Audiophiles, generally don't like class D amps!

[tuga]

As I said, the Ferrari offers performance on the track the Toyota can't compete with, I wasn't making a comparison based on street driving. Again, the point is while the Ferrari costs 10x the Toyota, it also would outperform the Toyota on the track/dyno. The Merrill costs about 30x the price of a Purifi amp yet on the track/dyno (Audio Precision) it doesn't outperform. Geez.

You criticise the manufacturer for cheating and the buyer for being gullible, but all I see is a case of supply and demand. No one needs a Ferrari when you can buy a FIAT.

Edit: try looking at everyday street use as the thresholds of audibility.

 

[goryu]

You criticise the manufacturer for cheating and the buyer for being gullible, but all I see is a case of supply and demand. No one needs a Ferrari when you can buy a FIAT.

No, I have done no such thing. I have criticized manufacturers who offer expensive products that are more show than go to cater to buyers who care more about impressing people with their expensive toys then using their wealth in a responsible manner. That's why I appreciate this site- it helps people make rationale, responsible choices and outs the pretender products and audio posers.

 

[F1308]

Check what this thread is about.

I was joking...
If it sounds as it should, it doesn't matter the audio chain type, naming or whatever.

 

[rwortman]

using their wealth in a responsible manner

Who is going to head the commission to judge responsible spending? If we wanted to go down that road we might say an American who pays $15,000 for a made in America audio component is spending his money more responsibly than the guy who spends $500 on a cheap imported one.

 

[Feyire]

As an EE I have designed an industrial audio class D amp.

But Class D has sometime difficulties high midrange and high frequencies.
But Class D is subject to hiss (in the high frequencies) that is never quantified in the measurements.

Do you have any theories on why this may be?

For example, have you ever given some thought to the last electrical component that an amplified audio signal passes through in commonly found class D amplifier output filter designs?

Hint: It is a distortion factory that gets worse with higher frequency. Some say it is adequately negated through the use of feedback, others claim and/or hear otherwise.

 

[nyxnyxnyx]

I'm sorry if it's a bit unrelated but have anyone here used a class D speaker amplifier to drive headphones?
this question was born from the occasions I've seen people from other forums using speaker amps to drive their headphones (f.e HE6/Susvara) but the thing is the models they talk about are mostly class A or AB. Back then I did not think much about it because I did read about the main advantages of class A designs, and thought it was inherently a natural choice to select the "best".

 

[GXAlan]

I'm sorry if it's a bit unrelated but have anyone here used a class D speaker amplifier to drive headphones?

Sony TA-ZH1ES: A DAC/Headphone Amp with a Sonic Signature?

Sony TA-ZH1ES: A DAC/Headphone Amp with a Sonic Signature? Stop. やめる. Halt. Arrêt. You probably shouldn’t read the rest of this post, it's triggering. There's a lot of speculation even though there are a good amount of measurements too. If you're looking for a transparent DAC/headphone...

www.audiosciencereview.com

You can make Class D headphone amps with high distortion. The S Master design is what they use for their SA-Z1 and the old DA-series AVRs.

 

[MaxBuck]

If you want to comment on a hobby were self delusion trumps all no need to look at audiophiles, golfers are much worse. At least audiophiles don’t dress up like Coco the clown when pursuing their hobby.

I'm a golfer, and I resemble that remark.

 

[Suffolkhifinut]

I'm a golfer, and I resemble that remark.

Hope you take the walking seriously?

 

[MaxBuck]

Hope you take the walking seriously?

Absolutely. A little unusual here in SoCal, but it happens.

 

[kemmler3D]

the cleanest electronics don't always sound the best.

In that case, it's a matter of philosophy when it comes to recordings. Do you just shrug at the fact that the mix isn't very good? Or do you take matters into your own hands and tweak the mix to your liking?

 

[Sokel]

If I could make a REALLY decent recording of matched volume amps I would post you what an Ice Power Edge,Purifi Sparkos edition and ARC reference 160 mono do and sound like in comparison.
(hint: difficult to tell which is which,take my word for it)

 

[DonH56]

Can you get lower output impedance from an OTL design?

That's a good question! I am not really competent to answer. Transformers reduce the high plate impedance to something around typical speaker loads in conventional designs. I have very little (and very old) experience designing OTL amps and used cathode-follower outputs to reduce the output impedance. It takes a lot of tubes to get cathode follower impedance low, or decent gain-bandwidth for feedback. The way to the very lowest output impedance is using feedback IME, and with feedback my OTL achieved much lower output impedance than the transformer-coupled commercial amp I had, but I have insufficient data and/or experience to say if that is a general rule. The output impedance of my OTL was also flatter over a broader frequency range (higher and lower) than the transformer design I was comparing, but again insignificant sample size.

Good question for @atmasphere, @SIY, or another tube guru.

 

[Scott Lanterman]

My experience with class D is new, but the mids seem very smooth and just as smooth as tubes. I like a warm sounding system, and the Nilai fits in great, more detail but thats about it.

The logical next step is not really class D. For me it seems like starting over and just getting rid of all the little boxes all together. Do we need 100 separate black boxes? The next logical step is active speakers with the ease of adjustment that you get with class D.

 

[SIY]

That's a good question! I am not really competent to answer. Transformers reduce the high plate impedance to something around typical speaker loads in conventional designs. I have very little (and very old) experience designing OTL amps and used cathode-follower outputs to reduce the output impedance. It takes a lot of tubes or decent gain-bandwidth for feedback. The way to the very lowest output impedance is using feedback IME, and with feedback my OTL achieved much lower output impedance than the transformer-coupled commercial amp I had, but I have insufficient data and/or experience to say if that is a general rule. The output impedance of my OTL was also flatter over a broader frequency range (higher and lower) than the transformer design I was comparing, but again insignificant sample size.

