I thought it was time we had a pro- Class D thread. There's plenty of threads about comparisons, or detractors of Class D.
That's fine, you don't have to like Class D amps, and if you don't please go participate on one of those threads.
For those of us who are very happy and excited about having musical, capable amps that we can afford to keep on 24/7 and don't require large spaces to put them in, this thread is for you.
jollygreenaudiophile2 "Have you ever heard of (Flying Mole), amps"? I imported some of these a few years back after a friend in Japan recommended them.
Yes it was the very first Class-D I listened to and tested back in around 2004, sorry wasn’t pretty, in sound or test against my Threshold Stasis S500 Optical at the time on the ML Monoliths. Then I got a Channel Islands Class-D with linear supply, better but still not near hiend.
Since then the only Class-D that has piqued my interest was the BelCanto 600M monoblocks but only on a 2 way speaker with a very benign 6ohm load, with Raal ribbon
with In my experiences with good quality class D ampsThey just faithfully amplify the inputted signaout adding or subtracting anything. They’re like the audio amp ideal of a "straight wire with gain".
which I have proved couldn’t be further from the truth
So, My two cent begins with , "Have you ever heard of (Flying Mole), amps"? I imported some of these a few years back after a friend in Japan recommended them. The one's I received were about the size of a paperback novel. They weighed under 2Lbs. and were housed in a really beautiful, single piece of "Brushed Silver finished", aluminum extrusion. With a rounded front face. Beautiful piece of gear! And at that size and weight? 160Wpc @4Ohm! They use a, "Bi-phase tech.", that they invented. Paired with a "Schiit", "Freya", tube pre? I found that the Freya, with, "Sofia Princess, Carbon plate", type tubes sounded amazing! Alas I didn't need them as I went in a different direction. I am kind of sorry I sold them all! They were just $220 a pair from Japan at that time. And the story was that they were being developed by the top engineers at "Yamaha", in Japan when word came down that Yamaha would stay, "A/B", when it came to their component separates. The Yamaha crew quit, and started the, "Flying Mole" company. They finished the amp and debuted them to a people un-willing to embrace the tech. "At that time". I also had a 13.6.4.3, surround system for a bit in which I used three, "Rotel", "RMB-1575", amplifiers with allot of success. Five channels each, 500Wpc, @4Ohm, weighing in at 22Lbs. and making LESS heat than my, "Chihuahua"! I did go to, "All tube, All the time, though", awhile back. With, "Manley Lab's", but that will eventually change. The "ZOTL", tube amps do interest me. And since I do live near to Mr. Bern and his Company. I shall be hearing a few of those soon.
That's right, what I said and why you can't see much switching noise on the square waves Without those "special testing filters" the square wave will look like this https://cdn.stereophile.com/images/1212AM1fig02.jpg Sorry it's is you that needs to get some tutoring on this, as I said the output filter limits bandwidth and also because it's a low order creates phase shift down into the audible frequencies.
I just replaced a Schiit Vidar with a Parasound Zonemaster 2305 and find it a great addition to my system (and I really like the Vidar!).
I can’t speak to the technology points being raised however for myself Class D gives me a level of performance that I could never afford in a Class A, A/B amp.
So while not perfect, however when compared to a similarly priced Class A amp a well implemented Class D seems to me to be a significant improvement.
It is not appropriate to use an oscilloscope to measure the audibility of signals. If you are having trouble using one, I suggest going to an electronics forum to help ensure you are using it correctly, and are not connecting it in a way that leads to incorrect results.
You've repeated the same 2-3 points on this thread, over a dozen times, with basically the same set of logical debunking happening immediately afterwards.
Are you offended if I ask you to go make your own thread to bash Class D?
@H2Oaudio nailed the crux of the matter on the proverbial head. Like amps of other topologies, some class D amps do sound extraordinary... The Rowland Daemon integrated that I am reviewing is definitely one of these. It is already trending to sound extraordinary, after just a little more than 300 hours of break-in.
heaudio , Slope on the edged is not caused by phase shift, it is caused by bandwidth limiting.
Oh dear! Which is caused by the output filter which and causes phase shift and yes if you must have that included, "bandwidth limiting" as that’s what the filter is there to do, without bandwidth limiting you have no phase shift!!!! please get it right.
heaudio
This is another ClassD no filter with a bit of overshoot likely due to underdamping also indicating from a frequency response peak.
