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Class D amp long term reliability

EJ3

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My Dad always said if you have a spare, you'll never need it. All about outwitting that old b#stard Murphy's Law. I took it to a whole new level (and have the storage sheds to prove it).
I have a friend whose last name is Murphy. He says that whenever there is trouble, that there is a Murphy around.
 

EJ3

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When was the last time you had the motherboard of your desktop computer fail? These rarely do, and the SMD assembly is if anything more intricate than on an audio amplifier PCB. I'm around thousands of amplifiers daily and the number which come back for service could probably be counted on one hand over the course of a month. I can't speak to the reliability of other brands, but ours is impeccable.

As to the schematic issue, that is mostly due to liability issues. The minute a schematic is included, that is a tacit license for the consumer to attempt home repairs. Parts are the same, however we routinely ship replacement amplifier modules to customers.
There should be a service manual made available to those who want one (for a fee perhaps). Then a person who actively obtained one would put themselves into a different category than just a consumer. Which should alleviate the legal issue.
 

restorer-john

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As to the schematic issue, that is mostly due to liability issues. The minute a schematic is included, that is a tacit license for the consumer to attempt home repairs. Parts are the same, however we routinely ship replacement amplifier modules to customers.

Every piece of Sansui gear in the early 1970s came with a full schematic. Yamaha provided them on the last page of the owner's manuals until the mid-late 70s. Those were the days when things were simpler, sure, but people also had a lot more common sense than they do now. And a huge amount of HiFi buyers were electronic hobbyists and engineers.

I had to pay serious money for certain S/Ms and schematics in the early 90s for some brands, others provided them (printed back then of course) for free and as many as we wanted. Now pretty much all my data is on my NAS, with ease of navigation and access in a whole other world, compared to filing cabinets full of dusty manuals incorrectly filed by someone else...

But I want access to schematics. It still gives me great joy to return something from the dead that was deemed BER (beyond economic repair) or the classic BS line "parts are NLA". I've done it my whole life- fix things people said couldn't be fixed.
 

MakeMineVinyl

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Every piece of Sansui gear in the early 1970s came with a full schematic. Yamaha provided them on the last page of the owner's manuals until the mid-late 70s. Those were the days when things were simpler, sure, but people also had a lot more common sense than they do now. And a huge amount of HiFi buyers were electronic hobbyists and engineers.

I had to pay serious money for certain S/Ms and schematics in the early 90s for some brands, others provided them (printed back then of course) for free and as many as we wanted. Now pretty much all my data is on my NAS, with ease of navigation and access in a whole other world, compared to filing cabinets full of dusty manuals incorrectly filed by someone else...

But I want access to schematics. It still gives me great joy to return something from the dead that was deemed BER (beyond economic repair) or the classic BS line "parts are NLA". I've done it my whole life- fix things people said couldn't be fixed.
I agree with you, schematics should accompany gear or at least service manuals should be available. Unfortunately the world is different - I don't particularly like the current state of affairs either.
 

MakeMineVinyl

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There should be a service manual made available to those who want one (for a fee perhaps). Then a person who actively obtained one would put themselves into a different category than just a consumer. Which should alleviate the legal issue.
All of this is above my pay grade. I'm an engineer, not management. I know why they do it, but I'm powerless to change anything. All I can say is that we're more accommodating than most manufacturers.
 

EJ3

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As to the schematic issue, that is mostly due to liability issues. The minute a schematic is included, that is a tacit license for the consumer to attempt home repairs. Parts are the same, however we routinely ship replacement amplifier modules to customers.
I can get a service manual (and do have one) for every car I own. A car is much more dangerous than a piece of audio equipment. If I cannot repair it or have it repaired (because some entity won't provide the repair manual) then I don't own it. therefore, I am highly unlikely to buy it. That is why there are laws being fought for and being passed here in the USA for the "right to repair":
iFixit's self-repair manifesto
 

MakeMineVinyl

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I can get a service manual (and do have one) for every car I own. A car is much more dangerous than a piece of audio equipment. If I cannot repair it or have it repaired (because some entity won't provide the repair manual) then I don't own it. therefore, I am highly unlikely to buy it. That is why there are laws being fought for and being passed here in the USA for the "right to repair":
iFixit's self-repair manifesto's self-repair manifesto
I agree with you but like I mentioned before there's nothing I personally can do about it. I buy gear also that I wish I could get service information on but can't.
 

