Monoprice 605030 Class D Amp Teardown

[ROOSKIE]

Thanks so much for the excellent teardown.
I am in for one.

 

[restorer-john]

230 × √2 or if you account for variance 250 × √2= 353Volt

120 × √2=170V. Close to 180V. (voltage doubler mode). Too close for my liking.
If you go 250V primary, it's closer. 353V to (series capacitor connection) 360V rated.

Most manufacturers use 200WV capacitors in series.

 

[carlob]

120 × √2=170V. Close to 180V. (voltage doubler mode). Too close for my liking.
If you go 250V primary, it's closer. 353V to (series capacitor connection) 360V rated.

Most manufacturers use 200WV capacitors in series.

Exactly. Too close.

 

[AudioTodd]

This thread reminds me of why I wandered over to these forums -- and stuck around! The teardowns are great!
Thanks so much for doing these; they're fascinating!

Happy Monday, all y'all!

My favorite part of ASR!

[Except when I buy something and it later gets great measurements here, thus proving my outstanding audio savvy - LOL]

 

[cistercian]

Exactly. Too close.

The power supply...it is always where corners are cut for price/profit.

 

[cistercian]

Thanks for the tear down Amir! They are epic!
Poor wire routing and fastening. Good catch.

 

[laudio]

As a DIY'er, love the teardown threads that call out the type of class D design used.

 

[typericey]

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

View attachment 84034

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

@RayDunzl this your brand?

 

[RayDunzl]

@RayDunzl this your brand?

Let me check....

http://www.junzl.com/

Nope.

 

[KaiserSoze]

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

A successful business model widely deployed over diverse industries and going back to the early days of the industrial revolution is where the profit made from the initial sale is minimal, with most of the money made from the perpetual servicing. Many radio & TV stores from the old days made much of their money from house calls to replace burned-out tubes. Glance inside to see which tube is melted or not glowing, replace it, check to see if the thing works. How about printer cartridges? Everyone knows that printer cartridges are a ripoff and that this is how the printer manufacturer makes the money off you, but what are you going to do? Even if you use original cartridges with refilled ink, you risk damaging your printer. And what about those electric toothbrush heads? Within a year or so you've spent more on the brush heads than you spent on the toothbrush. Hmmm. I'm surprised that no one has come up with an exotic cord that doesn't cost a whole lot initially, no more than your typical integrated amp, but that requires regular servicing in order to insure optimal performance.

 

[ezra_s]

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.

I was thinking the same, it seems it blows air above downwards, which is quite odd, you generally want to blow hot air upwards right?

 

[ROOSKIE]

I was thinking the same, it seems it blows air above downwards, which is quite odd, you generally want to blow hot air upwards right?

Mine just arrived. I won't be using it until Monday or Tuesday at the earliest. I did already disconnect that fan. (There was some glue at the connection point so if there is ever anyone else who sees this and is also disconnecting the fan, remove that connection slowly and work to break the glue bond.)
I will report back and confirm whether or not this fan is indeed "optional" in a non-rack mount and running in stereo (not bridged) with typical 4-8ohm nominal speakers.
I realize this is not likely a hot commodity among the crowd here but FWIIW it seems solid and I like the utilitarian looks and feeling. $100 after discounts = seemly a good deal so far for what I am after.

 

[LBec]

A successful business model widely deployed over diverse industries and going back to the early days of the industrial revolution is where the profit made from the initial sale is minimal, with most of the money made from the perpetual servicing. Many radio & TV stores from the old days made much of their money from house calls to replace burned-out tubes. Glance inside to see which tube is melted or not glowing, replace it, check to see if the thing works. How about printer cartridges? Everyone knows that printer cartridges are a ripoff and that this is how the printer manufacturer makes the money off you, but what are you going to do? Even if you use original cartridges with refilled ink, you risk damaging your printer. And what about those electric toothbrush heads? Within a year or so you've spent more on the brush heads than you spent on the toothbrush. Hmmm. I'm surprised that no one has come up with an exotic cord that doesn't cost a whole lot initially, no more than your typical integrated amp, but that requires regular servicing in order to insure optimal performance.

