I am at a loss.
I read all this lingo about class D and I am not really sure what the purpose of class D is used for as an audio amplifier. I thought it was for high current fast switching maybe in power supplies or SMPS type circuits. Can someone explain why you would want to use class D for audio amp? Obviously it would be more power efficient. I know that, well for a BJT amp, when the load is matched to the output Z for maximum power transfere, the Thevenin equal circuit (simply a current source in series with two impeadences, Z out and Z load), the power to each impeadence is approxamatly equal. What would the Thevenin equal circuit look like for class D?
Is it just power efficiency?
What is a good bandwidth for class D?
What is the harmonic distortion of output, particularly symetric distortion? (relative to BJT or MOSFET amp)
Chris
I read all this lingo about class D and I am not really sure what the purpose of class D is used for as an audio amplifier. I thought it was for high current fast switching maybe in power supplies or SMPS type circuits. Can someone explain why you would want to use class D for audio amp? Obviously it would be more power efficient. I know that, well for a BJT amp, when the load is matched to the output Z for maximum power transfere, the Thevenin equal circuit (simply a current source in series with two impeadences, Z out and Z load), the power to each impeadence is approxamatly equal. What would the Thevenin equal circuit look like for class D?Is it just power efficiency?
What is a good bandwidth for class D?
What is the harmonic distortion of output, particularly symetric distortion? (relative to BJT or MOSFET amp)
Chris
ClassD
I build class-d amps because I need to develop a lot of power and I don't have a lot of space to do it in. Specially no room for heatsinks. However, we did not go class-d until the technology reached our high standards for sound quality. We found the ICE Power amplifers were the first Class D amps that reached this level.
The UcD amps also reach this goal and I have built a 180W per channel amp with them into a single rack space enclosure. The limiting factor was the power supply.
I build class-d amps because I need to develop a lot of power and I don't have a lot of space to do it in. Specially no room for heatsinks. However, we did not go class-d until the technology reached our high standards for sound quality. We found the ICE Power amplifers were the first Class D amps that reached this level.
The UcD amps also reach this goal and I have built a 180W per channel amp with them into a single rack space enclosure. The limiting factor was the power supply.
cunningham said:I am at a loss.
Is it just power efficiency?
What is a good bandwidth for class D?
What is the harmonic distortion of output, particularly symetric distortion? (relative to BJT or MOSFET amp)
Chris
Hi Chris,
I agree with Alain. A well made Class D amp (like the UcD180) sounds better than a well made conventional amp (Accuphase E407) at a fraction of the cost. I have both amps (I also have a Tripath based amp). But the UcD180 very clearly outperforms both the Tripath and the Accuphase. Last year when I bought that Tripath based Marantz (4 channelsfor about $1000), I was really surprised that it ourperformed my far more expensive Accuphase. From that point on I became a Class D believer.
Just try and see (ear).
best regards
Gertjan
cunningham said:I am at a loss.
Is it just power efficiency?
What is a good bandwidth for class D?
What is the harmonic distortion of output, particularly symetric distortion? (relative to BJT or MOSFET amp)
Chris
What would cach your attention to it ? Basicaly its nothing but designing better input stages, it may bee of little interest for some, but others; som know the importance of good design in input stages. Thiese stages can with ease also bee used as innput stages in normal amps. So If the innput- stages develop as for marked demand for it. The development is also there for "analog" amplifiers.
A snapshot from the "scetchboard", just a friday night idea, may i ask for a comment ?
Attachments
sss said:
I see a very good reason: Sound quality.
A good Class D amp really sounds better than a conventional amp. The difference is very significant and very clearly audible even with my not extremely high-end B&W CDM9NT speakers. And as I said in my previous post, the conventional amp that I have is an Accuphase E407, it can`t compete with the UcD180 Class D modules.
Hearing is believing
Gertjan
Commercial technology push
I see a different reason.
The quality criterium goes for all classes of amplifiers. A, AB, B, D, T, etcetera. One can build bad and good amps of all kinds, so forgte the criterium that "Class D" Amps sound better. I don't think that's valid.
