Why Pay More For Purifi 9040 vs Hypex NCX2k?

[sceptical1]

Sorry to veer slightly off topic but I've asked before and the question still nags. Is it worth upgrading to class D from a "Proper" late 90's heavyweight amp like a Bryston or Threshold? I'm tempted to have a go at a DIY class D amp but will I hear a difference?

Most amps with SMPS have 10 to 20db less noise than a linear supply at typical listening levels of 1 to 5W. You may notice something that sounds like an increase in resolution if the background (room) noise level is low enough. For power, the linear supply usually has a significantly higher peak output (the real clipping point, not steady state) so if you actually needed the gobs of power on hand currently getting a Class D with twice the power of your Class AB amp should equalize things.
If you are a serious listener the desktop ti 3255 amps with -60db thd. above 5khz are best avoided, just in case. The good Class D amps are cheap enough anyway.
The greater efficiency I don't see.

 

[ahofer]

Indeed but there's something visceral about large chunky aluminium amps all sat in a row. I feel an itch for a pair of 1200 wpc Icepower amps in custom enclosures. Best of both worlds!

Tech Hifi used to have a house brand like that. Tiny circuit board in a massive, beefy enclosure with lots of LEDs. Nikko was the brand.

http://www.magnat.tv/nikko.shtml

 

[Everett T]

Tech Hifi used to have a house brand like that. Tiny circuit board in a massive, beefy enclosure with lots of LEDs. Nikko was the brand.

http://www.magnat.tv/nikko.shtml

Boy they looked pretty impressive . I almost got suckered in to buying some of their components before my father-in-law gave me an education.

 

[Audionaut]

That's....no.

Yes, I don't find the examples very helpful either, but I also don't like ASR's general credo that amplifiers sound the same when they measure the same.
In my opinion, the measuring stations used are not complex enough or do not represent the truly complex load of a difficult-to-operate loudspeaker.

Even though modern amplifiers measure essentially identical at typical listening levels and into benign load, and therefore sound indistinguishable under those conditions, that does not mean they behave the same under all conditions.

Loudspeakers are not resistive loads; they are complex electro-mechanical systems with significant impedance variation, phase shifts, and back-EMF. Once the load stops being linear and the amplifier is no longer driving an idealised resistor, the operating conditions can shift far away from the assumptions of purely linear, voltage-source behaviour.

Depending on the design of the power supply, current-delivery limits, protection mechanisms, output stage stability, and the available feedback margin under stress, amplifiers can respond very differently when the load becomes demanding. This may show up as earlier or later onset of compression, different clipping behaviour, variations in how well the amplifier rejects back-EMF, or differences in stability when faced with capacitive or inductive components of the load. These behaviours are rarely captured by standard measurements into a fixed resistive dummy load but can become relevant with real music driving real loudspeakers, especially when high SPLs, low impedance dips, or extreme phase angles are involved.

In such situations, amplifiers, regardless of topology, do not remain indistinguishable. The practical differences arise not because amplifiers have a “sound” of their own, but because they differ in how far they can stay within their linear operating region under dynamic, stressful conditions. Where one amplifier may remain clean, another may already be limiting, invoking protection, or approaching clipping. And these behaviours can become audible, not as tonal coloration but as differences in headroom, dynamics, and control, which are at the end hearable.

In short: under normal conditions, a good amplifier is a good amplifier. But once a loudspeaker presents a challenging load or demands high, fast current peaks, the determining factor is not the circuit class but the overall robustness of the amplifier and his power supply. How well it maintains linearity under stress can vary and that variance is precisely where audible differences may arise, even though standard bench measurements into simple loads show almost no divergence.

 

[mike70]

Yes, I don't find the examples very helpful either, but I also don't like ASR's general credo that amplifiers sound the same when they measure the same.
In my opinion, the measuring stations used are not complex enough or do not represent the truly complex load of a difficult-to-operate loudspeaker.

Even though modern amplifiers measure essentially identical at typical listening levels and into benign load, and therefore sound indistinguishable under those conditions, that does not mean they behave the same under all conditions.

Loudspeakers are not resistive loads; they are complex electro-mechanical systems with significant impedance variation, phase shifts, and back-EMF. Once the load stops being linear and the amplifier is no longer driving an idealised resistor, the operating conditions can shift far away from the assumptions of purely linear, voltage-source behaviour.

Depending on the design of the power supply, current-delivery limits, protection mechanisms, output stage stability, and the available feedback margin under stress, amplifiers can respond very differently when the load becomes demanding. This may show up as earlier or later onset of compression, different clipping behaviour, variations in how well the amplifier rejects back-EMF, or differences in stability when faced with capacitive or inductive components of the load. These behaviours are rarely captured by standard measurements into a fixed resistive dummy load but can become relevant with real music driving real loudspeakers, especially when high SPLs, low impedance dips, or extreme phase angles are involved.

In such situations, amplifiers, regardless of topology, do not remain indistinguishable. The practical differences arise not because amplifiers have a “sound” of their own, but because they differ in how far they can stay within their linear operating region under dynamic, stressful conditions. Where one amplifier may remain clean, another may already be limiting, invoking protection, or approaching clipping. And these behaviours can become audible, not as tonal coloration but as differences in headroom, dynamics, and control, which are at the end hearable.

In short: under normal conditions, a good amplifier is a good amplifier. But once a loudspeaker presents a challenging load or demands high, fast current peaks, the determining factor is not the circuit class but the overall robustness of the amplifier and his power supply. How well it maintains linearity under stress can vary and that variance is precisely where audible differences may arise, even though standard bench measurements into simple loads show almost no divergence.

OK, so... why they're indistinguishable in a proper blind test with adjusted gain?

If your (lengthy) argumentation is right, the blind test will be passed by anyone. And the evidence is totally against you.

