Purifi 1ET400A new range of class D amp modules

[kukynas]

45 minutes ago, misternavi said:

what was this topic about originally?

fresh veggie, 400 watts of it to be precise, but who cares, nobody's willing to read what's in the menu so no worries, it'll be shut down soon, I'm receiving last set of orders 

[March Audio]

47 minutes ago, buddyev said:

I hate to fall back on that awful philistine defence of personal prejudice and ignorance contained in the cliche ‘I don’t know much about ... [fill in appropriate subject matter] ... but I know what I like’. Unfortunately that’s where I am at with hi fi ( or, in my case, mid fi). i’m a mug punter whose only interest in this world is how it sounds. It’s a fair cop, guv - i’m a crass subjectivist. So sue me. 

 

 Like a lot of people here who like to listen to music in as high a quality as they’re capable of hearing  i have a passing interest in various products and approaches but really know sweet FA about audio engineering. I have a reasonable grasp of what ought to work by checking out basic specs but beyond that I don’t give a toss about the technicalities of audio reproduction, amp construction etc. I’m perfectly happy to leave it  to smart audio engineers to employ their theoretical frameworks and knowledge to produce the best kit they are capable of. As a customer I will take advantage of that range of competing designs and spend my hard-earned on what I like,  on what sounds good to me.  It’s a market place governed, as far as I’m concerned, only by my preferences. 

 

I understand that a commitment to purist engineering principles is a laudable thing - for engineers - and without proper measurements it’s all going to be sh11t. I also understand why engineers might very wisely not care WTF  I think about capacitors, or what people on the internet might think about anything. Fine, I’m cool with that - they’d be fools to do otherwise.  But I would humbly suggest that holding your customers and their audio preferences in 7contempt is not a great business model for a manufacturer of audio. 

Then you have completely misunderstood my position. 

 

I have repeatedly said like whatever you like, it's of no consequence to me.  In this thread I have explained technical reasons for some amplifiers sounding different.  It was actually a response to someone else saying x was better than y. 

 

  I used measurement data to do so.  It actually seems more like there is an anti measurement position here with some views that have been expressed, rather than anything going on to denigrate subjective opinion. 

 

Just for info you wouldn't Beleive how much feedback I get from people in forums and customers along the lines of "thank goodness for a manufacturer who avoids the Audiophile BS" so the business model works just fine. 

Edited September 13, 2019 by March Audio

[March Audio]

If anyone has any questions about the Purifi please ask. 

[Suopermanni]

Just now, March Audio said:

If anyone has any questions about the Purifi please ask. 

Since you will be making amps using the Purifi modules, from what I have read, do you have an idea of how much they would sell for?

[March Audio]

Last time I spoke to Purifi I only got indicative pricing so it would be speculative.  Put it this way, similar to hypex. 

 

I do need to speak to Purifi soon to firm up orders when they are in production. 

[buddyev]

7 minutes ago, March Audio said:

Then you have completely misunderstood my position. 

 

I have repeatedly said like whatever you like, it's of no consequence to me.  In this thread I have explained technical reasons for some amplifiers sounding different.  It was actually a response to someone else saying x was better than y. 

 

  I used measurement data to do so.  It actually seems like there is an anti measurement position here rather than anything to denigrate subjective opinion. 

 

Just for info you wouldn't Beleive how much feedback I get from people in forums and customers along the lines of "thank goodness for a manufacturer who avoids the Audiophile BS" so the business model works just fine. 

There has been a great deal of misunderstanding of positions - this thread is filled with straw men, and you’ve set up and knocked down your share of them. 

[andyr]

2 hours ago, rantan said:

Very true @andyr.

 

Proper and meaningful evaluations of any audio component or speakers requires several days at a minimum and preferably two weeks.

 

I cannot and would not make a meaningful evaluation and comparison of two components or two pairs of speakers in hurriedly conducted  DBT, albeit these have their place.

What I can say is that over a period of days or weeks it becomes abundantly clear to me which amplifier or pair of speakers I am able and willing to live with on a long term basis after it has been correctly set up in my room and used to play the very wide variety of music to which I listen.

I also wish to point out that I believe in objective testing via measurement and it most definitely has a proper and vital part to play in any evaluation.

 

In fact ,I see them as synergistic.

 

You seem to have a leg in both camps, rantan. 

