[Kenobi]

I have a Nuforce MCH3SE which better all my previous amps I have owned or auditioned at home...by a long mile.  In fact, to me the acquisition of this amp has been the most significant audio purchase in my 15yrs as an audio nut.  Bi-amped from its available 7 channels, this thing sounds better to me than the Ref 9SE V2 mono pair, for the same price!!! 

One word of caution, this is not a "plug-and-play" solutions for all.  There has to be some work-around in terms of mating w/ synergistic gears, cablings, conditioners, isolation.  Also, give it time to burn in (at least a few good hundred hours) before making any premature judgment.  But, the reward at the end far outweighed the inconvenience and trouble. 
YMMV,

Kenobi

[James Romeyn]

Only class D I've heard at home was the Spectron Musician III; I would not call it a reference amp.  The Bel Canto heard at CES a few years ago sounded not good on similar speakers that sounded state of the art on Pass XA amps. 

The following is not for shock value, but only to share one highly experienced person's opinion.

TAS, August '08, Issue 183, page 33, Bob Carver interview (Physics PhD. Carver may have more patents currently licensed & in use than all other living high-end inventors combined): 

Q: How do you feel about the new generation of Class-D amplification?

A: "Class D amplifiers have been around since the beginning of time, and every year I thought that they were finally going to come of age.  I tried making a Class D amplifier twenty years ago and failed miserably.  I couldn't make it sound good, and so I gave up.  They've always seemed to be on the threshold of fulfilling their promise, which is high power, great fidelity, lightweight, and no heat, but it hasn’t happened yet. 

They have a fundamental problem-they don't sound good.  They haven't come of age yet, but every time I turn around there's a new one that makes the promise that switching technology has arrived.  It’s the linear guys who are carrying the day.  Theoretically, switching amps should be good, but they’re not yet.  And there’s some technical reason for that, and I could explain it but I don’t need to now unless you want me to.“

I wish TAS asked Carver to explain.  (Actually, the interview does not state conclusively whether or not TAS asked Carver to explain.  The article does not state whether or not it was edited.)

It is safe to assume the question & answer applies to full-range applications.  Readers are left to ponder if Carver’s answer would be the same or different if the question was limited to bass applications.  IIRC even an audiophile/engineer/designer as picky as Lynn Olson (a low-mid-power tube lover w/ a very limited acceptance of fullrange SS) find class D acceptable for bass applications, up to what frequency I don’t know.

TAS is a high-end home-audio publication.  It is not necessarily a contradiction if class-D amps were made &/or sold by one of Carver's pro audio companies, which I believe to be the case.  Cost, heat, size, longevity, efficiency, power output & reliability are larger priorities in pro audio.  The same qualities matter in high-end home-audio applications but are usualy secondary to musical resolution & pure sound quality.          
 

[Wind Chaser]

I purchased a Spectron Musician III SE (recently upgraded to Mk2)

I understand the Musician SE puts out 1400 watts per channel at 2 ohms.  With Paul Speltz ZERO's you could manipulate your speakers impedance so they were perceived by the amplifier as being 2 ohms.  What that would sound like is another matter, but in a previous application, it worked wonders for me.

[Wind Chaser]

The following is not for shock value, but only to share one highly experienced person's opinion.

TAS, August '08, Issue 183, page 33, Bob Carver interview (Physics PhD. Carver may have more patents currently licensed & in use than all other living high-end inventors combined). 

With all of his expertise, what "reference" gear has Mr Carver contributed to the industry in all his years?

[jrebman]

Wind',

The Carver Cube, of course .  Let's see, class D or magamps?  Which would you choose?

-- Jim

[IronLion]

This guy sounds like he's bitter that people are enjoying Class D amps that he didn't design.  His Ph.D and design experience doesn't relate to how I perceive music so his opinion is about as important to me as anybody else's [EDIT]- or less so.   

[James Romeyn]

The following is not for shock value, but only to share one highly experienced person's opinion.

TAS, August '08, Issue 183, page 33, Bob Carver interview (Physics PhD. Carver may have more patents currently licensed & in use than all other living high-end inventors combined). 

With all of his expertise, what "reference" gear has Mr Carver contributed to the industry in all his years?

$17k/pair USD in early '90s; they've maintained a high resale & are generally considererd a high-end classic. 


