A New Wave of Class D Integrated Amplifiers

[KyoichiOda]

Mr. Tsukioka describes his idea:

What attracted our attention to 1ET7040SA was not the novelty of this module, but the increased number of GND pins, which strengthens the GND coupling of the board. 1ET400A did not solve this problem and we only had a prototype. It has the same problem as NC500.

The problem with NC500 (including 1ET400A) was that the number of GND coupling pins on the Class D amplifier board and preamplifier board were small, making it vulnerable to high-frequency fluctuations. This problem is serious because the Class D amplifier itself operates at high frequencies.

The fact that the GND of the amplifier board and the GND of the pre-amplifier board are fluctuating separately means that the signals that pass through will also fluctuate at the same time. Of course, this is mitigated to some extent by differential transmission, but it is not perfect. Integrity is broken by asymmetries in the transmission path. Worse because the pin layout of NC500 is asymmetrically assigned it is an imperfect differential characteristic.

Therefore, we addressed this problem in the design of NC500 by using a 4th-order filter to cut off the problematic frequency range. As this is a problem on the amplifier module side, we concealed the module design problem by cutting the problematic bandwidth on the pre-amplifier board. The result is a transparent and smooth rendering that is not noisy. Instead, it is slightly rounder than NC400. NC500 is inherently noisy enough to require a wide bandwidth and a fast preamplifier, so some countermeasures were needed.

Thus, the NC500-1ET400A generation could not be combined with a true wideband preamplifier. The sound was rough and harsh unless the signal was rounded off by a preamplifier. Conversely, NC400 and NC1200 modules with an integrated preamplifier have a full GND and therefore have natural high frequency extension, despite the inherent roughness. This is an advantage of the integrated type only. This cannot be achieved as long as you use a module with a lax GND coupling, such as the NC500.

However, in 1ET7040SA, this GND coupling pin has been significantly strengthened. Finally, it is now possible to achieve characteristics close to the continuous solid GND of NC400 and NC1200. So our goal for the 1ET7040SA amplifier is to combine high frequencies with more focus and extension than NC400 with the transparency and smoothness of the existing NC500.

What we did to achieve this was to use a current-feedback pre-amplifier and to optimise its high-frequency response. The key is to combine the rejection of overshoot with a fast slew rate. Not only must the load drive capability be high, but at the same time the peaks must be removed. This requires the optimisation of various constants. It is a matter of simulation and trial and error. The characteristics must be matched to the substrate.

The other is to strengthen the power supply: in 1ET7040SA we combine it with an SMPS3k. two 1ET7040SAs are balanced with an SMPS3k. Some manufacturers claim the superiority of SMPS1200, but we are convinced that SMPS3k is far superior in terms of sound quality, with more drive, stability and room. This is a sound quality decision.

This has resulted in amplifiers that are not noisy but have extended high frequencies, focused imaging, transparency, immense drive and stability, all of which are compatible with each other. However, Nilai 500 and 1ET9040BA will appear in the future. We need to try all of these and reconsider which is the best again. So the production of 1ET7040SA amplifiers will be limited and will come to an end as soon as they are sold out.

Most Hypex and Purifi module-using manufacturers clearly ignore this optimisation. Curiously, interchangeable op-amp options are popular among them, but they are the furthest concept from optimisation and make optimisation impossible.

The disadvantage of such a design is then placed on the customer's side by the manufacturer as "the responsibility of a wrong choice". What is certain is that none of those "free and open choices" are optimal after all. Optimal is inconvenient, not free choice.

What they should do before promoting their proud careers of the past, in my opinion, is to put their great skills to real-world challenges.

 

[KyoichiOda]

I got the plan of AUSE Audio new power amplifiers, with NC1200 and 1ET7040SA, will be launched soon.

About 1ET7040SA version from their website:
"The design policy has resolved the shortcomings of the previous module, thus further enhancing the accuracy of the high frequencies, sound rise and focus description, and driving force."
"It took a fair amount of trial and error to achieve a sound that is not harsh and noisy while improving the precision of the high frequencies, but the result is a sound that is closer to the world's high-end oriented sound, with a wider range in the high and low frequencies, improved detail description and a firm separation between attack and release. This is expected to be a 'result of optimisation', which is not possible with common Ncore-type overseas products where the op-amps can be replaced."
"It is important to note that while this direction increases the limits of clearly depicting soundscape and localisation, it is also true that the limits themselves are strongly dependent on the setting and system. The goal is to accurately extract the detailed information contained in the rise of the sound, so imperfections are left out as they are."