 

Remember what Confucius said: "Man with foot either side of fence ... liable to slip and lose his testicles! " 

 

Andy

 

Edited September 13, 2019 by andyr

[lemarquis]

2 hours ago, kukynas said:

fresh veggie, 400 watts of it to be precise, but who cares, nobody's willing to read what's in the menu so no worries, it'll be shut down soon, I'm receiving last set of orders 

Don't be so precious  Just be thankful for starting a thread that (no doubt unbeknownst to your good self) would go for over 20 pages of interesting and spirited contributions  

[ghost4man]

6 hours ago, lemarquis said:

Don't be so precious  Just be thankful for starting a thread that (no doubt unbeknownst to your good self) would go for over 20 pages of interesting and spirited contributions  

Well said. 

 

I think that this discussion has by and large been conducted with robust enthusiasm. 

 

I just want to add I see tremendous value in Alan's position of promoting objective testing and leaving the audiophile flowery stuff to the side. 

 

My concern with benchmark testing is is a true indication of how well that amp will couple with a specific speaker. 

 

As I've stated previously, there are plenty of amps out that claim to have unconditional stability into 4 ohm loads but have shut down when tested on a pair of Maggie's when the going has got tough. 

 

I would not be averse to trying out the purifi but I wonder if the NC 1200 is inherently "better" than the purifi due to the extra power and current. 

 

Alan what would you say about the differences between the two. 

 

 

[Addicted to music]

13 minutes ago, ghost4man said:

. 

 

As I've stated previously, there are plenty of amps out that claim to have unconditional stability into 4 ohm loads but have shut down when tested on a pair of Maggie's when the going has got tough. 

 

I had 3 class D amp and a Magtech to test at a GTG at my place.  One class D went into shutdown after a few minutes of play.  2 including the one that went into shutdown didn’t sound right.  However the nc400 powered on.   The nc400 came back a few weeks latter and we were testing out different types of speakers.  Maggie’s are no doubt to me extremely difficult speakers to drive, just because it’s a resistive load doesn’t make it easy by any stretch,  a speaker such as the 1.7 that dips below 2 ohm resistive at 16-17k and nominal at 4 is a real prick to drive. Ohms law dictates what it requires in total power and you will need this to work out SOA if output devices used are to reliably work.  I also had a 200W into 8ohm MF amp here, the owner quote “ I’ve never  felt the  heatsink this hot before....”.   And this was only on for about 10mins, we didn’t use it afterwards driving 1.7.  I have 1.8ohm ribbons that I refuse any class D and Pass Labs to drive them, these ribbons accelerate the thermal runaway in any device used that it’s attached to.    

When I looked up the specs of the nc400 it’s the only class D At the time to quote a current rating, all the others that were here did not!   Running the 1.7 did increase the case temp, I’d be lying if I didn’t say so but it never shut down no matter what we threw at it and how long.  I have no doubt that the Puriti and the nc1200 can handle any maggie panel taking the experience I had with the nc400. 

BTW when we volume matched between the nc400 and the Magtech, you’d be surprised at just how far class D has developed,  its a bargain when it comes down for everyday use. 

[Aussieamps]

4 hours ago, Addicted to music said:

I had 3 class D amp and a Magtech to test at a GTG at my place.  One class D went into shutdown after a few minutes of play.  2 including the one that went into shutdown didn’t sound right.  However the nc400 powered on.   The nc400 came back a few weeks latter and we were testing out different types of speakers.  Maggie’s are no doubt to me extremely difficult speakers to drive, just because it’s a resistive load doesn’t make it easy by any stretch,  a speaker such as the 1.7 that dips below 2 ohm resistive at 16-17k and nominal at 4 is a real prick to drive. Ohms law dictates what it requires in total power and you will need this to work out SOA if output devices used are to reliably work.  I also had a 200W into 8ohm MF amp here, the owner quote “ I’ve never  felt the  heatsink this hot before....”.   And this was only on for about 10mins, we didn’t use it afterwards driving 1.7.  I have 1.8ohm ribbons that I refuse any class D and Pass Labs to drive them, these ribbons accelerate the thermal runaway in any device used that it’s attached to.    

When I looked up the specs of the nc400 it’s the only class D At the time to quote a current rating, all the others that were here did not!   Running the 1.7 did increase the case temp, I’d be lying if I didn’t say so but it never shut down no matter what we threw at it and how long.  I have no doubt that the Puriti and the nc1200 can handle any maggie panel taking the experience I had with the nc400. 

