Class D amp long term reliability

[ahofer]

There are many, many class AB amps in landfills, probably many millions if you count all the stereo receivers over the years they died and were tossed in the trash. I have some old, old gear for sentimental reasons, though I rarely use it now, but there some impediments to restoring old equipment. Figuring out the circuit and what failed, often without a schematic, finding old parts (often discontinued) or replacements, and having or finding someone with the knowledge, skill, and tools to do the repair can be daunting.

I have an Adcom 5802 sitting around that I was able to repair once (just a switch fault), but is unused. There's a guy who restores them, but is simply full up. So here it is. I'm using my 1987 Bryston 3B in one of my setups, but at some point I will tire of the heat, and some lack of speaker protection. So yes, AB can end up in landfills, although I've mostly avoided it so far. Some landfill probably has my old Onkyo integrated from around 1978.

 

[EJ3]

I think you've assumed a lot here that isn't yet in evidence.

That's exactly why I do things the way I do, there is not much evidence either way. But it' is about the TOTAL COST, not just what someone pays to buy it. & If you have to replace it, the time involved, the transportation involved, etc. And the time out of your life that you could be doing something else with (such as enjoying your family or hiking, kayaking or even, yes, you probably guessed it: enjoying your RELIABLE sound system that did not let you down by quitting on you.
Well, the evidence that I have seen (on islands that have power issues) is that the survivability of what I have is way better than the survivability of the other "new" stuff. All of my stuff runs on UPS's. Even so, I once had 45 amp relay blow (due to some unknown surge). It took out one of my 3 NAD 2200's that was idling at the time. But it was easily repairable (with parts that were rounded up from several sources on the island I was residing on island and some other islands).
(& I wouldn't be willing to trade places).
I like it that the temp doesn't vary more than 8 degrees a day & never goes below 73 or over 96 (& rarely gets to either of those extremes) & that the water is so clear that when you throw an anchor off a 20 FT boat in 100 feet of water, that you can see the anchor hit the bottom, & that when ships go by you can see their screws (propellers for you non-mariners) turning.
That CLEAR ocean water is one of the advantages of not trashing your local environment. (We still have some issues with things that you can't see, like e-coli in some areas due to the way waste water is not always done correctly. But we are working on that.
When we make trash, it goes into OUR landfill. So trash, waste, whatever you want to call it, is a daily problem in our lives. Something as simple as car batteries are a major problem. I can't wait to see what happens with electric cars in a place where electrical power is 9 or more times the kilowatt rate of most places in the mainland USA, disposal of those will become quite costly because the hazardous materials can't go into our ground. They will have to be shipped out to somewhere.
In New York City (my wife was there on Oct 7 for a couple of days) your trash disappears from you when you get rid of it from your personal domicile. That just means it becomes someone else's trash to deal with. It is going into a landfill somewhere that will one day be overwhelmed.
When you are living on an island where the minimum temp is 73F & the max is 96 & it is not unusual to take 4 to 6 months to get a replacement part, you will get a good handle on reliability. You ASSUME that everyone is in your physical situation. They are NOT. Nor do they want to be.

 

[EJ3]

We've spent a lot of time on reducing the heat on our Vera Audio amplifiers exactly in order to expand the life span. The PA400/1000 with Hypex modules uses temperature controlled fans which are non audible among other things that we have done to reduce the heat.

One moment, please...

We have shipped a unit to Prosoundtraining for a test and it will be forwared to Amir afterwards.

Well done, I hope that your heat mitigation strategies work.
EJ3

 

[EJ3]

The only car that I got well over 300,000 miles was a 1972 Ford Mustang Grande with a 351 Cleveland engine & a cast iron case FMX 3 speed (3rd was 1:1) automatic. It had the torque to weight ratio to pull the 3.00 final drive gear and keep the engine RPM down. The fuel economy wasn't great but you could fill the tank and know that you were going to get to the end of the tank without issues. I had changed the distributor to electronic & changed the intake & carburetor to a 600 CFM BBL. The death knell was the distributor gear. When it went out, I decided that I did not want to rebuild the engine & sold the car for some pretty good money. At the time I had already moved to island in Oceana & it made 0 sense to import a car to there. I bought a well used base 1996 Ford Ranger 2.3 L truck on one island & a 1980 Mercedes 300D on one of the others.
All of my 8 amps are from the mid-1980's to mid-1990's. 2 NAD 2100's, 5 NAD 2200's & 1 1977 Radio Shack Realistic SA -2000 (& 1 ADVENT 300 receiver) [one of my 2200's & my ADVENT 300 were both given test reviews here by Amirm]. All work fine, as I have done (or had done) as restorer John does.

