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Class D - heaven or hell ? - Page 3

post #31 of 133

LMAO Steve you are way out thereksc75smile.gif

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post #32 of 133
Quote:
Originally Posted by DaveBSC View Post

The market wants small two-way monitors that can extend below 50Hz, and they have to be reasonably affordable. Amplifier power isn't a problem, that's why the speakers are built that way.

Yep. This is exactly it. People want "cute lifestyle products" not high quality performance. Look up Hoffman's Iron Law for the background on what Dave's talking about - you get extension, size, and efficiency. Pick two. Amplification (in terms of output power) is cheap; so what's easy?

Honestly I feel it's a little nuts to have a 1000W amplifier for a bookshelf speaker.

Quote:
Originally Posted by Steve Eddy View Post

Here's a nice bookshelf speaker. Doesn't hold a lot of books, but man, what a speaker! biggrin.gif

se

That made my day. basshead.gif
post #33 of 133
Quote:
Originally Posted by obobskivich View Post


Yep. This is exactly it. People want "cute lifestyle products" not high quality performance. Look up Hoffman's Iron Law for the background on what Dave's talking about - you get extension, size, and efficiency. Pick two. Amplification (in terms of output power) is cheap; so what's easy?

 

For what it's worth, I haven't heard a better monitor than the 86dB Nola Micro Grand, and yeah that includes Magico. Opting for low efficiency can still produce incredible results.

 

MicroGrand-sm.jpg

post #34 of 133
Thread Starter 

Again, Dave, at 14K a pair they would want to be damned good. I dont expect you to lower your standards for cheap b*stards like myself, but that is so far out of reach for most of us as to be the Focal Grand Utopia .... 

post #35 of 133
Quote:
Originally Posted by estreeter View Post

Again, Dave, at 14K a pair they would want to be damned good. I dont expect you to lower your standards for cheap b*stards like myself, but that is so far out of reach for most of us as to be the Focal Grand Utopia .... 

Alternately, you can go the more efficient route:
233 (Okay, I found this image looking for images for another thread, and it reminded me of Steve's post - I just wanted to post something bigger and more absurd).

Those are uh, 97 dB/W and take 300W. Those are 12" woofers if memory serves.

Full range and they use less power than most audiophile bookshelves to do it. Sign me up!

And before you ask, no I haven't heard them. I've heard other (lessor) members of their series (they're Technics Linear Phase SB-9500s; they're bloody rare and I've never gotten a decisive answer as to whether they, or the equally huge SB-10000s, are the top model), and there's not a one of them I haven't liked.

Basically make the choice: can you live with speakers the size of a fridge? If not, buy a bigger amplifier, if yes, enjoy your 10wpc SET or whatever else you've got.
post #36 of 133
Quote:
Originally Posted by obobskivich View Post

(Okay, I found this image looking for images for another thread, and it reminded me of Steve's post - I just wanted to post something bigger and more absurd).

 

They're certainly bigger!

 

Though I don't see anything particularly absurd about them.

 

se

post #37 of 133

I'm also for the high(er) efficiency speaker route. I've been using 93 dB/Watt speakers for the last 3 years; that should be considered on the very LOW end of efficiency. Recently heard the Tannoy Yorkminster SE (95dB; one model up from my Kensington) in my same setup, and holy cow what a difference those extra 2dB efficiency and 6Hz deeper bass extension make! Doesn't look like much on paper, but it's extremely audible -- completely effortless lifelike dynamics, and bass extension that will frighten you. The difference in cabinet volumes (105 L vs 200 L) is more telling. Those Yorkminsters are big boys; the combination of efficiency and extension is paid for in size, as with any proper speaker. Not quite as sweet mids as with my Kensington though; maybe I'll have to look to the next model up. What I like about the old school Tannoys is that you can keep scaling up the cabinet and woofer sizes while the sound remains coherent and integrated from top to bottom, due to the dual-concentric driver arrangement. Sound is as coherent as with great headphones, except that they're also far more resolving and dynamic (and have a soundstage).

 

With even 93dB speakers, you can't quite get away with ~20 Watts in a not-small room while playing high dynamic range material loud. There's some really sweet sounding tube amps in that power range, too. 95-96dB/Watt speakers can do that with gusto. The more efficiency the better, I imagine, as long as you're not sacrificing extension and/or coherence to get it.

