I will not post after your next "always have to have the last word" post.That "sunshine" as history shows is your way, not mine.
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?
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?
Showing 49 responses by georgehifi
Wow!! in one post your "suing me" and now your "recruiting me", how polarized can you get, suppose it depends on what it was on tap at the time. This is not a recruitment forum for whatever it is your trying to sell. You can't sell voodoo or snake oil to audiophiles using the love/hippy card, maybe some will bite. |
jaytorNot saying which are better Class-D modules but yes!! my NC500’s took a giant leap also, with big linear power supplies, made me realize smp’s no matter how well designed are not very good for audio. And then there was another jump again going direct in, with no input buffer, so long as your source has the gain, and <50ohm output impedance output stage/buffer. Cheers George |
Nothing like a tweaked IceEdge or tweaked Purifi.Save use all, looks like another one bringing out his new "tweaked" Class-D, probably has an orange fuse in it too Can anyone save us us against boutique Class-D manufacturers using threads to promote their own yet to be released stuff onto the market. BTW Those $300 3000w Behringers are ICE POWERED modules!!!! Two problems Class-D have still. The switching frequency, which is fixable with GaN technology the way only Technics so far have used it. And the second, is current delivery, where wattage goes up almost doubling for each halving of impedance down to 2ohms or even less. |
It must be getting close to the release of the your new Class-D to respond like that with such verve and virgor with doubling of wattage v halving of impedance loading. Take it up with the likes of D’Agostino, Curl, ect ect manufacturers of the greatest amps that are recognized as being able to drive speakers with loadings that make Class-D’s run for the hills, they will tell you the same thing. Like I said "if" all that matters is wattage with Class-D, and what you and your mate say is anywhere near true, then all anyone needs is this $300 3000w Class-D https://www.bavasmusic.com.au/behringer-nx3000-power-amplifier-with-smartsense?gclid=EAIaIQobChMIqIa... As much as I like my NC500 monoblocks on my easy to drive secondary speakers, they can’t compete in an A/B against my friends Gryphon Antillion on his Wilson Alexia MkII’s, and the Gryphon is less than half the wattage of the NC500’s |
. doubling does not matter.....only the power you need mattersTell that to a pair of ML-2 monoblocks 20w only at 8ohm and can double all the way to 1ohm, one of the most magnificent amps you’ll ever hear. http://www.hifido.co.jp/photo/05/504/50446/c.jpg You just shot yourself in the foot, listening to you all you need then is one of these Class-D 3000w for only $399aud, that just $313usd!!! get two and bridge them. https://www.bavasmusic.com.au/behringer-nx3000-power-amplifier-with-smartsense?gclid=EAIaIQobChMIqIa... |
Class D amps are only current limited by the designerShow us just one that’s not, and can almost double it’s rms measured wattage from 4ohm to 2ohm. The true indication of not current limiting, like many good A/B bjt amp. The Purifi module does 400 watts into 4 ohm...and over 500 watts into 2 ohms (25amps)This is pathetic to show off it’s current ability, some NAD’s can do that current, it’s actually limiting, should read closer to 800w into 2ohms if it were good at current into low impedances. A 175w- 8ohm Gryphon will do 350w - 4ohm 700w - 2ohm 1600w - 1ohm 9000w - 1/4ohm NOW this IS an amp that does current without limiting. |
As Hypex say, "The NC500 poweramp module is devoid of any sonic signature" this is "without the buffer". And it will give the best "sonic transparency/dynamics" if doable, as I do without any compromises, just better sound and a purer signal path from input to output. No additional "house sounding" opamp buffers with colourations/distortions in the signal path. |
Did you test to see if they actually do that in this application?Yes, that why I said it. I would think that due to the low impedances involved the interconnect issues wouldn’t be an issue.And to have the MSB buffer at the Hypex input or 1mt away with quality interconnect, is no difference at all and you know that. But what is worse, is having one buffer in series with another buffer. When if one "can" if loud enough do the job perfectly and yield even better sonic results. You have probably already seen this, but again for the masses, from the Hypex NC500 data sheet. Audio input"good way of tuning in a “house sound”" Take that as I would as colouration distortions, countering what they say earlier in the same sentence as "The NC500 is practically devoid of any sonic signature ” And this is what you hear by not! having an extra buffer in series that’s not needed. |
Datasheet: The output drives a 100Ω load
Sorry, just looked at my notes, the MSB’s output buffer could be the LT1819 https://www.analog.com/media/en/technical-documentation/data-sheets/18189fb.pdf Cheers George |
Data sheet: Each output drives a 150Ω load to ±7.5V with ±15V supplies No they are the output buffers in the rear of the MSB discrete R2R dac, which can swing 7.5v and do it with ease into 2kohm, with no temp rise or voltage drop or heat sink needed into the raw NC500 module And the proof is how it sounds, far better than having "any additional buffers" at the input of the NC500 module/s. And everything is direct coupled with no DC offset from dac outputs right through to speakers. ("small very fast settling" switch on low level bump from the dac) so amps go on last how it should be anyway. Cheers George |
