Integrated Amp discussion...

[John Parks]

In my experience ignored member can still send a message which I found even more annoying. You'll also experience some weird stuff from time to time like a member appearing to bicker with himself as you'll see only one side to the story.

Really? I bicker with myself every day, so no biggie!

 

[John Parks]

If Crown, ATI, Bel Canto's not digital enough for you, try Lyngdorf's.

Oh my - Lyngdorf! I would really like to hear this beauty. Digital, totally.

 

[lovinthehd]

If Crown, ATI, Bel Canto's not digital enough for you, try Lyngdorf's.

Elaborate if you are saying class D is defined as digital....

 

[Irvrobinson]

I do. A brick wall filter that occurs before the power amplification stage is reasonable, as PCM audio uses, but a filter that has to exist after the power amplification stage for measurements (apparently) to look good for marketing purposes makes me suspicious. I've never seen an article that compares filtered and unfiltered measurements of a full-range Class D amplifier to highlight why the filtering is specified. If I did, and the artifacts were really innocuous, I might become an advocate. The weight and power dissipation of my ATI 3000-series amp are not attractive attributes.

Thanks to @BoredSysAdmin for pointing us at the audiosciencereview.com site. In this thread:

https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-hypex-nc400-diy-amp.5907/page-4

Amir measures the nc400 broadband (no filtering),and the high frequency distortion anomalies, while present, are at a low-enough level to quell my paranoia. At least for Hypex-based Class D amps I'm setting aside my concerns. I'm not going to rush out and replace anything, but now I see what ATI sees in Ncore modules.

(As an aside, Amir, site founder and also founder of Madrona Digital, is the shop I purchased my Salon2s from in 2009. My local dealer was useless. I see he also uses the identical models, even in black, as I have.)

 

[JerryLove]

I totally agree that the future is in Class D. There are too many benefits to overlook. Engineers have done truly exceptional work to date to iron out the bugs, but development must continue. Then, and only then, will Class D topologies be able to convincingly replace Class A and AB designs.

You seem to be relying heavily on the single EE article, which was published 13 years ago.

Even if we accept the opinions of the article as accurate, given the consensus, including from you, that the tech "will improve"; hasn't it?

The movement over the last 10 years of even many prestige brands to class D and its derivatives like class H would seem to indicate a market full of competent engineers that have come to that conclusion.

As for fidelity... faithful to what? A THX theater is using class D (or a variant). They all are and have been for a long time. A home theater is intended to match the non-home theater. Concerts have been Class D for a long time as well. How shall we reproduce a concert.

I've not heard the concerns being described play out in production units I've listened to in the last decade. Perhaps I don't know what I should be listening for to identify it (and by extension, cannot tell you it does or does not effect my listening enjoyment); and I'm well aware of the concerns over older class D amps (though to what extent they were in audibility, I don't know, I wasn't using them at the time), but of practical issues, I've seen little to nothing.

 

[highfigh]

Oh my - Lyngdorf! I would really like to hear this beauty. Digital, totally
View attachment 28370

Have you heard the full blown Steinway-Lyngdorf system?

 

[Andrein]

There are lots of choices available around amplifiers. If you are concerned about class D, you can choose one of a, ab amplifiers. There is no lack of them on the market. Even if ererybody says class d is good, buy the one which does not make you worry about potential drawbacks.

 

[John Parks]

Have you heard the full blown Steinway-Lyngdorf system?

Unfortunately, no - but it looks great (and expensive). I am trying to figure out the relationship between Steinway Lyngdorf and Lyngdorf Audio...

 

[highfigh]

Unfortunately, no - but it looks great (and expensive). I am trying to figure out the relationship between Steinway Lyngdorf and Lyngdorf Audio...

The relationship is, Steinway makes the furniture which, admittedly, matters only when looking at it, and Lyngdorf makes the electronics, but holy crap! I heard the system at CEDIA in '05, in the big hall when they were still in Indianapolis. Over the din and from a distance, I heard a piano playing and it really sounded like a piano, not reproduced music. It was almost like an old cartoon, where someone smells something and some kind of smoke takes them by the nose as the person floats to the source. As I moved closer, it still sounded like a real piano and when I stood closer to them, it STILL sounded like a real piano!