 

Something else to keep in mind with the modern horrendously inefficient small bookshelves and mini-standers (sacrificing all efficiency for a cute size and "wish-it-were" bass extension): by the time you're dumping in enough power to coerce them into attempting decent levels & dynamics in a normal room, you're probably hitting and/or exceeding their power ratings (and likely frying a tweeter). Remember, for all the internet demonization of clipping: it's power that kills tweeters dead; too much clean power will do it just as well! Not to mention the huge excursion required of tiny woofers at higher levels, and the resulting issues with linearity. Just because you've got a 1000W amp doesn't mean you can safely use a fraction of it on your "WAF-fi" speakers :)

 

Get the biggest damn things you can afford and are able to haul into your space. Do it before you get a wife that has been granted veto powers -- that way they're grandfathered-in :)

post #38 of 133
Quote:
Originally Posted by Steve Eddy View Post


Though I don't see anything particularly absurd about them.

se
Quote:
Originally Posted by mulveling View Post

Get the biggest damn things you can afford and are able to haul into your space. Do it before you get a wife that has been granted veto powers -- that way they're grandfathered-in smily_headphones1.gif

You're both alright. beerchug.gif
post #39 of 133
Quote:
Originally Posted by estreeter View Post

Again, Dave, at 14K a pair they would want to be damned good. I dont expect you to lower your standards for cheap b*stards like myself, but that is so far out of reach for most of us as to be the Focal Grand Utopia .... 

 

The 87dB, $3650 Vapor Cirrus isn't that far off from them. Buying direct certainly has its advantage in terms of pricing. Efficiency has never been a top priority for me, I'm much more interested in the quality of the drivers, crossover, and cabinet design and construction. The Cirrus is made from stacked Baltic Birch Ply, just like the original Magico Mini. For $3600 most speaker companies are still giving you an inch of MDF.

 

The Micro Grand is indeed very expensive at $14K, but it also provides about 95% of the performance of the $25K Metro Grand floor stander, the only thing missing is a small amount of deep bass impact. The Grand Utopia Be is a $90K bore. Incredibly underwhelming. I've yet to hear an impressive speaker from JM Labs.

 

I also don't really agree with the concept of just buying the biggest things you can afford and squeeze into a space. I'm not really a fan of horns to be honest, most for me have at least some of the "cupped hands" issue, and have trouble disappearing as obvious sound sources. I'm much happier with a speaker that runs out of breath at 55Hz, but completely disappears into the image.


Edited by DaveBSC - 5/16/12 at 2:35am
post #40 of 133
Thread Starter 

This thread is humming along nicely - I hope others wont be too offended if I paste a few of the forum comments from elsewhere as I plan to address some of these when I return to this thread in 2 years time (!). Sounds like an eternity, but consider how long some of the other threads on Head-Fi have lasted - its always a shock to find the OP started the thread in 2009 ...

 

=============================================================================================

Source: various threads on CanuckAudioMart and AudioKarma from 2009-2012:

 

 

(apologies if I seem to have singled out the comments specific to Nuforce, but they seem to have copped a particularly nasty hiding on the forums)
 
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If the OP is determined to buy a pair of Class-D monoblocks, I would suggest sticking to the ones based on the Hypex modules (Channel Islands, Kharma...), staying away from ones that employ the B&O ICE module (Wyred for Sound, Bel Canto, Jeff Rowland...). Some of the units using proprietary modules (Nuforce, Hephaestus) are quite good, but as I said in my original reply, a really good Class A/B linear amp, dollar for dollar, performs better in my opinion. 
 
As a "family", Class-D amps have merits - bass control, transparency, and efficiency*. They also have their costs - cool/thin midrange, and strange highs (some call them "chalky"). Personally, I think it is the harmonics that they portray strangely, rather than the dominant tone itself, but that is another conversation entirely.
 
There are a couple of hidden costs with Class-D amps though. For starters, I am not convinced my the claims of efficiency (hence the * above). The serious listeners I know with Class-D monoblocks leave them turned on all the time. Why? Because they sound like a horse's face when cold. How efficient is that?
 
Second, Class-D amps are VERY sensitive to cabling, and you end up spending more on power cords, interconnects, and speaker cables than you might need to with a traditional linear amplifier.
 
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I have heard several of these designs (including the Axiom as well as the Bel Canto Ref 1000) and remain on the fence about them - I like the power that they can put out and the control they can manage over large drivers, making them a natural bass-amp for a 'vertical' bi- or tri - amping situation.
At higher frequencies though, they have, at least to my ears, always sounded a little dry and compressed. I am not sure I could live with them for very long if they were doing full-range duties.
==============================================
Put them beside a new Blue Circle SS chip amp and you'll never be able to listen to Class D again
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No one who has heard my system since I replaced the 300B Cary amp with the Red Dragons, has said the system is lacking anything.Or that they preferred the Cary, and these fellows all have tube amps from Acoustat, Nagra, Art Audio and Lumley.
 
No one has said they thought the tubed Cary was more musical.No one missed it or said they liked the sound before with the tubed unit.
And the Cary is a very nice amp.
No one has said the Dragons sound unnatural,digital, edgy sterile or any of the other negatives used by some on this thread.
 
