Lots of great responses. When switching frequencies are 5x higher than today's, what will be improved? Will that prevent the saw tooth waveform challenge? Or prevent the need for a low pass output filter?
What makes today's class D amps sound cold and dry? I have experienced this firsthand with an ICE Module that I once owned.
Mapman alluded to a totally black noise floor. I also experienced this with the ICE module. So far, this is the only benefit other than efficiency & power output that has been discussed and can be attributed directly to the Class D topology. Or maybe this noise floor issue is unnatural and sounds are being cut off prematurely by not allowing for decay? |
Mapman, you said earlier in the thread that the high dampening factor of Class D makes them a better fit for larger speakers that like high dampening...with your smaller speakers sounding towards the cold and dry side with Class D. So would it be safe to say that Class D should be carefully matched to speakers that like high dampening? |
Thanks mapman. That is consistent with the new KEF LS50 active monitor. It uses Class D for the bass and Class AB for the highs. |
Guido, I understand your practical advice. However, companies such as Bel Canto & Rowland don't make Class D amplifiers. They take Hypex or Ice Modules and make mods to them so they can add their house sound. So, I think that Class D can be discussed as a topology. There is general agreement that the sound of Class D is improving, which is to be expected since this is a high tech product. |
Mapman +1. People are tossing terms like "nonlinear" or "lots of distortion" without even understanding the principle of operation. I can understand when people don't like sound of particular class D amp with their speakers, but tossing pseudo-technical terms is plain silly while starting thread using such terms is ill minded.
kijanki, here is my reference for Class D not being a linear technology and having a lot of distortion that needs to be removed with an output filter. http://www.infineon.com/dgdl/an-1071.pdf?fileId=5546d462533600a40153559538eb0ff1 |
Some other manufacturers, such as Merrill Audio, do a thorough "passive" component design around the modules... They implement highly dampened chassis, highest quality internal wiring (e.g. Cardas), and I/O connectors: see for example the Merrill Audio Veritas monos that I have reviewed for PFO a couple years ago. In some cases, like in the entry level Merril Teranis stereo amp, they design custom input stages. Hi Guido, I was referring to the custom input stages as an example of adding a house sound...such as the tube input stage that Peachtree uses. If all a company does is add a chassis and nice wiring to the I/O connectors using an Ice Module, that is basically a DIY project...which I agree isn't bad if the module is of sufficient quality. I had a DIY setup with the Ice Amp 125ASX2 and unfortunately it didn't meet my expectations with regards to accuracy. It had dead quiet moments during songs that could be viewed as a positive or as artificial blackness.
I have never heard Hypex, but many indicators point to it as being a superior implementation of Class D when compared with ICE Modules. |
Does anybody know what causes the dead silences in songs that is a characteristic of Class D? Is it the output filter or dead time? I really noticed this with my Ice Module and couldn’t figure out if the amp wasn’t allowing for the music to decay or if it was something else causing the inky blackness. |
It looks like Merrill is taking Hypex modules, putting them in beautiful cases with Cardas wiring, Cardas connectors, custom house brand power cable, & stillpoint feet...and putting a seal on the bottom of the case saying the warranty is void if the case is opened. Then their Veritas & Thor amps get reviewed and the reviewers claim that the sound is as good as amps costing 2-3 times as much. I don't doubt that Hypex is state of the art, but these appear to be clone amplifiers. |
If you are listening to Diana Krall, and you hear Katy Perry, the problem is much larger than amplifier technology. You either have one heck of a malfunctioning system, a set of speakers that were dropped out of a truck before being delivered to you, or you are experiencing neurological problems that require immediate medical attention. I'm not being facetious...Katy Perry and Diana Krall sound nothing alike, aside from both being female. If that's genuinely what your ears heard, you have bigger issues than deciding what amp to buy.
bcgator, it was an analogy. Diana Krall has a warm voice and the Ice Module made her voice sound cold and thin. Katy Perry has a cold and thin voice...hope that clears things up. ;-) |
But they still had a stripping of the harmonic structure of the upper/midrange and highs, leaving what seemed to be just the fundamental with no decay and an opaque sound with larger than usual "nothing" gaps in the music.
