Class D amp long term reliability

[audio2design]

So the power supply gets hotter than the amplifier module?? Is this typical? If so is it just when idling?

It's typically where the highest losses are. Some of these Class D amps have high idle power. For the transformer as long as the wire and insulation temp rating is high enough it's not a reliability concern. Biggest issue is thermal cycling of the solder joints.

 

[valerianf]

"So the power supply gets hotter than the amplifier module"
It is exactly what is happening when the output power is low (low volume listening).
I have a WXA-50 that drive the surrounds and it is always warm because of the power supply design!

I may have to ask Yamaha for the technical manual in case of power supply failure.

 

[Madjalapeno]

The small transformers in SMPSs can run extremely hot, especially when delivering high power.

I did another set of measurements with it idling, and after 45 minutes got similar results.

 

[antennaguru]

Back in Posts 254 and 255 I described yet another Class D module failure that I had experienced. This one was an ICEpower 50ASX2 that recently just wouldn't turn on. I ended up ordering another 50ASX2 module from China and proceeded with the removal and replacement operation as that was the easiest solution and just under $100 for the shipped module. This was the 3rd module failure out of 6, and with this replacement now 7 Class D Modules I have purchased.

I removed the approx. 5 year old module that had very low hours on it, and as I started to install the new module in its place I noticed it had only one speaker output connector. Upon closer examination I realized they had sent me a BTL (mono) module to replace my SE (stereo) module. All that really meant was that I needed to rob one of the speaker connectors from my dead SE module and install it in the new module, and also remove the BTL soldered-in jumper and install an SE soldered in jumper. Not a big deal but the additional desoldering/soldering work added some 30 minutes to the project. Their solder has a really high melting point! I guess all is well that ends well, as the amplifier now is playing fine with the new module in it.

Having the dead module completely out of the casework led me to perform a closer visual inspection of the failed module looking for signs of the failure. Yes, there were two components that had let out some magic smoke that was apparent on some white adhesive glue and and adjacent white plastic connector. It's not worth doing on board repairs from a time and energy standpoint with a module this inexpensive, but I can share close-up pictures of the parts that I could visibly see went Chernobyl:

 

[antennaguru]

I know. I have threatened to have a skylight put in. We live in the sunniest place on earth and here I am fighting with illumination. But I have a plan for 2022. It involves a lot of MR16 LEDs, an old ATX power supply and a design that will put an operating theatre/examination lamp to shame.

I have moved in the direction of using these screw-in LED lights in places I need to have extra bright light. I have not seen anything brighter in that small a package that simply screws into a standard porcelain light socket. I have them over several work benches, and in a boiler room, and they are truly bright - "Beyond Bright" is the product name. I have seen them selling from $20 - $40. The alloy metal wings adjust/aim the light and actually do get warm as they are clearly doing some heat sinking...

 

[Madjalapeno]

restorer-john said:

I know. I have threatened to have a skylight put in. We live in the sunniest place on earth and here I am fighting with illumination. But I have a plan for 2022. It involves a lot of MR16 LEDs, an old ATX power supply and a design that will put an operating theatre/examination lamp to shame.

At the start of lockdown I needed some space for making some prototypes at home. I wanted it to be shadow free and had seen something similar online.

It's basically a 10m length of LED strip attached to a length of aluminum that is then gently bent into an arc. Worked pretty well considering.

 

[mhardy6647]

At the start of lockdown I needed some space for making some prototypes at home. I wanted it to be shadow free and had seen something similar online.

It's basically a 10m length of LED strip attached to a length of aluminum that is then gently bent into an arc. Worked pretty well considering.
View attachment 178974

A very cool idea!
As an aside: I was looking at the view out the window & thinking "looks like northern New England" (i.e., our neck of the woods) -- so I looked at your location

 

[Madjalapeno]

"looks like northern New England"

Seacoast NH - doesn't look like that today.

 

[mhardy6647]

Seacoast NH - doesn't look like that today.

We're on the other side of the state (CT River "Upper Valley") and it's every bit as grey -- whiter, though, otherwise... and s'posed to get effing cold as the day goes by.

... and that's the weather forecast for today. Back to our regular programming!

 

[Madjalapeno]

We're on the other side of the state (CT River "Upper Valley") and it's every bit as grey -- whiter, though, otherwise... and s'posed to get effing cold as the day goes by.