although you wouldn't be able to drive it to full powerNo need to, I'm still only at 3/4 volume on the MSB for ear spitting level, I think I'd blow the 90db speakers before the amp. And so it doesn't matter if I can reach full level or not on the NC500's, think of it as a safe guard against blowing them up. So it is possible that George was telling the truth, but that would mean that he had a pretty gutzy preamp on hand. Most preamps I can think of wouldn't drive a load like thatNo not really, the output buffers have .7ohm output impedance, but use a 50ohm series resistor for protection https://www.analog.com/media/en/technical-documentation/data-sheets/13645fa.pdf Cheers George |
Like I said, you have no idea, even with proof from Scott. Also no idea either on streamers, all are still waiting for you to prove yourself right to everyone. We’re still waiting for your proof with links and CD cat. no. to prove you know what your talking about |
No, it is not, especially with the Hypex amps. The input is meant to be driven by a very low impedance source.Once again, you have no idea! The input impedance of the NC500 Hypex is 2k across the band, and can be driven by any buffer from a source that has 50ohm or less output impedance and the voltage gain needed to give you the max level that you need listen to. Once again, you have no idea!! I'll try to get my friend who heard it yesterday to post on it. |
In my past experience with the Nord Hypex NC500 monoblocks using the Sparkos and Sonic Imagery opamps, the differences were pretty obvious.Best is no buffer at all, direct in, as I’ve done. (you don’t need a buffer driving another buffer) If the output buffer in your source (pre or dac) is less than <50ohm output impedance and has high enough voltage output gain to give the volume you need, you’ll have better sound than any additional buffer (regardless of how good) that’s in the signal path Cheers George |
I’ve been told by experienced audiophiles here and elsewhere that the default Hypex board is junkAny one that says that is junk themselves and needs to be committed. I’ve shown what the Hypex board is, it’s opamps may not be the "absolute very best" of opamps, but they’re not far off it. Anyone that can hold a soldering-iron can build one. And you’d have to be an absolute idiot to stuff up a buffer design using them. And I doubt Putzey is one. https://forum.audiogon.com/discussions/purifi-class-d-junk/post?postid=2080260#2080260 Cheers George |
Wow you need to look at the LM4562 a bit better than what your waffling on about. Texas Instruments designed it to work it’s optimum between 5-17v, and from what i can find it works with +-12v with the Purifi +-12v gives .00004thd +-17v gives .00003thd sweet all in it.https://www.ti.com/lit/ds/symlink/lm4562.pdf?ts=1609274706414&ref_url=https%253A%252F%252Fwww.ti... |
Have you heard them in combination? I have, and I found them not a good match together.Are you saying it sound like **** like ricevs, and it’s a bad design bad sounding buffer? Or the impedance match is no good as a buffer? then any buffer will have the same problem. Do you think Putzey made a bad one on purpose? Because it is a "simple buffer", made by someone who could make one in his sleep, using good sounding opamps, which is hard to get wrong. He could teach just about anyone how to make one in 15 mins, even adjusting the gain of it Here is one using the opa1632 opamp https://ibb.co/njDHP1H Pin 6 is a misprint, should be 5. Pins 3 and 6 are then for + and - from the powersupply. No, like I said there’s something else the OP is hearing, and all that’s left is the Purifi itself. Cheers George |
Wake up!! Did you come down with the last shower? It doesn’t sound ****, like your making out. And of course, leave out any buffer regardless of how good if one can with high output source, and you’ll reap those benefits of extra transparency/dynamics and slam, by going direct into the Class-D module with no buffer at all in the way. And that Hypex buffer is a perfect match with the Purifi module, that’s why it’s called and marketed as a buffer. It something else the OP is hearing, and you know what that leaves, the Purifi module itself! |
If the defeault Hypex board is really that compromisedI’ve got those those Hypex buffer boards in my NC500 mono’s that have my own big linear supplies, there’s nothing wrong with the buffers (they don’t sound bad as some here would like you to believe) Your problem is elsewhere. Saying that, my MSB discrete R2R dac has got volume control in the digital domain with up to 5v out balanced, and by-passing the Hypex buffers altogether and going direct from the MSB's balanced output into the balanced input of the NC500 modules, the sound took on a massive improvement in transparency/dynamics and slam. (Moral of the story: Less is more, just like I always say with passive pre’s vs active pre’s also when possible) Cheers George |
I’ve repaired a few Naim 250’s, the best was the first model with regulated rails back in the 80-90’s and they weren’t that good, they all oscillate at a drop of the hat, don’t think it would take much to beat them. If fact Naim dealers warned against putting them together with Quad ESL’s. And in the 80's Tocord speaker cable made them blow their guts. Cheers George |
I prefer to use Littlefuse or Bussman.These are what I recommend and use, for those that don't know, these are quality fuses around 50cent. Not $150+🤦♂️ Remember change your old fuses that have see too many turn on cycles, especially on amps Just change the fuse if old for a quality brand EE industry standard 50c fuse, as fuses (even the snake oil ones) do age after many turn on cycle surges. Cheers George |
