I am sick of failing amplifiers

[Atmasphere]

We're also going to see a lot of failures with class D amp years to come. The reason is that many companies build them with very poor cooling, thus components will get over heated

We've already seen it with some only after a few years where they literally cooked, but this will increase after more years have passed. Many of these are simply not build to last.

This isn't true of all class D amps. If designed properly they stay nice and cool even if left on all day long.

I use a Crown class D in my keyboard setup for my band. Its rack mounted on a wooden equipment box so does not have particularly good cooling. I've been running it at least 15 years at this point. It's probably going to need new filter caps before any other failures occur and its already seen a fair amount of abuse. If a class D is built properly it holds up just fine.

I was uneducated to think that tube gear was supposed to be grounded.

If its to follow proper electrical safety rules, like EU Directives, it will be grounded. Proper grounding has nothing to do with tube/solid state. Its just proper grounding. It is true though that a lot of small 'high end' tube equipment producers really don't seem to know how to do grounding and so are copying things they see done in older tube gear made before grounded outlets were a thing; in that regard a bit like the Wild West.

But at the output there is a coil which, together with capacitors, lowers the switching noise to livable levels and there a good deal of heat develops both at idle and especially at high currents. Since class D amplifier modules are typically made physically small, the heat from this coil will in practice heat up the entire module to temperatures that will eventually cause the electrolytic capacitors to dry out.

?? Never heard of this. The coil in our module runs cold and its heating up was never a problem during prototyping.

 

[Bjorn]

You're missing the point Atmasphere. What I said had no relation to class D in general. So no reason to get on the defense. I sell class D amps myself and we take great care in cooling and designing for a long life span. But my point was that it's not the case with many manufacturers of class D, that's very evident.

 

[Kingrex]

I thought most people making quality class d amplifiers were making good amplifiers that will last a very long time.

Class d has the advantage you can create $89 product that will sound very good. Those devices are not expected to last a long time. Probably as long as the $1000 apple phone you bought. Yet it's one tenth the price.

 

[Republicoftexas69]

You're missing the point Atmasphere. What I said had no relation to class D in general. So no reason to get on the defense. I sell class D amps myself and we take great care in cooling and designing for a long life span. But my point was that it's not the case with many manufacturers of class D, that's very evident.

Is it?

But my point was that it's not the case with many manufacturers of class D, that's very evident.

 

[analogsa]

Class d has the advantage you can create $89 product that will sound very good.

Another, even bigger advantage, is that you can then sell it for $8900. You don't even need a nice case or nice termination.

 

[Atmasphere]

You're missing the point Atmasphere. What I said had no relation to class D in general. So no reason to get on the defense. I sell class D amps myself and we take great care in cooling and designing for a long life span. But my point was that it's not the case with many manufacturers of class D, that's very evident.

I'm not on the defense, just straightening out some things, like the comment about chokes. But this comment:

We're also going to see a lot of failures with class D amp years to come. The reason is that many companies build them with very poor cooling, thus components will get over heated

We've already seen it with some only after a few years where they literally cooked, but this will increase after more years have passed. Many of these are simply not build to last.

has a very general feel about it, just so you know. Not sure why you put the post up if your intent wasn't of a general nature.

I thought most people making quality class d amplifiers were making good amplifiers that will last a very long time.

Class d has the advantage you can create $89 product that will sound very good. Those devices are not expected to last a long time. Probably as long as the $1000 apple phone you bought. Yet it's one tenth the price.

That $89 class D can sound OK but 'very good'... well they aren't at the 'excellent' level yet, let's put it that way.

I've tried a pile of them (they're so cheap) but they all have problems, such as noise. They're not supposed to radiate noise, but often an old technique is used to deal with it, called 'lying'; marked with the CE mark but likely wouldn't pass if actually tested. The noise isn't super bad mind you; I've been placing the amps beneath my phono preamp and seeing if I can hear a change in the noise floor (I can) when they are plugged in. For some, its the power supply that is noisy (which makes me wonder how they would sound with a low noise supply but apparently that sort of thing costs real money).