I've heard the Amazing Loudspeaker Signature several times owned by two friends; if it's not a reference loudspeaker I don't think such exist.  I doubt either friend would sell them for just about any amount of money. 



I regret not having purchased these when new for only $2k/pr.  They sound fantastic.  Used they sell for about the new price if in excellent condition.  Ask anyone who has heard them w/ even mid-fi gear how great they sound.   

[James Romeyn]

This guy sounds like he's bitter that people are enjoying Class D amps that he didn't design.  His Ph.D and design experience doesn't relate to how I perceive music so his opinion is about as important to me as anybody else's.   

I'm highly surprised it took five minutes for purely hypothetical vitriolic personal attacks to appear.  From exactly what words or phrase are comprised your analysis

this guy sounds like he's bitter

?

I know Carver personally.  I can personally state for the record your above analysis is aboslutely incorrect & false.  In fact, anyone who knows Carver personally would find your above analysis preposterous.  Carver is not a bitter person & certainly not bitter about anyone else's so-called success in the audio world.  He built several multi-million dollar businesses from scratch & hard labor.  How can he be "bitter" about someone less succesful than himself?  This makes no sense to me but maybe you can explain it better.    
 

[Kevin Haskins]

What people consider as a "reference" certainly varies, not just with individuals, but with the season.     

I like the Hypex solutions better than anything else I've tried of any topology.   The National Semiconductor chip amps are easy to work with and I've considered using them for active speaker designs but the Hypex seems to be cleaner/clearer sounding.    That may not be the case in every application and I'll give them another try A/Bing them in the active design.   

I like the fact that the Class D amps are a green solution.    I like the fact that they color the sound very little.  If there is such a thing as neutral they seem to fit the description and I agree that they allow upstream components to show their character.   I like using tube preamps with them and have had particularly good results with Dan Wright's unit.    In terms of power supplies, a good SMPS seems to be as good as the transformer/rectifier/caps solution.    The SMPS actually has better regulation but it doesn't seem to matter as the PSRR of the Hypex units is very good and I have found very little audible difference between the two.    Switching noise can be handled in the design.   

 

[doug s.]

shameless plug time:  who is gonna take my home-brew hypex ucd180 amp off my hands?  i took it in trade, & i like my tube colourations enough so that i have never even tried this amp!   

doug s.

[Rashiki]

I like the fact that the Class D amps are a green solution. 

This intrigues me, and I have a follow-on question based on what Kevin says next:

In terms of power supplies, a good SMPS seems to be as good as the transformer/rectifier/caps solution.    The SMPS actually has better regulation but it doesn't seem to matter as the PSRR of the Hypex units is very good and I have found very little audible difference between the two.    Switching noise can be handled in the design.   

Is there any difference in "greenness" between a switching power supply and a linear supply? Certainly a SMPS will be smaller and lighter than the equivalent transformer-based power supply, but is there a substantial difference in energy efficiency?

 -Rob



 

[Kevin Haskins]

I like the fact that the Class D amps are a green solution.

This intrigues me, and I have a follow-on question based on what Kevin says next:

In terms of power supplies, a good SMPS seems to be as good as the transformer/rectifier/caps solution.    The SMPS actually has better regulation but it doesn't seem to matter as the PSRR of the Hypex units is very good and I have found very little audible difference between the two.    Switching noise can be handled in the design.   

Is there any difference in "greenness" between a switching power supply and a linear supply? Certainly a SMPS will be smaller and lighter than the equivalent transformer-based power supply, but is there a substantial difference in energy efficiency?

 -Rob

I guess it depends on what you call substantial but yes... there is an improvement in efficiency both under load or in standby mode.   You also have the ability to deal with power factor correction.

http://powerelectronics.com/power_management/power_ics/resonant_power_supply_audio_system-0608/

[TheChairGuy]

I've heard quite a few D's and T's....by no means all....but they inevitably fall short of standards with excellent 'traditional' solid state amps I've tried.  And, then, the SS amps have sounded lacking next to many tube amps.

I'd have bet you $100.00 some 2-3 years ago that I'd NEVER own and enjoy more tube amps more than anything else...but, that's how it goes around 

All the D's and T's tried benefited from power conditioning...some tremendously so.  The tube and SS amps sounded best as naked (drinking from the wall)   

I found the same with CD/redbook...it largely benefits from 'conditioning', but the other audio components (pre, amps, DC motor'ed TT's, did not).