pseudoid

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Maybe the story of Hem and Haw's travels thru the maze in the book "Who Moved my Cheese?" should be mandatory reading for those who resist change.
If I was the designer of some audio hardware (whether it got 'Class' or not), would I really want to give the schematics away, so that my IP could be cloned elsewhere and instantly? Heck No! Schematic are sooooooooooo pre-'80s!
Do we possibly think that the 2022 shiny new eVehicles' electronics will be available for 10 years, like pre-00s ICE vehicles? Heck No!
Do we really need spares of ANYTHING, when EVERYTHING (in the post-10s) is designed to be a throw-away item within a few years, when that other shiny new thingy comes out?
Ummmmm… someone should ask Alice about Kansas!
Schematics: LOL
 

Rick Sykora

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Ok, for the sake of full disclosure, I am a Hypex OEM. That said, I am an ASR member first and still think objectivity and science remain pertinent to the discussion...

1. While am concerned with the potential design issue that @restorer-john found, do we have more than one failed Hypex module? Lacking a lot more data, anything more is a major extrapolation. Not sure how many modules Hypex has sold, but pretty sure the failure rate is pretty small. I really doubt Hypex (intentionally) wants to deal with high field failure rates. Having been at the receiving end of customer calls when reliability issues have occurred, can definitively state I would much rather spend my time helping make a better product!

2. When a member had trouble with a Hypex power supply, they did send me partial schematics. They are much more protective of the amp schematics. Maybe this will get better eventually, but if you do not like the protectiveness, you have a choice to buy elsewhere.

3. As mentioned, it takes different tools and more training to fix SMD parts. Even if you have a schematic, it does not mean you can readily fix.

4. I highly doubt that Hypex or most of the other Class D amp manufacturers are designing for planned obsolescence. That said, given some of what has been brought up here and elsewhere, would be nice to see a published MTBF or MTTF. Has anyone asked for one? Not expecting that would get actual numbers, but some assurance of comparable reliability to other electronics seems reasonable.

5. Given the state of the electronics supply chain, expect we will more frequently see vendors substituting parts from secondary suppliers. Likely this may result in more failures than using the same primary supplier. Having been involved in electronics manufacturing for decades though, even your primary supplier may have quality (or other severe) issue occasionally, so having reliable secondary suppliers is smart business. What we saw with AKM was a small taste of comparable issues that electronics manufacturers deal with regularly.
 
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EJ3

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Ok, for the sake of full disclosure, I am a Hypex OEM. That said, I am an ASR member first and still think objectivity and science remain pertinent to the discussion...

3. As mentioned, it takes different tools and more training to fix SMD parts. Even if you have a schematic, it does not mean you can readily fix.
I'll just focus on 3 for the moment: If I have the schematic & was not able to 'readily fix' it, I could definitely go down to one of my local "makers" groups, such as Reforge Charleston: (from them)

LEARN​

We provide a wide range of classes covering everything from sewing to ardunio programming.

WORK​

As a member you have access to a variety of tools such as Laser cutters, 3D printers and CNCs. It is the perfect place to complete any project.

COLLABORATE​

Our members have a plethora of knowledge and experience. If you want to pick up a skill or learn something new, Reforge is the place to go.

Another tack would be the local technical college (who trains in electrical, robotics, computer circuit design, manufacture & repair [not just replacing modules but actual repair] {and a number of folks & groups around that have the equipment to do so}) for Boeing, Robert Bosch, Volvo, Mercedes & many others. I know a man here who has been able to design & make proprietary computer circuits for industry and airplanes since the 1990's. If I can find people to do things like this in the Charleston, SC area: don't you think think that I could find people that are even more capable in cities such as Charlotte or Atlanta, which are both just a short flight or a little longer drive (if you count time going through the airports). Yes, people who want to get it done, certainly can get it done. And many learn to do it themselves & purchase the equipment for their makers group. This presumes that no one can learn how to do this.