 

[PENG]

The relationship is, Steinway makes the furniture which, admittedly, matters only when looking at it, and Lyngdorf makes the electronics, but holy crap! I heard the system at CEDIA in '05, in the big hall when they were still in Indianapolis. Over the din and from a distance, I heard a piano playing and it really sounded like a piano, not reproduced music. It was almost like an old cartoon, where someone smells something and some kind of smoke takes them by the nose as the person floats to the source. As I moved closer, it still sounded like a real piano and when I stood closer to them, it STILL sounded like a real piano!

Their theory sounds good (practically too I guess, based your audition experience) though understandably not much details on their website. That means potentially, if not yet, it should be an excellent alternative to some of the excellent class D amps such as Bel Canto's.

 

[GrimSurfer]

I was away for three days, though not by choice having been locked out for " trolling" on this thread. Not sure if I did that... but my incessant use of Central American revolutionary rhetoric was intended to make a very specific point: The stupidity of blind acceptance, particularly when it is based on political or commercial interest.

Maybe this point was too subtle to be recognized for what it was.

You seem to be relying heavily on the single EE article, which was published 13 years ago.

Even if we accept the opinions of the article as accurate, given the consensus, including from you, that the tech "will improve"; hasn't it?

The movement over the last 10 years of even many prestige brands to class D and its derivatives like class H would seem to indicate a market full of competent engineers that have come to that conclusion.

As for fidelity... faithful to what? A THX theater is using class D (or a variant). They all are and have been for a long time. A home theater is intended to match the non-home theater. Concerts have been Class D for a long time as well. How shall we reproduce a concert.

I've not heard the concerns being described play out in production units I've listened to in the last decade. Perhaps I don't know what I should be listening for to identify it (and by extension, cannot tell you it does or does not effect my listening enjoyment); and I'm well aware of the concerns over older class D amps (though to what extent they were in audibility, I don't know, I wasn't using them at the time),but of practical issues, I've seen little to nothing.

I used a 13 year old article from a professional engineering journal to make another point, perhaps one where the message was lost in its subtlety.

Class D amplification started in the late 1950s. At that time, the central design goal was to solve a specific problem: power efficiency. It was successful due to a great deal of focus by talented engineers.

Like many engineering endeavours, it solved one problem (power) but creating others (TIM, switching noise, non-linearity). This was hardly important to 90% of the engineering effort because they were focused on electrical efficiency. This electrical efficiency reduced heat, which reduced heat sink mass and volume, which reduced weight and physical size on a watt-per-watt basis.

This saved money in materials, shipping, electricity, air conditioning, is why they're great for so many applications where such things are important, including theatres (cost of power, aircon),live music (power, weight),and mobile devices (power, weight, size).

The reason why I used a 13 year old article was to demonstrate a very important point: The problem had not been solved after 45 years of development.

There's a very good reason for this: The problems of non linearity and certain kinds of distortion are *inherent* to the design of Class D topologies (a point made in the article). Just as certain problems and their sonic effects are inherent to the nature of Class A (power inefficiency, heat, low order distortion) and Class AB amplifiers (crossover noise and power inefficiency).

I'd be a little less sceptical of Class D amps if manufacturers of such devices included specs on linearity, TIM, induced noise from smps etc. But they very often don't.

I'm not sure whether they solved these inherent problems so long ago that they no longer matter -or- they simply don't want to talk about them because they've yet to address them. I suspect the latter because many of those same companies continue quote specifications that matter for their Class A and/or AB products (when/if they produce them).

This view on the limitations of Class D topologies may/may not apply to all such amps out there. I do, however, adopt a certain scepticism when people dismiss inherent design issues that weren't resolved after 45 years of trying... especially when audio component manufacturers don't appear to address them in their product specs. Until they do, I'm not confident that the problems inherent to Class D amplifiers have been resolved to the level needed to outperform AB amps in sonic quality.

This is obviously a very broad generalization and does not mean that a very expensive Class D cannot beat a very inexpensive AB. But dollar for dollar, I still believe that AB is superior in most areas other than power efficiency, heat, and packaging potential until proven otherwise.