1. NC1200 power amplifier
Stereo power amplifiers in NC1200 + SMPS3k configuration. Connectors are WBT.
Launched in August or September. Only three sets.
Expected price is 2k USD (depends on currency rate).

2. 1ET7040SA power amplifier
1ET7040SA + SMPS3k stereo power amplifier.
Launched in early Winter. Around 20 sets.
Expected price is 3500 USD (depends on currency rate).





These photos are trial version. The actual design will be:

 

[johnsonlwu]

picked up an SU-R1000 from Japan and hauled it back home to CA yesterday. Exchange rate too attractive to pass. First impressions is it’s a very midrange warmth and clarity focused amp. Absolutely no overshoot and you don’t have to crank it up to enjoy music. My other gear include many Counterpoint NP220s at various build levels, VAC Phi 70 mono, and Tenor OTLs. The SU-R1000 can’t beat 2 NP220s running in bridge mono in terms of slam but excels in every aspect (including when compared w my tube amps) driving my Hailey 1.2s.

 

[CKKeung]

Please watch till the end which is about the opamp choices.

 

[Hear Here]

Please watch till the end which is about the opamp choices.

Isn't this just a guy building a DIY Purifi Eigentakt amp from the basic Eval module?

Anyone can do that as the DIY Purifi module and power supply boards are readily available and lots of "garage-built" Purifi-based amps can be found on Ebay, etc. This will result in a fine Class D amp, but if you want ultimate quality, go for an amp that's built by a big brand where they work with Purifi to produce a better module that they build under licence using higher quality components - and you get a worthwhile warranty! The brand can develop their own power supply, include it in their own, much more desirable case and use materials of their choice to get the sound they are looking for - not possible from the basic off-the-shelf DIY Eval board. The brands that currently use this excellent Eigentakt technology are T&A with their 200 Series and NAD with their M Series and one of their less costly C Series amps. There may well be others now.

 

[PYP]

Isn't this just a guy building a DIY Purifi Eigentakt amp from the basic Eval module?

Anyone can do that as the DIY Purifi module and power supply boards are readily available and lots of "garage-built" Purifi-based amps can be found on Ebay, etc. This will result in a fine Class D amp, but if you want ultimate quality, go for an amp that's built by a big brand where they work with Purifi to produce a better module that they build under licence using higher quality components - and you get a worthwhile warranty! The brand can develop their own power supply, include it in their own, much more desirable case and use materials of their choice to get the sound they are looking for - not possible from the basic off-the-shelf DIY Eval board. The brands that currently use this excellent Eigentakt technology are T&A with their 200 Series and NAD with their M Series and one of their less costly C Series amps. There may well be others now.

That is what I found. Ironically, the same Mike Galusha (very knowledgeable and a great guy) helped me build an Core-based amp, my first Bruno Putzeys amp. Sounded great and that got me interested in the NAD version (many years ago now). The NAD was significantly better.

Since the fever did not subside, I then decided the Mola Mola Kaluga, which was Bruno's all-out effort to maximize his modules, was the amp for me. The difference between the Kaluga mono amps and the NAD was greater than the difference between the stereo DIY and the stereo NAD.

Of course, nothing stands still and Bruno improved upon his Ncore design when he co-founded Purifi. Perhaps these modules are so good that the differences in implementation are now smaller (especially if measured), but I would be very surprised if the differences are not clearly heard. As Bruno has said, the input circuit has a large effect on the overall sound. Separating and shielding components must also be important and you don't often get that with DIY.

 

[thomask]

Since I had been impressed with Merril Audio amps during Pacific Audiofest.

I am in line for home audition of Orchard class D amp.

Orchard Audio Starkrimson Stereo Ultra Amp Tour!

One surprise is that others mentioned it … (clip) Marty If the “lean” reference was from my review, I think that might have been someone else’s...

forums.stevehoffman.tv

 

[CKKeung]

Another youtube, Thomas paired the Purifi modules with a Neurochrome input buffer board.

 

[Hear Here]

That is what I found. Ironically, the same Mike Galusha (very knowledgeable and a great guy) helped me build an Core-based amp, my first Bruno Putzeys amp. Sounded great and that got me interested in the NAD version (many years ago now). The NAD was significantly better.

Since the fever did not subside, I then decided the Mola Mola Kaluga, which was Bruno's all-out effort to maximize his modules, was the amp for me. The difference between the Kaluga mono amps and the NAD was greater than the difference between the stereo DIY and the stereo NAD.

Of course, nothing stands still and Bruno improved upon his Ncore design when he co-founded Purifi. Perhaps these modules are so good that the differences in implementation are now smaller (especially if measured), but I would be very surprised if the differences are not clearly heard. As Bruno has said, the input circuit has a large effect on the overall sound. Separating and shielding components must also be important and you don't often get that with DIY.