In the ancient days this was called the razor, razor blade philosophy. Sell the razor cheap and make the money on the razor blades.

 

[Jinjuku]

Mine just arrived. I won't be using it until Monday or Tuesday at the earliest. I did already disconnect that fan. (There was some glue at the connection point so if there is ever anyone else who sees this and is also disconnecting the fan, remove that connection slowly and work to break the glue bond.)
I will report back and confirm whether or not this fan is indeed "optional" in a non-rack mount and running in stereo (not bridged) with typical 4-8ohm nominal speakers.
I realize this is not likely a hot commodity among the crowd here but FWIIW it seems solid and I like the utilitarian looks and feeling. $100 after discounts = seemly a good deal so far for what I am after.

Any updates? Looking at these at $106 for driving some surround speakers.

 

[ROOSKIE]

Any updates? Looking at these at $106 for driving some surround speakers.

I don't see any reason to spend more to power your surrounds. Maybe if you have a very large theater and thus need crazy power.

I removed the fans on both, they both do have 1" feet that added to the bottoms to ensure some airspace for the venting. Instead of that approach you could likely set them directly on a metal surface that work help suck any heat away from the case and thus the inner airspaces and Chip amp. i don't think I will be adding quiet fans, that is still an option. The circuitry has thermal protection built in some if that ever gets triggered then I know. So far they just get a little warmish.

I have used two of these now for quite a bit of music listening. Sometimes very loudly for extended periods - high 80's SPL with 95+db peaks in a medium room a 10 foot listening distance. No problems.

My overall review right now is these are very serviceable. I have not directly compared much with other amps yet in the same set-up. I get the sense they are very average amps which by modern standards means more than good enough. They deff don't sound bad, I suspect I have had some smoother amps (is this more hifi or just different?) and perhaps amps that would sound a tiny bit better in a direct shoot-out. Nothing about them makes me want to buy more expensive amps for the projects I have going right now. I am really losing interest in amps - nearly every one I have owned sounded great and only one ever stood out and seemed an bit harsh/bright. (a buy-out special $20 FX audio chip amp) I think as long as it is average quality by modern standards and you have enough power and amp is designed for the speakers impedance load, MHO is you are good to go in 95+% of set-ups. The rest is in one's head.

 

[Jinjuku]

Thanks. I pulled the trigger. I'm going check what a replacement fan would look like as I have an assortment of 60 and 80mm fans hanging around.

 

[TimW]

Thanks. I pulled the trigger. I'm going check what a replacement fan would look like as I have an assortment of 60 and 80mm fans hanging around.

Did you (or anyone else here) end up replacing the fan in one of these?

 

[funeralcrasher]

Confirming fan blows downward through the vent holes and not into the enclosure.

The fan is Crown/Cofan part number AGE08015F12U. It measures 80x80x16mm.

Specs:

Part No	Bearing	Voltage	V Range	Rated Current	RPM	m3/min	CFM	mm/H2O	in/H2O	dBA
AGE08015F12U	F	12	7.0~13.2	0.3	4500	1.28	45.2	5.23	0.21	43

I plan to replace with a slightly less robust Noctua NF-R8 redux-1800 PWM, which has 31 CFM rating at 17dba. Since many are running without fans altogether this should be a good compromise. I will atttempt to flat-mount the fan against the cooling fins and ensure I have 1U open below the unit.

 

[audio2design]

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.

View attachment 84038

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

Late to the thread. Line spec is +/-10%. (132-2) * 1.414 > 180. Not cutting close. Cost cutting where not warranted. Going to guess a "special" cap as 180V are not normal even from typical good quality Chinese suppliers.

 

[audio2design]

Japan tried longevity, the product didn't die, so the company died.

South Korea tried the 3-year approach. It works.

Japanese capacitor suppliers still have very large market share. Many pretty good Chinese capacitor suppliers that make reliable product too.