This is the perfect description of my experience with Ice Power. I have heard others describe this sound as neutral and uncolored, but to me the vocals and instruments sounded stripped. Diana Krall sounded more like Katy Perry. The larger than usual nothing gaps in the music made me focus on the recording instead of enjoying the song. It seems like some companies are aware of this and add tube input stages to try and add harmonics and meat back to the bone. |
So its pretty much on par with everything else audio these days. Some like it and some not so much.
its nice to have choices.
The difference is Class D will only continue to get even better.
Someday soon everyone may agree.
Mapman - I would say Class D is similar to tubes as far as opinion goes. People either like the sound or they don't. I am not saying that tubes sound like Class D (far from it), just that they are both controversial. Very rarely will you hear someone say something bad about Class A solid state relating to sound quality/accuracy. |
I recall when I was in college I could hear well to 20khz. I know because I ran tests.
I also found it much harder to get sound that was not fatiguing. This is back in analog days even.
These days I know I cannot hear to that extent which is normal for ears my age. I find listening not fatiguing at all and can listen enthralled for hours and not want to stop. With most any kind of music or recording. Well except the occasional really bad modern loud pop mp3. That’s what its all about. Maybe there is some advantage to getting older after all.
Mapman, with all due respect, how old are you? |
Companies such as Devialet are creating hybrid AD Amplifiers. In theory, that could be the best of both worlds with sound & efficiency. Are the hybrid amps subject to the same issues with phase & bandwidth?
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I am in the market for new amplification, moving on from my trusty Krell KAV250 and was considering giving class d a try again. I say again as about 3 years ago i tried a pair of bel canto 500m mononblocks and found them to be so cold and sterile that I could not stand them.
History is quite interesting for Class D. If you believe the reviews, Class D has been state of the art for lets say 10 years. When the Tripath amps came out they were declared to be superior to prior class D generations that sounded poor in the higher frequencies. Boutique companies such as Red Wine audio made reference gear using Tripath and the reviews were glowing. Next came Ice Power generation 1. They were claimed to be superior than Tripath and the boutique amp makers and Stereophile reviews claimed their superiority as reference grade. Next came Ice Power generation 2 same story. Then Hypex NCore, etc. A snippet of a 2009 Stereophile review is below. "The Bel Canto Ref1000 Mk.II can be compared with the cream of the other amps I've had in my system: the Classé CA-3200, Mark Levinson No.433, and Ayre Acoustics V-6xe. Each of these distinguishes itself in different ways, and particularly with different speakers. Because of this, I think I must keep the Bel Canto Ref1000 Mk.IIs as a reference amplifier—an easy decision even when based solely on its sound, but also: in my living room, none of the others can be so easily hidden in plain sight." |
The real strengths of Class D are low cost, high efficiency (about 85%) and because of the latter, smaller size as large heatsinks are not as important. Lower cost for manufactures, which seems to result in higher margins instead of reduced retail prices. Manufactures have to of course be careful of cannibalization. |
The Rogue Pharaoh is an integrated though? Emotiva Monoblocks running 600 watts of power with their best preamp compared to a 185 watt Rogue integrated?? You can’t compare pricing on monoblocks plus preamp with an integrated that has a fraction of the power. It’s 3 pieces compared to 1.
Those Emotiva monoblocks will also run in Class A mode. If Emotiva were to sell a 185 watt integrated, it would be priced around $500 and of course couldn't compare with a $3500 Pharaoh.
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Fast forward 6 months and I can truly say the Emotiva gear was mid fi. The Rogue gear outclasses in in every way. I don't care that Magnepan says to avoid Class D. They are wrong for making such a blanket statement, and I was wrong for heeding the advice.