Thanks for that - it confirms my belief that a brand-built amp should and does sound better than a DIY one based on what some DIY'ers believe is an identical module. Even the modules are tweeked and built under license by NAD, T&A, etc. I'm thinking of going the Atmasphere Class D route when their stereo version becomes available. Peter

 

[KyoichiOda]

AUSE Audio launched new 1ET7040SA amplifier, P952.
The price is about 3.2k USD, 230-240V version is available.



The highlite from their website:

This is a seemingly common Purifi employed amplifier. As other manufacturers' products have already been available for a long time, we do not see the point in releasing an amplifier now that uses simple Purifi's latest modules. The difference between simple power supply capacity and amplifier generation is not important.

With the P952, it is not about ease of listening, but about shifting values to the focus of the sound and the timing of the rise. What we have done to realise this is as follows.

1. the buffer design has been changed from low noise specialisation to transient response reproduction. It uses high-speed amplifiers with optimised characteristics for transient response reproduction, and does not use easy op-amp replacement or discrete amplifiers.
2. it also has an out-of-band noise cut-off function, but the performance of this part has also been enhanced compared to before. This is because the filtering characteristics are more stable than before when driven into 600 ?, and filtering at an even higher order has been achieved.
3. the amplifier unit and power supply unit have been strengthened, and these drive strengths are also essential for focus rendering. Furthermore, the choice to use a mass-type case and WBT-type connectors, which are somewhat outside our conventional design concept, was also necessary for the stability and affordability of the sound. All these choices were made for the sake of sound.
4. an auxiliary CMRR compensation circuit is included. This function corrects for internal errors in balanced cables and level errors caused by output devices, and was first used in the P952.

In terms of sound direction, the high frequencies are more accurately expressed and the spatial localisation information and fine components in the rise are now well described. A side effect of this is a direction that is harsh on the environment and easily exposes system problems.

Main features
a. Equipped with Purifi's latest module 1ET7040SA
b. Ause's original -300dB suppression power circuit + high-speed wideband differential buffer design
c. New CMRR correction function, corrects differential signal errors in intermediate paths at the input stage.
d. 4th-order low-pass filter to suppress DAC and external out-of-band noise (however, input impedance of 600 ? or less recommended).
e. Loads up to 2 ? are supported. Maximum current 40 A.
f. Power supply capacity of 3000 W for improved marginal performance in suitable environments

Specification
Rated output: 500Wx2 (4?) 250Wx2 (8?) @ 200VAC 10sec
Gain: approx. 26dB
Noise distortion: 0.0008% (20Hz to 20kHz/200W)
Frequency response: DC to 60kHz (-3dB)
S/N (IHF-A): 129dB
Output impedance: 0.65 m? (20 to 20 kHz)
Dimensions: 43x33x9.5(cm)
Weight: 8.5kg

 

[AMR / iFi audio]

AUSE Audio launched new 1ET7040SA amplifier, P952.
The price is about 3.2k USD, 230-240V version is available.
View attachment 112079
View attachment 112080

The highlite from their website:

This is a seemingly common Purifi employed amplifier. As other manufacturers' products have already been available for a long time, we do not see the point in releasing an amplifier now that uses simple Purifi's latest modules. The difference between simple power supply capacity and amplifier generation is not important.

With the P952, it is not about ease of listening, but about shifting values to the focus of the sound and the timing of the rise. What we have done to realise this is as follows.

1. the buffer design has been changed from low noise specialisation to transient response reproduction. It uses high-speed amplifiers with optimised characteristics for transient response reproduction, and does not use easy op-amp replacement or discrete amplifiers.
2. it also has an out-of-band noise cut-off function, but the performance of this part has also been enhanced compared to before. This is because the filtering characteristics are more stable than before when driven into 600 ?, and filtering at an even higher order has been achieved.
3. the amplifier unit and power supply unit have been strengthened, and these drive strengths are also essential for focus rendering. Furthermore, the choice to use a mass-type case and WBT-type connectors, which are somewhat outside our conventional design concept, was also necessary for the stability and affordability of the sound. All these choices were made for the sake of sound.
4. an auxiliary CMRR compensation circuit is included. This function corrects for internal errors in balanced cables and level errors caused by output devices, and was first used in the P952.

In terms of sound direction, the high frequencies are more accurately expressed and the spatial localisation information and fine components in the rise are now well described. A side effect of this is a direction that is harsh on the environment and easily exposes system problems.

