Monoprice 150 watt 605030 Amplifier Review

[Francis Vaughan]

800 watts into 1 ohm. Not many amps can do this today.

No. Of course the Krell mythos was built on sand anyway. Afficanados waved their hands and claimed that speakers presented difficult loads that needed such superpowers. The reality is that this was gratuitous over-engineering. Owners paid for capability that was never called upon. Sort of like putting a Cat diesel in a family car and muttering about massive towing capability.

 

[Wombat]

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.

And who keeps testing them?

 

[Blumlein 88]

Might have had a fan (or two)

http://home.ca.inter.net/~lloyd.maclean/Krell/Krell.htm

Oops. Okay.

 

[Blumlein 88]

Well I picked the Krell out of several applicable choices. It applies to many of the vaunted amps of the past. They had very high current capability, good or great power, and usually rather low noise idling. But they usually weren't low distortion devices the way modern class D amps are. Krell, Levinson, Classe, Spectral, etc. usually only spec'd THD a bit below -60 db.

I'm not really advocating the use of what are intended to be PA amps for home high fi. I think class D has spoiled us and sometimes how good they are for so much power and so inexpensively isn't being well appreciated. Admittedly looking inside a Krell, Classe or Spectral at the high quality workmanship, parts quality etc is very impressive. But performance is performance.

 

[tomtoo]

And who keeps testing them?

At least you can test them without involving the department for magic and voodoo. What you have to do when testing tube amps.

 

[Blumlein 88]

No. Of course the Krell mythos was built on sand anyway. Afficanados waved their hands and claimed that speakers presented difficult loads that needed such superpowers. The reality is that this was gratuitous over-engineering. Owners paid for capability that was never called upon. Sort of like putting a Cat diesel in a family car and muttering about massive towing capability.

Written like someone who never owned an Apogee Scintilla ribbon. Admittedly the later Duetta was an easier 3 ohm load.

 

[Francis Vaughan]

Written like someone who never owned an Apogee Scintilla ribbon.

Yeah, OK, ribbons can be a bit of a boundary case. Arguably a good use for a current source amp.

 

[SpaceMonkey]

No. Of course the Krell mythos was built on sand anyway. Afficanados waved their hands and claimed that speakers presented difficult loads that needed such superpowers. The reality is that this was gratuitous over-engineering. Owners paid for capability that was never called upon. Sort of like putting a Cat diesel in a family car and muttering about massive towing capability.

Imho today i see two opposing trends: speakers going lower impedance while amps being barely 4 ohm stable. Plus many reviewers started meaduring EPDR on speakers which can reach 1 ohm on certain models. When seeing an epdr of 1 ohm it does make me wonder how well an amp can handle it.

 

[PeteL]

I find it funny this is now considered a not very powerful amp. One with not many use cases. Here are the specs not so long ago for a Krell KSA 100.

Description: Power output: 100W into 8 ohms (20dBW), doubles with each halving of load impedance down to 1 ohm. Frequency response: 20Hz–20kHz, +0.0/– .1dB; 1Hz–150kHz, +0.0/–3dB. Distortion: <0.1% at 1kHz; <0.5%, 20kHz, full power. Slew rate: 100V/µs. Input sensitivity: 1.4V RMS. Gain: 26dB. Damping factor: >60. Input impedance: 47k ohms. Power consumption: 100W, idle; 1400W, full power.
Dimensions: 19" W by 8.5" H by 19.25" D. Weight: 80 lbs (net).
Serial number of unit tested: 32-20216.
Price: $5500 (1994); no longer available (2007). Approximate number of dealers: 55. Warranty: 5 years, parts and labor.
Manufacturer: Krell, 45 Connair Drive, Orange, CT 06477-0533. Tel: (203) 799-9954. Fax: (203) 799-9796. Web: www.krellonline.com.

