What are the reasons to choose Class A/AB/H over D in this day and age?

[DimitryZ]

Your facility probably isn't involved in audio component manufacturing. We send all our boards out for SMD stuffing but there are a few operations which have to be done by hand or flow soldered with through-hole parts, leads, power transistors etc.

Radar and missile stuff, mostly.

And there is some hand soldering for magnetics, but we try to avoid that as much as possible.

The boards can be expensive enough that a repair is done for a failed component. I once watched a hand replacement of a failed small BGA - maybe 30-40 balls in a small package - less than 1/2". It was really skilled work, which was checked for quality in a " flying head" X-ray station. Alignment before heating was also X-ray assisted.

 

[sq225917]

I can do down to 0204 by eye, but multipin stuff gets hard, soic8 is OK, smaller nah...

 

[Rottmannash]

My viewpoint is perhaps colored by the fact that, when things broke in the old days and I got my "spanners" (wrenches, screwdrivers, soldering irons, etc.) out to fix them, I actually broke them irreparably. So there's that.

And that's how I got into electronics-to try to discover how to put all those turntables, speakers and receivers back together I broke taking them apart.

 

[antennaguru]

My cars in the 80s and 90s broke all the time.

My cars today almost never break.

I definitely don't miss being under the car with a wrench.

300k miles in northern latitudes is not possible without a garage, unless you drive crazy number of miles a year. The car simply rusts away.

I do still get 300K miles out of my vehicles in the northern latitudes, and yes, road salts hurt them, and yes, I have a 4 car garage at one of my houses.

 

[DimitryZ]

I do still get 300K miles out of my vehicles in the northern latitudes, and yes, road salts hurt them, and yes, I have a 4 car garage at one of my houses.

That's the way to do it!

Our next house will have a two car garage, hopefully.

 

[MaxBuck]

That's the way to do it!

Our next house will have a two car garage, hopefully.

What you really want is room for two cars and at least one golf cart.

 

[mhardy6647]

What you really want is room for two cars and at least one golf cart.

You know -- living in the comparative wilds of northern New Hanpshire... I've never wanted for a golf cart.
A four-wheeler or 4WD tractor, yes -- but not a golf cart.



^^^ that's what springtime looks like on the road to our house.
(for reference, our driveway is on the right, at that flat-ish spot along the road, just before the white birch)

 

[MaxBuck]

You know -- living in the comparative wilds of northern New Hanpshire... I've never wanted for a golf cart.



^^^ that's what springtime looks like on the road to our house.

Your garages need to be relocated to a more congenial climate.

 

[mhardy6647]

Your garages need to be relocated to a more congenial climate.

yeah, but then I'd need to commute to the garage!

 

[hyfynut]

FWIW the last time I was in EU skiing I noticed the prevalence of plug-in electric space heaters being used indoors. Maybe they should just use more Class A amplifiers for heating assistance.

So myopic the viewpoints I’m seeing here.

Well, there's the gigantic price difference between the space heater and the class a amplifier...

 

[mhardy6647]

Well, there's the gigantic price difference between the space heater and the class a amplifier...

Yeah, but the latter have that little incremental boost in efficiency by providing some music along with the heat.
Very green.

 

[antennaguru]

Well, there's the gigantic price difference between the space heater and the class a amplifier...

Sure, and also the vast difference in heat output that is directly related to the cost of operation. Furthermore electric space heaters seem to wear out a lot faster than Class A amplifiers, like by a factor of 10X as often - so multiply the price of the space heater 10X to get an equivalent cap ex cost to that of 1 Class A amplifier. A 220 VAC (14K BTU) space heater will cost in the area of $100 per month to operate intermittently during the cold months. That's what mine costs to operate.

Back in post #60 I compared the monthly operating costs of a bunch of different amplifiers. The Class A amplifier cost what was around the equivalent of buying one cup of latte from Starbucks per month, to operate. Meanwhile, the Class AB and Class D amplifiers were all within around two cents per month of each other, and all cost under seventy cents or so per month to operate.

Certainly the savings here (cost/energy) is not going to even move the meter when it comes to slowing down the Earth's progression out of its last Ice Age, the Ice Age it is still currently in (evidenced by the fact that there are still glaciers on Earth). The progression out of the Ice Age is kind of like a boulder naturally rolling down a slope - man has certainly run up behind that boulder and given it some shoves which have slightly accelerated its natural velocity down the slope. However, to try running around and out in front of the boulder, and then try slowing it down or stopping it is impossible as man will simply get run over by the boulder. The best we can do is to stop some shoving, and then the velocity out of the Ice Age only slightly slows to its previous natural velocity coming out of the Ice Age.

 

[DimitryZ]

Sure, and also the vast difference in heat output that is directly related to the cost of operation. Furthermore electric space heaters seem to wear out a lot faster than Class A amplifiers, like by a factor of 10X as often - so multiply the price of the space heater 10X to get an equivalent cap ex cost to that of 1 Class A amplifier. A 220 VAC (14K BTU) space heater will cost in the area of $100 per month to operate intermittently during the cold months. That's what mine costs to operate.

Back in post #60 I compared the monthly operating costs of a bunch of different amplifiers. The Class A amplifier cost what was around the equivalent of buying one cup of latte from Starbucks per month, to operate. Meanwhile, the Class AB and Class D amplifiers were all within around two cents per month of each other, and all cost under seventy cents or so per month to operate.