But the writing is on the wall at this point. We have a good quality class D bass guitar amp that has appeared in our studio, which displaced without complaint, a 400 Watt tube bass amp. 15 years ago that wasn't happening. Musical instrument amplifiers are 90-95% of the tube market; when class D gets established in the musical instrument world (and its well on its way right now) the tube producers will be painted into a progressively smaller market.

Another, even bigger advantage, is that you can then sell it for $8900. You don't even need a nice case or nice termination.

Probably not. See above.

 

[DonH50]

Some early class D had "singing" coils, often in the power supply rather than the output filter, but I've not heard that being an issue for several years now. And the issue was basically mechanical integrity rather than coils overheating. What is an issue is the output coupling capacitor; its self-heating is one limitation cited by manufacturers such as Hypex for limiting long-term power ratings of certain modules.

Current class D modules (e.g. Hypex, Purifi) require additional heat sinking to achieve full-power ratings for more than a short time. Some manufacturers are better than others at thermal management; just slapping a module in a case is not always a proper implementation. There have been issues with the thermal connection from output transistors to the heat sink plate of the Hypex module in the past but I do not know if that is a problem with modules sold now. That was at least partly a manufacturing issue. Like any electronic component, (excessive) heat is normally the largest factor in (reduced) lifetime.

Major (and competent) manufacturers are careful in their choice of components, particularly coupling and decoupling capacitors. The high switching rate makes proper capacitor choice (not always the lowest ESR) critical for performance and longevity.

FWIWFM - Don

 

[Atmasphere]

Current class D modules (e.g. Hypex, Purifi) require additional heat sinking to achieve full-power ratings for more than a short time. Some manufacturers are better than others at thermal management; just slapping a module in a case is not always a proper implementation.

We built our class D to be able to do full power into 4 Ohms on an indefinite basis- it can run all day like that without overheating. Proper heatsinks are important with class D amps including GANFET amps; the latter of which can heat up so quickly any moisture trapped in their solderjoints can blow them off the circuit board. So its vital they be properly heatsinked. But that isn't a defect of class D in some way, its simply understanding how it works and designing things properly, as @Bjorn pointed out above.

 

[Audiohertz2]

Class D is acceptable if proper Timbre means naught ...!

 

[Atmasphere]

Class D is acceptable if proper Timbre means naught ...!

This is very similar to saying all solid state amps are bright or all tube amps are muffled and slow.

The same can be said of any class of operation, such as class A. EV made a class B tube amp back in the 1950s that was quite musical. The design was brilliant and solved the usual problem that occurs when a tube amp is class B, having to do with an inductive spike that occurs when the tube cuts off and did it in such a way that the output of one tube was smoothly blended with that of the other so that a bias or balance control for the power tubes wasn't needed.

Reproducing proper Timbre has to do with the amp being properly designed and not the class of operation.

 

[christensenleif@msn.com]

Class D is acceptable if proper Timbre means naught ...!

UTTER BS and reflects complete lack of experience

 

[Audiohertz2]

UTTER BS and reflects complete lack of experience

Utter BS and reflects complete lack of hearing ...!



PS: I will stick with my experiences thank you ..!

 

[Atmasphere]

Utter BS and reflects complete lack of hearing ...!



PS: I will stick with my experiences thank you ..!

Not saying your experience isn't valid, but here's the problem- it has to do with that which you've not heard. Sort of a 'you know what you know, know what you don't know' and that extra bit of 'not knowing what you don't know'. That latter bit exists as a blind spot in terms of human understanding of the world.

Class D amps vary in sound all over the place! Some are bad at low volume, some are outright boring. Some don't seem to have any impact. But others can be quite convincing and easy to listen to all day long.

There are bad class A tube amps out there. They sound bad and a lot of people on this thread have heard them at one time or another as they resided inside portable record players. But would they be accurate in thus saying that all class A tube amps sound bad?

That really seems similar to what you seem to be saying.

 

[Audiohertz2]

This is very similar to saying all solid state amps are bright or all tube amps are muffled and slow.