Again I have to hammer it home that not all D amps sound the same.
The good ones, and I would say mine fits that description, do not sound alien.
They sound like a good solid state amp in some respects and a good tube amp in others.
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Yes I did hear the Nuforce amps.
I was eager to go up and have a listen.
Phil said to me "what do you think?"
I said they were the worst amps I have heard in a long time.
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I tried three different class D amps: Benefits; low energy usage, nice tight bass (they were originally invented for enclosure in subwoofers so no heat was important and bass was important), but I found they had a thin mid/high end and two dimensional sound stage; and have now thoroughly cured myself (for now) of this obsession with "being green". Class A/B thanks with a tube preamp.
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I owned the Bel Canto S300 and M300 series. Not to my liking at all. I owned some pretty good front end equipment at the time and I was so used of wide deep soundstage. That all but disappeared with the class D I owned.
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I have the Red Dragon Leviathan mono blocks, 500 watts into 8 ohms, 1000 into 4.
 
The closest to it would be the Bell Canto, same Ice power, upgraded from stock.
 
I have owned several power amps from tubes like Conrad Johnson, VTL,Michaelson Austin, Grant Lumley,Dynaco, Output transformerless tube amp from Atmasphere,and 300B SET from Cary. I have owned some Brystons,Bel Canto Evo,Spectral,Blue circle bc2 mono blocksHybrid)Meitner m100 mono blocks,Classe DR8 mono blocks,and others from the 1970's not worth mentioning.
 
After owning a lot of amps of all stripes,I would have to say that I don't think there are too many nits to pick with the Red Dragon or Ice amps in general.
 
They seem to walk the balancing line between the best of tubes and solid state and don't have any of those amps draw backs- not overly tubey sound, not sterile cold, and not inefficient
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I owned the Nuforce ref 9.02 for about a year and a half. They were phenomenal for ht due to their speed and dynamics. However, they lacked the harmonics for music. I demoed my current amps and it was an easy decision from there.
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I have listened to a number of them (2 channel only) and can only conclude that the D in Class D stands for depressing. They all sounded remakably similar to me, which leads me to believe that they were all built exactly per the application notes from the chip supplier with no added R&D. Perhaps there are some better sounding units out there, I dont know, but I heard enough to come to my own conclusions.
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Whoever said Class D amps haven't arrived must have gone to the wrong station or missed the train. This type of amp has evolved significantly over the last 15-20 years with the advent of faster signal devices, better materials for mosfets and improved designs. Its hard for me to look at a Class A or AB amp and not see all the wasted circuitry, metal and dollars going into heat dissipitation. The loss of audio energy must be in the realm of 50% for most of those A and AB amps and with it the onset of clipping at transients. 
 
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I've heard several Class Ds, the Nuforce Reference, BelCanto Ref 1000s. I was impressed with both the Nuforce and really liked the BelCantos. I finally purchased an Axiom A-1400-2 after comparing it in side by side listening session to the BelCantos. The performance was very close though I thought the A-1400-2 produced a more natural tighter bass with the same transparent mid and detailed highs as the BelCantos. 
 
Without the huge heat sinks necessary in conventional amps there is room for more important parts like bigger capacitors to provide fast abundant energy when needed. So clipping is virtually non-existent. And the Axiom also has the technology to dynamically allocate more power to the channel demanding it. So out went my pair of trusty Bryston 4BSSTs and in came the Axiom A1400-2 to take its place alongside my other favourite amp, a tubed McIntosh MC2102.
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I think one of the issues with class D is with type 3 in particular, and it relates to the power supplies as much as it does to the amplifier. Switching supplies have peculiar characteristics that are good in some ways, they behave like they are very stiff, up to a cliff-edge point, but may not be ideal for music playback. They also contribute to all the noise and interference. 
 
What the article brushes aside are digital amps with no feedback, and those are, by a good margin, the best ones for me. Ironically, Martin Colloms is one of the great proponents of low or no negative feedback in amplifiers. I just wish he would listen to the NAD M2, John Atkinson (http://www.stereophile.com/solidpoweramps/nad_m2_direct_digital_integrated_amplifier/)gave it his pretty unqualified approval, and he's a man out of a similar mould. 
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In our opinion, the real challenge now is not the audible performance, but confronting traditional attitudes about distortion in the specs. All of these designs can reach 1% or more at 20 KHz. In itself, although some would argue, it is not audible (What everyone ignores is that loudspeakers, no matter how good, exhibit far more distortion than that) If you address the other speaker interface problems then it comes down to audiophiles rethinking traditional wisdom.
 
The advantages of a properly designed class D are compelling: less weight and higher efficiency. In a world where the carbon footprint of electronics is becoming a big issue, this approach is compelling. However, we wouldn't move into an area that would degrade audible performance. For the record that no longer appears to be a barrier. We are getting close.
 
