The Absolute Sounds class d future

beachbum · « **on:** 11 Oct 2006, 08:21 pm »

just got finished reading the article in the latest tas, it was one of the tas round table discussion articles, with five members of the tas staff offering there opinions of class d amps and three designers on there opinions, they included eight models from different manufactures, i think the general consciences is class d is not ready yet, one of the tas members uses nuforce ref 9s as his reference amp, that would be chris martens, robert harley gave nuforce a thumbs up, and wayne garcia was one hundred percent against class d, when mags start this kind of confuseion over a product just think what you would do if you were considering a purchase, you probably would not buy, the reasons wg gave his negative review was detached bass, lacks microdynamics, top end headache, and a jittery quality like early cd, exaggerated bottom end and the top end was razor cut and glassy, by and large they believed the kharma class d was the best of the group,
i will give my two cents worth, my ref 9 se amps are magic in my system, they stage, image, produce unreal bass with no blot, the midrange is right on, and the upper end is clean and pure, my system is so musical its possible to sit and listion to music for hours on end, whats the thoughts of you who have nuforce and class d amps in your system, mike

James Romeyn · « **Reply #1 on:** 11 Oct 2006, 11:10 pm »

I want very much to hear the Nuforce & will at Lost Wages '07. It is generally BAD to make conclusions based on show sound. But at CES '06, downstairs the Andrew Jones TAD speakers (circa $45k) powerd by several huge Pass class A amps were about as good as I've heard. Upstairs the Pioneer/TAD (circa $10k) by the same designer powered by latest Bel Canto: Sound was extremely low THD, very pure, but sterile & uninviting seem to be the best descriptors. Who knows? The old adage that you really don't know till ya bring it home probably applies as much here as ever. Granted, the source quality was by almost any definition far far better upstairs.

My 2c.

timothyharnett · « **Reply #2 on:** 12 Oct 2006, 06:47 am »

I think it depends how you use them. One of the initial problems with CD was that people were using it with ancilliaries that were intended for vinyl. Once other ancilliaries are designed with Class D in mind that will help.

I don't like transistor sound and now that I've heard good class D, going back would be difficult. I think valves are better than both but the problem is that the best NOS valves are running out. In the end, the practicality/economics of 80-90% efficiency and a unit that you can pick up with one hand will win out.

The remaining problem is the RFI/EMI problem; once that's cracked, the transistor is dead.

warnerwh · « **Reply #3 on:** 12 Oct 2006, 08:16 am »

It appears some designs are better than others with some designs being very load resistant. Also some designs have much more problems in the noise department. This is why I'd not use any of these switchers.

An amp that is VERY load resistant is going to vary in it's sound greatly from one system to another. This makes trying one much more of a gamble than an amp that is stable into various loads. Even with linear amps it's noticeable but with switchers is a major factor to consider.

In the end the only thing that matters is the sound that the purchaser likes. The noise issue however is something that can be a major problem for people like me who listen to FM daily.

Even the designers of some of these amps were in agreement that there's a way to go before these Class D amps are what they can be. With linear amps however this has been refined for decades. I like the idea of an efficient amp especially as I believe in having more power than I could use so that I will never clip my amps.

The square waves that these amps produce is not pretty. The square waves many tube amps produce also is not pretty. This does indicate nonlinearity. A nonlinearity being defined as anything at the output varying from the input. How an amp with a nonlinearity sounds of course is not necessarily indicative of it being a bad sound but does indicate it's not accurate. Whether this is appealing or not of course depends on the end user. Being load sensitive as it appears many Class D amps are makes the issue worse for a prospective buyer such as myself.

gongos · « **Reply #4 on:** 12 Oct 2006, 04:02 pm »

Quote from: timothyharnett on 12 Oct 2006, 06:47 am

The remaining problem is the RFI/EMI problem; once that's cracked, the transistor is dead.

The Channel Islands class D amps don't have this problem and have a linear power supply.

James Romeyn · « **Reply #5 on:** 12 Oct 2006, 04:11 pm »

This is a great thread.

There are two audio designers whose work I respect. One is about to release a D amp so he or she obviously is a believer. The other tried a recently released & widely praised D amp. That second designer noticed the amp was very pure sounding but also noticed it apparently made him or her feel physicaly ill.

The controversy around the release of Red Book digital pales in comparison to that of class D amps.

timothyharnett · « **Reply #6 on:** 12 Oct 2006, 04:30 pm »

Quote

The Channel Islands class D amps don't have this problem and have a linear power supply.

Unfortunately, they also don't have the dynamics & I would miss this for orchestral. The problem that I've had with his stuff before is physical noise from transformers which I still have in a Monolithic power supply for my P1/P3a. It's a problem that doesn't happen in the US but does happen here in the UK even if you use transformer power conditioning. I don't know if this affects his amps. I currently have a book resting on top of it to kill the noise.

One possible suggestion for Nuforce for the future might be to separate the power supply from the amp so that aftermarket power supplies could be used. We've also yet to see how they tackle the RFI issue themselves. Power supplies of whatever type tend to be the most problematic parts of the chain for me. If you separate the two, you also get an upgrade path that doesn't require service intervention.