Notice it has specs actually a bit below this Monoprice rig. And it did slightly exceed them in Stereophile testing, but only slightly. And these babies were $5500 13 years ago. The Krell would have pumped out more current into tough loads, would have been quiet without a fan, but other than that is about on par with the Monoprice offering. FR was more extended and flatter too.

https://www.stereophile.com/content/krell-ksa-100s-power-amplifier-measurements

The performed measurments suite is not the same, but generally speaking, it says that the Krell operates in a more linear manner. I'm not one of those subjectivist that will come here and will try to convince anybody that some distortions are good to have, but at the same time I'm not one to think that all amps sound the same. The sole number of 0.1%, I don't think it tells the whole story. That's why we also look at distortion profile, and normally also at multi tone imd graphs (which we don't have in both cases). Yes same power in 8 ohms, but I am quite certain that if the Peak power mesurment would have been done Krell would have performed better. A hard clipping at 100W peaks would have been limitating then and still is now. I don't think those two amps would sound the same, even at moderate levels, we are not at transparency levels specifications. I think that class D amps from 15 years ago, subjectively, sounded worst than most class A amps then. This monoprice are arguably better than those first gen class d, but not fully sure that they are better enough with these specs to fully eliminate the intrinsync issues that made them then only suitable for subs and low frequencies at the time. Maybe I'm wrong. Now for the Use case comments, it's mainly the loud fan, on all the time that's the limiting factor. It needs to either live in a room other than the listening environment or have the listener far enough from it, or in a noisy environment where it becomes negligible. For Public adress or stage monitoring it's not powerful enough, and It's my feeling that if someone for home use has a complex enough sound system to have an equipment rack in a machine room isolated from it's listening room, that type of clientele is normally fortunate enough and passionate enough to aim for better, but again, I haven't listen to it. But, no doubt here, this monoprice is a better value than the Krell, but that don't mean they are equal.

 

[tomtoo]

Get a a800 it's not much more expensive and has no pesti fan.

 

[MediumRare]

Since Amir can't open the copy he has I might just buy one and then I can post pics here. I am looking for a 100watt x2 budget amp to run directly off my phone-minidsp Hd-amp to power an additional system.
I actually think this amp specs well for that (compared with say a Chinese version of a TI chip amp) and the loud fan means nothing to me as I will just buy a quiet fan or try fanless. Total guess without seeing the guts but I highly doubt that fan does much for the amp at all. Likely runs just fine without in while not rack mounted.

Hang on a few days. I have another one in the queue that might be price/value/transparency winner.

 

[MediumRare]

Strangely tough, it's not the specs on the Monoprice Website.where did you get this? Actually, they state 0.05% and this is what we get here. BUT, they specify Peak Power at twice the RMS (and twice what Amir tested) How did they come up with that?

Corrected the spec, thx.

 

[MediumRare]

Get a a800 it's not much more expensive and has no pesti fan.

I might; one more contestant has yet to reveal itself.

The price issue is I need three. Does anyone have a comment on the Outlaw 7000? The THD spec is the same as the Monoprice but of course it will have just one power supply instead of 3, so current/headroom be more limited, right?

 

[ROOSKIE]

Please don't do this just yet....

Okay... very, very curious why not of course.

 

[Vasr]

I really have no case friend.
Just hoping you will try one out and see what you think - hopefully saving you and others a lot of money and worry about the little things.
Anyway you do what serves you best, there are many fun options in audio that is for sure. No end to the good times.

First of all, you shouldn't assume that people haven't tried it out and are close-minded and therefore that is the reason they don't necessarily agree with you. That is an ad hominem argument that weakens your position/case or whatever you are trying to communicate.

Second, this was in reference to the specific case here with a fan on all the time which is too loud for any in-home or studio use not a no-brainer as you suggested (you defined HT in response).

Your statement wasn't any more valid than someone saying "You should open up your purse strings a bit more and see what you can get for a little more money. If you are stingy, you are happy with what you get". This is the ad hominem part.

People can disagree on their philosophy towards cost/performance but accusing people of being close minded for not agreeing with you is just intellectual dishonesty.

 

[Thomas savage]

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:

View attachment 83802

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:

View attachment 83803

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:

View attachment 83804

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:

View attachment 83805

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:

View attachment 83806

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

View attachment 83807

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:

View attachment 83808

Crosstalk is kind of average:
View attachment 83809

Power versus distortion and noise into 4 ohm load shows unacceptable rise at higher power levels:
View attachment 83810

We get the rated power and no more:

View attachment 83811

Into 8 ohm performance is rather strange:

View attachment 83812

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:

View attachment 83813

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

View attachment 83814

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:
View attachment 83817

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/

I'd take those tomatoes over the amp any day of the week.

Canning them you say , I will be sure to check my post daily and look forward to mine ha ha

 

[ROOSKIE]

First of all, you shouldn't assume that people haven't tried it out and are close-minded and therefore that is the reason they don't necessarily agree with you. That is an ad hominem argument that weakens your position/case or whatever you are trying to communicate.