Good question for @atmasphere, @SIY, or another tube guru.

More feedback and lower open loop source impedance, the latter of which is expensive, the former of which is tricky. Not to speak for Ralph, but I don’t think low source Z is his goal. In the past, he’s argued for a constant power source rather than a constant voltage source. I disagree with him, but I understand his reasoning.

 

[Shoaibexpert]

I think this is mostly bias, as with everything in audio...bias as to why people can get the same SQ as crazy expensive gear if they shop smartly and pay heed to measurements. Even though i can't call myself as someone who has tried it all but I did attend a few audio shows in the past years, after moving to Canada and I can say that after listening to Uber expensive gear, Class AB Amps actually sounded shrilly and thin sounding to me occasionally...could be my bias as I've started my journey with NAD C298 and now proudly own a M23 and all I can say is both those class D Amps are neutral sounding boxes which appear to get the most out of current SOTA DACs and Preamps (Pre-90 + VMVD1SE). I let the D1se's Tube 3 color mode add some tube magic which I really like...but I feel an amp should be as clean as possible and source /preamp can do the coloring if needed.

 

[dlaloum]

I've been on ASR for less than 2 years, but the point has been made almost endlessly by everyone from Amir down (or out, to be fair to our best minds) that not all playback attributes are measurable, and that controlled listening tests are the final tie-breaker. I personally hope we can stop chasing that circle round and round.

That said, I don't know what controlled listening tests HAVE been conducted for Class D v other classes....

There have been a number of double blind amplifier comparisons done, which included class D and Class AB amps.... the conclusion of which was that "all amplifiers sound alike".

The proviso to that being, they sound alike as long as they are running within their specified performance envelope... and that we are comparing "quality" components, and not the bottom of the market cheapies...

Given proper DBT rigour - proper precise output level matching, choice of speakers that do not strain any of the amps (put them outside their specified performance envelope), etc...
They ALL sounded the same.

Conclusion being: Topology of the amp is not relevant, implementation is everything. And choosing between topologies is ultimately not about audible difference at all.

It may be to do with specific speakers that one amp drives better than another
It may be related to long term maintainability / repairability (class D's mostly score poorly here!)
It may be sheer "Bling" - eg: that McIntosh amp looks great in my rack...

But you are unlikely to hear a difference between a Benchmark AHB2 and a Purify or Hypex amp in a properly constituted comparison test.

 

[valerianf]

Let us look at some simplified theory.
When a pure sinus waveform is injected at the input of a class D amp, its output usually generate a larger number of high frequency rectangular pulses.

An output low pass filter is in charge of reconstruction the sinusoidal waveform.
It is placed just before the speaker connection.

The detailed explanation is available there:

Class D Amplifiers - Electronics-Lab.com

Introduction In the previous tutorials, an important link has been established between the conduction angle of...

www.electronics-lab.com

What we see on the reconstructed sinusoidal waveform is that there is some high frequency noise that is superposed and also the shape of the sinusoid is distorted.

May be @amirm could make a simple test between a class AB amp and a class D amp using the laboratory equipment that he have.
Let say that we inject a 6khz perfect sinusoid with a 5W set gain on each amp and trace a FFT of the output signals on a 8 ohm load or better, a real speaker.
Will we observe a difference?
Please Amir, could you use your 2 best amps (class AB and class D) and make the test?

The result of this practical test will help us find an clear answer to this thread main question.

 

[theREALdotnet]

Let us look at some simplified theory.
When a pure sinus waveform is injected at the input of a class D amp, its output usually generate a larger number of high frequency rectangular pulses.

Let say that we inject a 6khz perfect sinusoid with a 5W set gain on each amp and trace a FFT of the output signals on a 8 ohm load or better, a real speaker.
Will we observe a difference?
Please Amir, could you use your 2 best amps (class AB and class D) and make the test?

The result of this practical test will help us find an clear answer to this thread main question.

You might find what your looking for in past amplifier reviews, for example:

 

[Kijanki]

Let us look at some simplified theory.
When a pure sinus waveform is injected at the input of a class D amp, its output usually generate a larger number of high frequency rectangular pulses.

An output low pass filter is in charge of reconstruction the sinusoidal waveform.
It is placed just before the speaker connection.

The detailed explanation is available there:

Class D Amplifiers - Electronics-Lab.com

Introduction In the previous tutorials, an important link has been established between the conduction angle of...

www.electronics-lab.com

What we see on the reconstructed sinusoidal waveform is that there is some high frequency noise that is superposed and also the shape of the sinusoid is distorted.

May be @amirm could make a simple test between a class AB amp and a class D amp using the laboratory equipment that he have.
Let say that we inject a 6khz perfect sinusoid with a 5W set gain on each amp and trace a FFT of the output signals on a 8 ohm load or better, a real speaker.
Will we observe a difference?
Please Amir, could you use your 2 best amps (class AB and class D) and make the test?

The result of this practical test will help us find an clear answer to this thread main question.

I don't understand this example. It shows 10 values per period reconstructing sinewave. I assume that 2Hz frequency of the sinewave is just an example. Class D amps operate at about 500kHz carrier, making it 25 values per period at 20kHz harmonics (that I cannot even hear). So, in real world highest audio frequency, a 20kHz harmonics, will be reconstructed in 25 instead of 10 values (way better). In addition picture shows high deformation of the wave when it is overdiriven (flatten on the top). It should be. Why are we worrying about reconstruction of overdriven 20kHz harmonics? How can we even overdrive them? At, for instance 100Hz, where signal amplitudes are high and can overdrive output, sinewave will be reconstructed in 500kHz/100Hz = 5000 values per period.