You really need to do some more understanding, JA used his high order special testing output filters because he didn't yet have the
Audio Precision's auxiliary AUX-0025 passive low-pass testing filter, which eliminates noise
Stereophile
Audio Precision sells a precision passive low-pass filter to be used between the output of an amplifier with a class-D output stage and an Audio Precision analyzer. Unfortunately, I have not yet upgraded my test system with one of these filters, so to examine the MX-D1's performance at low signal levels, I used an active sixth-order low-pass filter with a 20kHz bandwidth and a floating input.
Thanks to all of the recent kind words. As pointed out, I can't believe this thread is really 3 years old. I can't believe we are still reading and dismissing the same old arguments.
I hope to read more about what new products have come out recently worth listening to.
As a young electronic technician, and PCB designer, I was entranced at the idea of ultra-wide bandwidth electronics.
We often made gear for theaters that was flat to 100kHz. Very transparent sounding stuff. Tandberg was one of the brands I remember sounding great at the time, with astonishing slew rates.
However, in modern times, I can’t say it has been the slew rate or bandwidth that has won me over at all. Spectral is one such amp, which I heard, and it was OK, but no, it didn’t stop me from buying anything else. That is, if the ultra-wide bandwidth had benefits, it didn't win me over to it.
Thank you Erik for starting this thread. Since I am a manufacturer and of Class D at that. Therefore, I am obviously biased. So I think my comments isn’t worth much and rightly so I suppose. Anyway, I won’t get into endless debate on the technical mumbo jumbo, rather to say that class D CAN (and this is the key word) sound extraordinary. Then again, the same can be said for tube, conventional class A and class AB design.
It seems no matter how factual I am you complain about me being abusive to you.
You have made dozens of posting on this thread, and ignored the request in the OP and myself and others to start an anti-Class D thread if you are so inclined.
You've also made the same arguments dozens of times.
Would you please be a gentleman and go start your own Class D bashing thread?
HI @noble100 , GaN is has been around for awhile. Several manufacturers are using it. It is an interesting material, not only is it fast it is also more energy efficient. I have heard it in Class A and Class A/B products. So you can find amps using this material and they may have no heat sinks or small heat sinks.
heaudio class D amplifier, with fairly well defined harmonics hence why they can be filtered.
Incorrect, it is you that is saying something false, if it was completely filtered out as you say, then they wouldn’t still look like this, with much residual switching noise still riding on the audio test waves 1-10khz, and with severe phase shift indicated by the inward slope of the sides https://www.stereophile.com/images/1212AM1fig02.jpg
I just finished reading this thread from the start. I have to say that of all the areas of audio, I find the class D debate to be the most diehard and in some ways hardheaded; its almost like politics.
I think, like a lot of things in life, the danger or pitfall comes with the broad generalizations - e.g. all class D is (crap, lacking, great, musical, whatever); or the best class D can already compete with anything (or no chance against good class A at other end of spectrum), and with having intractable positions. But to each their own. I’m not here to change minds, and I don’t have strong opinions on the class in general, just making an observation.
I think it’s much more fruitful to focus on specific models and thoughts on them, rather than trying to paint whole class with a broad brush. I’ll give an example.
Two of my three systems use class D amps, the other class AB. My main system uses class D Audio Research DSI200, and paired with my Spendor D7 and Teac NT505 to my ears sounds absolutely amazing. I don’t foresee changing anything for 10 yrs. My third system uses class D Bluesound Powernode 2, and paired with my Spendor SA1’s to my ears really leaves me wanting, to the point of hopefully I’ll soon be replacing it with similarly priced class AB Marantz pm7000n.
So fwiw I personally love one of my class D’s and can’t wait to replace the other. So I’ll stake out a new position in this thread: some modern class D is really good to my ears and some is really not so good to my ears. It’s okay to admit both : )
I'm afraid I haven't had time to go out and listen to a lot since the last show here in ... Long Beach? Newport Beach?
I've also gotten to a poin where I'm very happy with the sound quality at home but not the remotes. :) Seems bad for me to find a dealer to listen to gear I'm not going to buy.
Maybe I should ask manufacturers to send me gear to review instead??
Erik, three years later, and still going strong, excellent thread. Class D is the bomb, and your thread would seem to amplify that message. I purchased a D.A.C. older amp for my first try at Class D, A/Bs left something wanting. My Signature Technology is a very nice tube amp, the cymbals never sounded right. The DAC4800a was my first thousand dollar amp. It has been a delight ever since, so much so, I purchased a used Maraschino 60 volt model. Absolutely delighted with each. The 4800a uses a toroidal transformer, the Maraschino a linear power supply. Currently saving my money for another 60v Maraschino, will have to be new as these amps seldom come up in the used market. In another class compared to my Acurus or MTX Soundcraftsman. Use any adjective in the audio lexicon and these fit and fulfill those descriptors. I would really like to hear a review about the DAC amps from you. With respect, Jerry.