So while my use of revolutionary rhetoric didn't make anyone here want to become a Sandanista, others' unsubstantiated assertions that all of the problems inherent to Class D topologies have been resolved isn't going to make anyone switch over (pun intended). In some cases, brick wall filters may help, but that only touches on one of several issues affecting Class D design.

 

[JerryLove]

Class D amplification started in the late 1950s. At that time, the central design goal was to solve a specific problem: power efficiency. It was successful due to a great deal of focus by talented engineers.

Like many engineering endeavours, it solved one problem (power) but creating others (TIM, switching noise, non-linearity). This was hardly important to 90% of the engineering effort because they were focused on electrical efficiency. This electrical efficiency reduced heat, which reduced heat sink mass and volume, which reduced weight and physical size on a watt-per-watt basis.

Although the primary area for improvement was cost/efficiency; it's certain that this was not the only criteria for the end product.

The product, after all, had to be usable in it's intended role of amplifying signals to power speakers for listening.

Consensus when I got into audio was that Class D amplifiers did have limitations/issues. Whether that was factual or not, I do not know. But since then, many of the same people and companies that avoided Class D (and similar) have embraced them stating that the issues are resolved.

I know only my own experience and that I cannot hear issue with any of the ClassD/ClassH/ClassT amplifiers I use. When run within their abilities, they sound the same as the class AB amplifiers I use.

The reason why I used a 13 year old article was to demonstrate a very important point: The problem had not been solved after 45 years of development.

Nor had rockets that could land under power and be re-flown with minimal prep.

But then it was.

Electric cars were a century old and the problems of creating practical, long-range vehicles hadn't been solve.

But then they were.

Solar power hadn't been able to get its costs below the competition because of problems inherent in the manufacturing process.

But then it did.

While I would not expect you to assume that the problems were gone; I would have expected that you agreed it was possible.

There's a very good reason for this: The problems of non linearity and certain kinds of distortion are *inherent* to the design of Class D topologies (a point made in the article). Just as certain problems and their sonic effects are inherent to the nature of Class A (power inefficiency, heat, low order distortion) and Class AB amplifiers (crossover noise and power inefficiency).

If you have a mathematical proof that such issues cannot be reduced below audibility I would love to see it.

Shy of that you are, repeatedly, saying "there are challenges that might be hard to solve".

Until they do, I'm not confident that the problems inherent to Class D amplifiers have been resolved to the level needed to outperform AB amps in sonic quality.

That's fine and appropriate.

But there's a difference between "I've not been convinced that X has occurred yet" and "X hasn't occurred".

Have you done critical listening to reputable class D (or derivative) amps manufactured in the last 5 years? Say Yamaha P-series amps, for example. Can you hear the distortions you are describing when you listen?

If so, I would have expected your post to be less revolutionary rhetoric and more personal narrative backed by numbers.

 

[GrimSurfer]

Although the primary area for improvement was cost/efficiency; it's certain that this was not the only criteria for the end product.

The product, after all, had to be usable in it's intended role of amplifying signals to power speakers for listening.

Consensus when I got into audio was that Class D amplifiers did have limitations/issues. Whether that was factual or not, I do not know. But since then, many of the same people and companies that avoided Class D (and similar) have embraced them stating that the issues are resolved.

I know only my own experience and that I cannot hear issue with any of the ClassD/ClassH/ClassT amplifiers I use. When run within their abilities, they sound the same as the class AB amplifiers I use.


Nor had rockets that could land under power and be re-flown with minimal prep.

But then it was.

Electric cars were a century old and the problems of creating practical, long-range vehicles hadn't been solve.

But then they were.

Solar power hadn't been able to get its costs below the competition because of problems inherent in the manufacturing process.

But then it did.

While I would not expect you to assume that the problems were gone; I would have expected that you agreed it was possible.


If you have a mathematical proof that such issues cannot be reduced below audibility I would love to see it.

Shy of that you are, repeatedly, saying "there are challenges that might be hard to solve".


That's fine and appropriate.

But there's a difference between "I've not been convinced that X has occurred yet" and "X hasn't occurred".

Have you done critical listening to reputable class D (or derivative) amps manufactured in the last 5 years? Say Yamaha P-series amps, for example. Can you hear the distortions you are describing when you listen?

