Class D amplifier- what is important?

[LG75]

Hi,
I considering ordering a three channel amplifier for my L/R/C from Audiophonics, the SPA-400ET that Amir really liked.
Now premium” (?) manufacturers has offering of triple mono design (three power suplies) and different “premium” OPA. The question does it matter? Would I be able to hear a difference if I’ll order three mono blocks? Does Sparkos OPA really sounds better than the LM4562 used in Audiophonics design (they offer a stereo version with Soarkos).
Amir did his measurements on a stereo version with a single power supply and the LM4562 OPA and the measurements looked great.

Cheers

 

[LG75]

what sort of difference do you believe could be audible? What are the possibilities?

I believe that if you cannot empirically measure a difference or if the difference is negligible then you will not be able to hear it. However, you can find reviews of people saying that if an amplifier measures well it doesn’t necessarily sounds well and that they can hear a difference between OPA options,
Mono designs have the advantage to eliminate crosstalk due to not having shared components. I’m sure you’ll be able to see crosstalk effects in measurements, but in a well designed circuit it might be so small it won’t translate to anything audible.
I just wanted to see if I’m not missing something.

 

[DVDdoug]

With any amplifier the most important thigs are low noise and adequate power. Most solid state amplifiers have flat frequency response and low distortion unless over-driven into distortion.

 

[lateralous]

To satisfy your curiosity, here is a direct measurement of op-amp options in a similar implementation:

Discrete OpAmp Review: Sonic Imagery vs Sparkos

Recently I reviewed the Nord Three SE 1ET400A Dual Mono Stereo Amplifier. That unit came with the Sonic Imagery's 990ENH discrete operational amplifier ("opamp") in the buffer stage (pre-amplifier). The owner then ordered a set of Sparkos Pro SS2590 discrete opamps. This gave me a chance to...

www.audiosciencereview.com

To put it shortly, not something you should worry about and certainly not something to spend money chasing unless the stock op-amp implementation is bad, which is not the case here. Note that the function of the op-amp here is as an input buffer, it is reasonable to believe an op-amp could change the sound audibly if it really messed with the impedance your source is seeing but again not something I would pay for

 

[LG75]

As an example to what I was referring, here’s Amir’s review of the VTV class D amplifier with tube. Based interface card: https://www.audiosciencereview.com/...ifi-amplifier-review-with-weiss-buffer.24887/
Measurements was not as good as other Purify based designs and it didn’t get Amir’s thumbs up. Then there’s reviewers ,like Thomas, reviewing the amplifier, based on their subjective hearing test:

He really liked it in comparison to the Purity reference design. Thomas also has a different review of the Purify amplifier reference design He said it’s OK, but great when replacing the interface card with this one:

Purifi 1ET400A / Hypex NC500 Input Buffer

This input stage features a fully differential output, which allows you to drive the Purifi and Hypex amps to clipping - even with an unbalanced source - with extremely low distortion. This input buffer is the perfect match for a Purifi 1ET400A Class D amplifier DIY kit. OEM pricing and custom...

neurochrome.com

The review:

I’m just bringing it as an example to times when measurements and subjective test don’t necessarily goes hand in hand, and for people who feels like the reference card makes a huge difference. As I said I’m a believer of data collection, based of measurements, but reviewer like Thomas always makes me wonder if I’m missing something.

 

[BDWoody]

I’m just bringing it as an example to times when measurements and subjective test don’t necessarily goes hand in hand

When there are no controls used (levels matched, unsighted) these subjective comparisons have limited value.

The brain is a tricky beast, so isolating the ears and removing other clues is key. Our host did a video on the subject that might be good for some of these reviewers to watch.