There is no such thing as straight wire with gain. Every single inch of wire sounds different from every other kind of wire and even the directionality of the wire makes an audible difference. Every single thing inside a power amp (class A, B, C, D or whatever) changes the sound. This is why every class D amp sounds different from every other one. They don't all have no sound or the same sound. I did 14 mods to the IceEdge modules to make them sound more dynamic, musical, extended and transparent. There is no end to infinity. We have not reached any sort of final class D sound orgasm.. If class D sounded perfect with mosfets, then why would we be looking at GaNs? Nothing is perfect on this plane....all is perfect in spirit......all is suppose to be this way....perfect in its imperfection.....and always we strive for more perfection.....hey, its fun!
,l with In my experiences with good quality class D ampsThey just faithfully amplify the inputted signaout adding or subtracting anything. They’re like the audio amp ideal of a "straight wire with gain".
Sorry they don’t look the same, just look at any 1-10khz test shot of input v output wave form. And then without their output filter, the input wave form will be unrecognizable from the output, because of the HF garbage, and melt your tweeters silently in a nano second.
It’s like a customers preamp I had to work on, the owner said it sounded little bit hard, a quick look on the scope showed the output wave form looked just like the input wave form, all looked fine?.
Then I looked with the scope in the center of the preamps circuit, and found the wave form unrecognizable from the input with the amount of hf garbage on it. That center amplification stage was oscillating its brains out!!! And all they (manufacturer) did was to filter it out at the end stage, instead of fixing the source of the problem.
I compensated the center stage so it didn’t oscillate anymore and removed the end stage output filter, and the customer was happy.
But you can’t do this with Class-D, so the only thing to do is to raise the sw noise in it even higher (1.5mhz) so then the output filter then can do it’s job fully without any phase effects down into the audible frequencies. Then a Class-D’s input wave form will be much closer to matching it’s output wave form.
"straight wire with gain"
I also have high expectations for the use of faster switching GaN output transistors in class D amps since they have the potential to eliminate dead-time, which even further reduces distortion, which in turn, typically results in improved sound quality. I've been using good quality class D amps in my combo music and HT system for almost 6 years now. In my opinion, they're the best option for attaining hi-end amp performance quality at an affordable price. In my experiences with good quality class D amps, I've discovered their most unique quality is that they have no sound qualities of their own. They just faithfully amplify the inputted signal without adding or subtracting anything. They're like the audio amp ideal of a "straight wire with gain". Due to this extreme neutrality of class D amps, I've come to the conclusion that the most important factor determining the overall sound quality level of a system utilizing a good quality class D amp is the sound qualities of the preamp chosen to pair with it. This neutrality also means the overall system sound quality contributions made by source components, and even interconnect and power cables, will be readily apparent and need to be chosen carefully, too. I've not yet listened to a class D amp utilizing the much faster switching GaN transistors but am looking forward to doing so, hopefully, at an affordable price. Based on my experiences with good quality class D amps, however, I suspect the use of GaN transistors will result in these amps being among the most neutral ever produced. Choose your preamp, source components, interconnect and power cables appropriately.
Would require more technical ability and energy than I have and my health could be better (I will leave the amp making to the younger guns) .....but mostly I am writing a book that hopefully will make more difference in the happiness of people than a better inexpensive power amp. I want everyone to be happy!
He loves them...bought them...replaced his tube amp.
AGD says they are using the IRS20957S PWM driver chip ($2.01@100).....and probably then a pair of $1.05@ GaNs on the output. You can see most of the circuit inside the tube in the above review. This means anyone can do this for practically nothing. Putting the circuit in a tube is just a gimmick. If they put that board inside the box and it was made in China with all the very same parts it would sell for around $1000 for the pair of mono blocks....no kidding AGD are using LM4562 op amps ($1.00 each) on the input. There are no expensive parts in this amp. You can see the very good sounding inexpensive Wima caps and Nichicon caps.
But we don't want to wait for the Chinese version that sounds as good for $1000......no, let's buy the one with the board in a tube for $7000......heck, we have money to burn.....he he. You see, fun times for cheap are right around the corner. Of course, anyone can make an amp similar to this....if someone else here is the US made it and sold it direct....probably $2500 the pair.....still...way less than $7K.
