[sumoking]

Audiophiles are some of the last to admit to change occurring.  I'm on my 2nd Class D.  My current Temple Audio mono-blocks are smaller, cheaper, and sound better than the 10 year old ones they replaced.  Just evolution in design.  Be flexible or cease to exist.

Well said! After having heard my Class D amps in my system, I couldn’t go backward.
Progress!

[Tyson]

I sure hope that class D displaces current SS amps.  I hate how hot and heavy and wasteful my class a power amp is.  If I could get something small and super efficient that sounded as good, I'd do it in a second. 

I have a very simple test that a piece of gear has to pass, though.  I put it in my system for a few weeks, acclimate to the sound then switch back to my original piece of gear.  Is the new piece an improvement, or not?  If so, it stays.  If not, back it goes.  I'll say this - most of the gear in my current setup has had remarkable staying power, especially for someone like me that used to churn gear at a fairly high rate. 

Anyway, I used to think all class D really sucked.  I don't think that any more, some of it is getting pretty good!  I'm actually pretty excited to see where things go in the next few years with the technology.  Between class D getting better and hirez recordings and DSD recordings getting better (and more available), it's maybe the best time in history to be an audiophile. 

[debjit.g]

Class D has really come a long way...as with any newer technology, it takes its own time to mature and I think we might be at a point where it really is, it can sing and can only improve over time. I remember my W4S amps that I bought couple of yrs ago and regretted. Its no longer the case with the newer offerings from BO and Hypex and I am quiet happy with the sound they make, until I hear a better one, off-coarse. However, my interest is still peaked to know how they compare with the high $$$ amps from Soulutions, Darts, LAMMs, Dags, VACs, Pass XS, CH etc - I know it wouldn't be a fair comparison from the price perspective but its interesting to see from purely sound qualitywise.

[trackball02]

I would love to audition a Class D amp that would be on par with my SET amps.
Currently, I have a 300b, 2A3 and 45 SET amps, all built by Tube Audio Labs. Can anyone make any suggestions for comparable Class D?

One disadvantage with a Class D, is the inability to tube roll. Swapping different power tubes alone can make a tremendous difference in sound. For example, with my 2A3 SET amp playing my Omega Alnico XRS, I like to match my turntable with a AudioTechnica ART9 cartridge with KenRads Black Glass, and with my Denon 103R with Emission Labs mesh plates.  Just my own observations and part of the fun the coaxing the best sound for my ears.

[Photon46]

Class D has really come a long way...as with any newer technology, it takes its own time to mature and I think we might be at a point where it really is, it can sing and can only improve over time. I remember my W4S amps that I bought couple of yrs ago and regretted. Its no longer the case with the newer offerings from BO and Hypex and I am quiet happy with the sound they make, until I hear a better one, off-coarse. However, my interest is still peaked to know how they compare with the high $$$ amps from Soulutions, Darts, LAMMs, Dags, VACs, Pass XS, CH etc - I know it wouldn't be a fair comparison from the price perspective but its interesting to see from purely sound qualitywise.

Not sure how much one can draw from the comparison, but I recently spent an afternoon listening to around 50k worth of DSA class a amps, preamp, and phono preamp driving speakers with a somewhat similar design to mine and was fascinated with the differences I heard compared to the AS1200 we were discussing in another thread. The class A DSA amps sounded different from the class D AS1200, no doubt. However, the DSA amp 1's did not really eclipse the quality of reproduction I heard from the AS1200, it was just different. I heard a certain detailed clarity, liveliness, and airiness from the AS1200 missing from the DSA amps and they had an integrated wholeness and ease that was better in some respects than the AS1200. A perfect amp would have integrated the best of both amps. The DSA Amp 1 mono blocks cost 25k a pair though and my mind was having some cognitive dissonance that a $1500-$2000 class D amp could deliver sound so equally compelling if not equivalent. The cost differences do have to be viewed from a proper perspective though. Most audio amplifier manufacturers are small scale affairs compared to a company like IcePower. IcePower invested many millions of dollars to develop tremendous manufacturing economy of scale compared to someone like DSA, Pass Labs, Constellation, Boulder, Soulution, etc.