My 1980 300D Mercedes's (I was running it on restaurant vegetable oil waste on the Island of Saipan) lasted until 2005, when the owner I sold it to used a homebrew bio fuel in it. My 2004 E320 is doing quite well, as is my 2012 Lexus ES350 and my 2000 Nissan Frontier truck. All of these are registered & insured to my mother, my wife & myself, so they see continuous use. They all get a major service each January, whether they need it or not. And minor services according to the heavy duty schedule of the owners manual. All oils & lubes are the appropriate Amsoil ones. I have never had a vehicle do less than 20 years or 225,000 miles (Unless I sold it before then [once I was a collector of vintage vehicles, so buying, selling or trading happened more frequently with those).

 

[antennaguru]

Incandescent bulbs for use in traffic signals came in two power levels; the largest (for the current 12” indication) drew 133 watts. It was rated at 130 volts. Expected life was 8000 hours. The smaller bulbs (for 8” indications) had a life of 10,000 hours.

The LED modules that have replaced the bulb and reflector have an expected life (at 50% reduction in output) of 100,000 hours. And they draw one-tenth the power. They are more expensive to buy, but with lower lifecycle costs. Incandescent bulbs are no longer used by anyone to my knowledge.

Class D has the efficiency advantage going in to reduce lifecycle costs. But I turn my amps off when not in use, so idle draw for me is zero. Heat management is often an implementation issue, however. @restorer-john is there anything you would do to a new Hypex amp to minimize heat issues?

Rick “whose AB amps use unobtanium transistors, by the way” Denney

 

[EJ3]

for example a VW Beetle gearbox was hugely overdimensioned (to several times the nominal engine torque) and would long outlive the engine (wear) and usually the chassis (corrosion) which might sound like "good old quality" but doesn't really make sense as it makes a product unnecessarily expensive and resources consuming.

That was done because so that the ease of just putting a new or rebuilt engine could be done (a 1 hour change out by a couple of competent technicians), in order to not waste the resources of the rest of the car by renewing it. If it was taken care of properly, it would not be much different than a new one. Also, it allowed for (eventually) the Salzburger Super Beetle Rally ([I think 1969] not to be confused with the later model designated Super Beetle in 1971) street legal Rally Car to happen (rumors say a Porsche/Audi type iv engine in place of the original designed VW type 1 engine. There where many people getting close to 30 MPG with more than 200 HP with the parts that were developed by the hot rodders and aviation experimental craft that made it into the type 1 aftermarket and the type iv production engines that made them quite reliable. And they were able to use most of the original cars to do this.

 

[antennaguru]

Two little dirty secrets that are keeping LED traffic light advertised longevity from being realized:
1. Rows of LEDs start failing because the grid of LEDs is divided up into rows of a dozen or more LEDs that use one common current limiting circuit which fails before the row of LEDs, causing blank rows.
2. In cold climates the warmth from the original incandescent bulbs kept the traffic lights from icing over, and the option to install heaters is unattractive from an LED life prrspective.

In any case there is far less than 100% adoption.

Personally I have had a lot of premature LED light bulb failures in our homes, at a fraction of the advertised life of the LED bulbs. I believe it was not the LED itself but the voltage/current limiting circuit that failed. Yes I use about half LEDs but am so far disappointed with their life. I used to bring the failed LED bulbs back to the big box store with the receipt taped to the box for replacement, but now the big box stores stopped taking them back and tell me I have to deal with the manufacturer (even for their own store brand). I guess too many customers were calling them on their lies. All in all a big disappointment from my perspective.

 

[ahofer]

You ASSUME that everyone is in your physical situation

I assumed nothing.

 

[Trell]

For many types of electronics the firmware is an essential part of it, and that’s is one major cause of needless obsolence.

I’ve several Android mobile phones I don’t use because there are no more any security updates. The mobiles where top of the line when I bought them, with at best two years if spotty support.

I switched to iPhone as they provide years more support than Android phones, and now they are just as expensive.

 

[EJ3]

Two little dirty secrets that are keeping LED traffic light advertised longevity from being realized:
1. Rows of LEDs start failing because the grid of LEDs is divided up into rows of a dozen or more LEDs that use one common current limiting circuit which fails before the row of LEDs, causing blank rows.
2. In cold climates the warmth from the original incandescent bulbs kept the traffic lights from icing over, and the option to install heaters is unattractive from an LED life prrspective.

In any case there is far less than 100% adoption.

Personally I have had a lot of premature LED light bulb failures in our homes, at a fraction of the advertised life of the LED bulbs. I believe it was not the LED itself but the voltage/current limiting circuit that failed. Yes I use about half LEDs but am so far disappointed with their life. I used to bring the failed LED bulbs back to the big box store with the receipt taped to the box for replacement, but now the big box stores stopped taking them back and tell me I have to deal with the manufacturer (even for their own store brand). I guess too many customers were calling them on their lies. All in all a big disappointment from my perspective.

