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Class D Switching Power Amplifiers and Power D/A conversion

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Old 18th January 2013, 08:09 PM   #11
Pano is offline Pano  United States
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Quote:
Originally Posted by jackinnj View Post
Hey, I'm not the one who asked the question in the first place. Just repeating the query in Michael Fremer's review of the ML#53 in the same issue.
Yeah, I know. And I know Fremer, he's not a bad guy (despite his reputation).
It's just the old chestnut "Class-D is suitable only for subwoofers and cell phones" that I object to. I've owned, built, heard and studied many Class-D amps. Sure there are bad ones (I own a few), but not the whole class. For the most part they are subjectively superior to Class-AB and rival some Class-A.

Maybe it's just a backlash from the love fest they had early on.
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Old 19th January 2013, 02:51 AM   #12
trisc is offline trisc  Australia
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I have to agree with Pano.

I am a newbie to the forum but a veteran of the 'pro audio industry'.

Through my career I have been one of (then younger) poor monkeys who carried racks of A/B class amps into venues for concerts and dance parties. Having herd the tramsition of A/B to D class on the same sets of cabinets I have to say there is a massive perception D-class is crap in the professional industry.

The fact of the matter is that technology eveloves and with it so does design and efficency.

As an example in 2002 I was forced to replace an entire left side of a system of A/B class Crown Macrotech amps (5000,3600, 2402 &1200) for D-Class Lab Gruppen equivilents after a 17yo newbie electrician lifted the neutral on the building power supply killing my faithful Macrotechs... returning to the system processor (& rta) the Labs performed so poorly i had to remove them the next day....
Fast forward to 2012 Ive just replaced all the A/B class Machrotech's with the new D-class Machrotechs and im hearing detail ive never herd before all with less energy consumption.

Thats just the pro industry... but for a major staple manufacturer like "Crown" (Now owned by Harman, whom also own JBL) to move away from A/B to D class shows something... doesnt it?
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Old 19th January 2013, 07:54 AM   #13
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Quote:
Originally Posted by Pano View Post
For the most part they are subjectively superior to Class-AB and rival some Class-A.


I tend to agree. What seems to be the biggest issue for me is the radiation of unfiltered carrier through the speaker cables. In my system this has a very unpleasant effect on high sensitivity MC preamps. In active systems with negligible cable length this is probably a non-issue.
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Old 19th January 2013, 11:14 AM   #14
kad is offline kad  Canada
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Personally, I'm sold on Class D amplifiers. For their musicality, definition, and efficiency.

The press appears to agree.

The Inner Ear Magazine - Discover High End

Quote:
Pioneer Elite SC-68 A/V Receiver | Home Theater
D to the Third Power
D3 is the third generation of Pioneer’s switching amplification strategy. Pioneer’s implementation of Class D, based on ICEpower modules, made its debut in the Elite SC-09TX, which cost $7,000 when Tom Norton reviewed it in 2008. Later and lower-priced versions went on to claim raves from Michael Fremer in 2009 in his review of the SC-07, and again in 2011 with the SC-57, which saw the first introduction of D3. Class D, in general, is more energy efficient than the Class AB used in most receivers because it dissipates less energy in the form of heat. Pioneer says D3 uses 44 percent less energy than its previous version of Class D, and 50 percent less than Class AB, while providing a wider dynamic range and supporting speaker impedances down to 4 ohms, even when more than one zone is operating. My review sample ran warm but not hot. The amp also benefits from a newly designed heat sink, discrete seven- and nine-channel inputs, and more direct signal paths, eliminating EMI filtering, feedback loops, impedance selectors, and current limiters. Pioneer says this reduces coloration, ringing, and noise, especially at high frequencies.
Pioneer's Reasonably Priced SC-61 Class D Receiver

My SC-65 has 9.2 outputs low-level and high-level. Each channel can deliver up to 220 Watts @ 4 ohm.

Total AC outlet power consumption: 330 Watts. Now that's efficient!

The Sunfire TS-EQ12 delivers 2700 Watts RMS @3.3 ohms impedance, yet only consumes 600W from the outlet...

Yes, efficiency (and quality/precision) is the way of the future.

Just my two cents.

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Old 19th January 2013, 11:43 AM   #15
johnm is offline johnm  United Kingdom
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I think there's a lot going on behind the scenes here, as it were. Many are disgruntled at the prospect of a 'simple' little chip giving such good performance, for so little money. There's the typical high-enders snobbery at work here too. Some dislike the idea of anybody being able to afford such high performing amps. High end performance should cost high end money and all that elitist (and thankfully fast becoming a thing of the past) crap! Good performance speaks for itself - all you need is a decent pair of ears and no market bias.