Main features
a. Equipped with Purifi's latest module 1ET7040SA
b. Ause's original -300dB suppression power circuit + high-speed wideband differential buffer design
c. New CMRR correction function, corrects differential signal errors in intermediate paths at the input stage.
d. 4th-order low-pass filter to suppress DAC and external out-of-band noise (however, input impedance of 600 ? or less recommended).
e. Loads up to 2 ? are supported. Maximum current 40 A.
f. Power supply capacity of 3000 W for improved marginal performance in suitable environments

Specification
Rated output: 500Wx2 (4?) 250Wx2 (8?) @ 200VAC 10sec
Gain: approx. 26dB
Noise distortion: 0.0008% (20Hz to 20kHz/200W)
Frequency response: DC to 60kHz (-3dB)
S/N (IHF-A): 129dB
Output impedance: 0.65 m? (20 to 20 kHz)
Dimensions: 43x33x9.5(cm)
Weight: 8.5kg

I have seen those modules in Munich. They are BEEFY.
Personally, I wish they made small ones for desktop applications.

 

[thomask]

I have seen those modules in Munich. They are BEEFY.
Personally, I wish they made small ones for desktop applications.

It looks good!

What type of tubes are used?

 

[AMR / iFi audio]

It looks good!

What type of tubes are used?

Sorry, not sure what are you asking for. If you could clarify, then I'm happy to answer!

 

[soundman]

Sure. I hear you. Of course all the impressions out there are subjective. Some based on a wider reference then others, which we all appreciate. And that is all good. We all appreciate reading some ones impressions / reviews, with the purpose of gaining insights. Yet again. When the numbers gets bigger, the tech more advanced and more resources have been invested into gear, I am of the believe that HIFI is like wine. At a certain level one wine that is better to you might be worse to me and vice verse. Two excellent components can exist at the same time. One need to be able to keep two thoughts in mind at the same time. But if we are going to play the quote game, I pick the greater clarity in the music every day before the "emotional connection". As said. I create my own emotional connections to the music just fine. I am 40 years old and I trust my ears that are working perfectly fine. Having said that, I would love to listen to the Line Magnetic my self, preferable in a A to B test to the R1000. I would be the first to make new plans for my HIFI set up if I could hear clear improvements in areas that are important to me. Nothing is holy in this game. But I suspect for others Tube or Class-A is some what of a religion, and that´s when thing can start to get ugly.

Exactly, this reviewer did not at all find the integrated cold or clinical quite the opposite https://www.soundstagehifi.com/inde...rence-class-su-r1000-integrated-amplifier-dac

Neither did AHC and he has been reviewing for The Absolute Sound for more than 20 years
Technics SU-R1000 Integrated Amplifier - The Absolute Sound

 

[soundman]

Have you had the chance to listen to the Su-R1000?

" The new Technics SU-R1000 integrated amplifier is one of the most innovative and best-sounding pieces of electronics I’ve had the opportunity to audition in recent years. "

Anthony Cordesman, The Absolute sound

You realize he means this regardless of construction or price?

I have listed to this "little"23kg box now for two weeks straight and I can not here anything digital about it. In fact, it sounds more natural and acoustic then basically everything else I have ever listened to. The Apurna PRÉLUDE might beaten the SU-R1000 in sheer "weight" and "punch", but does not reach the same "shimmer". The Apurna is 60k USD ca, so that is ok, even if it would. Of course I understand what is true for me might not be true to you, but that does not worry me to much.

No one was more closed minded to this piece than me until I started listening to the impressions of others and when collectively they say it is NOT as you are expecting it will sound, cold clinical divorced from engaging the listener then my obstinacy begins to dissolve and I pay attention:

 

[soundman]

No one was more closed minded to this piece than me until I started listening to the impressions of others and when collectively they say it is NOT as you are expecting it will sound, cold clinical divorced from engaging the listener then my obstinacy begins to dissolve and I pay attention:

And this too:

 

[soundman]

Sure. I hear you. Of course all the impressions out there are subjective. Some based on a wider reference then others, which we all appreciate. And that is all good. We all appreciate reading some ones impressions / reviews, with the purpose of gaining insights. Yet again. When the numbers gets bigger, the tech more advanced and more resources have been invested into gear, I am of the believe that HIFI is like wine. At a certain level one wine that is better to you might be worse to me and vice verse. Two excellent components can exist at the same time. One need to be able to keep two thoughts in mind at the same time. But if we are going to play the quote game, I pick the greater clarity in the music every day before the "emotional connection". As said. I create my own emotional connections to the music just fine. I am 40 years old and I trust my ears that are working perfectly fine. Having said that, I would love to listen to the Line Magnetic my self, preferable in a A to B test to the R1000. I would be the first to make new plans for my HIFI set up if I could hear clear improvements in areas that are important to me. Nothing is holy in this game. But I suspect for others Tube or Class-A is some what of a religion, and that´s when thing can start to get ugly.