ricevs atmasphere 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.I couldn't agree more (wow that's one for the books) Any manufacturer/designer or modder worth his salt, will use all the EE laws at hand to design, then build/measure/bench-test and listen. And if they don't like it, they change things using all the EE laws/measure/bench-test again and listen once again till they get it right. Any fool that say otherwise is a hoax and a snake oiler. Cheers George |
Don’t try to flip this, to another direction, your the only one here on this thread. I have the highest respect for those companies. (except for one that bridges his stereo amps into monoblocks and claims them as better performing amps), measurements/tests will call them out as lower performing, with one only plus of higher wattage. BTW this statement of yours a couple of posts back, another bit of............? It flows forth like the Nile. It is best just to ignore George. Let him have the last word or it will go on forever |
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. |
Maybe send it to @ricevs to do some magic mods to itDon’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 |
There’s also a new approx $10K integrated Class-D from Technics called the SU-R1000 Integrated Amplifier around 22 kg . Said to have many of the GaN Class-D features of the far bigger SE-R1, but nowhere yet can find if it uses the 1.5mhZ switching frequency that "makes" the SE-R1. Also it uses smp power supplies, even though it’s 22kg, Unlike the SE-R1 at some 60Kg because of it linear supplies. No reviews or measurement tests as yet for this one from Technics Cheers George |
He’s tried a few, and been on a disillusionment path with them, it’s expected to not feel confident with this one. I’m surprised he’s given them as much chance as this. I know what Class-D would probably make you happy madavid0 OP, and that’s the Technics SE-R1 if you want to give that a go, hard to get one but possible. Cheers George |
Ask him for concrete evidence on Class D stuff, and he will cry uncle and start posting Nelson Pass’s quotes.Shows what you know, think before you show your lack of................ That’s for an entirely different audio product not class-D. Stuff I post on Class-D’s Achilles-heel has to do with switching frequency and it’s filter and noise But seeing you bought up Nelson Pass’s quotes, here are his on Class-D, that I’ve never put up. Nelson Pass (Threshold, Passlabs)And just for good measure Conrad Johnson Lew Johnson (Conrad Johnson) Cyrill Hammer (Soulution) "if you want to have your product performing at the cutting edge it is not possible with today’s known switching technologies. In order to come close to the performance of the best linear design we would need high-current semiconductors that provide switching frequencies of several MHz or even GHz." And there are quite a few more, if you want me to keep going? Cheers George |
because of the false initial proposition on which it was based.Sez you, he has a valid but crude way of putting it. Technics so far with the SE-R1, are the only ones that have addressed the Achilles-Heel of Class-D. Output Filter, Noise, Phase Shift. All related to the Switching Frequency. By utilizing GaN Technology to it’s fullest, and having (3x higher) Switching Frequency, and eliminating the 3 Achilles Heels above from effecting/influencing down into the audio band frequencies. Cyril Hamer of Soulution- Audio at the bottom of my last post says it also. Cheers George |
Really? Not one?So you would purchase an audio product that was not designed using the Electronic Engineering laws and bench testing?? Good luck with that sunshine. Or maybe you need to comprehend a little bit better there’s not one piece of half decent audio equipment that’s any good, that has not been designed using all the EE laws and test/measurement procedures. |
I trust what George (and everyone) says about what he/they actually hears.....I do not trust what he/they says about things that he/they has not heardOne needs both listening/measuring, you need to back up what your hearing with measurement’s otherwise your just saying "trust me" I heard it which is subjective only. To all buying/modding anything, there’s not one piece of half decent audio equipment that’s any good, that has not been designed using all the EE laws and test/measurement procedures, if it hasn’t I would give them a wide berth. Especially modders that don’t give any EE measurement/bench test proof on what they’ve done to back up their subjective mods, these guys are just "snake oilers" and usually fusers saying trust me. Cheers George |
Once again on fuses for the gullible here that are thinking of throwing their money away paying $150+ for a 50cent fuse that’s just been dressed up to look glitzier. You’ll never see the manufacturers of these (snake oil) fuses defending themselves or their products with the claims made on forums like these. Just change the fuse if old fuse for a quality brand EE industry standard 50c fuse, as all fuses (even the snake oil ones) do age and still work but develop corrosion, sag and distort etc after too many turn on cycle surges. Cheers George |
I can make the amp you have jump at you like lightning. This is sounding like snake oil to me. |
Does not mean it’s junk just that there is a system mismatch.230ohm into 2.2kohm is fine, 1:10 ratio, and if he has enough gain there is no problem. "unless" there is a coupling capacitor on the preamp's output that's too small, and rolling off the bass, because the output impedance goes even higher than 2.3kohm at low frequency. This will cause the thin sound. Cheers George |
My preamp has an output impedance of 230 Ohms. A preamp with 230ohm output impedance will drive anything, even a low gain one, if you get high enough volume. And even drive a buffer with 2.2kohm input impedance "if correct", I can’t believe it is though. 47kohms has been the industry standard since time began, and tube amps were 100kohm Cheers George |