It's interesting that the modding community doesn't offer a product.

gongos · « **Reply #7 on:** 12 Oct 2006, 04:39 pm »

You're more than welcome to come over to my place and hear the dynamics.

If I ever receive a comment on my system, it's about the dynamics. As for noise, I have to put my ear right against the tweeter to hear any noise.

This has been my experience with the CI Audio monoblocks. I've directly compared them to a number of different amps in my system.

beachbum · « **Reply #8 on:** 12 Oct 2006, 09:55 pm »

there has been some very interesting comments here, and we know that this is just the beginning of class d amps for the hi end, no doubt designers are going to produce a class d amp that looks good on paper and does not interfere with radio signals, the new orleans area is not the destination it use to be, but thats where i live and if any one is in the area and would like to hear what class d can sound like you are welcome, i dont know if my tylers are the right speaker class d disign wise for my nuforce gear but to my ear the sound is sweet and pure with no artifacts, we are all humans and as different as our finger prints, how else can you explain how martens likes and garcia dislikes, there are to many reasons for peoples decisions, loyalties, design favorites, freebies, and many others, the most important though is your ears, mike

zybar · « **Reply #9 on:** 12 Oct 2006, 10:10 pm »

Quote from: gongos on 12 Oct 2006, 04:39 pm

You're more than welcome to come over to my place and hear the dynamics. If I ever receive a comment on my system, it's about the dynamics. As for noise, I have to put my ear right against the tweeter to hear any noise.

This has been my experience with the CI Audio monoblocks. I've directly compared them to a number of different amps in my system.

While I wouldn't call the D-200's bass shy in any way, I didn't feel they were SOTA in that area. Frankly, I thought their strong point was that they were well balanced from top to bottom and presented an open, natural sound that didn't sound artifical or leave me cold.

George

CErvin · « **Reply #10 on:** 13 Oct 2006, 04:38 am »

I read the article with sincere interest as I spent several months last winter listening to Ref 9.02's, CIA D200's, PS Audio GCC-100, and Rowland Class D amps. I had Nu Force P8, Sonic Euphoria PLC and Placette passive in my system. My baseline amp was a Krell KAV-300i. My speakers are Paradigm Ref100v2's. Source is a Marantz SA8260 SACD/CD player. My experience with all the above amps was that they all were significantly more transparent, soundstaged (both width and depth) and imaged better than my Krell. I thought that all had better command and control over my woofers than the Krell. Mids were better although I think it was mostly due to the greatly increased transparency. Again, in general, highs were more naturally extended and smooth then the Krell.

Individually I felt the Nu force was the best of the bunch. I purchased the P8/Ref 9.02 combo and have been deliriously happy ever since. The next "best" combo was the Placette with the Nu force amps. In fact, it may have been slightly better but I just couldn't get past the ergonomics of the Placette Passive. The CIA D200's were a close 2nd and very fine sounding but the very top end was slightly rolled off or softened and therefore the "air and space" were muted - when compared to the Ref9's. The GCA-100 was better than my Krell but had less transparency when compared to the others. I had the Rowland's in my system for the least amount of time so my memory is fuzzy.

The other area where there was no comparison - and again the Nu force amps were the best - is in the area of dynamics. I found all to be faster than the Krell. Leading edges seem more real and natural. The strum or picking of a guitar string, the hammer of piano on string, the honk of a sax, the impact of a kick drum or rimshot are far more convincing with any of the above than my previous amp. On some material the speed is so real its startling! Finally, the Nu force excelled in the area of air and space between the instruments. To my ears the sizzle of cymbals, the air around the shimmer and decay, room ambiance were best reproduced by the Ref 9's.

In other stops on my journey...I listened to Classe, Musical Fidelity, Mac, BAT, Pathos and probably a few others -- although NOT in my listening room so I can't say much about these other than that none of them impressed me enough to want to bring them home to audition them. They were better than my Krell but seemed slow, veiled and dynamically polite compared to the above.

Full disclosure: I don't listen to much if any classical music. The majority of my listening is confined to "rock" music from the 60's till present with modest doses of almost anything other than country music and rap.

My 2 cents.

Chris

Rocket · « **Reply #11 on:** 13 Oct 2006, 09:12 am »

Hi,

In January 2005 and i bought a ps audio hca - 2 which uses another form of class d amplification and it sounded terrible in my system. I sent it to an electronics engineer in the states who has a lot of experience modifying the hca - 2. He replaced the power supply caps, installed black gates in the signal path and a heap of other modifications for me.

Whilst it was in the states i bought a son of ampzilla and when the hca - 2 returned home i did many comparisons between the 2 amplifiers. I'm back in the analogue realm again as i really like the SOA compared to my hca - 2 which still is a good quality amplifier.

I've heard the nuforce amplifier a number of times and i really like the amplifier and in comparison to the bel canto evo2 gen 2 it is better imo.

I think the future is really bright for class d amplifiers and for audiophiles as they sound very good for the money.

