This is a review and detailed measurements of the Monoprice 150 watt "605030" rack mountable "pro" stereo amplifier. It was kindly purchased new and drop shipped to me for testing. The 605030 costs just US $119 from Amazon including Prime shipping which is remarkably low.
From a distance the unit looks like any other pro, R1U amplifier:
It looks rather cheap an unattractive to me but hard to imagine any pro amp getting some kind of design award for their looks.
Two gain controls are provided in the front which I appreciated. For testing I aspire for gain of 29 dB and I almost got there at max level as shown. That is how I tested the unit. There overload indicators which was nice
What I did not like one bit was the rather loud fan which runs continuously. Monoprice, please take another $5 from me and make the fan temperature dependent please!
Seeing balanced input in any amplifier at $115 price range is incredible but that is what we have here:
Output is provided in the form of SpeakOn and mono 1/4 inch sockets. Neither is convenient for in-home use but you can deal with it as I did.
The loud fan did have one benefit: the amp never changed temps above the room after all my tests.
Amplifier Audio Measurements
I powered on the unit and ran the dashboard and was immediately disappointed with the very high distortion:
I checked all of my connections and distortion persisted. I almost didn't run the rest of my tests but decided to do anyway. As another 5 to 10 minutes passed, I noticed the performance had improved so I went back and re-measured the dashboard again:
I have never seen an amplifier improve by 11 dB after brief warm up. Some kind of thermal compensation is left out to save money I guess. If the fan was not running, you could leave it running all the time but with the fan, I certainly would not. Anyway, the ranking is still below average but at least not in the broken category:
Frequency response shows anomalies in the filtering of the switching design:
Depending on your speaker and its impedance, you may get accentuated highs. There is also low frequency roll off which indicates likely capacitor coupling.
Signal to noise ratio is nothing to write home about:
Crosstalk is kind of average:
Power versus distortion and noise into 4 ohm load shows unacceptable rise at higher power levels:
We get the rated power and no more:
Into 8 ohm performance is rather strange:
Weird to see that smooth and gradual rise in distortion as if not much feedback is used.
Sweeps versus different frequencies indicates the same issue as distortion rises with frequency:
Finally, without my AES filter, here is the ultrasonic spectrum:
Pretty ugly but levels are low and of course well above our hearing.
Conclusions
The cheap looks, loud fan, and lack of power for a pro amp was enough for me to dislike the Monoprice 605030. Then I wondered what else you could get for so little money and there is nothing that comes close. Hell, if this doesn't work as an amp, you would get your money's worth in the form of chassis, power supply, etc!
Personally, I am too much of an equipment elitist to want to buy this amp. I would pay more to get a quiet unit, with more power and slightly better looks. But you all can decide as you want.
------------
As always, questions, comments, recommendations, etc. are welcome.
Still timesharing between doing reviews, working on the bloody broken dishwasher and picking ready fruit and vegetables from the garden. Just picked these and my wife is already canning them:
If that basket cheers you up as much as it does me, please donate a few dollars using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
From a distance the unit looks like any other pro, R1U amplifier:
It looks rather cheap an unattractive to me but hard to imagine any pro amp getting some kind of design award for their looks.
Two gain controls are provided in the front which I appreciated. For testing I aspire for gain of 29 dB and I almost got there at max level as shown. That is how I tested the unit. There overload indicators which was nice
What I did not like one bit was the rather loud fan which runs continuously. Monoprice, please take another $5 from me and make the fan temperature dependent please!
Seeing balanced input in any amplifier at $115 price range is incredible but that is what we have here:
Output is provided in the form of SpeakOn and mono 1/4 inch sockets. Neither is convenient for in-home use but you can deal with it as I did.
The loud fan did have one benefit: the amp never changed temps above the room after all my tests.
Amplifier Audio Measurements
I powered on the unit and ran the dashboard and was immediately disappointed with the very high distortion:
I checked all of my connections and distortion persisted. I almost didn't run the rest of my tests but decided to do anyway. As another 5 to 10 minutes passed, I noticed the performance had improved so I went back and re-measured the dashboard again:
I have never seen an amplifier improve by 11 dB after brief warm up. Some kind of thermal compensation is left out to save money I guess. If the fan was not running, you could leave it running all the time but with the fan, I certainly would not. Anyway, the ranking is still below average but at least not in the broken category:
Frequency response shows anomalies in the filtering of the switching design:
Depending on your speaker and its impedance, you may get accentuated highs. There is also low frequency roll off which indicates likely capacitor coupling.
Signal to noise ratio is nothing to write home about:
Crosstalk is kind of average:
Power versus distortion and noise into 4 ohm load shows unacceptable rise at higher power levels:
We get the rated power and no more:
Into 8 ohm performance is rather strange:
Weird to see that smooth and gradual rise in distortion as if not much feedback is used.
Sweeps versus different frequencies indicates the same issue as distortion rises with frequency:
Finally, without my AES filter, here is the ultrasonic spectrum:
Pretty ugly but levels are low and of course well above our hearing.
Conclusions
The cheap looks, loud fan, and lack of power for a pro amp was enough for me to dislike the Monoprice 605030. Then I wondered what else you could get for so little money and there is nothing that comes close. Hell, if this doesn't work as an amp, you would get your money's worth in the form of chassis, power supply, etc!
Personally, I am too much of an equipment elitist to want to buy this amp. I would pay more to get a quiet unit, with more power and slightly better looks. But you all can decide as you want.
------------
As always, questions, comments, recommendations, etc. are welcome.
Still timesharing between doing reviews, working on the bloody broken dishwasher and picking ready fruit and vegetables from the garden. Just picked these and my wife is already canning them:
If that basket cheers you up as much as it does me, please donate a few dollars using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/