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

Showing 3 responses by mspot

mspot
112 posts
 
So how bad IS the standard Purifi in the VTV? Will the upgraded input board and discrete opamps move it to another level?
In my experience, yes upgrading the input board changed the VTV Purifi amp from unacceptable to acceptable. Others have reported a similar experience:  https://www.audioasylum.com/cgi/t.mpl?f=amp&m=238411

My thought is the following. At $979, the VTV Purifi with Hypex buffers is by far the lowest price Purifi stereo amp on the market. Everybody else is selling Purifi stereo amps in the range of $1400 and above, and only with custom buffers. Presumably nobody else wants to offer the Hypex buffer because it is a poor match for Purifi. If you upgrade the VTV with custom buffers, then the price jumps up to $1400 and more, making it similar to the rest of the market. So the $979 price is only there to attract attention and bargain hunters, even if the Hypex board doesn't work well with Purifi.
mspot
112 posts
 
What Purifi offers and now VTV sells now too. Check out Eval 1 and 2:
https://purifi-audio.com/vare-kategori/transducers/
I do not believe that VTV offers the Eval 1 and 2 buffers, and nor have I seen any other vendors offer amplifiers with Purifi Eval buffers. On Purifi's order pages, they do not sell the Eval boards separately (only in kits combined with 1ET400A modules).

mspot
112 posts
 
And that Hypex buffer is a perfect match with the Purifi module
Have you heard them in combination? I have, and I found them not a good match together. Others feel the same way, for example https://www.audioasylum.com/cgi/t.mpl?f=amp&m=238411. VTV seems to be the only vendor offering this combination. I think there's a reason why nobody else is doing it.
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