Regards

Rod

woodsyi · « **Reply #12 on:** 13 Oct 2006, 01:43 pm »

I will say that my eAR 1001s drive midbass and bass woofers with complete control. They don't however compare with my tubes on midrange to treble -- good balance top to bottom but lean to the point of emaciation compared to my tubes. They may be better with dynamic drivers. Hmmmmm.

I am going to test and see if ICE amp sounds better with cones than ribbons.

rustydoglim · « **Reply #13 on:** 13 Oct 2006, 06:25 pm »

Half of the Class D amps in the special edition TAS have at least one reviewer who strongly favored it.
We can best concluded that high-end audio is quite subjective and you should audition it for yourself.

What we try to do is present a very wide spread opinion from all over the world (no other amps have been able to accomplish the same level of consensus worldwide). Another reviewer from Stereophile just adopted Ref 9SE as his reference amp (you'll find out from reading the articles from Stereophile). He did not review the Ref 9SE but requested to audition it and ended up purchasing the amps.
Here's another newly published review on Ref 9SE: http://www.positive-feedback.com/Issue27/nuforce9se.htm. The reviewer, John Brazier was very skeptical of Class D amps but now adopted Ref 9SE as his reference amp.

beachbum · « **Reply #14 on:** 13 Oct 2006, 10:25 pm »

congratulations Jason for another fine audition, the thing that really chaps me is how a guy with Garcia's reputation can come out and say his feeling so blatantly, of all reviews i have seen and thats be a heck of alot none has been as critical, sure would like to no how his audition was done, it seems to me that Harley was playing ref with his other reviewers, some what agreeing with both, like i said above Chris Martens feelings come across the way my system sounds with nuforce gear, its the weekend and can stay up late and will be pushing my gear hard, rock and rolling tonight, mike

accentstryping · « **Reply #15 on:** 13 Oct 2006, 11:40 pm »

Hows that tuner related thing going? Find a fix yet? Your SE's are amazing but...
MMM
What I mean is... can I play FM now without any interferance?
Or should I get seperate amps for tuner listening?

timothyharnett · « **Reply #16 on:** 14 Oct 2006, 04:58 am »

Quote from: gongos on 12 Oct 2006, 04:39 pm

You're more than welcome to come over to my place and hear the dynamics. If I ever receive a comment on my system, it's about the dynamics. As for noise, I have to put my ear right against the tweeter to hear any noise.

This has been my experience with the CI Audio monoblocks. I've directly compared them to a number of different amps in my system.

By noise I was actually talking about mechanical noise from the transformers themselves. Not from the speakers. Based on the response to this post, some people get the problem with the D200 http://www.audiocircle.com/index.php?topic=31665.0 and I suspect that because I get it from the Monolith power supply (which he designed) then I'm likely to get it from the D200. It's far more annoying than the RFI problem if you're unlucky enough to get it. With the Monolith, it's particularly a problem for some UK users dependent on local supply.

Linear power supplies are not entirely problem free.

rustydoglim · « **Reply #17 on:** 14 Oct 2006, 06:15 pm »

WG is quite dramatic with his comment. Read his negative comments about other amps too.
We don't know what could have trigger his comment. He doesn't seems to think that Class D is ready for prime time. Oh, he reviewed the Ref 9 and not Ref 9SE. We'll try to find out from him and perhaps send him some cables with Ref 9SE to try out.

Anyway, Nuforce is indeed controversial with a few (2 so far) very negative comment. But noticed that for every negative review, we have 10 more over the top endorsements. For other amps, you will find some general consensus but rarely raving endorsement. But for Nuforce, the majority of those who reviewed it unequivocally stated that it is the best thing they ever heard. You know reviewers or even audiophiles don't make that kind of dramatic statement often.

By the way, here's another just published review today!!! Another Reviewer Choice award:
http://www.hometheatersound.com/equipment/nuforce_reference_85.htm

bummrush · « **Reply #18 on:** 14 Oct 2006, 07:20 pm »

Sure you had a neg. view by one or two,i myself have not heard Nu Force,Bel Canto,Red Dragon mini's for me,Love em both.But man you sure must be doing something right,you just cant please everybody all the time or sometimes never.These amps sure have got people talking,thats a good thing.Now start to do some comparisons with similar priced components,well lets just say we added a couple extra innings to the game.

RichardS · « **Reply #19 on:** 16 Oct 2006, 01:28 pm »

Another happy convert to digital amps. I use Tact amps in my main system, with a Bel Canto ICE on the subs, and a modded PS Audio in another system. Only heard the Nu-force once, and in a friend's system, so can't really comment. I've used tubes in the past, and have previously owned Gamut, Rowland and Pass Aleph monos, Bel Canto EVos and big Classes, and still own a BV Audio SS amp used in a second system.

To my ears, IMS, the digitals hold their own, and have surpassed the others in some ways, at considerably less cost. Speakers used and personal taste will sway folks one way or another, and everything has its trade-offs, but I think the cost/benefit circumstances with the digital amps is generally much higher than what is offered by most conventional SS amps. And when you're multi-amping and living in the South the reduction in heat (and AC bills, and resultant noise) is refreshing. Not to mention the increases in sound quality for the masses offered by cheap mass-market digitals.

The Absolute Sounds class d future

accentstryping