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Bruno Putzeys ‘Life on the edge’

Purité Audio

Purité Audio

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There isn’t enything here I don’t wholeheartedly agree with ( towards the end of the article)
‘Integrated Systems are a Matter of…
The fundamental downside of exchangeable separates is that it precludes any kind of synergy. To clarify, consider the polar opposite, active speakers. By which I don’t mean passive speakers with the filters taken out and replaced by their active equivalent. Such toe-in-the-water products do no justice to what’s possible if you conceive a speaker to be active from the start and optimize the design to the hilt.

Active EQ lets you trade cabinet size for amplifier power, so you can make the product smaller. Digital phase correction lets you get rid of the time smear that’s a fundamental part of passive crossovers. Cleverly overlapping multiple drivers allows you to constrain directivity and reduce the impact of the room. Properly done, active speakers do things that are physically impossible for passive ones.

Sweeter still: active is cheaper: class D amplifier modules cost less than some inductors for passive crossovers. You can build something that runs rings around a top-flight separates rig and make it masquerade like a lifestyle product with a matching price tag.

…Life or Death
Not a week goes by without some pundit asking, “Is high-end audio dying” and why we can’t get the younger cohort interested in high-performance audio.

Isn’t it obvious? A young couple accidentally strays over the threshold of a Hi-Fi shop where they are peremptorily informed that they’ll have to school themselves in amplifiers, DACs, speakers, “interconnects” (i.e. cables), power cords, and “system tuning” before they can even think about parting with their cash. Are you surprised they decide it isn’t for them?

Not long ago, a leading Hi-Fi magazine ran an editorial proposing to remedy the problem using some kind of starter products: simple turntables, minimalist class A amplifiers, and chunky speakers, lifted straight from the author’s 1970s dorm room. This is beyond cynical. The transparent aim was not to get younger folks interested in high-quality sound as such, but in tinkering with boxes. It won’t even work: when did kids ever get excited about the same thing their parents loved when they were young?

How about giving them what they came into the shop for? A system that reliably sounds good and doesn’t present them with unnecessary choices. Preferably something that requires nothing but a power cable and a phone to play music. Give them all the user-friendliness of their cheap wireless speakers and soundbars but combine that with heart- stoppingly beautiful sound.

It’s not the fact that high-end amplification has become a commodity that should force manufacturers to rethink their strategy. It’s the survival of Hi-Fi itself that they need to secure. Class D isn’t the revolution, and neither will it trigger one. Class D is there to help the revolution along.’

Keith
 
Far too much to read there, but useful reference to GaN and NAD M33 interesting.

For me, what really matters is the sound an amp delivers and the pleasure this sound offers. Early Class D was pretty dire (I had Tripath in 2 earlier amps), but modern ones (largely thanks to Bruno) are such that there is now no valid reason for spending lots more on other technologies. I am very pleased with my Class D amps (NAD M33 and Atma-Sphere monos) and the former was bought after extensive tests at home with numerous other ss amps of all flavours, some far more costly.

The great thing is that Class D is continuing to improve and reduces in price - which other technology in audio is doing that?
 
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I'd say Bruno is one of the good guys and that article is just about understandable to a non-qualified engineer. His supply of 'bricks' will no doubt last until 'enthusiasts' my age are no longer here and maybe beyond, as so many, as he suggests, were brainwashed in the late 70s against feedback and so on (I remember my manager telling us back then, all about 'significant new amps and research' which suggested low or zero feedback was 'best' for amplifiers. I was pulled into that too, yet the trusty prosumer amps I now use, made in the early to mid 1970s, had plenty of feedback, just correctly applied.

I hope Bruno can continue to design and further refine his amps while keeping prices low for commercial makers and

The amount of disinformation and bulls**t still in this industry stuns me. But tech-ignorant people follow these 'gurus' blindly and without question.

(There's a controversial third party 'accessory' seller in the UK (he goes back as long or more than I do and only became this extreme when he needed to make a living out of his accessory sales) who does an 'upgrade' to BBC-speakers like mine - bypass the crossover, run the midwoofer wide open and put a single cap on each tweeter. I have an original review with crossover-less plots of the individual drivers in the box and just to say the 'upgrade' this man proposes, basically turns said speakers into NS10's or similar - less bass is tighter, don't you know!)
 
In hifi (and I realize I've offered this opinion before), I think the essence of synergy is the propitious combination of an amplifier with relatively high output impedance (ahem, low "damping factor") and a loudspeaker load with an impedance curve that suits it. :) No unicorns necessary. Not even narwhals (the unicorns of the sea, you know?).
 