BTW when we volume matched between the nc400 and the Magtech, you’d be surprised at just how far class D has developed,  its a bargain when it comes down for everyday use. 

 

 

That's an interesting point, as good as the Class D amplifiers have become, like any amplifier or piece of electronics they all have limitations. for their price point the Hypex and Purifi modules are very good and offer great value for money. At the end of the day designing any power amplifier is very much the art of compromise. No doubt Hypex modules can be made to drive lower

impedance loads, but like anything it just comes down to cost.

 

[ghost4man]

4 hours ago, Addicted to music said:

I had 3 class D amp and a Magtech to test at a GTG at my place.  One class D went into shutdown after a few minutes of play.  2 including the one that went into shutdown didn’t sound right.  However the nc400 powered on.   The nc400 came back a few weeks latter and we were testing out different types of speakers.  Maggie’s are no doubt to me extremely difficult speakers to drive, just because it’s a resistive load doesn’t make it easy by any stretch,  a speaker such as the 1.7 that dips below 2 ohm resistive at 16-17k and nominal at 4 is a real prick to drive. Ohms law dictates what it requires in total power and you will need this to work out SOA if output devices used are to reliably work.  I also had a 200W into 8ohm MF amp here, the owner quote “ I’ve never  felt the  heatsink this hot before....”.   And this was only on for about 10mins, we didn’t use it afterwards driving 1.7.  I have 1.8ohm ribbons that I refuse any class D and Pass Labs to drive them, these ribbons accelerate the thermal runaway in any device used that it’s attached to.    

When I looked up the specs of the nc400 it’s the only class D At the time to quote a current rating, all the others that were here did not!   Running the 1.7 did increase the case temp, I’d be lying if I didn’t say so but it never shut down no matter what we threw at it and how long.  I have no doubt that the Puriti and the nc1200 can handle any maggie panel taking the experience I had with the nc400. 

BTW when we volume matched between the nc400 and the Magtech, you’d be surprised at just how far class D has developed,  its a bargain when it comes down for everyday use. 

And I'm guessing all of these amps would have been bench mark tested? 

 

There is a valid point that's being made here and that is any Maggie owner knows through experience that an amplifier that is marked as being unconditionally stable into 4 ohm loads may not necessarily cut it. 

 

With Maggie's you really need an amp that comfortably sits with 2 ohm loads and below. 

 

Its good to see someone like Anthony Holton want to jump on board with Class D. 

 

To me that's a good sign of someone confident of taking the commercial risk with this venture.

[March Audio]

8 hours ago, ghost4man said:

Well said. 

 

I think that this discussion has by and large been conducted with robust enthusiasm. 

 

I just want to add I see tremendous value in Alan's position of promoting objective testing and leaving the audiophile flowery stuff to the side. 

 

My concern with benchmark testing is is a true indication of how well that amp will couple with a specific speaker. 

 

As I've stated previously, there are plenty of amps out that claim to have unconditional stability into 4 ohm loads but have shut down when tested on a pair of Maggie's when the going has got tough. 

 

I would not be averse to trying out the purifi but I wonder if the NC 1200 is inherently "better" than the purifi due to the extra power and current. 

 

Alan what would you say about the differences between the two. 

 

 

 

In those terms the NC1200 is superior.  Yes the Purifi has slightly lower distortion, but if ultimate drive capability is your aim then NC1200 it is.

Edited September 14, 2019 by March Audio

[March Audio]

7 hours ago, Addicted to music said:

I had 3 class D amp and a Magtech to test at a GTG at my place.  One class D went into shutdown after a few minutes of play.  2 including the one that went into shutdown didn’t sound right.  However the nc400 powered on.   The nc400 came back a few weeks latter and we were testing out different types of speakers.  Maggie’s are no doubt to me extremely difficult speakers to drive, just because it’s a resistive load doesn’t make it easy by any stretch,  a speaker such as the 1.7 that dips below 2 ohm resistive at 16-17k and nominal at 4 is a real prick to drive. Ohms law dictates what it requires in total power and you will need this to work out SOA if output devices used are to reliably work.  I also had a 200W into 8ohm MF amp here, the owner quote “ I’ve never  felt the  heatsink this hot before....”.   And this was only on for about 10mins, we didn’t use it afterwards driving 1.7.  I have 1.8ohm ribbons that I refuse any class D and Pass Labs to drive them, these ribbons accelerate the thermal runaway in any device used that it’s attached to.    