 

[ahofer]

As an example to what I was referring, here’s Amir’s review of the VTV class D amplifier with tube. Based interface card: https://www.audiosciencereview.com/...ifi-amplifier-review-with-weiss-buffer.24887/
Measurements was not as good as other Purify based designs and it didn’t get Amir’s thumbs up. Then there’s reviewers ,like Thomas, reviewing the amplifier, based on their subjective hearing test:

He really liked it in comparison to the Purity reference design. Thomas also has a different review of the Purify amplifier reference design He said it’s OK, but great when replacing the interface card with this one:

Purifi 1ET400A / Hypex NC500 Input Buffer

This input stage features a fully differential output, which allows you to drive the Purifi and Hypex amps to clipping - even with an unbalanced source - with extremely low distortion. This input buffer is the perfect match for a Purifi 1ET400A Class D amplifier DIY kit. OEM pricing and custom...

neurochrome.com

The review:

I’m just bringing it as an example to times when measurements and subjective test don’t necessarily goes hand in hand, and for people who feels like the reference card makes a huge difference. As I said I’m a believer of data collection, based of measurements, but reviewer like Thomas always makes me wonder if I’m missing something.

This happens a lot, so I have a copypasta response.

Welcome to ASR! You've made an unsupported assertion or a scientifically implausible claim that will cause most people in this science-oriented forum to react with skepticism (or scepticism if they are in the U.K.). Please don't take the reactions as overtly hostile - most of us are just frustrated with the many newcomers who have clearly come here just to "troll". Please do engage with the membership to find an objective, controlled method to support or discard your hypothesis. Our membership includes recovering subjectivists, manyengineers/scientists, and several famous figures in the world of audio engineering research. Generally, they can cite scientific, controlled research to support their views. Most believe in the fallibility of human sighted judgement, and think blind testing and measurements are critical ingredients for assessing equipment contributions to sound quality. We'd love to have you, but if all you want is a) to fight or b) to have others cheerlead for your subjective views or anecdotal evidence, I'd suggest you will be happier elsewhere.

 

[fpitas]

We get asked a lot why some reviewers like equipment that measures badly. The fact is, some people like the sound of certain forms of distortion, for example from (badly designed) tube amps. They have the right to like it, but you have to be a little careful. An amp like that is special purpose. Some tracks might be improved, but once you get a lot of different things going on in the music, the distorting amp creates intermodulation, which is the generation of a whole new set of signals not in the original music, and not even harmonically related. As long as the music is simple, say a singer and a guitar, that's not too bad. Get a lot going on though, and you have a sonic disaster. So, caveat emptor.

 

[ahofer]

Some people like the sound of certain forms of distortion, for example from (badly designed) tube amps. They have the right to like it, but you have to be a little careful. An amp like that is special purpose. Some tracks might be improved, but once you get a lot of different things going on in the music, the distorting amp creates intermodulation, which is the generation of a whole new set of signals not in the original music, and not even harmonically related. As long as the music is simple, say a singer and a guitar, that's not too bad. Get a lot going on though, and you have a sonic disaster. So, caveat emptor.

Auditioning equipment on solo guitar or small ensemble music only is a mistake, I’ve learned. Some orchestral or dense electronica is a must.

 

[fpitas]

Auditioning equipment on solo guitar or small ensemble music only is a mistake, I’ve learned. Some orchestral or dense electronica is a must.

I guess if you *only* listen to that kind of music, you're ok.

 

[LG75]

This happens a lot, so I have a copypasta response.

I’m not asking questions to troll. I’m planning to buy an amplifier and some of Purify class D amplifiers seems to offer a good value - measures well and relatively reasonably priced for their performance.
I’ll probably go with my leading choice, Audiophonics as it did great in the measurements test and priced right. I just asked to see whether it’s worth considering OPA or interface card upgrade. I think I saw Amir did a comparison between Soarkos discrete OPA to the stock OPA without seeing a measurable improvement. I stick with the stock setup.

The fact is, some people like the sound of certain forms of distortion, for example from (badly designed) tube amps

That was what I’m thinking. In the examples I brought before, in one of the reviews the reviewer describes the amplifier as “dry”. I started thinking what does it mean? Why doesn’t it correlate to something seems in measurements. The only thing I could think of is that non perfect measurements of his amplifier of preference, like higher distortion, is something that might explain in

 

[FlyingFreak]

Audiophonics looks like a great 'entry budget' company for those amp. I would follow that route too if I was in the EU.