That's very interesting about the traffic lights. Don't have to deal with freezing weather but that is more interesting if I ever have to.

 

[EJ3]

I think you've assumed a lot here that isn't yet in evidence.

Just returning the accusation. I have been around enough to know better than assume anything. But since you accused me of it, I thought I'd just throw it back ant you to check your reaction to it. I base my decisions mostly on empirical knowledge. Not what others say about something but what people I know or myself having experienced about something. I am sure that someone either has or working on the Class D issues (which didn't show up initially). It's a learning curve & some may have it down already but some certainly do not. Empirical evidence will eventually cause most of them to be good to great because we will know from associates, friends and family which ones survive in the long term. Until I see more positives than I do now, I'm not buying into it. I don't do the early adopter thing. & I know reason to do anything at all now. If I did have to, it would be a Benchmark ABH2. That may change tomorrow. But that's what it is today.

 

[AdamG]

Enough of the off topic arguing. Back on topic please and thank you.

 

[AdamG]

If the stars properly align. We may have a science project in the works. Where Amir try’s to replicate the inspection accomplished and results posted by @restorer-john in post 54 of this thread. I have sent a pm to the parties involved (@restorer-john, @DonH56 and @amirm) to get the ball rolling.

Amir currently has a brand new 3 module, 6-channel Hypex Nc502mp Buckeye Amp build in his Testing Que. if Amir has time maybe this unit can be inspected to determine if the same build conditions exist. More to follow. Cross your fingers!

 

[Trell]

If the stars properly align. We may have a science project in the works. Where Amir try’s to replicate the inspection accomplished and results posted by @restorer-john in post 54 of this thread. I have sent a pm to the parties involved (@restorer-john, @DonH56 and @amirm) to get the ball rolling.

Amir currently has a brand new 3 module, 6-channel Hypex Nc502mp Buckeye Amp build in his Testing Que. if Amir has time maybe this unit can be inspected to determine if the same build conditions exist. More to follow. Cross your fingers!

Yeah, when I saw that post I thought it was not a QC issue but a design flaw that should have been caught very early on and never have been released as a product. Things like that makes me hesitant to buy anything from them.

 

[rdenney]

Two little dirty secrets that are keeping LED traffic light advertised longevity from being realized:
1. Rows of LEDs start failing because the grid of LEDs is divided up into rows of a dozen or more LEDs that use one common current limiting circuit which fails before the row of LEDs, causing blank rows.
2. In cold climates the warmth from the original incandescent bulbs kept the traffic lights from icing over, and the option to install heaters is unattractive from an LED life prrspective.

In any case there is far less than 100% adoption.

Personally I have had a lot of premature LED light bulb failures in our homes, at a fraction of the advertised life of the LED bulbs. I believe it was not the LED itself but the voltage/current limiting circuit that failed. Yes I use about half LEDs but am so far disappointed with their life. I used to bring the failed LED bulbs back to the big box store with the receipt taped to the box for replacement, but now the big box stores stopped taking them back and tell me I have to deal with the manufacturer (even for their own store brand). I guess too many customers were calling them on their lies. All in all a big disappointment from my perspective.

The only reason there isn't 100% adoption is that some agencies haven't programmed the capital money to do the replacements. But I haven't met one yet that still wants to use incandescent bulbs, which are a maintenance headache. And I meet with state and local agencies routinely all over the country.

Yes, there are issues with the lack of heat from LED traffic signals not providing enough warmth to melt wind-driven snow and ice. I know of agencies that complain about it, but none of them are going back to incandescent bulbs, either. Some use incandescent bulbs for the critical red indication while they thought about the issue, but that was years ago. In critical locations, they are using supplemental heating elements, like the stuff on the rear window of your car.

The current crop (and for a number of years now) use diffusers over the LEDs themselves to meet the color and visual appearance standard of the Institute of Transportation Engineers, which would make it pretty difficult to see if one of the circuits had failed. As it is usually reported to me, however, such failures are more often caused by gunshots, which is why the display is divided into circuits. The problem was worse with the earlier generations, but gunshots are still a problem with all sorts of traffic-control devices.

But traffic signal head acquisitions are usually governed by agency specifications that define the operating temperature as -40 to +70 C, which will demand higher-spec components than in box-store household LED replacement bulbs. This is also the spec for control equipment at the roadside, which is governed by a NEMA standard.

By the way, traffic controllers also have capacitors in them. I have one on a file cabinet running behind me as I type, and it's been running continuously for about 30 years, two-thirds of which was out on the street. It was mentioned already, but capacitors can be specified appropriately to be durable in any given operating environment. But I rather though the issue that John uncovered wasn't so much poor devices (though he did note some) but assembly (or assemblage design) faults that prevented appropriate cooling.

