• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Monoprice 605030 Class D Amp Teardown

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
28,487
Likes
75,261
Location
Seattle Area
#1
This is a teardown of the Monoprice 150 watt Class D Amplifier which I just reviewed. The owner gave me kind permission to open it up.

Here is the overview shot of the entire unit:

Monoprice 605030 pro amplifier class D teardown.jpg


The heart of the unit is an integrated switching power supply and stereo class D amplification.

I was surprised to see an angled bottom mounted fan in a rack mounted device! Usually there is equipment stacked on top of each other, not leaving any air in there to suck in. Granted, this fan is tilted a bit but still. Even if intake air is available, it is just blown randomly against the top of the case. It will surely provide more cooling than without but most certainly not optimized. Good news is that it is a larger fan so you can get quiet versions or even temperature controlled ones. It is nicely socketed as marked so replacement should be easy.

That monster shrink wrapped bit must be some kind of choke/filter. Alas, it has already pulled apart the cheesy glued cable tie:

Monoprice 605030 pro amplifier class D teardown fastener unglued.jpg


All such fasteners should be screwed to the case, not glued. Even if it had not come loose now, it would have in the future.

Moving on, I noticed a serious safety issue:
Monoprice 605030 pro amplifier class D teardown wire touching case.png


These are the mains wiring and the one blue wire is in touch with the sharp edge of the fan shroud. The vibrations from the fan will cause the edge to act like a knife, potentially cutting through the insulation. Once there, it is shorting that wire to the chassis. If it is a neutral wire you will still be safe but may get ground loops and hum. If it is the hot lead, it may spark and potentially cause a fire. The whole harness needs to be heck away from that edge using a fastener on the side or something.

Let's now zoom into the amp/power supply board:

Monoprice 605030 pro amplifier class D teardown Power Supply and Amplifier Module.jpg


Other than over zealous goop put everywhere including partially covering a power transistor, the rest seems to be OK.

Class D amplification comes courtesy of IR/Infeneon, IRS2092:https://www.infineon.com/dgdl/irs2092.pdf?fileId=5546d462533600a401535675f1be2790

1600674874794.png


The IC is only a controller though and requires output mosfets for power delivery:

1600674830786.png


The MOSFET used is IRFB4020 which is a specialized part designed for output stage of a class D amp with a power rating of 300 watts: https://www.infineon.com/dgdl/irfb4020pbf.pdf?fileId=5546d462533600a4015356158ffd1e05

Looking at the weak point of switching power supplies which tends to be the capacitor, we find a no-name Junzl brand:

Monoprice 605030 pro amplifier class D teardown PS Junzl capacitor.jpg


Fortunately it is rated at 105 degree C so won't degrade quickly.

I could not find any useful marking on the boards to identify who designed them.

Conclusions
There is certainly a lot to this amplifier despite its extremely low price. The one safety issue is ready to remedy by moving the mains power away from the fan enclosure. Speaking of fan, its noise can easily be remedied by disconnecting it, making it temperature sensitive or putting in a quieter fan. If you do leave it in there, be sure there is circulation on the bottom and side of the unit.

Overall, not a bad showing especially for this price.

------------
As always, questions, comments, recommendations, etc. are welcome.

After having some nice take out Fish and Chips at our local waterfront seafood restaurant (consumed in our car :( ), the night's project was to dehydrate these Asian Pears from our orchard:

Asian Pear from Orchard.jpg


Well... that was easier said than done. These have extremely hard cores and I managed to jab my hand with the tool I use to take them out. It drew a bit of blood but the good news is that the dehydrator is full and running overnight. I think we have another 200 or more pears to go and no way I am going through this process with them again! So we will likely donate most of them to the local food bank.

As I noted, if you want these boring garden stories to go away, you need to donate money using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

restorer-john

Major Contributor
Joined
Mar 1, 2018
Messages
4,929
Likes
10,855
Location
Gold Coast, Queensland, Australia
#2
The power supply looks to have a removable jumper for the voltage doubler. It's obviously set for 120V (according to your rear photo). So it looks like it could be easily set for 230V countries by just unplugging the jumper. Main 180V capacitors are cutting it fine if you ask me.

1600676411703.png


@amirm Did you test the amp in bridge mode? That could be interesting.
 

YSC

Active Member
Joined
Dec 31, 2019
Messages
267
Likes
101
#3
the fan seems ok as it looks like it's blowing air out from below, though not efficient but it potentially draws in air from the other side?

The capacitors gets more disappointed recently. I seriously can't understand why the professional equipment manufacturer always want to skim on a few cents of cost per unit in sacrifice of performance or longevity in these.
 

sergeauckland

Major Contributor
Forum Donor
Joined
Mar 16, 2016
Messages
1,674
Likes
3,621
Location
Suffolk UK
#6
Japan tried longevity, the product didn't die, so the company died.

South Korea tried the 3-year approach. It works.
I am reminded of the story, possibly apocryphal, of the UK colour TV industry in the late 1960s/early 1970s. In those days, colour TVs were expensive, and not hugely reliable and thus expensive to repair. A lot of people rented theirs and in order for the rental agreements to be renewed, rental companies had to judge very carefully the reliability of their TVs. If the equipment failed too often, the companies would be out of pocket with repair costs, and customers would be unhappy at the frequent failures, although not unhappy that they were repaired for free. If the equipment was too reliable, then people wouldn't renew the rental on the basis that what were they paying all this money for, they might as well buy a TV on hire-purchase and risk the repair bills.