Instead, look at the origin. Switchmode amps were originally designed for commercial purposes, as are all amps. Its us freak trying to copy and improve them. So the question is: why were class D amps developed in the first place? I see 3 explanations:
1) High Efficiency.
2) Compact.
3) CHEAP!
Because Switchmode amps can be integrated into one single chip, generating less heat and needing less power for the same output, large amps can be integrated into a single chip, with a minimum of external components. So all you need is a slab of silicium, which practically costs nothing. Large production quantities bring compact high-power amps to the public, and here is your money.
Why did they develop swithcmode amps? because there's money in them
Bouke
I see a different reason.
The quality criterium goes for all classes of amplifiers. A, AB, B, D, T, etcetera. One can build bad and good amps of all kinds, so forgte the criterium that "Class D" Amps sound better. I don't think that's valid.
Instead, look at the origin. Switchmode amps were originally designed for commercial purposes, as are all amps. Its us freak trying to copy and improve them. So the question is: why were class D amps developed in the first place? I see 3 explanations:
1) High Efficiency.
2) Compact.
3) CHEAP!
Because Switchmode amps can be integrated into one single chip, generating less heat and needing less power for the same output, large amps can be integrated into a single chip, with a minimum of external components. So all you need is a slab of silicium, which practically costs nothing. Large production quantities bring compact high-power amps to the public, and here is your money.
Why did they develop swithcmode amps? because there's money in them
Bouke
Re: Commercial technology push
We do know that class T is not an actual class of amplifier, do we not?
Why is anything worth having worth producing? Sure, there's money in it, that's obvious, and so I don't think valide. You are correct, looking at it from a marketing standpoint.
The question is, however, what makes class D worthwhile in the first place, as an audio amplifier?
It simply has possibilities other topologies don't, which can mean far superior sound and at much higher power levels.
Class D has the potential to have near perfect linearity across the entire audio band while maintaining power levels not achievable otherwise.
So ideally, it's class A100.
Bakmeel said:I see a different reason.
The quality criterium goes for all classes of amplifiers. A, AB, B, D, T, etcetera. One can build bad and good amps of all kinds, so forgte the criterium that "Class D" Amps sound better. I don't think that's valid.
Instead, look at the origin. Switchmode amps were originally designed for commercial purposes, as are all amps. Its us freak trying to copy and improve them. So the question is: why were class D amps developed in the first place? I see 3 explanations:
1) High Efficiency.
2) Compact.
3) CHEAP!
Because Switchmode amps can be integrated into one single chip, generating less heat and needing less power for the same output, large amps can be integrated into a single chip, with a minimum of external components. So all you need is a slab of silicium, which practically costs nothing. Large production quantities bring compact high-power amps to the public, and here is your money.
Why did they develop swithcmode amps? because there's money in them
Bouke
We do know that class T is not an actual class of amplifier, do we not?
Why is anything worth having worth producing? Sure, there's money in it, that's obvious, and so I don't think valide. You are correct, looking at it from a marketing standpoint.
The question is, however, what makes class D worthwhile in the first place, as an audio amplifier?
It simply has possibilities other topologies don't, which can mean far superior sound and at much higher power levels.
Class D has the potential to have near perfect linearity across the entire audio band while maintaining power levels not achievable otherwise.
So ideally, it's class A100.
Apart from the fact that there's a lot to be done before this truly ideal amp is real, you are right about this one.
PA systems benefit from class D powerhouses, but these systems are quite a bit different cake than we have in our living room.
If I can build a perfecly linear class B amplifier (just to pick one) with around 200W output, and you build a perfectly linear class D amp with the same output, would we then still need to revert to the efficiency/size argument?
What use do I have with a 3 kW amp in my living room? Sonic preparation of milkshakes?
Or is class D actually the relief for PA systems, which do benefit from a linear high power amp.. ?
Bouke
Bakmeel said:
Apart from the fact that there's a lot to be done before this truly ideal amp is real, you are right about this one.