Can you answer that?

 

[Sokel]

Most amps with SMPS have 10 to 20db less noise than a linear supply at typical listening levels of 1 to 5W.

The short of PSU's have little to do with noise if done correctly.

For example most class D may have SMPS's for a start but local PSU's are usually fully linear like TI TPS7xxx/4xxx for example.
Same with fully linear PSU's, it's the engineering that matters.

 

[Audionaut]

OK, so... why they're indistinguishable in a proper blind test with adjusted gain?

It depends on the Conditions.
This is a part of the long answer.

Even though modern amplifiers measure essentially identical at typical listening levels and into benign load, and therefore sound indistinguishable under those conditions, that does not mean they behave the same under all conditions.

PS
I'm not concerned with sound signatures on an uncritical speaker with an 8-inch bass and 1-inch dome tweeter and impedance correction implemented in the crossover, but rather with the limits, such as PA stacks, large full electrostatic speakers, or, in the home environment, something like the Infinity Reference IRS/V.
Dogma is never helpful when it comes to exploring borderline areas where boundaries and standards can shift.

 

[101geo]

Stepping outside the world of audio you can find plenty of examples of people, sometimes experts who, when blind tasting, were completely wrong about the product.

A well-known experiment was conducted by Frédéric Brochet, a researcher at the University of Bordeaux.

• The Method: Brochet used the exact same middle-of-the-road Bordeaux wine but poured it into two different bottles. One bottle had a prestigious Grand Cru label (signifying high quality and price), while the other had a basic Vin de Table (table wine) label.
• The Participants: He then asked a panel of 54 experienced oenology (wine science) students and professionals to taste and rate the wines.
• The Result: The tasters described the "Grand Cru" wine using positive, complex, and sophisticated terms (e.g., "complex," "rounded," "rich pleasant palate"). They described the very same wine in the "Vin de Table" bottle using negative terms like "weak," "flat," and "simple". Not one of the experts noticed they were drinking the same wine.

That's one of many examples. The senses can be fooled you just have to be aware enough to know it and not dig yourself into a hole.

 

[1roger]

Then why do you seem to not want to listen to those who provide knowledge and evidence?

Just because you "think" one amp should sound different than another amp (which is a thought based on no evidence or experience)?

there is no complete evidence on how these amp sound. only measurements on signal to noise, watt, crosstalk and so forth

 

[Buckeye Amps]

there is no complete evidence on how these amp sound. only measurements on signal to noise, watt, crosstalk and so forth

That "and so forth" hides a big one: frequency response.

Again, you are glazing over the mountains of data and understanding on how sound works/how our ears pick up sound.

 

[1roger]

That "and so forth" hides a big one: frequency response.

Again, you are glazing over the mountains of data and understanding on how sound works/how our ears pick up sound.

ah frequency response.. the youtuber favourite. an important representation but also the most overrated aspect in audio. in my opinion anyways

but im not going to bore you any longer. have a good one

 

[Buckeye Amps]

ah frequency response.. the youtuber favourite. an important representation but also the most overrated aspect in audio. in my opinion anyways

What is your opinion based on, may I ask?

And again, how do ears work? Because the frequency they are converting to electrical impulses to the brain is a VERY important part of the process of sound...

 

[JeremyFife]

ah frequency response.. the youtuber favourite. an important representation but also the most overrated aspect in audio. in my opinion anyways

but im not going to bore you any longer. have a good one

I'm sorry, that's just a really strange statement to make. In what way is the ability of an amplifier (or anything) to accurately reproduce a frequency "overrated"? Genuinely do not understand what you are saying

 

[1roger]

I'm sorry, that's just a really strange statement to make. In what way is the ability of an amplifier (or anything) to accurately reproduce a frequency "overrated"? Genuinely do not understand what you are saying

the frequency response of a speaker for example, is important. for the sound signature, ear fatigue, deep bass etc..personal preference. but if you listen to a reviews and people talking about audio it tend to come across as be all end all for the outcome. there are a lot more aspects to sound then frequency response. its just dB output level at each frequency

 

[Buckeye Amps]

the frequency response of a speaker for example, is important. for the sound signature, ear fatigue, deep bass etc..personal preference. but if you listen to a reviews and people talking about audio it tend to come across as be all end all for the outcome. there are a lot more aspects to sound then frequency response. its just dB output level at each frequency

.....ok

 

[1roger]

by all means do tell how you would extract soundstage depth from a frequency response curve

 

[NTK]

by all means do tell how you would extract soundstage depth from a frequency response curve

Have you tried BACCH? Just a sprinkling some magic DSP dust and you have completely different soundstage. Same DAC, same amplifiers, same loudspeakers. Very little to do with the hardware, very much to do with the signal.

 

[1roger]

sure. but then why does soundstage change significantly with same signal, same amp but two different speakers. I have no problem with it, I use it.. but DSP is artificial. deliberately manipulating the signal? what does that prove. don`t get the point you were making here

 

[Everett T]

sure. but then why does soundstage change significantly with same signal, same amp but two different speakers. I have no problem with it, I use it.. but DSP is artificial. deliberately manipulating the signal? what does that prove. don`t get the point you were making here

Because of the speakers being different, unless the amp is performing outside of their parameters. DSP isn't artificial, it works just like a passive crossover but allows you to fix your room problems which designers would have no way of knowing, which is the biggest issue with your sound outside of the speakers themselves.

 

[Buckeye Amps]

Speaker design, room interaction, and physical placement within a room absolutely affects the soundstage. Some speaker designs require extreme toe-in (angle) to achieve the same soundstage as a speaker that requires no toe-in.
There is a reason in some setups that all a listener has to do is move their head a few inches and the soundstage changes noticeably.