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Audiophonics HPA-S400ET Review (Stereo Amplifier)

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 1 0.2%
  • 2. Not terrible (postman panther)

    Votes: 5 1.0%
  • 3. Fine (happy panther)

    Votes: 41 8.0%
  • 4. Great (golfing panther)

    Votes: 465 90.8%

  • Total voters
    512
At some point I would ask myself if the continuous increases or improvements over time are really hearable for me or only measurable with proper equipment & written on paper.
Anyway happy to see that they keep on working and improving!

Nah, tbh, it's done. The only thing left to optimize is price and production optimization. We are already WAY past the point where it's audible.
 
At some point I would ask myself if the continuous increases or improvements over time are really hearable for me or only measurable with proper equipment & written on paper.
Anyway happy to see that they keep on working and improving!
Of course it is not hearable! The Improvement of the 1ET6525 over the S400ET is exactly 3.5 dB if you are working with medium gain (which is about 20 dB gain): 110 dB instead of 106.5 dB SINAD.
Everything over 80 dB (0.01% Noise and Distortion) is nice and perfectly fine.
We are now reaching the limits of our measurement equipment and even Bruno can with his fourth generation digital amps not build a „tenbagger“ here. It is just twice at good measurements as the previous generation.

To improve the quality of Speakers or Analog Record Players is 30- to 100-times more important.

But perhaps it is nice to own something, which is so perfectly made!
 
I just realized that there is a new generation out now „Eigentakt 2“ which is the 4 th generation of Bruno Putzeys Hypex / NCore / Eigentakt Designs (since 2002 or so). Amplifiers are now mathematically fully understood and we can asume amps as a „solved problem“:

@boXem wrote:
„There are still 3 modules for Purifi: 1ET6525SA, 1ET7040SA and 1ET9040BA. The change is happening right now and a lot of manufacturers still have stock of 1ET400A waiting to be sold.“

So the next generation is the 1ET6525SA (and 1ET9040BA?). Bruno stated at one point (https://linearaudio.net/sites/linearaudio.net/files/volume1bp.pdf and also here: https://hometheaterhifi.com/30th-an...utm_id=18776575&utm_term=HTHIFI&utm_content=5) that any generation increased its qualities in round about a factor of ten since 2002 (compared to the generation before).

Buckeye and BoXem have started to sell amplifiers using these new modules in November 2024.

As an Example:

Can’t wait for @amirm to measure one!
 
Of course it is not hearable! The Improvement of the 1ET6525 over the S400ET is exactly 3.5 dB if you are working with medium gain (which is about 20 dB gain): 110 dB instead of 106.5 dB SINAD.
Everything over 80 dB (0.01% Noise and Distortion) is nice and perfectly fine.
We are now reaching the limits of our measurement equipment and even Bruno can with his fourth generation digital amps not build a „tenbagger“ here. It is just twice at good measurements as the previous generation.

To improve the quality of Speakers or Analog Record Players is 30- to 100-times more important.

But perhaps it is nice to own something, which is so perfectly made!

Agree 120% ... the improvement is merely academic, and it's valid, of course.
Our ears, speakers and rooms are the devil ... we don't listen with oscilloscopes or perfect transducers / acoustics.
 
Agree 120% ... the improvement is merely academic, and it's valid, of course.
Our ears, speakers and rooms are the devil ... we don't listen with oscilloscopes or perfect transducers / acoustics.
As someone who bought his first magazine on the subject of music reproduction at the age of 13 (Hifi STEREOPHONIE - January 1979) and has now been dealing with this subject for almost exactly 45 years and has repeatedly given detailed advice to friends, I tried to “condense” my findings last year:

So I developed a sheet where I wrote down my opinion on the subject of “What is how influential in the field of hi-fi”.

I divide it up as follows (and I know I'm being provocative):

Provided you have optimally produced music that has not already been destroyed by loudness wars during mastering, the following applies


45% The room and its reverberation times and their distribution.

