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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
audio2design
1,351 posts
 
While on one hand, op-amps in the same circuit can sound different, which often says far more about the circuit than the op-amp, anyone claiming to be immune to sighted bias is delusional. If you can't be honest with yourself?

Circuits need to be tuned to a particular op-amp for best performance, so I always take with a grain of salt op-amp swaps.
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jaytor's avatar
jaytor
765 posts
 
I never said I was immune to sighted bias. But there are often cases where the sound differences easily overcome this bias. In the case I mentioned, the differences were quite easy to hear by several listeners. 
djones51
4,947 posts
 
This past year , which I've had a lot of time,  I've listened to various class d amps. I have no idea what opamps were used but I couldn't tell which was which in an unsighted situation. One was actually a class A/B amp. Not a proper test I know. I guess I don't have golden ears.
djones51
4,947 posts
 
I'm using a class d amp now. I have no idea which amp it is, ICE, purifi, Hypex Pascal, I've heard them all in different amps and active speakers. Since the room and speaker contributed more to the sonics than any amp or DAC ever could I wasn't really surprised. 
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