If so, I would have expected your post to be less revolutionary rhetoric and more personal narrative backed by numbers.

For starters, I'm not here to prove that Class Ds are better or worse than ABs. I am saying that by the nature of their design, they are prone to issues that do not affect ABs as much. Manufacturers don't seem to be saying anything, one way or another, on these issues. So have the issues simply evaporated or is this a case of selling the product on its strengths and ignoring its weaknesses?

I find it odd that nobody here has taken exception to anything negative I've said about As and ABs. My concern, therefore, is that many here are more interested having a fanboy discussion on how good Ds sound instead of discussing whether they sound as good as they can, or should, relative to A and AB amps.

I have listened to a few Ds, mostly in the $1000-3000 range. I didn't hear any in that price range that sounded as good as ABs in that same price range. Perhaps one has to pay $5-10k to reach that level of performance? Or maybe $20k is the magic figure?

Dunno, though this would suggest that the state of the art has only "just" been achieved and hasn't trickled down to the price range for the majority of consumers. So if this is the case, then my comments suggesting Ds still have a way to go stand.

Why would I say such a thing? This is an audiophile site! Shouldn't I be selling my stuff, mortgaging my house and selling my kidney for sound? Nope. I enjoy sound but not enough to abandon good judgment to make anyone here think I'm a high rolling audioholic. For these same reasons, I cannot easily dismiss the inherent issues that are an inexorable part of Class D amplification on your (or anyone else's) say so. It's going to take more than that, starting with specs that manufacturers can be held to in independent testing.

Since you mentioned other manufacturers jumping onboard Class D...

Consider for a moment that manufacturers getting in the Class D game might not be doing so because of sound quality. It could be demand driven. It could be profit margin driven. It could be driven by market forces (such as standby and operating power requirements, such as impending green certifications.

We've seen the same bandwagoning on cables, very little of which has to do with consumer interest or sound quality after all. We've seen MQA being touted as the best thing since sliced bread -- the same thing claimed by SACDs not that long ago.

If you're expecting critical thinkers to believe what you say, post some specs used by Class D manufacturers on their amp's linearity. Then do the same for TIM. Links to public web sites would be much appreciated. Then we can talk.

 

[Out-Of-Phase]

Class A, B, C, D, E, F, G

Just listen to the music.

 

[JerryLove]

I find it odd that nobody here has taken exception to anything negative I've said about As and ABs. My concern, therefore, is that many here are more interested having a fanboy discussion on how good Ds sound instead of discussing whether they sound as good as they can, or should, relative to A and AB amps.

This is a common problem with your posts, at least the ones I've seen.

You seem to focus quite a bit on what you imagine the motivations of the other posters is rather than what you've said. It skews everything about your arguments. It causes you to repeatedly misinterpret what other say. It causes threads to derail as you start talking about posters rather than their posts.

You are very much doing both us and yourself a disservice when you do that.

I haven't taken exception to your comments on A and AB amps because I'm not talking about A and AB amps, except as strictly necessary (compare/contrast for example) in my discussion of Class D and related topologies.

Because they are not the topic I am discussing, I'm avoiding tangents, red herrings, and other general derails. I'd rather resolve the conversation about Class D than I would comment on your comment about Class A leading to a comment about [say] speakers leading to a comment about [say] of-aixs performance and somehow ending up in a discussion of muscle cars.

On a side note: are you saying that you've said something you know to be wrong about Class AB amps, are you saying that you've said something you know to be right and just assumed people would disagree? Or are you saying you've said something about AB amps that is directly germane to the discussion of class D? Because #1 is trolling, #2 is silly, and #3 should be revisited.

 

[JerryLove]

So have the issues simply evaporated or is this a case of selling the product on its strengths and ignoring its weaknesses?

That question is a false dilemma fallacy.

A third valid, and more likely, option is that some issues were overblown and others have been eliminated or reduced to the point of inaudibility though advances in technology and the hard work of professional engineers.

That said: I'm not asserting a how, nor am I accepting (nor rejecting) your presuppositions regarding what problems were there in the first place.

I'm asserting that I don't hear any difference based on topology, and I don't see any solid evidence that anyone else does either. Further, I see ever increasing evidence that the consensus in the industry is that such problems are negligible or non-existent based on their behavior.