The subjective review thing is really out there. It's super generous to give them the benefice of the doubt that maybe they prefer some sort of distortion.
Thomas, who I am sure is a great guy and do not doubt his integrity (as far as not being paid by company), hear differences between bit perfect streamers, perfect sounding dacs, etc.
I m no EE, I am a psychotherapist. From my professional point of view (not that I think anyone need a pro to see that), it is super easy to bullshit ourselves. I mean... without us bullshitting ourselves all of the time for everything, my profession would not need be. Another way to say it: if our job was to hear difference between cables and write about it, I am sure we would. I mean ... we would need to to make a living, so we would adapt and our mind would create differences. What we would actually describe would be a mix of preference in name of brand, status of said brand, look of cables, how much coffee we had that morning, our mood, the weather, etc. From a psycho biology point of view, it is much more efficient to lie to ourselves than to knowingly lie to others (it is less stressful).

People who say that they 'trust their ears' then go on hearing impossible things and proclaim themselves ready to die on that hill sounds like clients trying to convince me their abusive spouse is the greatest person in the world despite them describing the repetitive abuses and complaining about it in the first place. We are frail creatures and our mind is very far from our strongest features.

 

[Vacceo]

If you hear an amplifier, something is wrong with the amplifier. Its task is getting a signal and, well, amplify it without changing it. That is impossible, but the change can be so small that you can only detect it with measuring tools.

Tailoring the sound to your liking is far easier with a combination of speakers, equalization and room interaction. That is where you should focus. For amps, as long as they provide the power you need, hopefully in the most efficient way possible and without altering the signal, that is just good enough.

 

[LG75]

Audiophonics looks like a great 'entry budget' company for those amp. I would follow that route too if I was in the EU.

It measured great so I wouldn’t classify it a “entry”, at least performance wise. I’m not in the EU either but exchange rate is good right now and the shipping cost are reasonable. The total price is competitive. If you know of US based alternatives in this price/performance point I’ll be happy to hear about it. VTV is probably is not much more expensive, but measured poorly compared to Audiiophonics and t similar

 

[HarmonicTHD]

It measured great so I wouldn’t classify it a “entry”, at least performance wise. I’m not in the EU either but exchange rate is good right now and the shipping cost are reasonable. The total price is competitive. If you know of US based alternatives in this price/performance point I’ll be happy to hear about it. VTV is probably is not much more expensive, but measured poorly compared to Audiiophonics and t similar

Buckeye.
Boxem.

Both members here as well.

 

[Vacceo]

Apollon is another EU-based manufacturer with a great track record. Nord in the UK also does a good job.

 

[delta76]

As an example to what I was referring, here’s Amir’s review of the VTV class D amplifier with tube. Based interface card: https://www.audiosciencereview.com/...ifi-amplifier-review-with-weiss-buffer.24887/
Measurements was not as good as other Purify based designs and it didn’t get Amir’s thumbs up. Then there’s reviewers ,like Thomas, reviewing the amplifier, based on their subjective hearing test:

He really liked it in comparison to the Purity reference design. Thomas also has a different review of the Purify amplifier reference design He said it’s OK, but great when replacing the interface card with this one:

Purifi 1ET400A / Hypex NC500 Input Buffer

This input stage features a fully differential output, which allows you to drive the Purifi and Hypex amps to clipping - even with an unbalanced source - with extremely low distortion. This input buffer is the perfect match for a Purifi 1ET400A Class D amplifier DIY kit. OEM pricing and custom...

neurochrome.com

The review:

I’m just bringing it as an example to times when measurements and subjective test don’t necessarily goes hand in hand, and for people who feels like the reference card makes a huge difference. As I said I’m a believer of data collection, based of measurements, but reviewer like Thomas always makes me wonder if I’m missing something.

Amir reviews focus on clean amplification power. High SINAD + matching or exceeding specs get his thumb up.
other subjective reviews are simply if they like it. as tube amps have the signature warm sound, some like it some do not. the "reviewer" you linked like the sound (assuming he did not lie), and that's about it.