... and that's the weather forecast for today. Back to our regular programming!

Time to fire up those class-A's, or even (shudder) some valves.

 

[mhardy6647]

Time to fire up those class-A's, or even (shudder) some valves.

Dude.
Class A [ Boolean] and valves.





Ironically enough, I am sitting here ripping my wife's and my (!) Monkees albums -- all soiled solid state. Even the phono preamp.
Apostasy!
On the other hand I am using a nearly 50 year old tt and a Denon DL-103 LOMC cartridge to do it. The DL-103's been on the market since 1960 or '61.

 

[prasanth.nath]

I thought I should chip in with some facts

2 Hypex UCD180 OEMs failed me, after about 3 years. [All fairness, it could be me: the amp was untouched for 6 months plus, and I am told therefore moisture did it in. I wasn't aware that one should remove any moisture on the amps before use, if using after a long hiatus]
4 Hypex UCD180HGs have gone dead. I do not know the reason. [These happened over time, and it never made sense to ship them to Hypex for repair, given I am in India].
So that is a total of 6 dead out of 12.

The 4 Hypex SMPS-es that I bought so far are working fine.

 

[Zed]

Absolutely true, and well said.

But the thing is, those same poor design practices disappeared many decades ago in commercial A/B amplifier design. I spent years repairing equally bad f#$k ups. But the wonderful benefits available with collective hindsight, unfortunately, is it seems to be utterly ignored or forgotten by so-called "gun" designers or "paradigm shifters" intent on not listening to the past, learning from their predecessors mistakes, or acknowledging they don't know everything.

Thanks for this analysis @restorer-john. As someone who's about to pull the trigger on this amp, to power new ($$$) speakers, this gives me pause. Is there anything you can think of that could be done to compensate for these design flaws, and avoid the same fate? Thank you in advance.

 

[TurtleG]

I discovered that a class D amp could be more hot at idle than a class AB playing music!
I got a Yamaha WXA-50 that is hot at idle, I am guessing due to the design of the power supply.
It is not a good news for the reliability of the ICE module that is inside.

My Yamaha WXA-50 is about 5 years old with no problems I use it every other day, maybe a couple of hours or so. Sometimes it gets left on for days whether I'm using or not. It's probably averaged a few hours use ever other day. At idle it's warm but I wouldn't describe it as hot to touch, in fact I've never noticed it hot. I have the fan set to auto, and wouldn't have a clue if its ever come on.

2 x Yamaha AB, and 1 x Rotel AB no problems over about 5 years of use before I sold them.

2 x Audiolab and 1 x Hafler had several issues between them and got rid of them. Mostly the issues related to poor assembly.

 

[TheBatsEar]

So that is a total of 6 dead out of 12.

Damn, that hurts.

 

[pseudoid]

I know. I have threatened to have a skylight put in. We live in the sunniest place on earth and here I am fighting with illumination. But I have a plan for 2022. It involves a lot of MR16 LEDs, an old ATX power supply and a design that will put an operating theatre/examination lamp to shame.

Should you be spending some money on solar instead???

My Yamaha WXA-50 is about 5 years old with no problems I use it every other day, maybe a couple of hours or so.

Can you (2) just make it work like a WXC-50 (as a preAmp) and get a different powerAmp?
That way, your next excursion into an updated DAC, will have an already broken-in powerAmp waiting for it.

 

[restorer-john]

Should you be spending some money on solar instead???

Absolutely I should, but our roof is about to get major changes (extension) and then I'll have more roof area facing the right way for solar panels.

 

[freemansteve]

A benefit of Hypex PSU and amps and other similar modular gear, is its ubiquity. Easy and cheap to swap out sub-systems should you get a failure. Also the PCBAs seem to have relatively few parts, and it looks like board level repairs would be straightforward. More esoteric kit is usually a pain to repair in my experience.

 

[sq225917]

I'm only a sample of one, but have friends with various bits of hifi. Anecdotally, I'd say smsp audio amplifiers have a higher failure rate and shorter life expectancy than class a/b with linear supplies. This may well be changing as the technology and designs mature with class d and smps.

We're I buying a class d amp, it would have to have the smps and amp on separate boards. Other than that I'd have few concerns.

 

[Vacceo]

Has anyone, even handy guys, tried a watercooled amp in the style of a watercooled pc?