Certainly the savings here (cost/energy) is not going to even move the meter when it comes to slowing down the Earth's progression out of its last Ice Age, the Ice Age it is still currently in (evidenced by the fact that there are still glaciers on Earth). The progression out of the Ice Age is kind of like a boulder naturally rolling down a slope - man has certainly run up behind that boulder and given it some shoves which have slightly accelerated its natural velocity down the slope. However, to try running around and out in front of the boulder, and then try slowing it down or stopping it is impossible as man will simply get run over by the boulder. The best we can do is to stop some shoving, and then the velocity out of the Ice Age only slightly slows to its previous natural velocity coming out of the Ice Age.

Ahh, you are a "natural causes" man. Nothing to be concerned about - party on!

 

[Trell]

Oh, so taxing extra to introduce a penalty for not complying with green initiatives is a good solution? How about introducing an actual incentive for lower utilization?

It’s a combination of both.

Also, what are they doing with that extra taxation they collect?

The point of the taxes and incentives is to change behavior.

 

[hyfynut]

Sure, and also the vast difference in heat output that is directly related to the cost of operation. Furthermore electric space heaters seem to wear out a lot faster than Class A amplifiers, like by a factor of 10X as often - so multiply the price of the space heater 10X to get an equivalent cap ex cost to that of 1 Class A amplifier. A 220 VAC (14K BTU) space heater will cost in the area of $100 per month to operate intermittently during the cold months. That's what mine costs to operate.

Back in post #60 I compared the monthly operating costs of a bunch of different amplifiers. The Class A amplifier cost what was around the equivalent of buying one cup of latte from Starbucks per month, to operate. Meanwhile, the Class AB and Class D amplifiers were all within around two cents per month of each other, and all cost under seventy cents or so per month to operate.

Certainly the savings here (cost/energy) is not going to even move the meter when it comes to slowing down the Earth's progression out of its last Ice Age, the Ice Age it is still currently in (evidenced by the fact that there are still glaciers on Earth). The progression out of the Ice Age is kind of like a boulder naturally rolling down a slope - man has certainly run up behind that boulder and given it some shoves which have slightly accelerated its natural velocity down the slope. However, to try running around and out in front of the boulder, and then try slowing it down or stopping it is impossible as man will simply get run over by the boulder. The best we can do is to stop some shoving, and then the velocity out of the Ice Age only slightly slows to its previous natural velocity coming out of the Ice Age.

Wow that's an incredibly long reply that I'm not sure really got us anywhere?

 

[H-713]

You don't even need hot air for rework of something like 8 pin or 16 pin SOIC if you are not doing a lot of rework. Just pull up one leg at while heating with an iron to get them off and put the new one one with an iron. I never got the hang of hot air and this is how I do the minimal rework I have to do on those kind of parts. 1206, 0805, 0603 size resistors and caps are so easy that I don't know why anyone would rather deal with through hole.

I've gone mostly to SMD for my own projects. Desoldering 1206 resistors is way easier than dealing with plated through-holes.

Gone back to a lot of through-hole chips recently though, mostly because I have them, and their SMD counterparts are backordered for 18 months...

 

[jmillar]

The problem I see is "durability" of modern products. This is not just a "Class D" problem. Durable goods - such as washers and dryers - don't hold up like they used to. I am okay with paying more and getting reliability. Designs made to be reparable are worthwhile in the "Big Picture".

Yep, agree. "Durable goods" produced today are "better" but less "durable". This is a problem with practically every manufactured product, even at the "high end". CAD allows you to design and build very close to the "ragged edge". And things go "over the edge" more often than before. They DO cost less, though. Can't say I'm exactly happy. Durability remains a concern and should be a design target.

 

[Holmz]

Yep, agree. "Durable goods" produced today are "better" but less "durable". This is a problem with practically every manufactured product, even at the "high end". CAD allows you to design and build very close to the "ragged edge". And things go "over the edge" more often than before. They DO cost less, though. Can't say I'm exactly happy. Durability remains a concern and should be a design target.

Our Miele washing machine has lasted 20 years, and the dishwasher 15 or more.
And the Euro made refrigerator also is ~20 years old.

They were not cheap though.

 

[storing]

Yup. I used to be an adept of the '(almost) everything used to be more durable' crowd but I'm getting more hesitant which such claims now, just because of counter examples I personally experienced. Granted there is huge market with crap, and people just have more stuff in general, and there is also more variety in stuff to buy. But at the same time I have the impression that for a lot of items out there (especially the ones I actually need and use) one can just look somewhat further and find a similar item which lasts a long time.

Also: repairability can be orthogonal to durability. Really depends. I'm all for repairability of course, but I also have stuff lying around which is not repairable at all, or only small bits of it, yet lasts forever. Especially when looking broader than electronics.

 

[jmillar]

Reading about all the benefits around Class D amp's i was on the brink to replace my 20 year old NAD C370 for such D amp. Than the cost of repairing the NAD was so cheap that i repaired it for less than 50,- Euro (protection circuit capacitor plus some others be replaced ). After 2 years it's still going strong. I got a price if the NAD really breaks down total recapping with better parts than the original around 3 a 400,- Euro an it runs for another 20 years or probably longer due to the better parts. No wast whatsoever.

Ok, it makes sense. But a well designed "class D" well built with good components and enough margin for stress should in theory have a good service life.