I am finally very happy.
Magnepan recommends high current Class AB because they know their panels work well with that. Class D doesn't have a consistent track record and they don't want that to cost them in sales and returns. They also don't want to bad mouth Class D because their dealers sell it. I believe that their most recent advice is listen to their panels at the dealer with the amplification that is going to be used. Emotiva gear is mid fi for sure. Their most expensive amp is $1000 and Rogues cheapest amp is $1300. Hardly a fair comparison ;-) |
I keep reading the negative comments on class D amps here and then listen to my Devialet 1000 to Maggie 20.7 setup for flaws. I know the Devialet is a class D hybrid design..... but the system just blows away all the other amps I have tried.
For 35k I would hope so. I believe that this hybrid is unique in that it doesn't require an output filter....it's kinda like a thread where people are debating if class B amps can compete with tube amps and someone chimes in that their Class AB amp sounds brilliant and they don't get why folks rag on Class B. |
I had the Ice Amp 125ASX2 and it was awful. |
I've been living with ICEPower based amps for six months, I don't hear any of the issues being discussed, and my speakers have extension beyond 30kHz.
Some folks hear the issues and others don't. Some folks are really sensitive to phase/point source issues or maybe they focus on the image across the soundstage. If someone told me that the image was off, I would just shrug and keep enjoying my gear/music because it's not something that I notice. |
New class AB amp from Benchmark ABH2 also utilizes SMPS resulting in 132dB dynamic range.
They had to cut costs somewhere to hit that $2995 price point. The dynamic range and THD numbers, while appearing to be unusually good, may be partly the result of using too much negative feedback. I've never heard this amp, but too much negative feedback and you can end up with a soulless amp. |
Hi Tim, I believe someone explained it best when they said that there were two ways that amp makers deal with the noise produced in the audible band due to the switching frequency being too low. One way creates an overly smooth top end with missing detail and the other way creates a hard sound. Either way, both are forms of distortion. |
Well nothing’s perfect but in all honesty gotta say that Class D done well comes about as close in all ways that matter as anything I’ve experienced in home/high end audio. Even without breaking the bank in some cases. If I were competing with it these days rather than benefiting I would definitely consider it a threat to my existence and take actions accordingly.
Maybe we will start seeing Class D preamps then... |
call me stupid but what do you mean by a "Output Filter" ? A L/C for you amp? Thanks, I am thinking about a Bel Canto but have never heard them.
You might want to hear them first. They are not for everybody. Most people feel that they are incredibly clean sounding with great control of the bass. However, some people also feel that they sound lifeless in the midrange compared to high end linear amps. Of particular importance is the module that is being used. Of less importance is the brand name responsible for putting the module and power supply in the case and tweaking the input stage to create a house sound. Tube preamps can help with the lifeless sound, although some prefer that sound. Good luck. |
Thanks for the link Tim. This quote tickled me. Much the same with converters. If you know exactly what to look out for in a chip, you can find chips that are really suited for use in a $1000 product that, for the price, will offer fantastic performance, simply incredible value. Speakers ditto: You wouldn’t believe the performance of some $10 drive-units, but if you’re hung up on exotic cone materials, you just won’t discover those. |
There have been many positive reviews of the NC1200-based amps but for another perspective, read near the end of the linked review of the Mola Mola Kaluga.
http://www.monoandstereo.com/2015/08/mola-mola-makua-and-kaluga-review.html This review perfectly describes my experience with ICE Power. In learning about Class D, it appears that after the linear signal is destroyed and turned into a saw tooth wave form, the output filter? tries to put the signal back together...doing an incredible job considering the complexity of this task...but ultimately is unable to restore micro details to recreate the original signal...which people such as myself notice very quickly, while others either don’t notice or enjoy the new coloration. Perhaps my understanding of Class D that I mention above is incorrect and someone can correct me. |
It is silly, to avoid using stronger word. You originated this thread pretending you want to learn about class D, while knowing you hate it.