It turned out that 18 months between call-outs was about optimum. Customers thought they were getting value for their rental and not too annoyed, and the companies could afford one repair every 18 months. Not surprisingly, what failed was trivial to repair, and cost pennies, but would stop the TV working.

This could just be an urban legend, but I worked for a company that did have a laboratory that investigated MTBF very carefully to optimise reliability.

Now, equipment generally is pretty reliable, so stuff is made to fail software-wise or for fashion reasons.

S
 
Joined
Aug 20, 2020
Messages
22
Likes
29
Location
Germany
#9
Is this fan blowing or sucking?
Maybe this is an attempt at a positive-pressure set up.
BTW if it's 12V one could easily replace it with a Noctua or similar.
 

Timbo2

Senior Member
Joined
Feb 27, 2018
Messages
428
Likes
301
Location
USA
#10
Also love that the fan is installed so that part of the exhaust (assuming label down convention) is blocked by the case. I'm not sure why they didn't mount over a another inch or so.

I've seen plastic pieces in PC PSUs to direct airflow blocking fans, but that doesn't seem to be the case here.
 

anmpr1

Major Contributor
Forum Donor
Joined
Oct 11, 2018
Messages
1,802
Likes
2,647
#11
In those days, colour TVs were expensive, and not hugely reliable and thus expensive to repair. A lot of people rented theirs...
Anything expensive to purchase outright, and difficult to maintain, is an argument for rental. If it's cheap and if it breaks, it's not too much of a hit to buy another. I think it is that way with modern cars. When I was a kid I'd help the old man service the Rambler. Grease, points 'n plugs, oils changes, etc. With a few inexpensive tools the average man could actually maintain a car--all you needed was some basic skill (it didn't' take a lot of that) and an afternoon. Possibly a kid to help you hold stuff in place.

Nowadays, no one can work on a car without special special equipment, they are generally too complex, often you cant' even get to the parts that need replacing, and so on. Users don't have the time, inclination or knowledge anymore. So you see folks leasing them, which is essentially a rental agreement, with warranty coverage if something breaks.

I remember the days of toobs. If something went south it was not too difficult to l locate the problem and replace the bad part. Solid state changed all that. I've said it before, if my Dyna blows up I can probably fix it. If my Benchmark goes south, it gets shipped north.
 

pozz

ЦАП
Forum Donor
Editor
Joined
May 21, 2019
Messages
2,392
Likes
3,412
#12
Anything expensive to purchase outright, and difficult to maintain, is an argument for rental.
Real estate is the best example of that.
 

anmpr1

Major Contributor
Forum Donor
Joined
Oct 11, 2018
Messages
1,802
Likes
2,647
#13
Real estate is the best example of that.
LOL. I once met a guy who was living in his car. He told me that he'd lost pretty much everything, and with what little money he had left, he could either pay his rent or make a car payment.

That seemed like a strange choice to me--I mean, keeping the car instead of the apartment. He explained it to me succinctly--he said he could sleep in his car, but he couldn't drive his house. I immediately understood the wisdom in that.
 

MediumRare

Major Contributor
Forum Donor
Joined
Sep 17, 2019
Messages
1,099
Likes
1,177
Location
Chicago
#14
Does anyone see obvious things that could be done DIY to improve this amp's performance, other than the fan? For 360 watts into 8 ohms at $130 it's pretty killer if it can be "fixed".
 

AnalogSteph

Addicted to Fun and Learning
Joined
Nov 6, 2018
Messages
729
Likes
522
Location
.de
#15
Does anyone see obvious things that could be done DIY to improve this amp's performance, other than the fan? For 360 watts into 8 ohms at $130 it's pretty killer if it can be "fixed".
Well, I hope the black goop isn't the notorious Black Gunk of Death but rather some more harmless silicone for one...

The fan housing looks to be heatstaked rather than screwed. Not sure about the size, looks like it might be an 80x80x15? The connector is likely to be the usual power supply 2-pin job, not compatible with PC fans so may need resoldering or an adapter.

I'd review the ventilation concept as well, looks like it's negative pressure (mostly drawing air across the amplifier) but there are holes right next to the fan? A bit of cardboard for a baffle could reduce shorted airflow then.
 

Bruce Morgen

Active Member
Joined
Aug 3, 2019
Messages
132
Likes
90
#16
That IR chip-and-MOSFETs setup is pretty elderly as Class D technology goes -- I have the same parts in my 20 year old Infinity subwoofer. This amp would perform considerably better with a single modern monolithic Class D chip like TI's TPA3255.
 

ROOSKIE

Senior Member
Joined
Feb 27, 2020
Messages
411
Likes
569
#20
That fan looks like exhaust (the motor side is usually the direction it blows to), either way an odd decision as exhaust fan blowing down will go against rising heat.
Remember, heat doesn't rise. Hot air usually rises due to less density but heat moves to colder areas. Such as the cold case.
 
Top Bottom