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Monoprice 150 watt 605030 Amplifier Review

amirm

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#1
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:

Monoprice 605030 150 watt pro amplifier rack mount stereo review balanced.jpg


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:

Monoprice 605030 pro amplifier rack mount stereo review balanced speakon XLR inputs and outputs.jpg


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:

Monoprice 605030 pro amplifier audio measurements.png


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:

Monoprice 605030 pro amplifier Warm up audio measurements.png


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:

Best rack mount stereo amplifier review 2020.png


Frequency response shows anomalies in the filtering of the switching design:

Monoprice 605030 pro amplifier Frequency Response audio measurements.png


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:

Monoprice 605030 pro amplifier SNR audio measurements.png


Crosstalk is kind of average:
Monoprice 605030 pro amplifier crosstalk audio measurements.png


Power versus distortion and noise into 4 ohm load shows unacceptable rise at higher power levels:
Monoprice 605030 pro amplifier power into 4 ohm audio measurements.png


We get the rated power and no more:

Monoprice 605030 pro amplifier Max and Peak Power audio measurements.png


Into 8 ohm performance is rather strange:

Monoprice 605030 pro amplifier power into 8 ohm audio measurements.png


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:

Monoprice 605030 pro amplifier Power vs distortion vs frequency audio measurements.png


Finally, without my AES filter, here is the ultrasonic spectrum:

Monoprice 605030 pro amplifier 1 kHz FFT  audio measurements.png


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:
Tomatoes Garden.jpg


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/
 

Vasr

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#2
I am curious as to who amongst the audience here keeps buying these pro audio amps (which are never necessarily designed for hi-fidelity) and for what purpose. ;)
 

RayDunzl

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#3
I am curious as to who amongst the audience here keeps buying these pro audio amps (which are never necessarily designed for hi-fidelity) and for what purpose.
Something to power the garage or patio could be a reasonable option.

Be sure to break it in for at least 11 minutes.

You probably won't be hearing the -80dB distortion over the shop-vac or pool-pump anyway.
 
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amirm

amirm

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Thread Starter #4
I am curious as to who amongst the audience here keeps buying these pro audio amps (which are never necessarily designed for hi-fidelity) and for what purpose. ;)
They are bargain shopping for both stereo and in this case, multichannel amplification. The value they provide is incredible.
 

RayDunzl

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#5
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#9
They are bargain shopping for both stereo and in this case, multichannel amplification. The value they provide is incredible.
This is spot on for me. I don't have these particular amps, but I do have 4 Crown XLS amps, and 5 Behringer Europower amps. I'll be needing more channels in the next couple years and I'll probably turn to the pro market when the time comes.

I've been tempting to send one of the Europower amps in for testing, but I've been busy and just don't feel like de-racking one of them, and they sound fine, so I'm not sure I want to see the numbers.
 

ROOSKIE

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#10
Ha!
I was literally looking at this last night and wondering if you wanted to test it.
Totally okay for the cost.
Not what I hoped for though.

I believe the fan can be replaced with a quiet one or even removed for those who will not be rack mounting and running it at live show volume levels.
 

ROOSKIE

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#11
I am curious as to who amongst the audience here keeps buying these pro audio amps (which are never necessarily designed for hi-fidelity) and for what purpose. ;)
Home theater is a no brainer.
Also studio work.
Not to mention HiFi. I've used a crown on and off for several years and it has substantial power and excellent sound. To be quite honest the sound is subjectively as good as anything I have had that costs more.
(in terms of what is actually audible, yes we can measure much finer than we can usually hear in amps)
 

Vasr

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#13
Home theater is a no brainer.
Also studio work.
Nothing with a fan would be good for either of those because of noise. The ones with the fans are meant to be driven hard and so used in loud environments where the noise is not an issue, e.g., stage use or remote use with long speaker cables to listening position (hence the XLR connectors). These are definitely not good for HT or relatively quiet background studio use
 

Vasr

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#14
Blame this one on me. Can’t feel bad about trying Monoprice with their THX amp triumph. But a swing and a miss this time.
You do realize Monoprice is like Ikea right? :)

They have crappy stuff and they have high-end stuff all made by different OEM/ODMs.

But they do depend on confusing the consumers who give the crappy stuff a try because of the higher end line.
 

ROOSKIE

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#15
Nothing with a fan would be good for either of those because of noise. The ones with the fans are meant to be driven hard and so used in loud environments where the noise is not an issue, e.g., stage use or remote use with long speaker cables to listening position (hence the XLR connectors). These are definitely not good for HT or relatively quiet background studio use
As far as this louder amp I mean home theater, where there is a separate room for the electronics & a theater style room.
Most of the amps I use are silent (Crown XLS, dead silent), so not all of these pro amps are loud and generally the ones that are can be dealt with by splurging on a $10-25 quiet fan.
I'd put my money on that vs some crazy Mark Levinson $8k rip off.
Anyway, like I said I have used pro style amps - have you? They are good. A Crown or similar is all you will need. Everything else IMHO is like arguing over speaker wires.
To each their own, I suggest you try one sometime with an open mind. If your mind is closed when listening you will likely end up hearing what you want and not what is.
 

mrmoizy

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#16

ROOSKIE

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#17
@amirm Any chance of a picture of the inside? I am wondering what chips this uses and other things?

Also input gain - would this run well directly off of a Lg V series phone (.7ish volts)
 

PeteL

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#18
The performence in itself is not such an issue, at that price but the market is certainly hard to define. Not powerful enough for sound reinforcement applications. The XLRs instead of phoenix and no 70 Volts Speaker post imply that it's not for distributed corporate install neither. Not Hi-fi enough for critical nearfield monitoring. Fan too loud for home use. I don't know, maybe for a cue speaker in a broadcasting environment, where they would have an amp room? Very limited use.
 

cistercian

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#19
Cool review Amir! I find the power output too low for my taste and that and a noisy fan are a deal
breaker for sure.

I enjoy my Crown XLS 2502 tremendously though! I agree with other users that they sound great.
That is subjective of course and I am deaf over 14.4kc. It is interesting to observe the XLS amps objectively
poor performance at higher frequencies as far as harmonics are concerned...I strongly suspect that this makes them
just fine for older people like me. I find the silence black and can tell the amp is on if I get 6 inches from the HF horn.
I don't know if as a teen I would have liked the amp as much...because I could hear much better at HF then.

That all being said pro amps are great bang for the buck, especially if you want 400 watts per channel or more
at a low price. Especially if you need lots of channels.

High power has a quality all its own...
 

MediumRare

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#20
Cool review Amir! I find the power output too low for my taste and that and a noisy fan are a deal breaker for sure.
That all being said pro amps are great bang for the buck, especially if you want 400 watts per channel or more
at a low price. Especially if you need lots of channels.

High power has a quality all its own...
I submitted this amp for review because it can deliver 360 wpc into 8 ohms when bridged; for $130 per channel that would be amazing. It tested within specifications (0.05% THD). Alas, too many other flaws such as the on all the time fan. Stay tuned for the next candidate soon!
 
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