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
I spent some time today switching between my Purifi amps (using Neurochrome input buffer), Neurochrome Mod-286 amps, and Parasound JC5.

First, I should say that my ears aren't as discriminating as they used to be. I've suffered with Tinitus for many years, and my high-frequency hearing is not what it used to be. So take these observations with that in mind.

I used the same interconnects for all three amps, but I had to use longer speaker cables with the JC-5 since it's a stereo amp. The cables were exactly the same construction, just 2.5 meters instead of 1 meter. Also, I used a different (although similar) power cord with the JC-5 since I needed a longer one.

I set the levels using a pink noise -10db recording with a sound pressure meter with C weighting measuring 64db. For most of the recordings I listened to, this would be about my average listening level. A couple of the recordings were a bit lower volume than I'd normally listen.

The songs I listened to were Sophie Zelmani - Why, Jennifer Warnes - Way Down Deep, Shirley Horn - Beautiful Love, Dominique Fils-Aime - Birds, Ray LaMontagne - This Love Is Over.

I turned off my subwoofers for these comparisons since they have their own amps and I didn't want their contribution to influence my impressions. My main speakers (GR Research NX-Oticas) don't play very low without the subs, so I can't really assess the deep bass performance of the amps.

All three amps have a fairly similar presentation, although the JC-5 was slightly more laid back than the other two. The overall differences between the amps were not real obvious.

The JC-5 is slightly warmer sounding with excellent dynamics and smooth midrange. The highs (to the extent I can still hear them) sound clean and natural. Compared to the other amps, the biggest short-coming is a somewhat narrower sound stage. I suspect this is because the other amps are monoblocks.

The Modulus-286 amps were the weakest of the three. They still sounded quite good, but had a bit of honkiness (if that's the correct term) to the upper bass and some unpleasant sibilance on female vocals. At higher volume levels, I've noticed these amps get a bit more congested sounding, probably due to their more limited power, but at the volume that I was playing today, they sounded fine.

The Purifi amps were just a tiny bit rougher sounding in the upper midrange compared to the JC-5, but overall cleaner than the Modulus-286. They also had a touch more energy in the bass compared to the other two amps, most obvious on the Jennifer Warnes song.

At this point, I'd be perfectly happy with either the JC-5 or the Purifi monoblocks, but I'm hoping I can take the Purifi amps to the next level with the new input buffers I just got. I'm waiting on a couple of connectors before I can install them (hopefully next weekend). The Purifi amps are also a lot more efficient which is particularly nice during warmer months.
The definition of a shill is " an accomplice of a hawker, gambler, or swindler who acts as an enthusiastic customer to entice or encourage others." So you are saying I am a swindler and he is my shill? Shills get paid to swear false info and to entice.

To call someone a shill is slanderous, unless you have proof. You just don’t like me and you don’t like him......so you call us names. This is against the Audiogon rules of conduct. Please grow up.

Tweak 1 is an enthusiastic customer.....nothing more, nothing less. I don’t tell him what and when to post nor have I ever offered him free anyting or even given him a discount or any money. Again, please grow up.

Shill does not mean to sell or promote. It has a much more sinister implication.  You use the word to make it seem you are ridding this place of vermon.  Remember, when you point a finger at someone.....3 are pointing back at you.  Try pointing the love finger.  Then three self love fingers point back to you.  Love is much more fun and juicy then being right and making others wrong.   Make everyone RIGHT.  We are all beautiful.

Sorry ricevs, I’ll add corrections to the end of it.
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