The same can be said of any class of operation, such as class A. EV made a class B tube amp back in the 1950s that was quite musical. The design was brilliant and solved the usual problem that occurs when a tube amp is class B, having to do with an inductive spike that occurs when the tube cuts off and did it in such a way that the output of one tube was smoothly blended with that of the other so that a bias or balance control for the power tubes wasn't needed.

Reproducing proper Timbre has to do with the amp being properly designed and not the class of operation.

Not its not , its like saying all heavily biased SS Class A amps have a smooth , darker always in controlled sound, guess what , they do ..!

Class D have a fast sound with good jump all good if timbre is not important ...!

Can be harsh when driven
Lacks good bass grounding
Hashy in the top end on cymbals

If you dont hear it , then thats good , Enjoy!

No i haven't heard all class D amplifiers neither have i heard all class A/AB , SET, or PP Toobs .! But I have heard enuff over the years to know the difference ..!

As to class D heard many many demo’s and owned 4 of them myself ..!

Stand behind my assessment and opinions concerning what i like or dislike to hear in Amplifiers ..!

Enjoy

 

[Audiohertz2]

Not saying your experience isn't valid, but here's the problem- it has to do with that which you've not heard. Sort of a 'you know what you know, know what you don't know' and that extra bit of 'not knowing what you don't know'. That latter bit exists as a blind spot in terms of human understanding of the world.

Class D amps vary in sound all over the place! Some are bad at low volume, some are outright boring. Some don't seem to have any impact. But others can be quite convincing and easy to listen to all day long.

There are bad class A tube amps out there. They sound bad and a lot of people on this thread have heard them at one time or another as they resided inside portable record players. But would they be accurate in thus saying that all class A tube amps sound bad?

That really seems similar to what you seem to be saying.

All true and we are here ...!

 

[Atmasphere]

Not its not , its like saying all heavily biased SS Class A amps have a smooth , darker always in controlled sound, guess what , they do ..!

Class D have a fast sound with good jump all good if timbre is not important ...!

Can be harsh when driven
Lacks good bass grounding
Hashy in the top end on cymbals

If you dont hear it , then thats good , Enjoy!

No i haven't heard all class D amplifiers neither have i heard all class A/AB , SET, or PP Toobs .! But I have heard enuff over the years to know the difference ..!

As to class D heard many many demo’s and owned 4 of them myself ..!

Stand behind my assessment and opinions concerning what i like or dislike to hear in Amplifiers ..!

Enjoy

I know of class D amps that aren't harsh and do very well with timbre, play bass quite nicely (flat to 1Hz).

Not taking away from your personal experience. Put another way, because you heard a few of them does not mean you heard all of them in just the same way none of us have heard all the tube amps out there or all the class AB solid state amps. There's just too many!

 

[Bjorn]

Low distortion amps sounds harsh in many systems. Not because they add harshness themselves, but because they reveal flaws in speaker design (which there's a lot of IMO), poor acoustics with high gain specular energy plus the potential weaknesses in the recording/mastering of course.
But that's another topic

As for the topic, buy from brands that offer a long warranty. 1-2 years of warranty of electronics is in reality very short.

 

[Atmasphere]

Low distortion amps sounds harsh in many systems. Not because they add harshness themselves, but because they reveal flaws in speaker design (which there's a lot of IMO), poor acoustics with high gain specular energy plus the potential weaknesses in the recording/mastering of course.
But that's another topic

As for the topic, buy from brands that offer a long warranty. 1-2 years of warranty of electronics is in reality very short.

Or its because they are not actually 'low distortion' on account of how much emphasis the ear puts on higher ordered harmonics (which is to say: quite a lot).

 

[analogsa]

Low distortion amps sounds harsh in many systems. Not because they add harshness themselves, but because they reveal flaws in speaker design

Or is it because of poorly implemented negative feedback, applied with the sole intention of obtaining amazing paper specs?

What is your definition for low distortion?

 

[Atmasphere]

Or is it because of poorly implemented negative feedback, applied with the sole intention of obtaining amazing paper specs?

What is your definition for low distortion?

Feedback is a lot trickier than many designers think!