I have listened to a few Ds, mostly in the $1000-3000 range. I didn't hear any in that price range that sounded as good as ABs in that same price range. Perhaps one has to pay $5-10k to reach that level of performance? Or maybe $20k is the magic figure?

Which ones?
On what speakers? [before you assume motive, I ask because if, for example, you compared an Krell 150A to a Yamaha P4500 on a B&W 801N (something I've done) you'll hear issues with the inability of the Yammy to drive the low-impedence of the bass driver properly)
What, specifically, was wrong with the sound?

Dunno, though this would suggest that the state of the art has only "just" been achieved and hasn't trickled down to the price range for the majority of consumers. So if this is the case, then my comments suggesting Ds still have a way to go stand.

I directly mentioned an amp that's > 5years old in design.

But also consider for a moment that manufacturers getting in the Class D game might not be because of sound quality. It could be demand driven. It could be profit margin driven. It could be driven by market forces (such as standby and operating power requirements, such as impending green certifications. We've seen the same bandwagoning on cables, very little of which has to do with consumer interest or sound quality after all.

The major problem with that is, of course, that it's apologetic. You are creating an explanation to support your conclusion and base your conclusion on your explanation.

But there are some concerns when we attempt to make predictions from this hypothsis and compare those to reality.

A few examples.
1) we are seeing speaker manufacturers and builders turning to Class D (and related) amps to power their speakers in demos. If there's a performance hit, that's going to hurt rather than help them.
2) As you pointed out: Class D amps have been around for more than 50 years. For more than 50 years, these manufacturers did not use them. Now they do. Your hypotheses fails to explain the delay in adoption.
3) The manufacturers that are still building AB aren't shouting from the mountain tops this supposed demonstrable issue with Class D.

If you're interested in making me believe any of this, post some specs used by Class D manufacturers on their amp's linearity. Then do the same for TIM. Links to public web sites would be much appreciated. Then we can talk.

I'm not really interested in making you believe anything. I'm simply discussing the topic. You can chose to accept or reject what you chose to accept or reject.

 

[GrimSurfer]

This is a common problem with your posts, at least the ones I've seen.

You seem to focus quite a bit on what you imagine the motivations of the other posters is rather than what you've said. It skews everything about your arguments. It causes you to repeatedly misinterpret what other say. It causes threads to derail as you start talking about posters rather than their posts.

You are very much doing both us and yourself a disservice when you do that.

I haven't taken exception to your comments on A and AB amps because I'm not talking about A and AB amps, except as strictly necessary (compare/contrast for example) in my discussion of Class D and related topologies.

Because they are not the topic I am discussing, I'm avoiding tangents, red herrings, and other general derails. I'd rather resolve the conversation about Class D than I would comment on your comment about Class A leading to a comment about [say] speakers leading to a comment about [say] of-aixs performance and somehow ending up in a discussion of muscle cars.

On a side note: are you saying that you've said something you know to be wrong about Class AB amps, are you saying that you've said something you know to be right and just assumed people would disagree? Or are you saying you've said something about AB amps that is directly germane to the discussion of class D? Because #1 is trolling, #2 is silly, and #3 should be revisited.

My initial comments were about Class D relative to As and ABs. Sorry you missed that, but it's what I said... more than once.

Otherwise, the whole discussion revolves around the issue of what? Buying a Class D because it is a higher letter in the alphabet?

Newer... is this is discussion over new tech vs old tech?

I'm really hoping to receive information (vice opinion) that shows Class D has reached a point where I can stop looking at ABs when shopping for a new amp to deliver optimum sound quality relative to price.

Really, I am. Because I am actually planning to buy a new amp in the next six months and am currently looking at Bryston B60, Moon 250i and Benchmark AHB2 as my shortlist.

Anything you can do to get me onto a straighter path would be much appreciated. Really, it would.

 

[JerryLove]

My initial comments were about Class D relative to As and ABs. Sorry you missed that, but it's what I said... more than once.

Otherwise, the whole discussion revolves around the issue of what? Buying a Class D because it is a higher letter in the alphabet?

Newer... is this is discussion over new tech vs old tech?