When I looked up the specs of the nc400 it’s the only class D At the time to quote a current rating, all the others that were here did not!   Running the 1.7 did increase the case temp, I’d be lying if I didn’t say so but it never shut down no matter what we threw at it and how long.  I have no doubt that the Puriti and the nc1200 can handle any maggie panel taking the experience I had with the nc400. 

BTW when we volume matched between the nc400 and the Magtech, you’d be surprised at just how far class D has developed,  its a bargain when it comes down for everyday use. 

 

While the maggies are "more" resistive a load than many other speakers they still have fair deviations in phase.  Its this that makes the amp have to dissipate more power.  All of this is why I said previously we need to look at the specific impedance/phase plot for any speaker. 

 

 

Again to put things into context remember that low impedance at high frequencies may not be such a proble due to the much lower signal content up there.

 

Oh speaking of heat it is one thing to note, whilst class D is more efficient (circa 90%) it does still dissipate heat. As with any other amp they still need adequate cooling.  This is one area the Purifi has improved upon and they can run on the desk without any heatsinking quite cool at normal volumes.

Edited September 14, 2019 by March Audio

[ghost4man]

Alan, 

 

Given that the purifi is latest generation and with slightly less distortion would it be fair to say that its power output is disappointing when compared to the NC 1200. 

 

This seems to be a common theme where one questions what the latest models represent in terms of overall improvement. 

[Ahh- Schnoo Schnoo]

8 minutes ago, March Audio said:

 

In those terms the NC1200 is superior.  Yes the Purifi has slightly lower distortion, but if ultimate drive capability is your aim then NC1200 it is.

Would Duntech Crown Prince be best with NC1200, or the Purifi?

[March Audio]

1 minute ago, Ahh- Schnoo Schnoo said:

Would Duntech Crown Prince be best with NC1200, or the Purifi?

Hi Schnoo

 

Sorry I didnt get round to your PM yet.

 

I need to find some info about the speaker and specifically its impedance plot to really answer that question accurately.  I will try and look it up, but might be a day or two

[Ahh- Schnoo Schnoo]

1 minute ago, March Audio said:

Hi Schnoo

 

Sorry I didnt get round to your PM yet.

 

I need to find some info about the speaker and specifically its impedance plot to really answer that question accurately.  I will try and look it up, but might be a day or two

Thanks Alan, much appreciated :0)

[March Audio]

5 minutes ago, ghost4man said:

Alan, 

 

Given that the purifi is latest generation and with slightly less distortion would it be fair to say that its power output is disappointing when compared to the NC 1200. 

 

This seems to be a common theme where one questions what the latest models represent in terms of overall improvement. 

 

Actually no.    

 

Its their first product and fits a very wide range of the market.

 

Im sure the product range will develop.

[March Audio]

oh for those interested

 

https://en.wikipedia.org/wiki/Power_factor

[Primare Knob]

As people has mentioned before, the stability in impedance is one of concerns as well. (Martin Logan's 0.6ohm at 20kHz)

My other problem is that most amps and modules are to powerfull. I would ideally would like to see a 50W version.

Input impedance is another tricky aspect in my setup as I don't use a pre amp. Currently I use a pro audio DA converter straight into power amps in a multi channel setup.

All my gear is hidden away, so ideally I would like gear that doesn't run very hot.

50W for surround channels, 300W (8ohm) and 2ohm stability, for my center channel, and 200-300W(8ohm) and stable down to 0.6ohm, for my mains.

Are these things possible with these Hypex or Purifi modules?

I use a Sanders ESL for my mains, which is stable down to 0.3ohm and never seem to run hot, and that is using a very large power supply and a large number of output devices. Would a similar design work out the same with class D modules?

Often what I see is 2ohm becomes rather difficult with class D, introducing distortions, and the same often happens with the increase of frequency, which makes the Martin Logan's a nightmare for class D.

Please correct me if I am wrong, as I wouldn't mind giving class D a fair chance.

[March Audio]

1 hour ago, Primare Knob said:

As people has mentioned before, the stability in impedance is one of concerns as well. (Martin Logan's 0.6ohm at 20kHz)

My other problem is that most amps and modules are to powerfull. I would ideally would like to see a 50W version.

Input impedance is another tricky aspect in my setup as I don't use a pre amp. Currently I use a pro audio DA converter straight into power amps in a multi channel setup.