Yet people like me and others have been reverse engineering, writing manuals & repairing all sorts of things (such as the latest computer hardware. electronics, Mac, PC's, Phones, Medical Devices & more.

Don't believe me? Go to ifixit.com & see for yourself. I suspect that you will find that there is a segment of the general public that is quite proficient at doing these things, even without having a degree in engineering (mine degree [which I have on occasion found useful, mostly in what not to do] is in Business. I was brought up in a plumbing, heating and AC corporation owned by my parents. I have been part owner or full owner of 3 rather successful corporations myself. But my heart lies in the audio/video fields of acoustics & science (thereby encompassing electronics, computerized & otherwise).

Like retorer-john, some one of us will, at some point in time do it just for fun. It makes it more difficult without a schematic but that stops no one who wants to tear it down. & it might take more than one. But there are certainly people that will figure it out. And publish their results.
 
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EJ3

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I agree with you but like I mentioned before there's nothing I personally can do about it. I buy gear also that I wish I could get service information on but can't.
Precisely what a group of us are trying to change. I've been involved with things that resulted in positive change in a countries government before (not this one). But perhaps it can be changed. I believe that the "right to repair" movement is gaining some traction in the USA. Some local laws against you repairing your own farm tractor in some places have been changed. It is a start.
 

valerianf

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Dell lost $300 millions because of bad Chinese capacitors, copies of good Japanese ones.
From what I read in several tear down studies many class D amps are using very low cost Chinese electrochemical capacitors.
It is not surprising that some class D amps are failing after a short time.

Customers need to put pressure on built quality and warranty.
How long is the warranty of a class D module?
 

Graph Feppar

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Hi,

Looking for 2 channel amp to play a few hours 3-4 days a week. Would like to keep it for the next 10-15 years. Are class D amps today reliable enough to last that long without issues? Or should I go with AB amp? Don't really care one way or the other, but obviously my choice would be limited.

Are there any modules that are more reliable than others as far as D-amps go?

Thanks
The number one factor deciding longevity of electronics is heat. Class D is by far the coolest class of amplifiers. That being said, I would bet on high quality class A amp to have longer mean time between failures than cheap class D amp with inexpensive off brand capacitors that also serve as dual purpose fire crackers.

Take for example Stax SRM 1, these things are approaching 4 decades yet still run. They may need to have the capacitors replaced at this point and then they are good to go for another 20 years.
 
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Rick Sykora

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I'll just focus on 3 for the moment: If I have the schematic & was not able to 'readily fix' it, I could definitely go down to one of my local "makers" groups, such as Reforge Charleston: (from them)

LEARN​

We provide a wide range of classes covering everything from sewing to ardunio programming.

WORK​

As a member you have access to a variety of tools such as Laser cutters, 3D printers and CNCs. It is the perfect place to complete any project.

COLLABORATE​

Our members have a plethora of knowledge and experience. If you want to pick up a skill or learn something new, Reforge is the place to go.

Another tack would be the local technical college (who trains in electrical, robotics, computer circuit design, manufacture & repair [not just replacing modules but actual repair] {and a number of folks & groups around that have the equipment to do so}) for Boeing, Robert Bosch, Volvo, Mercedes & many others. I know a man here who has been able to design & make proprietary computer circuits for industry and airplanes since the 1990's. If I can find people to do things like this in the Charleston, SC area: don't you think think that I could find people that are even more capable in cities such as Charlotte or Atlanta, which are both just a short flight or a little longer drive (if you count time going through the airports). Yes, people who want to get it done, certainly can get it done. And many learn to do it themselves & purchase the equipment for their makers group. This presumes that no one can learn how to do this.

Yet people like me and others have been reverse engineering, writing manuals & repairing all sorts of things (such as the latest computer hardware. electronics, Mac, PC's, Phones, Medical Devices & more.

Don't believe me? Go to ifixit.com & see for yourself. I suspect that you will find that there is a segment of the general public that is quite proficient at doing these things, even without having a degree in engineering (mine degree [which I have on occasion found useful, mostly in what not to do] is in Business. I was brought up in a plumbing, heating and AC corporation owned by my parents. I have been part owner or full owner of 3 rather successful corporations myself. But my heart lies in the audio/video fields of acoustics & science (thereby encompassing electronics, computerized & otherwise).