I will remember your login and will be careful to answer your posts next time.
I've learned a ton about Class D from this thread and I appreciate everyone's input (including yours). I began this thread after having a poor experience with Ice Power. I wanted to like that tiny powerhouse and kept trying to talk myself into getting used to its tonal qualities. My goal has been to learn about Class D in general as well as limitations and strengths of the technology. It's hard to not step on toes when seeking to uncover information that is potentially upsetting to promoters of the technology. I would not have began this thread if I had given up on this technology as the internet has enough trolls. Happy New Years to all classes of amp lovers. |
I am not sure where obsession with the switching frequency comes from. It is inaudible while the only other thing that it might cause is filtering network phase shift - that can be beneficial since speaker has much larger positive phase shift at high frequencies. Placing nonsense about signal being "destroyed" (while SACD works exactly the same way) is trolling.
If you read my post I used a question mark and asked for clarification and correction...which Atmosphere was kind enough to reply to and correct my confusion. Kijanki, I don't think that anybody is doubting that your amplifier sounds brilliant to you. At the same time, I think it's okay for others to be less satisfied about what they hear. Don't get me wrong. I want a tiny powerhouse amplifier that sounds brilliant to my ears as much as the next guy. Class D is the future and there are a lot of audiophiles sitting on the sidelines, waiting for the technology to mature. We need early adopters to buy into the technology so I'm thankful that the modules are good enough or even perfect right now for many people. |
Don’t listen to the negative propaganda especially from just one or two who repeat the same thing over and over. Just try them for yourselves if interested and see.
Myself, I’ve had way less trouble finding top notch sounding Class D amps than others.
Mapman, I'm glad that you enjoy your Ice Modules. The KEF LS50 was just released in an active version. The woofer is powered by Class D and the tweeter is powered by Class AB. Does this mean that there is a problem with Class D higher frequencies to some ears...or is it just an issue with procurement budget and not being able to purchase the better Class D modules? I don't have those answers but it is food for thought. |
Fact is the times have changed in audio. Digital is blossoming with tech that combines dac, amp, preamp, room correction etc.. all into one or two boxes keeping the signal all digital up until the point the signal is sent to the speaker.
Read all the recent reviews of my Lyngdorf 2170 or the Exogal Comet and Ion amp. The future is here right now.
Grannyring - there really hasn't been much discussion on this thread about digital Class D...mostly analog Class D using modules from Hypex and Ice...a few from Pascal & Abletec. Your Lyngdorf appears to use the TI Equibit technology, which combines amp & DSP. Very interesting stuff. http://www.futurlec.com/News/TI/AudioSolution.shtml |
George - it appears that TI bought this tech.
Quote Originally Posted by amirm View Post
I thought Tact Licensed that technology and the actual company that designed Equibit was Toccata.
My sense is that it is a different design. But to be sure, I have email into Harman people and will report back what I hear.
The Equibit design was developed by Tocatta, originally implemented by Tact T. But TI purchased Tocatta and the Equibit design. Not many companies are using the technology that I know of. Lyngdorf (formerly Tact T) still does, and I know Panasonic built some AV receivers using the Equibit amps; I own one of those.
Tim
Todd_Packer said:
07-16-2012 02:18 PM
Quote Originally Posted by amirm View Post
I thought Tact Licensed that technology and the actual company that designed Equibit was Toccata.