Second, this was in reference to the specific case here with a fan on all the time which is too loud for any in-home or studio use not a no-brainer as you suggested (you defined HT in response).

Your statement wasn't any more valid than someone saying "You should open up your purse strings a bit more and see what you can get for a little more money. If you are stingy, you are happy with what you get". This is the ad hominem part.

People can disagree on their philosophy towards cost/performance but accusing people of being close minded for not agreeing with you is just intellectual dishonesty.

Howdy bud,
I come here for fun and everything I say here is friendly but of course tone in a forum can be tuff and folks will often go where they go.
I really think you reading my posts in a much different light than they are written.

Nobody really wants this thread to go south so to be clear I did not accuse you of anything at all. I did say listen to some pro amps with an open mind because on this site biases are well to keep in check when subjectively processing gear - they can creep right on in. Nor did I assume you have not heard pro amps, I asked you if you had. You stated "these pro audio amps ", which I took to mean pro amps in general in the context of your statement to which I deff wanted folks to know that each "pro" amp is different should be inspected on it's own not clumped. Even this one with a loud fan can still be a great option and geez it is $120+-.

All of these comments are on a public forum so they are always written with the understanding that they are not a reply to one person (I would PM you if I wanted to only address you) but a way of talking with the public - other folks are having this same debate in their heads and I am offering my take to chew on so some things are said in that context even though I quote you.

If your budget is large than considering pro amps may be of no concern, I suspect a huge number of people come here looking for a budget option. They are not stingy they are on a tight budget yet they still want excellent sound. That low budget excellent sound can happen.

I do find audible differences in many amp sound sigs, that said, in my experiences generally they have been fairly minor and really IMHO 90% of people would be completely happy with any of the amps I have ever tried (as long as the power the amp made available was enough for their listening levels). This includes some FX audio amps that I purchased to try from a PartsExpress buyout. $25 each and they sound excellent right now powering a DIY 2 way that I have been having fun with. Those amps were bettered in nearly every singe way subjectively by a $1000 amp I compared them with one night. The difference was very obvious - yet still IMHO 90% would have been fine with either one (as long as they could get by with 25 or so watts) and some would maybe have even preferred the FX Audio amp due to the slightly more edgy treble which to some will be perfect (hearing loss/ liking a brighter edge/ home theater effects/ ect).

 

[PeteL]

So, granted it's a cheap product, come on, we have to draw the line somewhere, It's a poorly performing amp. Most 100W in 8 ohms Amps that you'd get on the used market for 100$ would measure better than this. The Sony DH-190 tested here is not any worse than this. It was at the time 140$, has a preamp with 4 ins, a phono pre, even a tuner, and has amplification as powerful as this. It's at the the very bottom of what a mass market manufacturer like Sony would allow out there, aimed at people that need something but don't care enough about their sound system to put any money on it. We have to tell bad when we see bad.
Edit: I see that Amir blew the PSU running tests. OK this here may be a tad more reliable. Maybe (I still wonder why you would need a fan on a relatively low power class D amp)

 

[ROOSKIE]

I've never used that Sony but I have used the Yamaha 202 and 303 stereo receivers.
The 202 can often be purchased for $90-100 refurbished. It sounded great. Very much worth the $100.
That said there are some reasons for an amp vs a receiver. They are not 100% interchangeable.
Additionally spring clip connectors may not work for some folks - like me. The unit will be regularly moved around. All my cables are fixed connectors. I really don't want spring clips.
I am cross shopping small form factor chip amps such as the aiyima 07 with the TPA3255. I thought about the Niles 2150 just reviewed by the cost is $103 new for monoprice vs $370 refurb on the Niles. All for an amp I will be replacing in a few months with a DIY Hypex.
I think this monoprice is lightweight as well so easy to move often.
The specs meet the price, that said I have been told that another budget review is on the way and I ought to hold off and see what that mystery unit has on offer.
So I will wait.

 

[MediumRare]

I bought the Yamaha R-N303 for my daughter; she feeds it via WiFi, which is very handy. It claims 100 wpc but only 0.2% THD. So, probably transparent for her small room and you can't argue with the price. But not ideal for a larger room.

The system I need the amps for won't be for critical listening, but the rooms are fairly large (4,500 cubic feet), the speakers (M105) aren't especially sensitive, and their impedance drops to 3.8 ohms. Net, I want to have enough headroom to drive them hard. A little low pass DSP for the Revels wouldn't hurt, per Amir's recommendation. So, let's see what pops up.