I'm sure some manufacturers are 'scared' too. After all their hard work on discrete designs over the decades, suddenly these new compact Class D upstarts come along and risk taking a huge bite from their market.

I still own the infamous little Sonic Impact T amp. Serves as a reminder of what is possible these days from a budget device. I truly think Class D will eventually topple all others...

Interesting times for Audio!

John.
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Old 19th January 2013, 11:54 AM   #16
kad is offline kad  Canada
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Quote:
Originally Posted by jackinnj View Post
I've been keeping up with the reviews, and was struck by Kal Rubinson's comments about the Anthem Statement M-1 because it was very similar to what I heard from a fellow from a group out here -- a different Class-D amp, highly acclaimed in the press -- and the owner sent it back after a week. There was something "undeniably wrong" with the bass in both cases.

Seems that there's a rush of enthusiasm, but after more than a few days of critical listening nagging thoughts start to creep in.
Quote:
Originally Posted by jackinnj View Post
Hey, I'm not the one who asked the question in the first place. Just repeating the query in Michael Fremer's review of the ML#53 in the same issue. Mark Levinson Company describes some of the issues, and how their interleaved technology approaches them:
http://www.marklevinson.com/downloads/products/prod_22_634473655136955941_ML%20No53%20Technology% 20Background%20V5%2004032010_5.17.10.pdf

The Anthem review does point out the serious the pitfalls of Class-D, and I wonder how many DIYr's would be able to recognize the problem, let alone cure it. Perhaps it's just one amp in the greater world of amp-dom.

It's a serious question, not an attempt to just throw a brick through someone's window.
Could you please post links to the articles in question? For further edification of my understanding of the matter?

Concerning what you mention about Michael Fremer I amplified (pun intended) the research to focus on Pioneer; the consensus appears positive, if not superlative!
Click the image to open in full size.

Perhaps technical evolution is accelerating at an exponential rate? And the state-of-the-art of two or three years ago, isn't applicable today?

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Old 19th January 2013, 12:01 PM   #17
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To me right now class-d is a lot like the very first 14-bit cd players! They were very cool when they first came out, convenient, sounded good(at first) but once the novelty of it wore of, they left you wanting to go back to vinyl! FF 20 years later and we finally have some pretty good sounding converters and digital is livable. I imagine Class-D is probably a very similar thing. at the moment we have a lot of "14 bit" and maybe a few "16 bit" sounding class-d systems and in another 20 years we might have some pretty good sounding "24bit and beyond" class-d stuff????
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Old 19th January 2013, 12:27 PM   #18
kad is offline kad  Canada
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Quote:
Originally Posted by johnm View Post
I think there's a lot going on behind the scenes here, as it were. Many are disgruntled at the prospect of a 'simple' little chip giving such good performance, for so little money. There's the typical high-enders snobbery at work here too. Some dislike the idea of anybody being able to afford such high performing amps. High end performance should cost high end money and all that elitist (and thankfully fast becoming a thing of the past) crap! Good performance speaks for itself - all you need is a decent pair of ears and no market bias.

I'm sure some manufacturers are 'scared' too. After all their hard work on discrete designs over the decades, suddenly these new compact Class D upstarts come along and risk taking a huge bite from their market.

I still own the infamous little Sonic Impact T amp. Serves as a reminder of what is possible these days from a budget device. I truly think Class D will eventually topple all others...

Interesting times for Audio!

John.
I share your sentiments John. Apropos, here is an anecdote from HiFiFun:
Quote:
Pioneer also has a new Hi-bit32 processing included in the SC-65 and SC-67. This feature is questionable as traditional D/A converters are limited by noise and distortion to ~20 bits of actual resolution. The S/N ratio of the Pioneer amps is an excellent 105db. Also the residual low level spectrum with the ear-to-the-tweeter is clean which indicates excellent grounding and shielding. In this sense a receiver design is superior to separates as the designer has more parameters idealized and also under his local, direct control. Something like after 15 years and billions of dollars in development we'll get a damn ICE amplifier to sound good!
How Pioneer made digital amplification sound more musical
Click the image to open in full size.

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Old 19th January 2013, 05:35 PM   #19
aandy is offline aandy  United Kingdom
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Labs class D LOL
no they are not.
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Old 21st January 2013, 05:37 AM   #20
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Double blind tests anyone? This hobby (audio) has such a high ******** factor that very few rigid tests are done. I have been reading (and listening) to audio for decades and have rarely, if ever, seen a rigorous test that proved beyond a reasonable doubt that "A" sounded better, or even different, from "B." To me the reason is obvious -- there rarely are differences! Think about it: if (say) Krell could prove that their amp were consistently better than (say) a Mark Levinson, it would be in the ads. Objectivity goes out the window when there is profits or ego involved.
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