Ideally evenly under 0.15 s in the entire frequency range. Only in the bass up to a maximum of 0.4 s


35% Positioning of the loudspeaker in the room

Preferably far away from all walls. I once heard an LS 3/5a in a room 11.5 m (37 3/4 foot) long. Torsten Roscher, the guy who demonstrated it, was able to show a whole new dimension of freedom.
Ideally, the speaker level should be 38.2% of the room length away from the rear wall. Also far away from side walls!
The listener should also sit far away from all walls to avoid early reflections (ideally 23.6% (61.8% of 38.2%) from the wall behind the listener's head - not 33.33% or 25%).


18% quality of the loudspeaker - divided into 3 x 6%:

6% frequency response linearity with emphasis on linearity of the range from 100 Hz to 2 kHz on-axis and also measured 10 degrees or 20 degrees off-axis... this is where the frequency response must fall off EVENLY slightly.

6% Bass quality (linearity, depth, cleanliness and speed of the bass)

6% other characteristics of the loudspeaker:
a) Dynamics
b) freedom from distortion (especially in the mid-range)
c) “speed” of the loudspeaker (transient behavior, mechanical losses of the most important drivers (whereby the non-linear components of the mechanical losses are particularly important - uniformly somewhat higher mechanical losses are not so bad))
d) Phase linearity and group delay


2% quality of the equipment (except loudspeakers!)

these are subdivided as follows:

1.8% non-digital sources, such as tape recorders and turntables, tonearms and cartridges as well as tonearm cables, RCA cables and speaker cables

0.2 % digital sources to enhance the quality of non digital sources (AD/DA Converters, Digital parametric Room Equalizers, Convolvers etc.), RCA cables, speaker cables to connect them with the non-digital stuff.


If only digital sources are used:

0.2 % digital sources, Digital parametric Room Equalizers, Convolvers etc., RCA cables, speaker cables


(The remaining 1.8% would then have to be added to the above 45%; 35% and 18%).

I firmly believe in this classification of relevance if you want to do something about your hearing!


thw
 
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As someone who bought his first magazine on the subject of music reproduction at the age of 13 (Hifi STEREOPHONIE - January 1979) and has now been dealing with this subject for almost exactly 45 years and has repeatedly given detailed advice to friends, I tried to “condense” my findings last year:

So I developed a sheet where I wrote down my opinion on the subject of “What is how influential in the field of hi-fi”.

I divide it up as follows (and I know I'm being provocative):

Provided you have optimally produced music that has not already been destroyed by loudness wars during mastering, the following applies


45% The room and its reverberation times and their distribution.

Ideally evenly under 0.15 s in the entire frequency range. Only in the bass up to a maximum of 0.4 s


35% Positioning of the loudspeaker in the room

Preferably far away from all walls. I once heard an LS 3/5a in a room 11.5 m (37 3/4 foot) long. Torsten Roscher, the guy who demonstrated it, was able to show a whole new dimension of freedom.
Ideally, the speaker level should be 38.2% of the room length away from the rear wall. Also far away from side walls!
The listener should also sit far away from all walls to avoid early reflections (ideally 23.6% (61.8% of 38.2%) from the wall behind the listener's head - not 33.33% or 25%).


18% quality of the loudspeaker - divided into 3 x 6%:

6% frequency response linearity with emphasis on linearity of the range from 100 Hz to 2 kHz on-axis and also measured 10 degrees or 20 degrees off-axis... this is where the frequency response must fall off EVENLY slightly.

6% Bass quality (linearity, depth, cleanliness and speed of the bass)

6% other characteristics of the loudspeaker:
a) Dynamics
b) freedom from distortion (especially in the mid-range)
c) “speed” of the loudspeaker (transient behavior, mechanical losses of the most important drivers (whereby the non-linear components of the mechanical losses are particularly important - uniformly somewhat higher mechanical losses are not so bad))
d) Phase linearity and group delay


2% quality of the equipment (except loudspeakers!)

these are subdivided as follows:

1.8% non-digital sources, such as tape recorders and turntables, tonearms and cartridges as well as tonearm cables, RCA cables and speaker cables

0.2 % digital sources to enhance the quality of non digital sources (AD/DA Converters, Digital parametric Room Equalizers, Convolvers etc.), RCA cables, speaker cables to connect them with the non-digital stuff.


If only digital sources are used:

0.2 % digital sources, Digital parametric Room Equalizers, Convolvers etc., RCA cables, speaker cables


(The remaining 1.8% would then have to be added to the above 45%; 35% and 18%).

