the unit to 2 volt input to get this:
As we see, its modern competitors all have tons more power.
The digital input though does better as we see in this IMD comparison:
If the PMA-50 had more power, it would be a real contender here.
Signal to noise ratio using USB input at nearly 5 watts and max power yielded this:
We barely miss the spec at max power. Even at 5 watt though, we are reasonably close to noise floor of CD/16-bit audio. So not bad.
Conclusions
The Denon PMA-50 seems to be competently designed. It has none of the performance quirks of cheap class-D amps. It has a solid cabinet and controls to go with that engineering.
The big knock against it is modest amount of power and high price relative to competition. And in this day and age, lack of streaming support.
I personally put huge value on power in amplifiers so can't recommend the PMA-50 on that front. But you have the data and can judge for yourself with your priorities.
------
Questions, comments, critique, etc. are welcome.
The weather has warmed up and we are having a glorious, dry spring which is unusual for us. The panthers have noticed the same and have been pestering me for a picnic lunch. They may seem small in pictures but they have voracious appetite so I need money for food and drinks for them. Please help with this cause by donating generously 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).