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Purifi 1ET400A new range of class D amp modules

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3 hours ago, Addicted to music said:

The issue with it is that no matter what maths is used to prove it,  the fried tweeter by ultrasonic freq always show up in any classD thread....

 

We don’t know the history of those tweeters that got fried,  all we know is that it was last driven by a classD when it had issues,  doesn’t mean that classD caused the issue either....  just saying!   

 

Your are highly likely to fry any tweeter if you pushed a conventional amp into clipping or severely exceeding its max power rating..    

 

What tweeters though :)? Can anybody actually cite a documented example? 

 

Where is the evidence of the switching frequency being the cause? 

 

It's really just an urban myth. 

 

I have indeed fried a tweeter with an AB amp during a party.

 

 

Edited by March Audio

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3 minutes ago, March Audio said:

I have indeed fried a tweeter with an AB amp during a party.

Classic way to do it.   

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8 hours ago, keinesorge said:

Yes really.

 

Disclose his business interests in non class d amplifiers and let us all reread the thread in a new light.

 

What cheap shot are you talking about ?

On page #13 georgehifi references the blown tweeter.  And this is not the only forum thread with its mention.

 

Have a look at the diyaudio forums:

https://www.diyaudio.com/forums/class-d/

You wont find much of his push back there.  After all, there are plenty of "misguided" audio enthusiats who are happily enjoying a whole heap of class d amps.  And who is going to save them from the dreaded blown tweeter ?

 

I have not heard the purifi.  Perhaps i will contact Alan for a listen.  (i have no commercial interests with anyone on these forums).

Have you heard it ?

 

If individuals with electronic design experience would chime in and share about creative snubber design to better attenuate carrier content going down the speaker cable, post filter feeback etc, i'd view the comments in a different light.  To slam the topology and denigrate the design - with nothing positive to bring to the class d table (and this bring a class d thread) reeks of subversive commercial marketing.

No it is a cheap shot because you have made it personal and in particular the reference to a WA business where you have insinuated that a type of treachery has or is taking place which you wholly attribute to George. 

 

So let's be clear about this. During the course of this thread can you point to a specific example where George did that. If not then your narrative is nothing more than unnecessary flame throwing in an attempt to denigrate another person by attributing foul play. 

 

I have not heard the purifi. I have heard Class D and have been very impressed with what it brings. 

 

A the risk of being judged by association, I believe that  another contributor who goes by title Mivera is dead on in his assessment that Class D has progressed incredibly over the last 5 years which will bother many of the traditionalists. 

 

I've stated privately to Alan that I'm not comvinced that Class D is necessarily the answer for magnepan speakers. 

 

Unless you've experienced Maggie's you won't realise the challenges involved with them and especially to get the best out of them. I take on board Alan's attempt to at least source an impedance curve but that doesn't tell the whole story. 

 

If you ask Bill McLean who has more experience with Maggie's than pretty much anyone in Australia the first question thst he asks is what amp do you intend on using with them. That should tell you something about them. 

 

There's currently a conversation at the minute on another thread where one of the contributors questions the value of high end McIntosh gear and what he considers their ability to have grip on the bass. 

 

Bear in mind that the chap has heard Maggie's with the Jeff Roland Relentless Monoblocs driving them and doing so superbly. We're talking absolute hi end gear here. 

 

I'm not saying that good Class D aren't viable. I'm just reserving my opinion until I hear them in action. 

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As you have mentioned him several times I think it's worth mentioning that (Mike) Mivera has benn banned in many forums including ASR where he trolled my business under a pseudonym.  Mods checked IP address to confirm. 

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3 hours ago, ghost4man said:

 

 

I've stated privately to Alan that I'm not comvinced that Class D is necessarily the answer for magnepan speakers. 

 

Unless you've experienced Maggie's you won't realise the challenges involved with them and especially to get the best out of them. I take on board Alan's attempt to at least source an impedance curve but that doesn't tell the whole story. 

 

 

 

 

 

 

As I asked in the PM, what are your concerns? 

 

What is the "rest of the story" if it goes beyond being able to drive complex loads and low impedances? 

 

I can't do it from here, on mobile ATM but I will show you some Maggie impedance plots. 

 

If anybody hasn't figured yet, I do prefer to deal with technical fact as opposed to teeth sucking oooh difficult load types of comments and unsubstantiated opinion. ;)

Edited by March Audio

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I am not involved in this thread as regards to the merits or otherwise of any particular amplification topography, but I really feel that some of the negative, carping and demeaning posts about  March Audio and his products are not only unwarranted,but also against the spirit of what form debates should be about.

 

It goes without saying ( although I will say it anyway ) that I have no association of any kind whatsoever, with March Audio and I feel that Alan has conducted himself with great patience and goodwill in the face of some personal attacks. Obviously, he neither requires nor seeks my opinion, or support, but I did feel the need to post about this thread in any case.

 

It is completely acceptable to have a very negative view of equipment, provided that opinion is based on some sort of actuality and personal experience  ( One cannot slander something inanimate ) but making it personal and playing the person is 100% unacceptable.

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2 hours ago, March Audio said:

 

What tweeters though :)? Can anybody actually cite a documented example? 

 

Where is the evidence of the switching frequency being the cause? 

 

It's really just an urban myth. 

 

I have indeed fried a tweeter with an AB amp during a party.