Since someone has brought up the "emotional connection" here from Australia

THE VERDICT​

This amplifier is exceptional in my view, as it offers outstanding sound quality. In terms of clarity, detail, naturalness, and dynamics, it's among the best I've ever heard. It really is remarkably good. With many recordings played – whether LP or CD – I've never heard them better, and some of these I've known for fifty years. By 'better', I mean fresher, clearer, and more effortlessly detailed and dynamic, as if you were listening to the original master tape. It's also highly musically engaging and involving. The sound isn't just superior in a technical sense; it's communicative and emotionally rewarding to listen to. https://www.stereonet.com/reviews/technics-su-r1000-integrated-amplifier-review

 

[GuutEnuff]

AUSE Audio launched new 1ET7040SA amplifier, P952.
The price is about 3.2k USD, 230-240V version is available.
View attachment 112079
View attachment 112080

The highlite from their website:

This is a seemingly common Purifi employed amplifier. As other manufacturers' products have already been available for a long time, we do not see the point in releasing an amplifier now that uses simple Purifi's latest modules. The difference between simple power supply capacity and amplifier generation is not important.

With the P952, it is not about ease of listening, but about shifting values to the focus of the sound and the timing of the rise. What we have done to realise this is as follows.

1. the buffer design has been changed from low noise specialisation to transient response reproduction. It uses high-speed amplifiers with optimised characteristics for transient response reproduction, and does not use easy op-amp replacement or discrete amplifiers.
2. it also has an out-of-band noise cut-off function, but the performance of this part has also been enhanced compared to before. This is because the filtering characteristics are more stable than before when driven into 600 ?, and filtering at an even higher order has been achieved.
3. the amplifier unit and power supply unit have been strengthened, and these drive strengths are also essential for focus rendering. Furthermore, the choice to use a mass-type case and WBT-type connectors, which are somewhat outside our conventional design concept, was also necessary for the stability and affordability of the sound. All these choices were made for the sake of sound.
4. an auxiliary CMRR compensation circuit is included. This function corrects for internal errors in balanced cables and level errors caused by output devices, and was first used in the P952.

In terms of sound direction, the high frequencies are more accurately expressed and the spatial localisation information and fine components in the rise are now well described. A side effect of this is a direction that is harsh on the environment and easily exposes system problems.

Main features
a. Equipped with Purifi's latest module 1ET7040SA
b. Ause's original -300dB suppression power circuit + high-speed wideband differential buffer design
c. New CMRR correction function, corrects differential signal errors in intermediate paths at the input stage.
d. 4th-order low-pass filter to suppress DAC and external out-of-band noise (however, input impedance of 600 ? or less recommended).
e. Loads up to 2 ? are supported. Maximum current 40 A.
f. Power supply capacity of 3000 W for improved marginal performance in suitable environments

Specification
Rated output: 500Wx2 (4?) 250Wx2 (8?) @ 200VAC 10sec
Gain: approx. 26dB
Noise distortion: 0.0008% (20Hz to 20kHz/200W)
Frequency response: DC to 60kHz (-3dB)
S/N (IHF-A): 129dB
Output impedance: 0.65 m? (20 to 20 kHz)
Dimensions: 43x33x9.5(cm)
Weight: 8.5kg

Any reviews on this or other Ause amps? Couldn't find any with a quick search. This seems well specced for the price

 

[KyoichiOda]

Any reviews on this or other Ause amps? Couldn't find any with a quick search. This seems well specced for the price

They were carried in some magazines, but only in Japanese.

ＭＪ無線と実験　2023年4月号 | 株式会社誠文堂新光社

【特集】最新チャンネルデバイダー３機種による３ウエイマルチアンプ再生　小林貢、井上千岳●フェーズメーションCHD-1000●アキュフェーズDF-65●CSポートACN400『オリジナル

www.seibundo-shinkosha.net

Ause has a trial programme. If you want to try their amps, ask by email. I would help if a language barrier in your correspondence.

お問い合わせ | 逢瀬

お問い合わせ合同会社逢瀬MAIL：info@ause-audio.comFAX：020-4664-1240〒300-2436 茨城県つくばみらい市絹の台5-19-5

ause-audio.com

 

[KyoichiOda]

I listened JAVA HiFI Carbon double shot Integrated amplifier in the Warszaw AV show.
It was brilliant, the best class D I have ever listened.
Simply I thought I could not return nCore and Purifi
and have to try other GaN FET amplifiers too.