Purité Audio said:
There isn’t enything here I don’t wholeheartedly agree with ( towards the end of the article)
‘Integrated Systems are a Matter of…
The fundamental downside of exchangeable separates is that it precludes any kind of synergy. To clarify, consider the polar opposite, active speakers. By which I don’t mean passive speakers with the filters taken out and replaced by their active equivalent. Such toe-in-the-water products do no justice to what’s possible if you conceive a speaker to be active from the start and optimize the design to the hilt.

Active EQ lets you trade cabinet size for amplifier power, so you can make the product smaller. Digital phase correction lets you get rid of the time smear that’s a fundamental part of passive crossovers. Cleverly overlapping multiple drivers allows you to constrain directivity and reduce the impact of the room. Properly done, active speakers do things that are physically impossible for passive ones.

Sweeter still: active is cheaper: class D amplifier modules cost less than some inductors for passive crossovers. You can build something that runs rings around a top-flight separates rig and make it masquerade like a lifestyle product with a matching price tag.

…Life or Death
Not a week goes by without some pundit asking, “Is high-end audio dying” and why we can’t get the younger cohort interested in high-performance audio.

Isn’t it obvious? A young couple accidentally strays over the threshold of a Hi-Fi shop where they are peremptorily informed that they’ll have to school themselves in amplifiers, DACs, speakers, “interconnects” (i.e. cables), power cords, and “system tuning” before they can even think about parting with their cash. Are you surprised they decide it isn’t for them?

Not long ago, a leading Hi-Fi magazine ran an editorial proposing to remedy the problem using some kind of starter products: simple turntables, minimalist class A amplifiers, and chunky speakers, lifted straight from the author’s 1970s dorm room. This is beyond cynical. The transparent aim was not to get younger folks interested in high-quality sound as such, but in tinkering with boxes. It won’t even work: when did kids ever get excited about the same thing their parents loved when they were young?

How about giving them what they came into the shop for? A system that reliably sounds good and doesn’t present them with unnecessary choices. Preferably something that requires nothing but a power cable and a phone to play music. Give them all the user-friendliness of their cheap wireless speakers and soundbars but combine that with heart- stoppingly beautiful sound.

It’s not the fact that high-end amplification has become a commodity that should force manufacturers to rethink their strategy. It’s the survival of Hi-Fi itself that they need to secure. Class D isn’t the revolution, and neither will it trigger one. Class D is there to help the revolution along.’

Keith
Click to expand...
First let me say I like how Bruno writes, with a lot of substance but also entertaining with his joking along the way.

On the idea of focusing on all-in-one products, though, I think there is a certain beauty in products that do one job very well. He uses the NAD M33 as an example of the kind of product manufacturers should offer. As a main system I would much rather have a "Steampunk" stack of streamer, preamp, power amp that does exactly what I want, gives me more power, and costs less than the M33. At the same time I am not against integrated stuff as I have some of those as well. So I would say yes make affordable all-in-one stuff available, but also show the more traditional approach and the benefits of going that way, if you really want to pull people into the hobby.

Also I don't know why he is shitting on soundbars and boomboxes as unworthy of decent amplifiers. Why can't ucd go in those?
edit: I know he doesn't sell ucd now, so maybe it is because Purifi doesn't have anything cheap enough for soundbars.
 
I don't get any of the TLDR feedback - totally disrespectful. I read the entire article. A humorous, enthralling, technically substantive piece from a genius engineering design "auteur." Made my day.

Thanks for posting the link, Keith.
 
I enjoyed it too, as I have enjoyed all of Bruno’s designs, Grimm LS1 , Kii Three, hypex, mola mola, purifi amps and soon Purifi based transducers.
Keith
 
Thanks for posting. For those of us following Bruno Putzeys work and articles through the years there is nothing really new, just a compilation of history and logic written with light humor.
 
Purité Audio said:
Bruno discusses class-d evolution and much else,
hometheaterhifi.com

Life on the Edge - A Personal Perspective on the Past, Present, and Future of Class D Audio Amplifiers - HomeTheaterHifi.com

The past quarter century of class D developments look strikingly different when seen through the eyes of the audio consumer and through...
hometheaterhifi.com hometheaterhifi.com

Courtesy of hometheatrehifi
Keith
Click to expand...
I enjoyed reading that and learned some stuff too. Thanks!

I feel a little abashed at this though
Barring a few geeks and cranks, nobody buys an amplifier based on measurements alone. People listen and only shell out if they enjoy what they hear.
Click to expand...
Um.
 