 

 

It’s on another class D threads in this neck of the woods,   didn’t really pay any particulars to it because it was just entertaining reading.  But every time someone brings up class D there are certain opinions for ultrasonic leakage with comments that it “dirty the SQ “. And if this was a typical conventional amp then it wouldn’t pass noise certifications....   Even the screen shot of a scope showing the ultrasonic hanging around the main fundamental it’s like “really”. It’s that tiny for peak-peak there’s no way that even at that amplitude will have the energy to destroy any tweeter!   And what they don’t realise is what you @March Audio have brought back to reality is that at those subsonic freq even though you feed it to the same tweeter the Z impedance is different at 450khz to what it is for 20-20k.  

Theres also the preconceived idea that all SMPSU are noisy and generate and radiate noise,  Some of the SMPSU are actually cleaner than Linear supplies,  also most SMPSU would have regulation that keeps a constant voltage, that’s why ASR is so good,  we can see on a scope the magnitude and at which frequencies.  

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On 08/09/2019 at 3:21 PM, March Audio said:

 

I havent actually done it with the Purify but I certainly have with Hypex modules.  They just shut down.  They have a "hiccup" mode where if the max output current is exceeded for more than a set period it shuts down.  They have a microcontroller on board which does monitoring.

 

From Hypex NC1200

 

image.png.6f39d36aadb2fc4a6aa1e12c72cc2244.png

 

image.png.ffcc7b2b9feeec352ad95139d6bf0f42.png

 

image.png.5b1d133e33e43d34ab2b3bdc0f7bec68.png

 

Purify is even more sophisticated

 

image.png.61b4db6048fc9df29a5ade3af1fc663f.png

 

Don’t quote me on it but I think the dedicated PSU also has protection where if there’s an over load it shuts down.   

 

When manufacturers produced this type of documentation,   I’m not game enough to put it through the test,  some of the products I work on use what’s called “fold back circuit “  basically limits the current and shuts down via microprocessor,  they theory goes that when the  fault condition is removed,  the intelligence is supposed to restore to normal,  well they never do!  So not only you are dealing with the initial fault that caused the PSU to get into this condition,  you have to replace a PSU that has the smarts....  where previously it would take out a fuse and that’s it.....

 

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35 minutes ago, Addicted to music said:

It’s on another class D threads in this neck of the woods,   didn’t really pay any particulars to it because it was just entertaining reading.  But every time someone brings up class D there are certain opinions for ultrasonic leakage with comments that it “dirty the SQ “. And if this was a typical conventional amp then it wouldn’t pass noise certifications....   Even the screen shot of a scope showing the ultrasonic hanging around the main fundamental it’s like “really”. It’s that tiny for peak-peak there’s no way that even at that amplitude will have the energy to destroy any tweeter!   And what they don’t realise is what you @March Audio have brought back to reality is that at those subsonic freq even though you feed it to the same tweeter the Z impedance is different at 450khz to what it is for 20-20k.  

Theres also the preconceived idea that all SMPSU are noisy and generate and radiate noise,  Some of the SMPSU are actually cleaner than Linear supplies,  also most SMPSU would have regulation that keeps a constant voltage, that’s why ASR is so good,  we can see on a scope the magnitude and at which frequencies.  

I thought the problem people had with switching power supplies is what they fed back into the mains, that supposedly can effect other equipment.

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15 minutes ago, rocky500 said:

I thought the problem people had with switching power supplies is what they fed back into the mains, that supposedly can effect other equipment.

There'd be a big problem these days if that was a concern with soooo many devices using them these days

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1 hour ago, rocky500 said:

I thought the problem people had with switching power supplies is what they fed back into the mains, that supposedly can effect other equipment.

 

Well there is potential for noise to be fed back on to the mains, but if it were significant it wouldn't pass the conducted noise regulations (CE, FCC, RCM etc). 

 

There is another point to consider here.  Whilst any piece of kit shouldn't put significant noise back on to the mains, equally other kit should not be sensitive to it.  It is a given that your mains will be noisy.  As mentioned above practically everything has an smps in it these days. Any audio equipment should have this fact covered as part of its design. It's bad design if it is affected. 

Edited by March Audio

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For transparency, I run a stereo Class D Ncore 500 amp myself.

Looking forward to all these new designs.

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1 hour ago, aussievintage said:

There'd be a big problem these days if that was a concern with soooo many devices using them these days

Bruno Putzey is a brilliant individual, contribute well to the industry.  

I’ve posted this many times here b4 Have a look at this video go 38mins in....  if you think a SMPSU that passes all EU certifications and it would be noisy on the mains you’d may hear it if your play vinyl,  usually when there’s silence, no tracks with the volume cranked up....but listen to what she said about this SMPSU.  And she’ll use it on all her gear she manufacture where it will fit in.  It’s no brainer!  Also look at what the equipment is, valves!

That’s taboo to audiophiles using a SMPSU in valve gear hey! 😱

 

 https://www.manley.com/news/2019/6/17/a-factory-tour-with-produce-like-a-pro-and-a-chance-to-win-a-micmaid

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1 hour ago, March Audio said:

 It is a given that your mains will be noisy.  As mentioned above practically everything has an smps in it these days.

 

Exactly :)

 

Several metres from my stereo there are 16 x 295W micro-inverters on my roof. If you're in Australia I suspect there's somewhere between 1 and 20+ inverters running on your 230V from the street.

 

If I noticed the inverters, the problem would be with my components. It's also the only part I could do anything about.

Edited by stiben
typo

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Later I will post some measurements showing how little RF these smps supplies and amps emit.  Blocking AM radios is another myth (with properly designed units) 

Edited by March Audio

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