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
And we're still waiting for the LSA Voyager, which should be out soon, perhaps even before that $9500 Technics.
Almost all tube manufacturers....they pick caps, etc. by ear....and they don't measure any different.
This statement is false- they do indeed measure differently (whether some companies bother to measure the differences is a different matter). We use custom made resistors as well (made by Caddock); they sound better but they also measure better.
Most equipment stand manufacturers......I mean, can you measure a better stand?
Certainly! Sound Anchors was measuring the differences in performance of their stands 30 years ago. Its not hard.
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"

Its easy enough to measure the effects of a fuse, and the different fuses. Its not rocket science either. All you need is a DVM. Having said that I'm personally not a fan of boutique fuses. At least one of them uses a Teflon tube to 'damp' the fuse element. The problem is the fuse actually has to blow in order to protect; this type of fuse can have the metal of the fuse element go liquid and finally to a plasma state simply because of that Teflon tubing in which its held. Such a fuse will not reliably fail at its rating, and thus we don't recommend them.


Its easy enough to measure the effects of a fuse, and the different fuses. Its not rocket science either. All you need is a DVM.


Hi @atmasphere

Can you illuminate me on what types of differences, among equally rated and types of fuses you have encountered?  How precise did the DVM have to be for you to measure it, and what qualities do you look for?


Best,

Erik
I am sure that changing a part here and there could change a measurement. However, this us not the usual case. You can take 10 different brands of normal metal film resistors and they will all measure the same.....and all sound different (I have done this).......maybe a non inductive Vishay or Caddock could change a measurement....but most things cannot.....and this includes brands of solder.....that also....all sound different. Yes, there are certain measurements you can do with a component stand that will be measurable.....However, there are no agreements as to which measurements mean what sonically and which component stand sounds best with which component. In fact, some people prefer to "add certain natural resonances.....to enhance the sound" Fuses all sound different and you cannot measure all the sonic differences with a meter of any kind. The only meter that matters is your ears. I have never seen anyone state that good film caps measure differently (certainly, ceramic,Tantalum and Electrolytics should never be used in the signal path).......yet all types and brands of film caps sound different. Please, use your ears.

Here is a good one. I bypassed a fuse with a 12 gauge wire soldered across the fuse solder on its inside bottom (fuse holder was a board mount fuse jobbie). It made an impressive improvement over the stock fuse. However, the tabs that normally would hold the fuse up slightly in the air were still sitting there......and I figured they might be adding some resonance. So I broke off these 4 tabs and the sound was noticeably improved. Measure that!!!!! This game is not simple....it is infinite....enjoy the infinite.....it is all there is......and it is infinite love and joy.

Here is another good one.  Years ago it was said the Nichrome thin film surface mount resistors were the bomb.  So, I bought 4 different one eight watt 75 ohm resistors from Mouser and tried them on the output of a low jitter clock.  These things are so tiny you can hardly see them.....and they all look the same except for color.  But all four brands sounded different.....one being way bad and one being way good.  I still use the way good one today.....but now I use the quarter watt versions and parallel them for best sound.  Did i say this game in infinite?  Cannot say it enough.
I am sure that changing a part here and there could change a measurement. However, this us not the usual case.

What is it with people feeling its okay to pontificate and lecture about things they clearly haven't the foggiest about? To an audience chock full of people who do?  

Ralph has more experience in his little finger but even I have enough to know its darn near the OPPOSITE of what this ricevs guy is saying. First swap I ever did was a diode, just a dumb little $8 hexfred, and the improvement was massive! Changed caps- huge. Fuse- ditto. On and on.  

Actually did these things. Actually heard these differences. Just a suggestion ricevs, but I really do think what you should do for at least a while, every time you're all set to start blathering about that which you have no actual experience or knowledge of, type the words, "Of course I have no clue if this is right or not because I haven't done anything even close to this before but...." and then type away. 

Deal?