I'm really hoping to receive information that shows Class D has reached a point where I can stop looking at ABs when shopping for a new amp. Really, I am. Because I am actually looking for a new amp and am looking at ones such as a Bryston B60, Moon 250i and Benchmark AHB2.

Anything you can do to get me onto a straighter path would be much appreciated. Really, it would.

Well. Let's start back at the top.

You've asserted that, in current competent designs (and to avoid no-true-scottsman issues, I'm happy to name names); there are audible issues in Class D amps which are not present in competent class AB amps.

Have you heard them? What do they sound like?

[Also: please confirm that, for the sake of this discussion, Class D, Class H, Class T, and other related systems are interchangeable. If not, please let me know]

 

[shadyJ]

I had a T+A Powerplant with....

 

[GrimSurfer]

Well. Let's start back at the top.

You've asserted that, in current competent designs (and to avoid no-true-scottsman issues, I'm happy to name names); there are audible issues in Class D amps which are not present in competent class AB amps.

Have you heard them? What do they sound like?

[Also: please confirm that, for the sake of this discussion, Class D, Class H, Class T, and other related systems are interchangeable. If not, please let me know]

Limited impact at low listening levels. Some might call this a lack of muscularity. The limited muscularity goes away at completely at moderate listening levels. At higher sound levels, higher freqs don't have the same crispness. The frequency is there (as well as muscularity),along with a trace of sibilence that I do not hear in the ABs I've listed. It's almost Naim-ish if you get my drift, though not quite as shrill.

Now, to be fair, the ABs do consume more power. I have a dedicated 20A line serving a dual socket for my sound system and know that 50-100W @ 8 ohms driving speakers in the 87-90 dB/W/m range is more than sufficient to get the spl I need in my 23x13x9 space.

Also, a few hundred watts of energy going out the heat sinks doesn't mean much when I'm cooling a 3000 sq ft ranch style home (lots of roof area) in the middle of summer. It means even less during the other six months of the year when I have the furnace or fireplace on. It might even be welcome, if I didn't think too hard about the energy inefficiency of seeking heat from an amp!

So the issue is sonic characteristics. Perhaps it's a price range issue, but I haven't yet heard a D in that general range that measures up to my short list. And it's not as if I'm comparing a $8k Mc with a $2k D either.

Am I listening to things in the same space, thru the same speakers? Nope... Not always (did with the Bryston though). But I do bring the same music and even my DAC to auditions to get as close to fair as I can. I also avoid the classic mistake of auditioning amps through different classes/types of speakers. (Standmounted, towers, 2 or 3 driver, bass reflex, acoustic suspension etc.)

Were it just on specs, the Benchmark (a hybrid H/AB design, which would suggest that I'm not a AB purist) would win... against ABs or Ds in the next several price categories. It's THAT good in terms of specs. But in terms of listening, the Bryston (conventional AB) and Moon (conventional AB) are of comparable audible quality. However, the edge must go to Bryston by a nose if I'm to be honest.

All of these are light years ahead of a friend's PS Audio M700 monoblock set up (which is the best Class D I've heard in the $3000 range) in qualitative terms, though the M700 crushes them on power.

Now it's true that I can buy far more watts/$ in a class D amp. But huge power isn't needed. It rarely is. Power is oversold by many amp maunufacturers (AB and D included) instead of the more pertinent issue of headroom anyway. So I don't find watts to be all that seductive past a certain point. A simple calculation of watts vs. sensitivity vs. distance proves the futility/stupidity of this in most spaces and cases.

You can see the dilemma here...

Now as much as some might like to turn this into product x vs. y discussion, it really isn't about that in my view. It's about where things stack up sonically in an equal terms Class D vs AB/other comparison. A great D will likely match or beat an average AB. But on equal price, and comparing the best of breeds out there in the price range I'm looking at, AB wins.

I'd like to know why this is. I don't think I'm being biased (a hybrid H/AB is on my list, I listened to G class etc.). I was hearing this stuff before I did a lot of research into Class Ds, so I don't think this is an issue of confirmatuon bias.

I just can't ignore what is, and has been written, about the issues that affect Class D amps. Just as I spend an equal amount of time obsessing/looking for types of AB amps that minimize their inherent weaknesses (save power consumption which, frankly, lies somewhere between whale poop and the seabed on my list).