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Review and Measurements of Purifi 1ET400A Amplifier

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amirm

amirm

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pirad

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Hypex brought a paradigm shift onto the "hi-fi" DIY audio market. You can get FA122 for 300.- euro with remote. It's a stereo n-core plate amp
with a great DAC (AKM) and DSP. Put it into a nice old wine box and 99% of the population won't be able to tell the SQ difference in direct comparison with any amplifier possibly costing 30x more.
Next marketing model? IKEA-like "order-by-website" electronic innards and the case to taste to put together at home in 10 minutes.
Or "ready-made" box for 20$ extra.
 

restorer-john

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I had to put a lot of care in my dummy load design to measure distortions that are -130 dB down.

I particularly like how you put wheels on the bottom for easy manoeuvring. ;)

1562571951321.png
 
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maty

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Hypex brought a paradigm shift onto the "hi-fi" DIY audio market. You can get FA122 for 300.- euro with remote. It's a stereo n-core plate ampwith a great DAC (AKM) and DSP. Put it into a nice old wine box and 99% of the population won't be able to tell the SQ difference in direct comparison with any amplifier possibly costing 30x more.
Next marketing model? IKEA-like "order-by-website" electronic innards and the case to taste to put together at home in 10 minutes.
Or "ready-made" box for 20$ extra.

The immense majority only listens to modern commercial music, so badly recorded. And in compressed format. They do not need to spend a lot of money to be happy and it is even counterproductive to buy a good audio system because they would discover that the music they love so much sounds much worse than they thought. That is the audio business drama.

The crops planted years ago are being harvested.
 
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maty

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Although in class D the distortions are very low, it does not hurt to make sure. Especially if the power supply is polluting the audio band.
 

pirad

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My personal ranking of factors in SQ perception: brain/ears, room/loudspeakers, the recording, electronics, cables/fairy dust/etc.
However, the quality of electronics reached a point where any progress is extremely diminishing in returns. I put money on solutions
like FA122 to fight off anything costing 10x, 30x --- in PROFESSIONAL auditory tests. That has been my experience with n-core and
AKM DAC, anyway.
 

maty

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PROFESSIONAL auditory tests
in PROFESSIONAL auditory tests. That has been my experience with n-core and AKM DAC, anyway.

The key is the type of the music. Electronic, very processed at studio, synthesized instruments, voices with Autotune... and DR < 10 dB? For that kind of music you do not need an amplifier that measures very well!

Yesterday, two very good vinyl rips of Aqualung: https://www.diyaudio.com/forums/music/6958-playing-listening-post5843985.html

dr.loudness-war.info Jethro Tull - Aqualung

No rumble, clicks or anything that makes me think that the source is vinyl, at least with my LOVED speakers.
 
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pirad

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I am skeptical about vinyl rips having the detail necessary for resolution tests.
Also the range of the test music must be wide: vocals, single instruments, percussion, chamber, orchestra, jazz...
The crude "DR meter"is not really a metric how good a recording is. It simply compares peak and RMS levels.
Even with the same master the processing for vinyl will often result in spikier waveform. This reduces the RMS
and results in higher DR values. The processing can use filters that change broad peaks into alpine rocks
and/or the stereo separation and deep bass are reduced for the limited medium. The vinyl playback system can also
change the DR. Eg. the poorer the bass reproduction the higher the DR.
 

maty

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I am skeptical about vinyl rips having the detail necessary for resolution tests.
Also the range of the test music must be wide: vocals, single instruments, percussion, chamber, orchestra, jazz...
The crude "DR meter"is not really a metric how good a recording is. It simply compares peak and RMS levels.
Even with the same master the processing for vinyl will often result in spikier waveform. This reduces the RMS
and results in higher DR values. The processing can use filters that change broad peaks into alpine rocks
and/or the stereo separation and deep bass are reduced for the limited medium. The vinyl playback system can also
change the DR. Eg. the poorer the bass reproduction the higher the DR.

dr.loudness-war.info Jethro Tull - Aqualung

CD, Vinyl... if you have not done dirty with the CD or odd things with the vinyls the DR is very similar or the same.

I listen to music regardless of the format, I look for the best sound possible and that excites me. It is not my fault that many do their job badly despite the best current technology.

If I put the DR is to raise awareness of the loudness war.
 

maty

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FrantzM

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I know very well that DR is not everything, nor do excellent measurements necessarily indicate a fantastic sound.

Dire Straits - Dire Straits (1978), Vinyl, Vertigo, UK

https://www.diyaudio.com/forums/music/6958-playing-listening-post5839810.html

Same vinyl and system but with other cartridge and something more. Same DR. With the new cartridge the sound is BETTER.

https://www.diyaudio.com/forums/music/6958-playing-listening-post5839812.html

I am not a moderator here but feel compelled:

@maty can you open up a thread in which you would post your subjective impressions and the DR value of the albums you have or have heard? That tendency to post links on almost every post, pollutes too many threads with off-topics ...err .. posts .. The one I quoted being one example among several others. It would also help if you substantiate your point of views. It is more about objective metrics here at ASR. The mods and owners are lenient but ...
You have too much to contribute to put you on ignore however the way you thump us with those posts, is bothersome. I could have sent you this via PM. Decided to go public.
If it is too much as hominem the mods can simply erase the post.

P.S. miero beat me to it ...
 

pirad

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dr.loudness-war.info Jethro Tull - Aqualung

CD, Vinyl... if you have not done dirty with the CD or odd things with the vinyls the DR is very similar or the same.

I listen to music regardless of the format, I look for the best sound possible and that excites me. It is not my fault that many do their job badly despite the best current technology.

If I put the DR is to raise awareness of the loudness war.
Well, you changed your original post by deleting the vinyl cover and track DR figures.
It leaves the response posts somewhat out in the left field.
 

Thomas savage

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@maty we are very much at the bridge of less is more wrt your posts. More focus and less ' carpet bombing' please.

You need to remember these threads are often used as a information resource for folks and we must keep their experience of reading through them in mind.

This is your second little nudge on this subject, I do value your enthusiasm but alas less is more maty ..

Cheers
 

maty

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I have read many times in these forums that vinyls have a DR higher than their CD equivalent. Many times. It turns out that it is not true. What is the use of putting the link to dr.loudness.war in the first comment?

@Thomas savage

I suppose you will apply the same criteria to certain comments that are supposed to be funny and that are often used to discredit personally (in others threads), demonstrating with it the inability to argue properly.
 

JohnPM

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In Benchmark's literature, they state the following (https://benchmarkmedia.com/blogs/ap...ory-use-of-the-benchmark-ahb2-power-amplifier):
The important difference between the AHB2 and class-D amplifiers is that the AHB2 does not produce switching noise. Class-D amplifiers are measured with brick-wall AES17 filters that ignore the switching noise above 20 kHz or 40 kHz. Tweeters can demodulate this ultrasonic noise and fold it into the audible band.

Some of us (at least me!) can't help wonder if there could be some kind of harm from having the ultrasonic noise. Really I think I am fairly well convinced that this is harmless, but I would like to hear what you have to say about the above, and your response to any other critical points you have heard regarding Class D ultrasonic noise.
The intermodulation effects of ultrasonic content were studied in this paper.
 

pirad

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Class-D intermodulation noise from the switching?
Really? 500kHz played by tweeters?
 
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