PA systems benefit from class D powerhouses, but these systems are quite a bit different cake than we have in our living room.
If I can build a perfecly linear class B amplifier (just to pick one) with around 200W output, and you build a perfectly linear class D amp with the same output, would we then still need to revert to the efficiency/size argument?
What use do I have with a 3 kW amp in my living room? Sonic preparation of milkshakes?
Or is class D actually the relief for PA systems, which do benefit from a linear high power amp.. ?
Bouke
For me , the first very important reason is still the sound , no matter the efficiency
Because i listen to very good speakers in a very good room , i've spent a lot of time and money trying all kind of amps ( i need only 100w) , and the best amp i've ever connected on my speakers is the UCD180 , the good news is that it's very cheap
Alain
Bakmeel said:
If I can build a perfecly linear class B amplifier (just to pick one) with around 200W output, and you build a perfectly linear class D amp with the same output, would we then still need to revert to the efficiency/size argument?
What use do I have with a 3 kW amp in my living room? Sonic preparation of milkshakes?
Or is class D actually the relief for PA systems, which do benefit from a linear high power amp.. ?
Bouke
Big IF! Does your fantastic class B compete with a UCD module?
I think we'd revert to the "mine sounds better than yours" admittance. Don't worry I wouldn't rub size or cost into the wound at all.
As for a 3kW amp in house well, ever paint your windows shut? Have to replace shingles? Change a tile floor? Kill rats/cockroaches? Hmmmm Could probably use it to wash your clothes more efficiently.. Vibrating bed.. Automatic Random Furniture and Dish Re-Arranger (patent pending), don't make me go on
Seriously it's a bit much but ~500w per channel leaves you wanting for nothing, depends on the place. Excellent home theatre too I might add. Better to have too much than not enough yes? Good amps in that range are both few, and
~$$, $$$.$$
I wouldn't know... I never built a class B amp, nor have I ever heard a UCD module. I mean to say that for now, it's equally hard to build a perfectly linear class D amp, then it is to build it class B.Big IF! Does your fantastic class B compete with a UCD module?
But the thing is.. we're comparing goats to cows here... Both give milk, but they are quite different animals
I don't really like goatsmilk, to be honest I myself actually favour Class A amps, but you appearantly better like the class D sound... And hey, John Doe would better want a class B in his living room. That story goes for all of us, and that is why a perfect amp will never exist; everyone has a different taste of sound quality. So in the end, I would be happy to have class D amps in the house as well as class A, B, etc.
So if the quality argument is personal for all of us... Can we then justify the development of Class D as something like an extra choice in the collection of amps?
Bouke
so what?
Bakmeel,
So you come to a class D forum just to declare that you prefer class A to class D, even though you have not heard a class D amp before?
Apart from the fact that discussing class A vs class D in these terms is a bit pointless (there are excellent and there are crappy class A amps; the same could be said of class D amps), people here are simply saying that they find a particular type of class D amp (UcD) to be better than many other (class D, Ab, whatever) amps. And that well-designed class D amps can sound excellent, and cost relatively little money in terms of purchse cost and electricity bills (nice for those of us who are of an ecological persuasion...).
Nobody is going to force you to own a class D amp. Peace, man!
Goliardo
Bakmeel,
So you come to a class D forum just to declare that you prefer class A to class D, even though you have not heard a class D amp before?
Apart from the fact that discussing class A vs class D in these terms is a bit pointless (there are excellent and there are crappy class A amps; the same could be said of class D amps), people here are simply saying that they find a particular type of class D amp (UcD) to be better than many other (class D, Ab, whatever) amps. And that well-designed class D amps can sound excellent, and cost relatively little money in terms of purchse cost and electricity bills (nice for those of us who are of an ecological persuasion...).
Nobody is going to force you to own a class D amp. Peace, man!
Goliardo
Neither have I to be honest but I soon intend to.
I trust you've at least tried goatsmilk before you condemned it?
Tastes like the farm doesn't it?
