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Purifi Class D: Junk?

So, from the previous thread about high-end class D the Purifi module was brought up. I decided to get a cheap example from VTV, a simple stereo unit with a single Purifi module and matching Hypex SMPS. Standard input buffer. I got it in yesterday. First impression wasn't what I was expecting: weak, congested dynamics is what stood out to me. I expected greater expression through my ProAc D30Rs. The other problems such as poor soundstage, thin / boring character, etc, I marked up to needing burn-in before evaluating. So it's been 24 hours, I would still expect to get at least the high control / damping of high end class D and dynamic power, but it's just not present.

Could it be an impedance mismatch? Other manufacturers selling the Purifi with their custom input buffers are reporting 47k Ohms. VTV doesn't say in the manual or on the site. I checked the Purifi data sheet which reports...2.2k Ohms on SE???? That can't be right?? That's absurdly low! Am I reading the right spec? My preamp has an output impedance of 230 Ohms. Can someone confirm that the stock Purifi has this ultra-low input impedance?
madavid0
georgehifi's avatar
georgehifi
10,312 posts
 
because of the false initial proposition on which it was based.
Sez you, he has a valid but crude way of putting it.

Technics so far with the SE-R1, are the only ones that have addressed the Achilles-Heel of Class-D.

Output Filter, Noise, Phase Shift. All related to the Switching Frequency.

By utilizing GaN Technology to it’s fullest, and having (3x higher) Switching Frequency, and eliminating the 3 Achilles Heels above from effecting/influencing down into the audio band frequencies.

Cyril Hamer of Soulution- Audio at the bottom of my last post says it also.

Cheers George
madavid0 OP
214 posts
 
So, burn-in continues. There's a troublesome mid-range artifact, a harshness / blurriness that shows up in voices with "hot" recordings. Also the image seems to project especially high, but I'm not sure if that's the amp or something with the speakers because I did move them yesterday. If this midrange issue doesn't fix itself with continued burn-in then it'll have to go back as I know this will kill it for me, it's very uneuphonic. Maybe a custom input buffer option fixes it if this continues to be a problem, we'll see.
twoleftears's avatar
twoleftears
5,320 posts
 
From the OP's previous thread.
"So....I think I'll buy a VTV Purifi. I suspect I'm heading for disappointment again"
This thread is about as unbiassed as the Star Chamber ever was.
georgehifi's avatar
georgehifi
10,312 posts
 
He’s tried a few, and been on a disillusionment path with them, it’s expected to not feel confident with this one. I’m surprised he’s given them as much chance as this.

I know what Class-D would probably make you happy madavid0 OP, and that’s the Technics SE-R1 if you want to give that a go, hard to get one but possible.

Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 


There’s also a new approx $10K integrated Class-D from Technics called the SU-R1000 Integrated Amplifier around 22 kg
.
Said to have many of the GaN Class-D features of the far bigger SE-R1, but nowhere yet can find if it uses the 1.5mhZ switching frequency that "makes" the SE-R1.

Also it uses smp power supplies, even though it’s 22kg, Unlike the SE-R1 at some 60Kg because of it linear supplies.
No reviews or measurement tests as yet for this one from Technics


Cheers George
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