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
madavid0 OP
214 posts
 
I'm one of the few people online who actually tries things and reports my findings accurately. I do understand that most don't actually want to read critical information about a product, they just want to have their bias confirmed. I've learned that what I do is not really welcome on the Internet and so I've been banned from most forums, most recently ASR which in particular is a vile, toxic cult.
djones51
4,947 posts
 
You're banned because you're a troll. You take a product this time purifi and carry on as if you've done something by buying the cheapest amp you can find and complain about it in subjective terms. How many blind tests did you do? I doubt you could tell this VTV amp from an old crown in a blind test. Get real noone here takes you seriously either.
madavid0 OP
214 posts
 
@djones I'd definitely be willing to do a blind test, but understand that's a pretty tall order when we're talking about comparing amps. In reality your requirement for blind testing is just a roadblock to protect egos and confirm biases. Listening impressions are fake and the correct method of conducting them are too difficult to achieve in everyday life, so you can remain comfortable in willful ignorance.

For example, in my ASR thread about Purifi, I noted that my reference mains cable chain had no effect. Responders agreed with this finding. Strange, shouldn't this sighted, unscientific listening impression also be invalid? How do I know there isn't an difference between mains cables? Maybe the lack of difference is just in my head, ie, I expected to change so I heard none? Funny. Weird. How does the requirement for blind testing disappear when the results conform with negative expectations? Of course because the responders just want to have their biases confirmed, the requirement for blind testing, ABX, etc, is just a tool to support the bias.
djones51
4,947 posts
 
If you don't like the amp return it and move on. The stock opamp is perfectly fine on the purifi boards you wouldn't be able to tell the TI from the sparkos or the silly tube contraption anyway. I don't have a bias I can't tell an Ncore from a purifi from a Pascal from a McIntosh SS amp. 
madavid0 OP
214 posts
 
I've been told by experienced audiophiles here and elsewhere that the default Hypex board is junk, so in order to give it a fair shake I ordered a set of custom ones from VTV. I think it's pretty obvious I'm not doing this just to make you feel bad about your support of class D / Purifi. I got the cheapest base unit to begin with because I figured there wouldn't be a substantial difference and at least I'd get a baseline grasp of the sound. I'm told that's not the case and the default configuration is compromised. Listening to the awful midrange I can see that there MAY be truth to that statement. Also it might be just that the artifacts are most noticeable in the midrange and that it's impacting the whole audio band. If these custom boards and opamps fix the issue and elevates the sound, I will faithfully report it. If it doesn't, then back it goes.
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