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Hypex are the one class D amp that I haven't heard, but I suspect it's the best of the analogue class D bunch. 
 
For what its worth, I recently bought and compared an Emo XPA-5 and a few ICEPower amps. I thought the Emo was clearly better, though having said that my old NuForce MCH3C7 was very good in its own analytical and dramatic way. 
 
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I can understand the distaste for such an amp from an engineers standpoint as I don't think there is any elegance to the design. It seems Class D exists through sheer brute force engineering. It is like a Rube Goldberg of amp design - an exceedingly complicated design to accomplish an otherwise simple task:D. It is a layman's interpretation, but that's the way I see it.
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That's not to say that ICEPower amps are bad; I think they're a good solution for multi-channel receivers, but when you get up to separates quality gear, they're just not as transparent as the better linear amps, by which I mean Emotiva, Bryston, Arcam - amps with HiFi pedigree. 
 
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post #41 of 133
Thread Starter 

Just while I am monopolising the thread, I wonder if any of the more technical Head-Fiers have any comments on JA's measurements of NADs M2, current poster child for Class D ?

 

http://www.stereophile.com/content/nad-m2-direct-digital-integrated-amplifier-measurements

 

 

No question that Stereophile are play-for-pay, but I doubt that he would publish fabricated measurements. If we can put aside our skepticism for a microsecond, I'd be interested to hear others opinions - as an ignoramus, those graphs look a lot 'cleaner' than the graphs he has published for CEntrance, Peachtree, Bel Canto and other Class D designs - I need to hear from someone who has a better grasp on the measurements than 'cleaner graphs' ....

post #42 of 133
Quote:
Originally Posted by estreeter View Post

Just while I am monopolising the thread, I wonder if any of the more technical Head-Fiers have any comments on JA's measurements of NADs M2, current poster child for Class D ?

 

http://www.stereophile.com/content/nad-m2-direct-digital-integrated-amplifier-measurements

 

 

No question that Stereophile are play-for-pay, but I doubt that he would publish fabricated measurements. If we can put aside our skepticism for a microsecond, I'd be interested to hear others opinions - as an ignoramus, those graphs look a lot 'cleaner' than the graphs he has published for CEntrance, Peachtree, Bel Canto and other Class D designs - I need to hear from someone who has a better grasp on the measurements than 'cleaner graphs' ....

 

JA has ripped many products based on poor measurements.  claiming that Stereophile is "play-for-pay" is a bit much.  

post #43 of 133
Remember Tyll too works for the same parent company as Stereophile, and he definitely isn't play for pay. They've crapped on quite a bit of gear that had issues. I feel it's more an issue of how the measurements relate to what we hear, which isn't discussed enough.
post #44 of 133

My $0.02 - I've owned class D amps from Channel Islands, Wyred for Sound, and Bel Canto, and I've been happy with them; the main reason is that my planar speakers demand a lot of current. Implementation of the ice power gear has improved quite a bit, I think; still it's no match for class A amps, if price is no object. Since price is always part of the calculation - as are size and efficiency - I find that I'm well served (and I can always go for a different flavor with my tubed headphone amps). Getting this level of control out of my large panels with any other type of amp would require significantly bigger monetary commitments, and I want to play with other toys, too...

 qui

post #45 of 133
Quote:
Originally Posted by Sam Lord View Post

Class D amps like latest Bel Canto (which I have) and Hypex (world-beaters) are very fine, I expect they'll replace all A, AB and tube amps for speakers. But the best can amps would see no benefit, IMO, they already get 120+dB S/N + THD/IMD, no?

 

Quote:
Originally Posted by thune View Post

I suspect you are being ironic, but I'd like to see measurements of these can amps if they exist. Looking at some semiconductor datasheets, one might suspect headphone amps with these specs are easily found in the real world, but I don't see them. If you are being serious, please link some measurements of these amps, I'm very interested.

 

Thune,
Once again on forums I make an apology after a late-night post, sigh.  You're right, I couldn't find one either after long searches on diyaudio and many other places.  In short the Johnson noise monster battles the low-Z monster to a draw.  Best I found was Benchmark Dac1HDR at -111dB THD+IMD.  Looking at opamp performance on the front end and available buffers, it looks possible.  I expect exotic resistors, caps, matching, and complementary devices could buy another 4dB(?), since the can amp section of the aforesaid unit probably accounts for half of the $1800 unit.  But that is still 5dB short.  Again my apologies!

 

On the Hypex ncore amp question, *its* measurements beat the best Halcro in most or perhaps all respects.  There is no HF nastiness to contend with, and I expect those who decry its sound before listening will be upset.  If anybody thinks the Hypex guys can't do great circuits, they had better look at DXD circuits and Grimm's lineup and their implementation in audio recording and mastering.

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