There have been many advances in circuit topologies and devices in the last few years that allows class-d amplifiers that qualify for hi-end status. Vendors such as Halcro, Jeff Rowland, Canton, Coda, Rotel, PS Audio and several others are now delivering class-d amplifiers that have received glowing reviews in the press. The Absolute Sound awarded SonicWeld, vendor for a system that uses class-d amplifiers in their speaker enclosures, the best sound award in the 2006 CES show. Have a look at the icepower site for a description of their class-d products. For a technical description of the technology, have a look at AudioDesignLine

Check out the Stereophile archives for the Channel Island review. Also, class T is very hot right now.

http://forum.ecoustics.com/bbs/messages/1/193312.html

http://forum.ecoustics.com/bbs/messages/47077/209464.html

http://forum.stereophile.com/forum/showflat.php?Cat=0&Number=3855&an=0&page=5#Post3855

Look for the recent review of the Sonic Impact amplifier in Stereophile.

I have been considering getting a digital amplifier but I can't find any of those digital ready speakers anymore.
When CDs first came out digital ready speakers where everywhere. If I can't find any will I need to use a high power DAC to drive my analog speakers?

I

Which magic wire seller will soon have insulation and magic twists to work to the "D" and "T" advantage? Will class D or T need air or vacuum for the correct "dielectric", not mere insulation, but dielectric, that lets them charge more bigger wurds, bigger price. I want nitrogne charged woires, like the phone company has on some pole set ups. Audio grade nitrogen of course.

Hi

With regards to internal combustion, this is also a very efficient technology. The whole purpose being that tractors can be made very efficient and therefore smaller and cheaper.

Ive looked at the links posted and there is nothing there that makes a good argument about why steam is not the best form of plowing.

As DUP would say this whole kerosene thing has a snake oil feel to it. It just seems to go against every known farming principle.

The fact that it's high end companies introducing this into the agricultural world when its the cheap mass market companies introducing it into the industrial world just makes it very suspect and looks like it's just a latest new flavour to stimulate the market with no real benefit except commercial for the industry.

If you'll take the time to read the class T articles, you'll find that the technology requires no more circuitry than a "conventional" amplifier. No more negative feedback should be required than in a "conventional" amplifier. The output of the amplification stage requires filtering but that is not uncommon in "conventional" amplifiers. Experience has shown that when designers cut the corners on such "conventional" methods of amplifier design, the reliability of the product (and often the equipment connected to that product) suffer from the omissions made in favor of marketing or misguided belief. If you do take the time to read the articles regarding class D & T technology, you'll find that many of the time honored principles of good amplifier design still apply and only the device used to do large scale gain changes is different from most "conventional" amplifiers.

Solid state is unconvincing to many of us. Common sense would sugegst that small wattage single ended triodes connected to single driver, full range speakers are the most logical way to amplify a signal. If amplification is required, that is. A good mechanical horn directly connected to the stylus is sufficiently more dynamic, especially in the audiophile adored "micro-dynamics" department, throughout most of the bandwidth than any "conventional" amplification stage with its attendant problems and limitations.

The original post seems to place fault with the logic of the amplification stage and ignores the problems concomitant to loudspeaker design which has been allowed to stagnate at a driver construction with less than 2% efficiency. Inefficiency seems to be the object of worship for the original poster.

The original rhetorical question seems to require an answer which puts to rest any consideration regarding all other methods of amplification. The post beggars a definitive statement which can then only be prosected by those who would disagree with any part of the answer. It appears to be a political statement rather than a real question.

The subsequent reply indicates a mindset that says no other information need apply. With no concession given to DUP, common sense at one time suggested all wires sound alike, all passive parts are the same and the loudspeaker is the only component that affects the sound quality. If the original poster isn't even willing to consider spending $30 dollars on a class T amplifier to find out what the commotion regarding class D is all about, then words seem to be wasted on someone who has made up his mind and shut the door behind him.

I hesitate to mention the competition here, but the Absolute Sound had an issue on Class D amps with interviews with some of the top designers including Jeff Rowland.
One of the most musical amps I've ever heard is the Rowland integrated which is class D.

What about all the spurious emissions that has been found spuing out from most, if not all, the digital amps? Have they corrected the problem? Is PWM any better? I hope so.

Those emissions have been getting into everything, AM, FM radios and including the source components up front, causing hissing through the tweeters. Guess they can't rid it since the oscillators are too close to the audio frequencies and can't slope the filters enough.

Sounds like real high fidelity to me.

SS tramples valve amplifiers in every way? Are you joking or serious?

As far as SACD beating LPs. Well, I was listening with a Goldring entrance level cartridge and it immediately beat almost all the CDs I have using a Rotel player. Hmmmm. I guess I should switch to inferior electronics to please you.

Maybe audiophiles are recommending LPs etc because when we pulled them off the shelves again, and LISTENED to them again, we find valves and LPs superior?

Quote:

"So just maybe your sarcastic posting is more than a little two faced ??? what does hifi stand for ? sound quality or technology ? theres numerous examples of the two not being complementary."

I assure you, sir, I have but one face. All the while you hypocritically state sound and technology are not necessarily the complement of one another even as you declare class D and T are quite obviously inferior modes of operation after reading the technical specifications.

You have deduced that from an internet link; have you?

And my post(s) have not been meant as sarcasm. In the most basic sense of what I consider "hifi", they suggest you should spend $30 (or more if you like) to listen with an open and curious mind to the technology you claim is being snake oiled to you at exorbitant prices. My posts are meant to imply reading how a circuit operates is not going to leave you with an impression of how the circuit sounds in the hands of a competent designer. If you are satisfied with reading technical specifications and passing judgement on sound quality, then you have missed what I consider to be the very essence of modern high end audio. Obviously more than one (well regarded) listener has reported exceptional results from class D and class T technology. Almost everyone who encounters this class of operation, when done well, sits and smiles for long periods. If you are better than most of the rest of us at deducing the sound of a component without once hearing it, then you may offically join the DUP glee club. Your aluminium hat will be sent to you by pony express.

If, after hearing the technology in a fair demonstration, you should decide you prefer another component, then you will have learned the other lesson of my posts. No one is telling you class T will be the best sound quality for you, but I am suggesting you cannot pronounce the entire class of operation as lacking, where others find merit, without giving a single piece of equipment a fair audition. You can do so no more, at least, than you can flatly state class A operation is superior in every way to any other form of music reproduction. If you truly do not understand that everything is a trade off, then there is no further discusssion that is required.

Should you listen to the $30 class T amp and not come away with a respect for the efficiency of the design and the fact that it will put a smile on your face for very few dollars, then you are welcome to your class A amplifier at whatever exorbitant cost you can afford.

In other words, sir, entry into this class of operation is quite cheap. That is one reason for the stir around class D & T. Listen for yourself and make your own decision as to why someone might find class D & T interesting. There are multiple reasons and sound quality is just one of the many. Listening with an open mind is all I suggest.

And please do not suggest that if we are not running class A amplification, we are hearing inferior sound quality. I have more than once been driven from the room by a class A amplifier.

I would (wouldn

I don't believe I'm confused about the job of the filters in class D or T amplifiers. I understand what function they serve. My comment was there are by necessity no more output filters or circuits than in many conventional designs.

There seems to be an assumption that all class D/T amplifiers run a switch mode power supply. If you'll refer back to the Channel Island review, you'll find that is not necessarily the case.

Quote:

"Some of the other class-D amplifiers use switching power supplies, but I just don't think they sound good enough yet to use in audiophile amplifiers