I firmly believe in this classification of relevance if you want to do something about your hearing!


thw
I do agree on a lot of what you are saying, but I might be opening a can of worms here: your amp comes third and is a lot more influntetial than we like to admit, and I give it 10 %. I own the Audiophonics, use it every almost every day, except when I switch to some old AB's from time to time. Because they have a 'sound'. I switch speakers too:) After being in the hifi-hobby (that's what i call it for myself) for over 25 years now I learned mainly one thing: perfect reproduction is something most people don't really desire, understand and some even dislike. I sort of remember the sound of my 90's boombox at full volume. The distortion was off the scales, but it was FUN and we didn't care. I've got a pretty nice setup here now, but not many people are actually that impressed when they hear familiar music trough it, especially at first. Because they are used to radio and streaming, mainly in their cars ot trough bluetooth speakers. The DSP going on between source and ears in those situations can be mild to mindboggling. Because most people just want the artificial punch of their radio station or their speakers. It is what they conceive as 'normal', and what they think music should sound like.
 
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I do agree on a lot of what you are saying, but I might be opening a can of worms here: your amp comes third and is a lot more influntetial than we like to admit, and I give it 10 %. I own the Audiophonics, use it every almost every day, except when I switch to some old AB's from time to time. Because they have a 'sound'. I switch speakers too:) After being in the hifi-hobby (that's what i call it for myself) for over 25 years now I learned mainly one thing: perfect reproduction is something most people don't really desire, understand and some even dislike. I sort of remember the sound of my 90's boombox at full volume. The distortion was off the scales, but it was FUN and we didn't care. I've got a pretty nice setup here now, but not many people are actually that impressed when they hear familiar music trough it, especially at first. Because they are used to radio and streaming, mainly in their cars ot trough bluetooth speakers. The DSP going on between source and ears in those situations can be mild to mindboggling. Because most people just want the artificial punch of their radio station or their speakers is what they conceive as 'normal', and what they think musicc shuld sound like.

you're right, but generally we're talking about "hifi" ... i mean, fidelity to the source, to what the artist and audio engineers made in the recording.
So, the opinion of people that wants "fun with lots of distortion" goes on another way (i don't talk about importance or worth / worthless).

I understand perfectly what you said (i had those experiences with "people") ... is only that we're on a niche, not on a mainstream hobby.
 
I do agree on a lot of what you are saying, but I might be opening a can of worms here: your amp comes third and is a lot more influntetial than we like to admit, and I give it 10 %. I own the Audiophonics, use it every almost every day, except when I switch to some old AB's from time to time. Because they have a 'sound'. I switch speakers too:) After being in the hifi-hobby (that's what i call it for myself) for over 25 years now I learned mainly one thing: perfect reproduction is something most people don't really desire, understand and some even dislike. I sort of remember the sound of my 90's boombox at full volume. The distortion was off the scales, but it was FUN and we didn't care. I've got a pretty nice setup here now, but not many people are actually that impressed when they hear familiar music trough it, especially at first. Because they are used to radio and streaming, mainly in their cars ot trough bluetooth speakers. The DSP going on between source and ears in those situations can be mild to mindboggling. Because most people just want the artificial punch of their radio station or their speakers. It is what they conceive as 'normal', and what they think music should sound like.
The amps- 10 % influence? Na, meh! Only 2 % at most……
Says the man who purchased the Topping B100 50 Watts Monos yesterday at Shenzhenaudio.com because he could not resist at only EUR 470,— for a pair of the best measuring amp ever……. (Black Friday/Cyber Monday)

Our hobby is not so rational all the time…. ;)
 
This has now been discontinued but a new version soon to be released

And the cheaper version:

And 3 channel version:
 
This is a review and detailed measurements of the Audiophonics HPA-S400ET. It was sent to me by the company after member request and costs 1 490,00 € (US $1,638).
View attachment 194285

I must say this is one of the best packaging of class D amplifiers (Purifi in this case) that I have seen! It is slick and has style. While the heatsink on one side is cosmetic, the other is connected to the power supply power transistors although in use nothing rose above room temperature. Back panel shows extremely high quality speaker connections:
View attachment 194286
You can see it better with the lid open:
View attachment 194287

I must say, this is so clean you can eat of of it! :) I simply cannot find any fault with the assembly and design. Bottom to modules are Purifi 1ET400A modules fed by their own custom buffer/pre-amp gain stage. Jumpers let you select from different settings (see measurement section).

