What is up with Class D amplification?

[Craig]

I had the opportunity recently to home audition the new Cary A-306 600w digital stereo amp. This amp was large, heavy, nicely finished billet aluminum front a chassis and have 3"x5" acrylic window with ""CARY" etched on it that glowed blue. It was pretty but was not sure if I liked the billboard effect. This model was definitely high-end and I was fortunate to have an unselfish friend loan it to me for a few days. As far as I know this amp is the most seriuos application of "D" class amplification yet.

It sounded wonderful driving my Ascents. Bass was tight but definitely not overdone at all. I was expecting a little more bass from such a powerful amp but it was just right if not a just a tad on the shy side. The midrange was beautiful with plenty of tone and the highs were smooth. I would have been very happy keeping this amp. I tried it with the Summits but strange were going on with the speakers so I removed without any further attempts. Something obviously was not right with combination. I later learned the earlier model Summits aren't compatible with the new digital amps.

ML has a new control module that can be swapped to correct this and of they are very accommodating if your speakers need to be updated for this. I don't know if the Vantages have the same thing going on. If you are considering using a "D" type amp and you have Vantages or Summits then it's best to call Martin Logan first to have them verify if your speakers are updated or need to be.

The Cary gets a high recommendation from me but it is pricey at around $6K.

 

[ernio1]

Bel Canto Evo and Martin Logans

Sorry, I have to disagree about the Bel Canto Evo (IMO)

I purchased an Evo4 Gen II several months ago based only on glowing reviews and many positive comments on various websites. I really liked the amp when I first hooking them up to my Ascent i's. It had good detail, great depth and seemed to have good power. I eventually got rid of the Evo4 since it later started becoming fatiguing to my ears in the high frequencies and also, for some reason got boring to listen to. I found that they were lacking in the low frequency areas(with the Ascent i's) which seemed to enhance the highs that were impressive at first (actually, I did not realize the lack of bass so much until later).

I've had a couple of other amps until I purchased a Pass X250. I now know that there is no replacement for a nice, large, hot, high current amp for the Ascent i's. As soon as I hooked it up, I knew it was a great match with the ML's. There was an abundance of organic, effortless power and very low-room filling bass which did not exist with the Evo4's and now I longer need my subwoofer which is now out of the room.

Ernie

 

[Popipipo]

Hi,

I've also heared some good stories about Nuforce amps, which also fall into this category ...although they are called analog switching amps, the principle is very similar.

The good thing is that they only cost $1500 per channel and apparantely are able to give the Krells and Mark Levinsons of this world a serious run for their money...

I'm going to check them out shortly to team them up with my Aerius I's.

Here's one of the many raving reviews on the net:
http://www.positive-feedback.com/Issue23/nuforce_9.02.htm

 

[Andre]

Thought that Digital amps can't drive low impedance loads like Martin Logans. They are more optimised for 6-8 ohms loads? I have read that Panasonic digital avr are respectable, yet cheap!

 

[Ironic77]

The reason you're seeing class D is actually also legal reasons. Places like Europe and California are having stricter requirements around efficiency. This motivates companies to improve performance, etc.

So space, cost, efficiency -- including legal requirements.

 

[MarkNewbie]

What an interesting post this has become. Anytime any Goverment becomes involved in the "Audiophile" realm, that scares the dickens out of me. So now we are saying that saving trees, fuel, the Caribou, & the Environment is going to govern how our equipment is manufactured?

Oops, I did it again...

<----Putting on "Fire-Proof" suit!!

 

[user 593]

Hello,
BelCanto does not work any more with modules Tripath but IcePower.
Astonishing like change not?

On the other hand, I am particularly interested by BleCanto e.One REF1000
Believe that it is able to make go of CLSIIz without problem?
You it will not be put in protection? The CLS have a very low impedance.

Thank you.

Jeff Rowland and Rotel also use IcePower...


http://belcantodesign.com/prod_eOneREF1000.html
http://www.6moons.com/audioreviews/eone2/1000.html

 

[unclemonty]

I agree, this is an interesting post. I posted on an identical subject about a year ago here, when I had just moved from a Krell FPB600 to a PS Audio GCC500 (Icepower, like most these days, Bel Canto included) to power my Ascent i's.

I view it as a little futile to argue over which is best because the sound from a good class A-type amp is very very different to this new breed of amps we're seeing now. Both are good if not excellent, just very different. For me it was also important to reclaim some real estate in my front room, and the Krells (I had 3 units at that time) just ran too hot here in tropical England, where I live. Of course, what is very important in all of this is that with the IcePowers, Nu Force etc you get an awful lot of amp for the money compared to Krell, Plinius etc and I they they ARE comparable in quality terms, just sound different that's all.

Since my last posts, I upgraded to Summits (just wish they sold them at Costo here as well though....) - fantastic speakers, best MLs I've heard to date. However, my Summits were used and predate the change ML has made to enable them to work OK with IcePower amps. Mine are now at the importers having their balls removed, or whatever they need to do.

Regards

 

[roberto]

severelost of high frequency info with electrostatics

Hola amigos. Well, my experinece with the Digital amps driving MLs is that they lost a all the upper octaves. I had tried Nuforce, Bell Canto and Audio Research. All of them, to my ears didn´t like electrostatic speakers. They where fine with dynamic speakers like Uhser and B&W. Very fast and precise. I did like with dynamic, but did not with electrostatics. I had the Odyssy and the Prodigy. Did not try with the new ML models, but I think they don´t like very low impedance. the highs drops like a brick. They are class D and class T. Hope this can help...happy listening,
Pura vida,
Roberto.

 

[Munster]

"Mine are now at the importers having their balls removed, or whatever they need to do.'

Hope it doesn't change their personality.

 

[garmtz]

Because of the output filtering, class D amps only work optimally in 1 load. When the load decreases (less impedance), the highs are rolled off progressively with it.

The only proper class D implementation for these low impedances is Hypex UcD.

 

[Thiem]

Try this

This is my first post to the forum. I have been a reader for some time but after reading the above thread, thought that it might be interesting to share my experience with you.

I am running my ML Summits off two monoblock JOB 150 amps. These amps are made by Goldmund and are very affordable (USD 975 each). The sound is very detailed, fast, never hard and certainly does not roll off at the frequency extremes. I had Oddyssey Audio Extreme monoblocks which worked fine with my Magnepans, but these JOB's are a revelation. The JOB's are kind of class D amps, although the site below claims to use in-house developed technology.

Check out www.jobsys.com. Also the Goldmund website makes reference to the JOB technology.

In the future I will post pictures of my system. Whoever lives in the Netherlands (or abroad) is more than welcome for a listening session.

Thiem