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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
 
Maybe send it to @ricevs to do some magic mods to it
Don’t know about mods without any tests/measurements/to back up any subjective listening claims. But "voodoo" and "snake oil" maybe.

As for the LM4562 it one of the better opamps around, it’s even used in some discrete MSB dacs and many others.
And as for your OPA1612 is no better and cost around the same. Just more "snake oil" talk from Tweakaudio, EVS or whatever you call your self these days

ricevs
1,543 posts
 
It is best just to ignore George. He goes on and on saying the same nonsense about stuff he has never listened to. Let him have the last word or it will go on forever......go on George, you know you have to.

Maybe we should use a new word for people like this. How about Anti Snake Oiler or ASO. Much better than "fuser" (word made up by George to vilify fuse lovers). If you look closely you will see the humor.....he he. I love you George. You are so entertaining.
georgehifi's avatar
georgehifi
10,312 posts
 
He goes on and on saying the same nonsense about stuff
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"


Let him have the last word or it will go on forever
I’d say you just tried to have the last one, just like a fuser.
soix
9,510 posts
 
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"
So if there aren’t measurements it can’t work, eh?  Guess you can’t just trust your own ears without some kinda measurement for justification — is that it Georgie?  Are you really that insecure about your own hearing and/or listening ability?

I bought Ric’s original Millennium DAC decades ago and it still works and sounds great, even without measurements.  Hundreds of audiophiles have bought his products and his mods, and he’s earned lots of praise and a solid reputation doing it.  Measure that Georgie.  And by the way, what the hell have you ever produced other than half-assed, armchair quarterback criticism of other people’s work?  Keep on measuring Georgie while the rest of us enjoy listening. 

georgehifi's avatar
georgehifi
10,312 posts
 
So if there aren’t measurements it can’t work, eh?
No, it means they don’t know what their doing if non are done and presented, so give this kind of modder a very wide berth, "could" even be dangerous to the owner let alone the equipment.

Measure that Georgie.
Measurements/testing is half the story, listening to what was done is the other, and if you don’t like it, mod again using measurements and test once again, till your happy with both.

That’s how any decent piece of equipment is developed. not with snake oil and voodoo and "trust me’s"

Keep on measuring Georgie while the rest of us enjoy listening.
Keep on doing both listening/bench testing and measuring as they very much do! back each other up.
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