Rick "offering a glimpse of some of what ole' Rick does for a living" Denney

 

[Trell]

The current crop (and for a number of years now) use diffusers over the LEDs themselves to meet the color and visual appearance standard of the Institute of Transportation Engineers, which would make it pretty difficult to see if one of the circuits had failed. As it is usually reported to me, however, such failures are more often caused by gunshots, which is why the display is divided into circuits. [bold added]The problem was worse with the earlier generations, but gunshots are still a problem with all sorts of traffic-control devices.

I didn't see that one coming.

 

[EJ3]

Two little dirty secrets that are keeping LED traffic light advertised longevity from being realized:
1. Rows of LEDs start failing because the grid of LEDs is divided up into rows of a dozen or more LEDs that use one common current limiting circuit which fails before the row of LEDs, causing blank rows.
2. In cold climates the warmth from the original incandescent bulbs kept the traffic lights from icing over, and the option to install heaters is unattractive from an LED life prrspective.

In any case there is far less than 100% adoption.

Personally I have had a lot of premature LED light bulb failures in our homes, at a fraction of the advertised life of the LED bulbs. I believe it was not the LED itself but the voltage/current limiting circuit that failed. Yes I use about half LEDs but am so far disappointed with their life. I used to bring the failed LED bulbs back to the big box store with the receipt taped to the box for replacement, but now the big box stores stopped taking them back and tell me I have to deal with the manufacturer (even for their own store brand). I guess too many customers were calling them on their lies. All in all a big disappointment from my perspective.

I went from incandescent to 100% CFL with a couple of early failures Not a big problem, just 2. My power bill went down (as much because the AC didn't run as hard as the reduced wattage of the CFL's. Then I went to 100% LED with 4 times the failure rate. My power bill eeked down a tiny bit. But total cost of replacements & time to go back & forth to the store set back the total recoupment for the difference to something that may not happen in my life time.
That is exactly what I worry about with Class D. Will a class D amp provide me with the saving that make up for the trouble of replacing modules or the whole thing? Being as I have no need to replace any of my amps at the moment and the track record of CLASS D seems iffy, I'll abstain until I both have a need & the Class D is better as a whole.

 

[AdamG]

If the stars properly align. We may have a science project in the works. Where Amir try’s to replicate the inspection accomplished and results posted by @restorer-john in post 54 of this thread. I have sent a pm to the parties involved (@restorer-john, @DonH56 and @amirm) to get the ball rolling.

Amir currently has a brand new 3 module, 6-channel Hypex Nc502mp Buckeye Amp build in his Testing Que. if Amir has time maybe this unit can be inspected to determine if the same build conditions exist. More to follow. Cross your fingers!

Great news. The stars have aligned for us! Amir has agreed to do the extra visual inspections after amp operational testing is complete. Many thanks to @amirm and @restorer-john for taking on this extra work. Now we just wait for the amp to make its way from the “to do stack” to Amir’s Test Bench.

 

[paulraphael]

I just ran into the class-d / reliability question. My amp for electric bass (an Aguilar TH-500) just started giving me problems. Noise and distortion and reduced output as it starts to warm up. The DI output is fine, so I assume the problem is the power module (an IcePower ASX250-2). A repair guy I talked to agrees it's probably the module, but he hasn't looked at it yet.

I don't get the impression that there's a reliability problem with these modules—the same one is used in several popular bass guitar amps, and there's no lore about trouble, from a community that's pretty vocal about trouble. And it's safe to say these things generally take more abuse than a living room amp. I used mine gently, but I bought it used. Who knows if it came from a Swedish death metal household.

But anyway, the issue isn't about it being broken, but what comes next. The repair guy says the module has to be replaced, and it probably costs close to half the cost of the amp. I asked him if the problem was that he couldn't get a schematic. He said even if he could, it would be above his paygrade—it's all microelectronics and SMDs and stuff that was soldered by robots. I don't know if he was exaggerating, but he was clear on not being able to fix it.

So repairs are automatically expensive. And somewhat wasteful. And dependent on the module continuing to be available. And, thanks to the global supply chain shitstorm, not happening anytime soon—Aguilar estimates they won't have any modules in stock for months.

This isn't a dealbreaker for me. I found another amp (same make and model) on ebay and snatched it. I'll either sell the old one for parts, or repair it when I can and sell later. But this was an eye-opener.

Is this a unique situation with class-d modules, or are other modern amp topologies this proprietary and hard to repair?

 

[bravomail]

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

longevity of the amp has nothing to do with its class.
As for 10-15 years - let's say u buy an amp for $2000. Or u buy Aiyima A07 for $75, which will last 5-10 years. Would u really care about 10-15 years longevity for cheap amp?