Sorry I am back again with this thread
. It was the Amir's review
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). 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...
www.audiosciencereview.com
and especially this measurement
that has shown that even the best current class D module, Purifi 1ET400, suffers from quite severe high frequency non-linearity. Thank you
@amirm for performing this kind of @45kHz BW distortion vs. power test as a rule. I have decided to accept it as my standard test method as well and I have tested 3 of my amplifiers under same test conditions, the comparative result I have posted here in this thread:
I was reading the May 2022 edition of Stereophile and while reading the review of the Japanese flagship Luxman M-10X stereo power amp (20k usd) it reminded me of this topic, in particular this part quoted above.
This beauty runs on class AB (with 12W into class A bias). Let's see how it measures with frequency:
This is 20 volts (P = U^2/R = 20^2/4 = 100 watts). I can read THD+N at 4 ohms in 15 kHz is around 0.03% = - 70 dB.
It is significantly higher than the Purifi 1ET400A from Audiophonics above, which measures about -88 dB.
Or at 5kHz, Luxman THD+N is about 0.013% = -78 dB.
Audiophonics Purifi is -99 dB.
Power the Luxman M-10X reaches 350W into 4 ohms (THD+N 1%) while the Audiophonics 1ET400A does 367W in the same conditions, so they are equal here.
What about high frequency intermodulation then?
From the Purifi 1ET400A datasheet we don't have the exact same conditions, but taking a worst case, 200W into 4 ohms:
Luxman IMD skirts are about -98 dB while Purifi's (worst case!) around -112 dB.
So I guess the extra 18.4k usd buys a very, very nice chassis and meters, along with real pride of ownership. Also bragging rights about owning a Japanese flagship class AB amp and laughing about class D toys. But better measurements and fidelity to the input signal? Sorry, not the case here. Even in high frequencies.