) I'm sure, as the reasonable person you seem to be, would do the same for class d amps, not just the "boomers" for car audio either but the decent full range ones.
They aren't what they used to be, and there's a good chance you'll find yourself having a new preference, don't just say you don't like them because you're afraid of change or going against the grain.
It's probably harder to build a good class d amp, thankfully we can buy them cheap
I agree with a lot your points however.
Personally, an issue of mine is that class A just doesn't have the power I'm after. If you forget efficiency for a second, and just look at quality for the dollar, it's easy to see the one alternative I'm left with.
The average man's affordable amp is pure garbage, and I am really displeased with them. People really pay for garbage when it comes to audio, all those flashing lights blind them from the inflated price tags. Seems people could care less what they had to endure listening to, and most just don't know any better, the audio industry largely are a pack of wolves who thrive on it.
Honestly I feel if you want high quality at a reasonable price, you really only have one choice, and it's not a choice we had all that long ago either, so yeah I'm happy for it, just spreading the news
Someone has to, classd.org just keeled over and died, it hasnt' been updated in the longest time anyway..
You likely have the best answer for the "why class d" question, it "is" an alternative.
Btw, say in 5 years, class d will have fully infested the market because they are so cheap to produce and getting better in quality all the time. They wont' be able to make anything else and stay competitive. Anyone wanting a different type of amp will be hitting yard sales and antic shops with the tube guys, so you may as well come to the dark side now, while you can do it with dignity.
Cheers
Bakmeel said:
I wouldn't know... I never built a class B amp, nor have I ever heard a UCD module. I mean to say that for now, it's equally hard to build a perfectly linear class D amp, then it is to build it class B.
But the thing is.. we're comparing goats to cows here... Both give milk, but they are quite different animals
I myself actually favour Class A amps, but you appearantly better like the class D sound... And hey, John Doe would better want a class B in his living room. That story goes for all of us, and that is why a perfect amp will never exist; everyone has a different taste of sound quality. So in the end, I would be happy to have class D amps in the house as well as class A, B, etc.
So if the quality argument is personal for all of us... Can we then justify the development of Class D as something like an extra choice in the collection of amps?
Bouke
Hello Bouke,
As another Dutchman on this board, I have only one thing to say: I did not want this UcD180 module to sound better than my $4000 Accuphase E407 integrated amp (considered high-end by many). But the simple fact is that it does sound better and not by a small margin. In fact, my experience with all Class D amps that I have had in my living room this far (Tripath based Marantz, ZAPpulse and UcD180) that all 3 of them sound better than the Accuphase. Both the UcD180 and the ZAPpulse are better sounding than the Marantz.
My reason to switch to Class D is not based on cost, size or whatever, purely based on sound quality.
I hope you really get a chance to compare a UcD based system with any conventional amp. I`m quite sure you will be surpirised.
Best regards
Gertjan
Goliardo, Ghemink,
Don't get me wrong here. I never intended to say that Class D is bad and/or Class A is better. If we started thát discussion, it would surely end up in a serious fight with moderators binning the lot of us. That is why I want to avoid the "It sounds better" aspect in this discussion. It is too personal for all of us.
The term "quality" should not be mistaken with "it sounds better". Quality has a broad definition, but if we want a clear definition of quality, don't start about how it sounds. If you tell me that your amp sounds great, I'm prefectly happy for you. But does that make an amp "better"?
So here I am, never ever heard a Class D amp, (do actually intend to build one soon), and I find this very interesting question "why class D?". And since I like a good discussion, here I am
So, back on topic:
Classd4sure, I'm right behind you. Class D is here because it is the market for the masses that demands it. It is also here, because it gives us more choice on what to buy or build. And last but not least, it is here because it sometimes IS quite handy to have kilowatts of power in a small box.
But I don't think all other classes are doomed. At least, not while there are still enthusiasts buying and making them. Like the single ended class A, like tube amps, like Vinyl records. They just don't want to die, and that is a good thing
Merry Christmas!