It seems that many folks hear one or two examples of a particular technology and if they like them then they equate that like across that platform. And vice versa some do not like the one or two examples of a tech they've heard and so they think that all examples in that tech sound bad.
Erik, you and I, Guido, and Ralph (and I'm many others) know that Class D can sound good. Obviously Ralph thinks so since he is working on bringing a Class D amp to the market. We also know Ralph made his mark in tubes and so working to offer a Class D amp he is basically stating that Class D can sound good, maybe not like tubes, but good in an of itself.
For those who've heard Class D and don't like it, I challenge you to go listen to Mbl or TAD. They both have Class D offerings that are very very good. You can't judge a book by its cover or its categorization. Don't listen for the Class, just listen for music. You may be very surprised and preconceptions may just be shattered.
It’s one of the first, commercial Class-D that came after the original Class-T (Google these also as they only used N channel fets which allowed in some cases a higher switching frequency)
I wonder if this is the reason why I only like Tripath amps under Class D category. Class D amps other than Tripath, give me kind of fatigue after 30 minutes of music. When I put my Tripath amp back, I can listen to my Harbeths for hours.
but replace my simple little single ended tube amp?
First, @wolf_garcia , I applaud you for being willing to expose your audio quirks without fear. I wish I had that kind of personal courage. ;-)
But that’s just it. If you love the LP sound, only the LP sound will be good enough. If you have a particular niche of amp, no other amp will sound as good. It’s not proof Class D is behind the best solid state amps. If you have a love for 30 watt Class A, same thing. It's a bit like comparing all restaurants to mom or dad's home cooking. Kind of unfair to rate them that way, unless of course your mom (or dad) was an absolutely terrible cook.
As I always say, buy and enjoy what you like, even if it’s’ some quirky SET or full-range with a giganormous bass horn. That’s fine.
But I think it’s unfair to diss Class D because it doesn’t sound like a SET. Among large solid state amps, I don’t know anyone who can listen and say "Oh, that’s a Class D amp, I can tell because....."
The technological backflips and design hurdles inherent in making Class D viable seem challenging to every designer who bothers with it, and clearly some are more successful than others. I think cheap Ice modules in a box or whatever Atmasphere Ralph is designing may work for many (I have one in an Ampeg 350 watt bass amp a friend traded to me...matches a vintage looking speaker box I already had), but replace my simple little single ended tube amp? Why? Less heat maybe, less distortion perhaps, more power that I don't need...and the biggest thing by far, an amp that likely doesn't sound as good to my ears as the harmonically rich and musically profound tube amp and preamp I'm using now. The "sounds like tubes" argument for some items, including the Schiit Aegir (not Class D but I'm tossing it in anyway) I recently auditioned and sent back, never really sounds like tubes (Nelson Pass tries, and the things of his design I've actually heard do sound real nice...but...)..."drives like a sports car"...right...until you drive a sports car.
Like Tube amps, or Pass (who makes it clear this is his goal) the
distortion profile may have more to do with euphonic capability than
merely lower distortion.
He is certainly right in that regard IMO. But we can hear that difference provided the distortion profile is also correct. The problem is that in most cases the difference between 0.05% and 0.005% isn't the issue- the fact that the distortion that is there is mostly higher ordered stuff that is highly audible even in those trace amounts. The correct distortion profile can mask those higher orders making the amplifier easier to listen to. But a class D amp tends to have a different distortion profile than a traditional solid state amp. Many of them using PWM encoding tend to have lower ordered harmonics too- which is the profile you're looking for.
Whether a designer takes advantage of this fact is another matter but generally speaking GaNFET amps should sound better as they have less distortion on that account.
@atmasphere
As you are well aware, I’m kind of touching on an issue of specmanship that that affects us with all amps. Can we hear "better" when you go from 0.01% distortion to 0.001%? I know distortion can be reduced, which technically means more fidelity to the input signal. What I don’t know is that this alone is audibility, let alone desirable.
Like Tube amps, or Pass (who makes it clear this is his goal) the distortion profile may have more to do with euphonic capability than merely lower distortion.
If there are actually audible benefits to GaN based amplifiers I look forward to hearing them.
There should be. GaNFETs are generally faster than MOSFETs (although MOSFETs aren't done by any means) and so the use of GaNFETs means you can run the amp with less dead time. Whether a designer takes advantage of this fact is another matter but generally speaking GaNFET amps should sound better as they have less distortion on that account.
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