Hear Here said:
I am very pleased with my Class D amps (NAD M33 and Atma-Sphere monos) and the former was bought after extensive tests at home with numerous other ss amps of all flavours, some far more costly.
Click to expand...

The Atma-Sphere monos are ones that I would love to see here. We know they won’t have the lowest distortion measurements but it would be valuable to add it to the database by quantifying the distortion versus frequency of the unit under the same test conditions that all of the other amps have been tested. Perhaps you can coordinate with Amir so that the turnaround time is minimal…


Purité Audio said:
Active EQ lets you trade cabinet size for amplifier power, so you can make the product smaller…Properly done, active speakers do things that are physically impossible for passive ones.
Click to expand...

It’ll be interesting to see how the speaker I just sent Amir measures. :)

Purité Audio said:
A system that reliably sounds good and doesn’t present them with unnecessary choices. Preferably something that requires nothing but a power cable and a phone to play music. Give them all the user-friendliness of their cheap wireless speakers and soundbars but combine that with heart- stoppingly beautiful sound.
Click to expand...
+1

We are already there. For the youngest group of audiophiles, even something like the Sonos Era 300 is going to produce beautiful sound in the average dorm room or bedroom.

It’s only big rooms that really *need* big speakers.
 
pjug said:
Also I don't know why he is shitting on soundbars and boomboxes as unworthy of decent amplifiers. Why can't ucd go in those?
edit: I know he doesn't sell ucd now, so maybe it is because Purifi doesn't have anything cheap enough for soundbars.
Click to expand...

Anybody dissing BT speakers in 2024 screams audiophile insecurity to me.

Creative Muvo Play aux'ed with a JA11 dongle made my jaw drop for the price of a restaurant lunch for 2. Of course there's better sound with traditional setups but that also magnitudes more in price, clutter and power draw with non of the portability and convenience.
 
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It is a good article but not without flaws. Take this:

"Every time I and afterward my competitors made such strides, class D amplifiers got accepted into ever higher strata of the Hi-Fi market. Not because of how they measured, but because of how they sounded. Barring a few geeks and cranks, nobody buys an amplifier based on measurements alone."

He is completely wrong about this. Class D had and continues to have a terrible reputation for "sound" quality. I constantly see pushback against them. I would say 99% of the high-end subjectivists consider it non-starter. Class D's technical achievements are great, but its marketing stinks.

At the risk of being immodest, it us that came to rescue class D. We created rankings. Showed the good and bad. And designs such as Brunos floated to the top. Folks started to take notice. I have seen this clearly in our local audiophile group.

I dare say outsid of DIY forums, few heard or cared much about Hypex amps 10 years ago. Today it is massively different. Yet the sound has not changed.

And on sound, we all know that it is impossible to show that sound advantage at the top tier of class D. I don't know how a person who is on the objectivist side of thinks believes in drinking our Koolaid that much.

Finally, he seems to be unaware or ignoring the incredible transformation we have seen in class AB designs using active feedback. Has he not seen what Topping has done?

index.php


In low power department, when it comes to lowest noise and distortion, Topping rules by a mile.

We have all seen how the TI chip based implementations from likes of Fosi and AIYIMA show that you can bring class D performance to be "hi fi" for so little amount of money. This is another revolution. Again, fueled by the demand we have created for great objective performance.

Purifi came to us on the launch of their amplifier. I assumed they knew how critical it was to show and compare objective performance of their amps and not "the sound."
 
mhardy6647 said:
In hifi (and I realize I've offered this opinion before), I think the essence of synergy is the propitious combination of an amplifier with relatively high output impedance (ahem, low "damping factor") and a loudspeaker load with an impedance curve that suits it. :) No unicorns necessary. Not even narwhals (the unicorns of the sea, you know?).
Click to expand...
Esl with high impedance at low frequencies and low impedance at high frequencies paired with the high output impedance of tube amps is one such synergy.
 
I also don't agree with this, but maybe for pedantic reasons:

"How about giving them what they came into the shop for? A system that reliably sounds good and doesn’t present them with unnecessary choices. Preferably something that requires nothing but a power cable and a phone to play music. Give them all the user-friendliness of their cheap wireless speakers and soundbars but combine that with heart- stoppingly beautiful sound."

What he describes is what would get people to love high fidelity music. Being an audiophile is not that. It is to learn the technology and have choices of how to build an optimal system and improve it over time. The Kii speakeers are great but come in one size and one price. That is the negative of full integration.