[Jonathon Janusz]

One disadvantage with a Class D, is the inability to tube roll. Swapping different power tubes alone can make a tremendous difference in sound.

I know the price points get up there compared to some tubes, unless you are talking rare NOS tubes, but what you do with tubes in a tube amp you would do using different cables (and one of the runaway threads right now here on AC would suggest input, output, and power connectors) to tune the sound to mesh the way you want it in your system.  There seems to be a reasonably broad consensus that Class D amps (even the newest ones) react pretty dramatically to wiring changes.

I know saying such is kind of like throwing taboo on top of taboo from an objectivist point of view, but it hard to argue that so many different ears would be wrong even if they don't agree on which combination of stuff sounds subjectively better.

[OzarkTom]

Too bad one size does not fit all. But it might someday.

[dcbingaman]

Where do I even start on this topic.  Making the generalization that a Class D amplifier has revolutionized solid state amplifier design ignore a whole bunch of issues, like WHAT linear amplifiers (Class A or A/B) are you comparing to ?  Solid state amplifier design must start with the amplifying device itself.  MOSFETs make great switches but have issues with basic linearity.  Their use as high speed switches makes Class D ICE modules possible by rapidly (up to 6 MHz), switching complementary devices on and off using PWM and then filtering the result with a massive low pass filter.  One huge byproduct is massive amounts of noise (EMI) that can adversely impact every other component in your system.

More linear FETs like the JETs used in preamps, make the use of Class D circuits unnecessary.  For instance, from a voltage amplification standpoint there are no tougher tasks than a low noise MC phono preamps or wide bandwidth, low noise I/V converters in your DAC.  These are almost all Class A circuits instantiated with JFETs because their outstanding linearity and low self-noise.

The linear power amplifier is a tougher problem because of the non-linearity of compatible output devices.  The exception are the VFET / SIT amplifiers built in the 1980's by Yamaha, Sony, and more recently by Pass First Watt.  No Class D ICE amplifier can match these amps in linearity or perceived performance, but SIT devices are rare and low in dissipation.

In the process of building his SIT amplifiers, Pass has learned how to use a new generation of much higher power density, more linear MOSFETs from IXYS, IRF, Fairchild and others.  The first amplifier using these new devices is the Pass XA25.  It is unmatched in linearity and uses only two devices per channel.  I do not think a PWM amplifier will ever match the transient performance of the XA25, simple because of part count.  Bloggers should go listen to one of these before selling Class A short.

[Jonathon Janusz]

In the process of building his SIT amplifiers, Pass has learned how to use a new generation of much higher power density, more linear MOSFETs from IXYS, IRF, Fairchild and others.  The first amplifier using these new devices is the Pass XA25.  It is unmatched in linearity and uses only two devices per channel.  I do not think a PWM amplifier will ever match the transient performance of the XA25, simple because of part count.  Bloggers should go listen to one of these before selling Class A short.

I think part of the "revolution" as discussed here isn't exclusively arguing class D is overwhelmingly outperforming class A (or any other typology) on audio quality metrics (although the assertion is that it can now at least trade punches honestly with the best of them), but that for what can be had in a class A design to get 50 watts and 10 amps with 2 amps draw at idle (using the XA25 as example of the current state of the art in class A), one can build a darn close if not comparable class D design that can get 1200 watts, 30-odd amps, and idle at about as much power as an LED nightlight, and it can be done for say 20% of the total parts cost to manufacture.

As Tyson said earlier (I don' remember if here or in one of the Mivera threads), although a great number of audiophiles will gladly make the exchange of power consumption, weight, consumables, lack of convenience, etc. for a last 0.00000X% improvement in sound if that is what it takes, there are also a lot of folks for a lot of reasons waiting - hoping - for the day when they don't have to.  For some, the word on the street is that day is today.