Audiophonics HPA-S400ET Measurements
Given the three different gain stages, it was a challenge to decide what to test so that this job doesn't become nearly infinite in scope. I will first show you the dashboard for all three gains starting from high gain:
View attachment 194288

This is superb performance already with distortion products at -125 dB. Channel matching is excellent. Here is medium gain petformance:

View attachment 194290

This is a nice setting as max power is achieved at 4 volts meaning you can use all of our modern/desktop amps to drive the unit and gain a bit of performance.

If you have a pro interface that goes up to 10 volts out, you can utilize the low gain mode:
View attachment 194291

This gain is actually close to how I measured our two top performers (Benchmark AHB2 and Topping PA5) so let's see how the Audiophonics ranks:

View attachment 194292

Looking at top 20 we see:
View attachment 194293

Amazing performance! Measuring SNR at low and medium gain we get:

View attachment 194294

View attachment 194295

OK, from here on I am going to stick with low gain mode. Here is our multitone:
View attachment 194296

Stellar as expected. Crosstalk manages to actually land in #1 position of any amplifier tested:

View attachment 194319
Frequency response is dead flat with no load dependency:
View attachment 194298

Let's sweep and see how we do with 4 ohm load:
View attachment 194299

Excellent performance. Here is how much power we get if we allow more distortion:
View attachment 194300

Switching to 8 ohm we see that the performance actually exceeds than of Purifi (although I think that was tested at higher gain):

View attachment 194301

Testing at other frequencies we still have great performance:

View attachment 194302

Finally, the amplifier is stable at power up so no need to wait for it to warm up:
View attachment 194303

Conclusions
The Audiophonics HPA-S400ET comes in a beautiful package with super performance to match its good looks. Yes, it builds on Purifi's excellent platform but they managed to add value without messing with its performance. The gain settings are well thought through. The whole thing is so well executed and must be a delight to our European members who can buy it locally. Having been built in France, it is also a feather in the cap of our French members. :)

I am happy to give my strongest recommendation to Audiophonics HPA-S400ET. You have a lot of power with superb fidelity and transparency.

Edit: video review just posted:

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Yeah. But what about the sound quality
 
Yeah. But what about the sound quality

What is "sound quality" for you? What you listen in your room with your acoustics / speakers / sources? That`s not the sound quality of the amplifier, that`s the result in YOUR room and with YOUR taste.

What the review shows is what you really need to know about the amplifier, stuff like ... is transparent to the source? power available?
If the amplifier (as an electronic device) have the technical requirements you need, then you can EQ / tinker as you want.

That's all. There's no magic goblins inside an electronic circuit and the technology to make a very good amplifier in the 21th century is no magic also.
 
Come on, if "66" is your birth year, you are too old to play troll.

Agree....specifically looking at the post he made 15 mins ago

 
Come on, if "66" is your birth year, you are too old to play troll.
Sorry man. Forgot to finish previous post with ;-) That said....it occured to me recently that we slate folks on here, in general (and quite correctly) for their subjective bullshit re so called various aspects of SQ. But then, after a smoke admittedly, it occured to me that could folks here tell, with properly double blinded, sound level matched tests etc, equipment that measured well with equipment that measured shit. Genuinely not trying to be controversial, but would be interested in your reply. I'm just a curious amateur don't be taking too seriously, or seriously at all which I'm sure you are not!! :) I have a first class honours degree in a scientific subject but not one with any relevance to hifi engineering or sound measurement...
 
But then, after a smoke admittedly, it occured to me that could folks here tell, with properly double blinded, sound level matched tests etc, equipment that measured well with equipment that measured shit
Speaking about normally designed solid state amplifiers, one with THD+N of -90dB, the other with -120dB, none of them clipping with the music sample used for test, and in a properly done DBT - no one will tell a difference, I am 100% sure. You know, that chase for ultra low distortion number is just a kind of a hobby only, for those who do not know it only creates another myth, another golden calf.
 
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