2. amps-preamps
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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

Showing 2 responses by milpai

milpai's avatar
milpai
2,313 posts
 
Alright, it is "sunshine from down under" on yet another Class D thread.Problem with george is, he feels we should trust his hearing and not our own.
Ask him for concrete evidence on Class D stuff, and he will cry uncle and start posting Nelson Pass's quotes. He does not have the full knowledge of class D. If you don't believe me, just wait for this thread to move on a bit OR go to other class D threads. And on top of that he calls on others as "policing" when he does the most himself. Looking at his past posts, I think he has some issues. Like digging up 13 year old posts and start calling out names. I suggest, ignore his posts and move on.
milpai's avatar
milpai
2,313 posts
 
Maybe we should use a new word for people like this. How about Anti Snake Oiler or ASO.
@ricevs , that is a good one :-). Assuming that george is the biggest ASO and he complains on fuses and other stuff like modding. But what surprises me is the -ve bias against Purifi and other class D modules that have come up recently. The folks on ASR have shown with measurements how good the Purifi module is and the potentials it has. Subjectivists and objectivists both agree on this one. It looks like he has "personal" agenda/motive against Class D. The only thing I could think of is that maybe Class D amps do not gel very well with his attenuators and hence is trying to discredit them? Not sure. Beats me.Well known designers still have to make a living and not run a charity. Why would they promote other designs over their own? And the quotes that they made, which george often mentions, are from "how long ago"? Technology changes, so we should see improvements in the new Class D amps, compared to the ones from a few years ago.

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