[JohnR]

Good point. Class A and B are limited in how far down they can push cost/performance because they need heatsinks and a larger power supply. Also, while not necessarily the case, Class A and B amps "traditionally" use mains-frequency transformers which inherently means a certain size and weight. Whereas Class D often comes with SMPS, which also (from what I can tell) is getting better quickly.

To the earlier point about EMI, this (it seems to me) is one of the things that has improved a lot. 15 years ago I think it was a real problem (IIRC), but I don't think it's true anymore to generalize with "One huge byproduct is massive amounts of noise (EMI)".

I'm inclined to think of the adoption curve:

[bavmike]

Good point. Class A and B are limited in how far down they can push cost/performance because they need heatsinks and a larger power supply. Also, while not necessarily the case, Class A and B amps "traditionally" use mains-frequency transformers which inherently means a certain size and weight. Whereas Class D often comes with SMPS, which also (from what I can tell) is getting better quickly.

To the earlier point about EMI, this (it seems to me) is one of the things that has improved a lot. 15 years ago I think it was a real problem (IIRC), but I don't think it's true anymore to generalize with "One huge byproduct is massive amounts of noise (EMI)".

I'm inclined to think of the adoption curve:

I think in the Audio world today it’s more like 80% in the laggard bracket. Innovators and early adopters are generally frowned upon. Then the early and late majority will adopt within 2 months. Following this the laggards all go belly up because you can’t teach old dogs new tricks.

Following this cycle we have a fresh new beginning full of enthusiasm towards the hobby once again like it’s 1958, instead of 2018. It will be like spring time in a fresh mountain valley. Flowers will be blooming, the sun will be shining, and everyone will be smiling

Then Eric Clapton shows up and plays this song:

https://www.youtube.com/watch?v=KXDf9UwHGF4

[Folsom]

So classD makes a nice summer amp? 

Nothing wrong with classD. But everything has a flavor of some kind, so I don't expect everyone to like it, or like class A or anything else.

It's too subjective to think there is some sort of truly dominate, well, anything.

[bavmike]

So classD makes a nice summer amp? 

Nothing wrong with classD. But everything has a flavor of some kind, so I don't expect everyone to like it, or like class A or anything else.

It's too subjective to think there is some sort of truly dominate, well, anything.

Time to listen first before judging how you like it. I compared the 1200AS directly to your amp. And it was done up with the best of the best parts. It sounded great.

[Folsom]

It seems like you think I was talking to you, Mike, or about your amp? I was not. But you are welcome to send me one that I can get a listen to.

[bavmike]

It seems like you think I was talking to you, Mike, or about your amp? I was not. But you are welcome to send me one that I can get a listen to.

If you want to buy one I can send it to you. Either that or drive up to Kelowna and come listen.

[Folsom]

Well, neither will happen anytime soon. I wouldnt mind stopping by our mutual friend's for a visit some time (who has your amp). I would have to start with a passport.

[bavmike]

Well, neither will happen anytime soon. I wouldnt mind stopping by our mutual friend's for a visit some time (who has your amp). I would have to start with a passport.

Well I have 20 acres right on the US/Canada border in Washington. Here's the fence you would need to jump



 

[Folsom]

They actually deploy motion trackers that look for a pattern. I will leave the fence jumping to you. I have stood in the middle gap before, where there are no trees. Its quite a site.

[bavmike]

They actually deploy motion trackers that look for a pattern. I will leave the fence jumping to you. I have stood in the middle gap before, where there are no trees. Its quite a site.

Oh well I'm thinking of turning this land into a resort for class D lovers. It's so peaceful, and the view is breathtaking. Can see for 80 miles.










If I do pop by for a visit. 20 minutes from Oroville.


https://www.youtube.com/watch?v=Q0iqg2UanEc

[Folsom]

This might be important to some, while classD produces less heat, it is not necessarily so much more efficient that it's worth really getting excited about compared to all other amp designs.