Like retorer-john, some one of us will, at some point in time do it just for fun. It makes it more difficult without a schematic but that stops no one who wants to tear it down. & it might take more than one. But there are certainly people that will figure it out. And publish their results.
Thanks for sharing. This is not unlike work I do already. Btw, also happen to align in favor of having access to schematics. Also, generally in favor of bettering environmental protections too. However, am pragmatic about it as well. If you have major players that do not honor IP and environmental protections, you end up with companies taking it into their own hands.

In any case, IMO, this is all off topic anyway. Some have hypothesized here that Class D is less reliable. I am not sure whether this is true or not. Am just skeptical of any claim without more proof than has been offered to date. Lacking this, further speculation that the intent is to create disposable products seems even less proven. Hypex has stated a position to continue to reduce its carbon footprint and has taken demonstrable actions to do so. But just because they do not supply schematics, does not mean the products are unreliable or are intended to create more waste.

Suggest the Repair Manifesto topic deserves its own thread and this one stick to the OP’s original question please. :)
 

mhardy6647

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The number one factor deciding longevity of electronics is heat.
True of course but slightly misleading. Components built to withstand heat withstand it quite well; it's all relative -- and heat x time degrades the components on a highly electrically efficient Class D module just as it does in a highly inefficient, room-heating vacuum tube Class A power amplifier circuit. The failure of Class D amps, SMPS etc. due to finite capacitor life is an obvious example.

This EICO HF-81 vacuum tube, push-pull EL84 stereo integrated amplifier, as a not entirely random example, is as old as I (and I am old).
It generates lots of heat -- indeed, EICO was 'famous' for using power transformers barely up to the demands of their kits (to keep costs down or to improve their own profit margins, presumably).
This particular HF-81 has had the power tubes changed, electrolytic capacitors replaced due to age, and also its ceramic coupling caps replaced (the latter being a "stylistic" decision; the ceramic caps have essentially infinite lifespans in such an application). Otherwise, it's pretty much as built by some buff in the late 1950s.



Best of all, almost all of its bits and pieces are still readily available and easily replaced. Indeed, the transformer manufacturer, Heyboer, is still around and will happily supply replacement transformers at a reasonable cost. In fact, given the above-mentioned bare adequacy of the PT, I bought myself an uprated replacement from Heyboer a few years after I acquired the amp (for ca. $90 US) as a spare -- just in case. B)
 

Count Arthur

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Is there anything intrinsically less reliable about class D designs?

I realise class D designs are generally more complex and use a greater number of components than class A and A/B and I guess each individual component in the circuit is a potential failure point, so the greater number of components the higher the overall risk of failure. In their favour, class D typically runs cooler.
 

pma

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Is there anything intrinsically less reliable about class D designs?

I realise class D designs are generally more complex and use a greater number of components than class A and A/B and I guess each individual component in the circuit is a potential failure point, so the greater number of components the higher the overall risk of failure. In their favour, class D typically runs cooler.

This post #54 by @restorer-john has settled the important question. In fact the most (and only) valuable post of the thread.
 

Gregss

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Hello,

Seems some are comparing very expensive Class A amps with much cheaper class D amps. Comparing apples to oranges IMHO. There are quality builds in every class and marginal ones as well.

Also, there seems to be a trend to fitting in class D amps into the smallest cases possible. Not good for cooling or keeping RF and magnetic coupling effects from being a problem. May be impressive fitting a 200 watt amp into a miniature case, but is it good design practice?

As far a providing schematics goes: I can understand manufacturers not wanting to provide schematics and service manuals, don't like it, but do understand that they don't want cheap (likely Chinese) companies using them to make their designs and sell them for a fraction of the price. Sadly, is happening and is not an unreasonable fear.

Regards,
Greg
 

Count Arthur

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This post #54 by @restorer-john has settled the important question. In fact the most (and only) valuable post of the thread.
This is an example of some questionable design choices and the dodgy soldering points to poor implementation and insufficient quality control measures, but doesn't really speak to whether class D is intrinsically less reliable.
 
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