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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
 
I’ve been told by experienced audiophiles here and elsewhere that the default Hypex board is junk
Any one that says that is junk themselves and needs to be committed.
I’ve shown what the Hypex board is, it’s opamps may not be the "absolute very best" of opamps, but they’re not far off it. Anyone that can hold a soldering-iron can build one. And you’d have to be an absolute idiot to stuff up a buffer design using them. And I doubt Putzey is one.
https://forum.audiogon.com/discussions/purifi-class-d-junk/post?postid=2080260#2080260

Cheers George
yyzsantabarbara
4,865 posts
 
I've been told by experienced audiophiles here and elsewhere that the default Hypex board is junk
You  also need to ask them about their last hearing test just so you have a proper baseline. There are some pretty good class D out there.

My Peachtree Nova 150, while not as good as my current gear (BM AHB2), was a very good Class D integrated. I now wish I did not sell it since I need an integrated today that will sound good with KEF LS50's and can also tolerate some toddler abuse.

The Purifi Class D is what I am likely going to get for this new requirement but it will cost me more than the Peachtree.
madavid0 OP
214 posts
 
If I report that the Purifi is, in fact, junk -- for midrange problems or just as overall lack of engagement (the real reason why you sold the Peachtree probably) would that influence your decision? My guess is -- almost certainly not. In my experience people just want to have their bias confirmed. If it's just one or two voices critical about the product, it doesn't matter if they're the honest ones with the discernment that should be listened to and not the masses of the echo-chamber who can only compare it with other bad-sounding gear. What matters is that the echo chamber tells you want you want to hear.
jaytor's avatar
jaytor
765 posts
 
I think it is perfectly reasonable to report that you weren't happy with the particular VTV model you have, but to lump all products that use the Purifi module in the same bucket is pretty rediculous. I haven't personally heard any products that use the Purifi module yet, but I know from my limited experience listening to products that use other class D modules that there is a lot of differences in the way these amps sound depending on how they are designed and built. 
mr_m
1,900 posts
 
jaytor,
Same can be said for Hypex modules. Many designers incorporate them in many different ways with excellent results.
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