Then there is the issue of repairability. High power circuits tend to have much less reliability. Hate to stuff them inside enclosures and rattle them with music and heat them up as well. One needs to put these things in context.
 
Flaws aside, I loved this article - thanks for sharing, Keith!

Of note:

"If anything inside the audio band is much more audible than anything outside it, trying to improve distortion outside the audio band at the expense of making it worse inside it, is a bad idea. Conversely improving distortion inside the audio band, even at the expense of distortion above 20kHz, is eminently sensible. So, the loop gets optimized so that high-frequency distortion that still falls inside the audio band is evenly matched with low-frequency distortion.

That gives us the optimal audio-band performance and will result in the least audible coloration for this particular circuit.

But how then do we verify that an amplifier can even handle signals above 10kHz? A single sine wave won’t cut it because all harmonics are outside the measuring range (and inaudible too). The amplifier could be grossly clipping, and we wouldn’t know.

The solution is to blast the amplifier to near-clipping with two sine waves right at the end of the audio band and to inspect the resulting spectrum. You’ll agree that this is just about the worst possible test signal that still technically qualifies as “audio”. Nothing like it ever occurs in real music, so it’s a proper stress test.

Intermodulation (IMD) test of a class D amplifier graph diagram measured by frequency [Hz]

The two tall poles 18.5 kHz and 19.5 kHz are the test tones. Even-order distortion components are visible at 1kHz and multiples, while odd-order components show up at 1kHz intervals from 17.5kHz down. So, despite using only audio-band signals and only looking at the audio-band outcome, this test is perfectly revealing of what an amplifier can do at the top of the audible range."


So can everyone now just let @amirm get on with the Class D amp reviews (including his IMD distortion tests), and kindly shut the f*** up about how Class D is allegedly "a toy" or "has a long way to go" simply because you have to band-limit THD sweeps when measuring them?
 
Purité Audio said:
There isn’t enything here I don’t wholeheartedly agree with ( towards the end of the article)
‘Integrated Systems are a Matter of…
The fundamental downside of exchangeable separates is that it precludes any kind of synergy. To clarify, consider the polar opposite, active speakers. By which I don’t mean passive speakers with the filters taken out and replaced by their active equivalent. Such toe-in-the-water products do no justice to what’s possible if you conceive a speaker to be active from the start and optimize the design to the hilt.

Active EQ lets you trade cabinet size for amplifier power, so you can make the product smaller. Digital phase correction lets you get rid of the time smear that’s a fundamental part of passive crossovers. Cleverly overlapping multiple drivers allows you to constrain directivity and reduce the impact of the room. Properly done, active speakers do things that are physically impossible for passive ones.

Sweeter still: active is cheaper: class D amplifier modules cost less than some inductors for passive crossovers. You can build something that runs rings around a top-flight separates rig and make it masquerade like a lifestyle product with a matching price tag.

…Life or Death
Not a week goes by without some pundit asking, “Is high-end audio dying” and why we can’t get the younger cohort interested in high-performance audio.

Isn’t it obvious? A young couple accidentally strays over the threshold of a Hi-Fi shop where they are peremptorily informed that they’ll have to school themselves in amplifiers, DACs, speakers, “interconnects” (i.e. cables), power cords, and “system tuning” before they can even think about parting with their cash. Are you surprised they decide it isn’t for them?

Not long ago, a leading Hi-Fi magazine ran an editorial proposing to remedy the problem using some kind of starter products: simple turntables, minimalist class A amplifiers, and chunky speakers, lifted straight from the author’s 1970s dorm room. This is beyond cynical. The transparent aim was not to get younger folks interested in high-quality sound as such, but in tinkering with boxes. It won’t even work: when did kids ever get excited about the same thing their parents loved when they were young?

How about giving them what they came into the shop for? A system that reliably sounds good and doesn’t present them with unnecessary choices. Preferably something that requires nothing but a power cable and a phone to play music. Give them all the user-friendliness of their cheap wireless speakers and soundbars but combine that with heart- stoppingly beautiful sound.

It’s not the fact that high-end amplification has become a commodity that should force manufacturers to rethink their strategy. It’s the survival of Hi-Fi itself that they need to secure. Class D isn’t the revolution, and neither will it trigger one. Class D is there to help the revolution along.’

Keith
Click to expand...
But speakers like Grimm and Kii are priced way out of what's achievable for young people. So there's no revolution there and certainly nothing that will save hi-fi.
That's rather seen with studio monitors with class AB, but lacking in the user friendliness.
 
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I still have a couple of Tact amps shown in the article. Those and the Tact RCS are what made me leave tube amps.
 
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