Oh BTW: classd4sure, Have you ever tried goatscheese? Now thát tastes gooood
Don't get me wrong here. I never intended to say that Class D is bad and/or Class A is better. If we started thát discussion, it would surely end up in a serious fight with moderators binning the lot of us. That is why I want to avoid the "It sounds better" aspect in this discussion. It is too personal for all of us.
The term "quality" should not be mistaken with "it sounds better". Quality has a broad definition, but if we want a clear definition of quality, don't start about how it sounds. If you tell me that your amp sounds great, I'm prefectly happy for you. But does that make an amp "better"?
So here I am, never ever heard a Class D amp, (do actually intend to build one soon), and I find this very interesting question "why class D?". And since I like a good discussion, here I am
So, back on topic:
Classd4sure, I'm right behind you. Class D is here because it is the market for the masses that demands it. It is also here, because it gives us more choice on what to buy or build. And last but not least, it is here because it sometimes IS quite handy to have kilowatts of power in a small box.
But I don't think all other classes are doomed. At least, not while there are still enthusiasts buying and making them. Like the single ended class A, like tube amps, like Vinyl records. They just don't want to die, and that is a good thing
Merry Christmas!
Oh BTW: classd4sure, Have you ever tried goatscheese? Now thát tastes gooood
Bakmeel,
The thread started because cunningham had questions about the use of class D for audio amps, apart from the obvious benefit of efficiency.
Few members replied that in addition to efficiency and cost, sound quality is is another reason. Some forum members said that class D amps sound better than amps of other typologies, other members simply sound that sound quality can be excellent.
At this point you jumped in and argued that amps of any class can sound good (which I agree with, but I do not think that previous posts had argued that class D is inherently superior) and that the only reason is money.
Most people would agree with that money and cost/efficiency are among the reasons. But, member replied for the second time, sound quality is also very good. So, the argument went, the advantage is great sound AND cost/efficiency. If you really wanted to have a meaningful discussion, rather then picking arguments, you might have left it at that.
Instead, you followed up by saying that one can build any class amp to sound good, and that it is just a matter of preference (you prefer class A, which people may or may not like to know), and why would we bother with efficiency.
It is both the selective mode of your replies (i.e., just picking on things you could argue about), and ignoring other points (that the advantage of class D amplifiers is that they sound great, and can cost much less for similar sound quality) that makes me think this is not the way to have a meaningful discussion
.
This is why I find your claim that you just want to have "a good discussion" rather disingenuous. I do not think there is anything more to discuss (in fact, the summary-cum-conclusion at the end of your message seems to imply just that). And let's leave Christmas and goat cheeses to where they belong...
Ciao,
Goliardo
The thread started because cunningham had questions about the use of class D for audio amps, apart from the obvious benefit of efficiency.
Few members replied that in addition to efficiency and cost, sound quality is is another reason. Some forum members said that class D amps sound better than amps of other typologies, other members simply sound that sound quality can be excellent.
At this point you jumped in and argued that amps of any class can sound good (which I agree with, but I do not think that previous posts had argued that class D is inherently superior) and that the only reason is money.
Most people would agree with that money and cost/efficiency are among the reasons. But, member replied for the second time, sound quality is also very good. So, the argument went, the advantage is great sound AND cost/efficiency. If you really wanted to have a meaningful discussion, rather then picking arguments, you might have left it at that.
Instead, you followed up by saying that one can build any class amp to sound good, and that it is just a matter of preference (you prefer class A, which people may or may not like to know), and why would we bother with efficiency.
It is both the selective mode of your replies (i.e., just picking on things you could argue about), and ignoring other points (that the advantage of class D amplifiers is that they sound great, and can cost much less for similar sound quality) that makes me think this is not the way to have a meaningful discussion
. This is why I find your claim that you just want to have "a good discussion" rather disingenuous. I do not think there is anything more to discuss (in fact, the summary-cum-conclusion at the end of your message seems to imply just that). And let's leave Christmas and goat cheeses to where they belong...
Ciao,
Goliardo
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