The Harman Drive Core amplifier chip is a completely in-house design done through Crown engineering. The only thing we used TI for was their expertise in IC Chip manufacturing. There are several patents on the chip design, although the basic topology is a Class D output stage. The Drive Core technology is used in several places, including the Lexicon DD-8, and several Crown amplifiers. There are 2 chips, one is a complete amp on a chip that includes an output stage that is capable of delivering 75 - 150 watts into 8ohms (depending on power supply and application requirements) and is table to 2 ohms, and the only thing that is really needed is a power supply and an input stage. The first use of the technology was in the Lexus LFA supercar. The requirements were high output, small size, high efficiency (greater then 90%), and great sound. Moving the input and output stages onto a single IC allowed much tiger tolerances of the clock and triangle wave form generator that is the heart of all digital amp designs, and often the cause of the "Class D" sound some people don't like. There is also a version that is everything without the high output stage (the input, waveform generator, feedback circuit, etc...) that can me used to drive higher output stages either Class D or our patented Class I, where more then 150 watts is needed.
thanks for the interest,
Todd Packer
Harman Luxury Audio Group
Field Application Engineer
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I'm not sure what this "class A input stage" is. Input stages are almost always class A (would be stupid not to), but class D amp is pretty much one stage - a modulator + output transistors.
I thought the Class A input stage is what voices the amplifier and keeps it from being a clone amp in a pretty box. |
Very elegant Ice Amp with a class A input stage. |
Kijanki - Yes I meant voicing as a coloration to differentiate a boutique amp from a stock Ice Module. Some feel that adding a custom input stage and not using the stock power supply creates a superior sound to their ears...which I can't argue with.
mapman14,180 posts01-03-2017 2:58pmI do not have "ice modules" . i have stated repeatedly I have BelCanto Ref1000m amps. These use ice modules but also custom input and power circuitry and the price and sound reflects that accordingly.
Again generalizing and glazing over facts and details to help an argument helps nobody and is a disservice.
I would likely not have been satisfied using that older revision of vanilla Ice modules to drive my speakers which is why I opted for a better design. The original Bel Canto ref1000 was vanilla icepower (and much cheaper) and the differences between the two are well documented.
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On the other hand, it is worth mentioning that ICEpower-based amps have traditionally been bears to break-in.... And for at least a couple hundred hours out of the box they tend to sound dry and uninvolving. Any idea what part of the amp is breaking in and what is happening during this process? |
Now after a very positive upgrade of my ht rig from a pair of emotiva space heaters to a single nuforce class d i am ready to be convinced.
Which Nurforce did you buy? Any idea who makes their modules? |
I hear the new Peachtree Novas have done a good job. I'd be curious how they sound
People either love them or can't stand them is what I have noticed. They are beautiful though. |
I never expected Bruno Putzey (inventor of UcD & Ncore) to answer the question of this thread, but he did in a very candid Sound & Vision interview. S&V: Generally speaking, what are the key benefits of Class D versus the traditional Class AB and Class A designs that have long been favored by audiophiles? BP: Efficiency and therefore the ability to construct amps that are powerful for their size. Only that. Modern Class D amps, in particular mine—ahem—sound good not because they’re Class D, but in spite of it. I can’t repeat that often enough. Left to its own devices, a switching power stage tries to do just about anything except amplify audio. You choose Class D to save energy but it’s all elbow grease after that. People don’t realize how much more challenging Class D is compared to Class AB. It’s truly an order of magnitude. Read more at https://www.soundandvision.com/content/bruno-putzeys-head-class-d#AIQPKcJQwFsL2Zkd.99 |
Although one should always be skeptical of audio reviews due to quid pro quo, this statement is quite the endorsement. I know that NuPrime has specifically tried to mimic the sound of linear amps (if you read their marketing copy) so their engineers may be doing something right.
I’ve heard many class D amps, but have liked very few. While bass control and neutrality are often a piece of cake for these amps, they are usually let down by thinness, harmonic deficiences and an unnatural timbre. The NuPrime ST-10 is the first class D design that sounds timbrally wholly convincing to me. Piano really sounds like piano, not like synthesizer and vocals are just as direct-coupled as they are in real life. Add in bass heft and thundering dynamics like I have not yet heard from other class D designs. Only the Mola-Mola Kalugas ultimately provide more refinement and transparency but these are placed at the complete opposite price spectrum.
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