It might be interesting to know if the negative feedback loop in these D and T amps are stabilized by something as simple as a Dakiom (see Audiogon for the over-the-top ads....but, dammit, do they work near wonders on 'digital' front ends).

http://dakiom.com/technology.htm

Ultimately, whatever floats your boat daily is what matters...no matter the 'reference' designation to it.

Enjoy - John 

[TONEPUB]

For me, the best experience has been with Vinnies Red Wine Signature 30.2.
It doesn't answer all the questions, but his taking it off the power grid and
making it battery powered, has made this one the most musical sounding
of any of the chip amps I've heard yet...

If you can get by with 30 or 70 wpc, I give Red Wine two thumbs up!

[James Romeyn]

The high-end contradictions still amaze me.  People like Carver & Dan Banquer swear D doesn't work, others who seem just as reliable in their opinions swear they do.  Who knows?  As usual, your ears are the judge (& your wallet).  FWIW: up till not long ago the only SS amp Lynn Olson recommended was DB's discontinued amps.

Attacks implying jealousy, bitterness, or ignorance attached to Bob Carver relating to audio designs are ludicrous & not much if anything else.  If Bob states he thinks D does not sound good & he has electrical data to back it up, that's all it is.  Bob's probably worth more than just about every other designer combined.  He very used to personal attacks & admits his youthful failures in his earlier audio attacks in the same interview. 

BTW, his new ribbon speaker got a rave review in the same issue & its staging is IIRC said to equal the state of the art.  Also, for reference, TAS takes advertising from many digital amp companies so it's hard to impune them on that issue.       

[bprice2]

I think regardless of what some have said, Class D can work just fine.  It seems Mr. Rossi as well as some others have figured out that high current matters in this application.  That's why many believe that Class D works very nicely powered with DC (batteries).

I'm still not sure I know what reference means.  Seems kind of relative to me.

If Bob states he thinks D does not sound good & he has electrical data to back it up, that's all it is.  Bob's probably worth more than just about every other designer combined.  He very used to personal attacks & admits his youthful failures in his earlier audio attacks in the same interview. 

Well, well, it looks like Mr. Carver has a fan...ya think? 

The school girl crush routine seems a bit much.

[dekkersj]

The high-end contradictions still amaze me.  People like Carver & Dan Banquer swear D doesn't work, others who seem just as reliable in their opinions swear they do.  Who knows? [...]

Well, if one swears it doesn't work it is suspicious in the first place. From a technical point of view there is no evidence that this is the case. I know Hypex modules quite well and they do not sound at all. And that is just what an amplifier should do 

Regards,
Jacco

[Kevin Haskins]

Hey... there is no reason to argue about it.   Just try one.   Trust your own ears and don't let someone else tell you what you should be hearing.   

I've had customers compare them to amplifiers up and down the price range.   Customers with zero engineering background and others with PhDs in physics and electrical engineering.    A high percentage of my customers are technical nerds with engineering degrees.    They tend to be swayed in their opinions based upon objective measurements rather than subjective ones.

I don't know if that helps the conversation any but I think that saying Class D doesn't measure up for some pre-conceived objective measurement reason is just wrong.   The objective measurements are good.   The THD numbers may be slightly worse than a good Class A/B design but I don't think anyone gives much weight to a simple THD number correlating to sound quality anymore.     

[Toka]

The THD numbers may be slightly worse than a good Class A/B design but I don't think anyone gives much weight to a simple THD number correlating to sound quality anymore.  

Very true...especially when given that many tube amps have even worse THD measurements...and SS amps that have "awesome" THD specs can sometimes sound awful. I really do think it is a case of pre-conceived notions dying hard (as true in audio as it is anywhere else). I really like what NuForce is putting out these days, and I'd love to hear the Spectron amp (both are proprietary designs). I'd also love to hear Kevin's multi-channel amp too. Like others stated I'm attracted to the "green" aspect, as well as the general lack of coloration they provide. I'm agnostic all around when it comes to topologies, speaker design, turntable drive systems, etc...I just like what works.

[2bigears]

   my new to be amp list has a couple of crazy #'s to compare,idle power is 40w on one and 300w on the other.the power bill likes the 1st one !! i thing power will get to be a big thing,just like water,just like oil,blaaah blahh blaah