2. amps-preamps
  3. 162284-76532

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
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tweak1
3,666 posts
 
+1 soix
milpai's avatar
milpai
2,397 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.

twoleftears's avatar
twoleftears
5,318 posts
 
And we're still waiting for the LSA Voyager, which should be out soon, perhaps even before that $9500 Technics.
atmasphere's avatar
atmasphere
11,834 posts
 
Almost all tube manufacturers....they pick caps, etc. by ear....and they don't measure any different.
This statement is false- they do indeed measure differently (whether some companies bother to measure the differences is a different matter). We use custom made resistors as well (made by Caddock); they sound better but they also measure better.
Most equipment stand manufacturers......I mean, can you measure a better stand?
Certainly! Sound Anchors was measuring the differences in performance of their stands 30 years ago. Its not hard.
More like calling you out, on your snake oil mods, that you don’t backup with any measurements, just a fusers "trust me it works"

Its easy enough to measure the effects of a fuse, and the different fuses. Its not rocket science either. All you need is a DVM. Having said that I'm personally not a fan of boutique fuses. At least one of them uses a Teflon tube to 'damp' the fuse element. The problem is the fuse actually has to blow in order to protect; this type of fuse can have the metal of the fuse element go liquid and finally to a plasma state simply because of that Teflon tubing in which its held. Such a fuse will not reliably fail at its rating, and thus we don't recommend them.


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