All my gear is hidden away, so ideally I would like gear that doesn't run very hot.

50W for surround channels, 300W (8ohm) and 2ohm stability, for my center channel, and 200-300W(8ohm) and stable down to 0.6ohm, for my mains.

Are these things possible with these Hypex or Purifi modules?

I use a Sanders ESL for my mains, which is stable down to 0.3ohm and never seem to run hot, and that is using a very large power supply and a large number of output devices. Would a similar design work out the same with class D modules?

Often what I see is 2ohm becomes rather difficult with class D, introducing distortions, and the same often happens with the increase of frequency, which makes the Martin Logan's a nightmare for class D.

Please correct me if I am wrong, as I wouldn't mind giving class D a fair chance.

 

Stability is something an amp designer of any type should be mindful of and designing for.  Capacitive loads often cause gain peaking and insufficient phase margin can cause the amp to oscillate into the "wrong load".  This is all able to be modelled and tested, and is why many A/B amps have inductors in their output.

 

However, when does this stop being an amp design issue and becomes a speaker design issue? 

 

0.6 ohms at any frequency *is*, plain and simple, bad design. 

 

Well I can't speak for all class d designs but Bruno Putzeys designs, Hypex ncore and now Purifi, are quite happy at 2 ohms with extremely low distortion.  They will go down to 1 ohm.  They have current limiting protection.

 

See below examples

 

Hypex NC1200

 

 

 

Purifi 1ET400

 

Edited September 15, 2019 by March Audio

[andyr]

24 minutes ago, March Audio said:

 

However, when does this stop being an amp design issue and becomes a speaker design issue? 

 

0.6 ohms at any frequency *is*, plain and simple, bad design.

 

 

There speaks an amp designer! 

 

Electrostatic spkr mfrs don't deliberately engineer in a 0.6 ohm impedance, Alan - it's an unfortunate byproduct of electrostatic spkr technology.  Every electrostatic speaker shows the same kind of issue.

 

As many people like 'statics (once they've heard them) - and own them - it becomes an amp designer issue IMO to come up with an amp design that can master the 'electrostatic problem'.  Some amp designers have been able to do this - like Maarten's Sanders amp or the Maya (by Hugh Dean) ... other designers have not.  When they:

• have - the amp runs cool and has no problems driving the speakers.
• haven't - the amp runs hot and may go into oscillation ... resulting in a quick demise! 

 

Andy

 

[March Audio]

5 hours ago, andyr said:

 

There speaks an amp designer! 

 

Electrostatic spkr mfrs don't deliberately engineer in a 0.6 ohm impedance, Alan - it's an unfortunate byproduct of electrostatic spkr technology.  Every electrostatic speaker shows the same kind of issue.

 

As many people like 'statics (once they've heard them) - and own them - it becomes an amp designer issue IMO to come up with an amp design that can master the 'electrostatic problem'.  Some amp designers have been able to do this - like Maarten's Sanders amp or the Maya (by Hugh Dean) ... other designers have not.  When they:

• have - the amp runs cool and has no problems driving the speakers.
• haven't - the amp runs hot and may go into oscillation ... resulting in a quick demise! 

 

Andy

 

 

 NO its not.  Ridiculously low impedance in speakers IS bad design.  It is NOT a given of electrostatic design.  It is the result of design choices - BAD ones.

 

0.6 Ohms  is utterly stupid.

 

Why do you think its acceptable to present , what to all intents and purposes, is a short circuit to an amp?

 

Quad certainly dont have an issue keeping it sensible.

 

    

 

 

Edited September 15, 2019 by March Audio

[andyr]

1 hour ago, March Audio said:

 

 NO its not.  Ridiculously low impedance in speakers IS bad design.  It is NOT a given of electrostatic design.  It is the result of design choices - BAD ones.

 

0.6 Ohms at 20kHz is utterly stupid.

 

Why do you think its acceptable to present , what to all intents and purposes, is a short circuit to an amp?

 

Quad certainly dont have an issue keeping it sensible.

 

    

 

 

 

Mmmm, I myself don't call them "nice smooth spkr impedances".  (From 3 to over 20 ohms ... then down to 4 ... then up to 16!  But, sure, they don't drop to 2 ohms, according to those graphs. 

 

Perhaps you could find the equivalent for Sanders electrostatics - given he designed his amp to be able to handle 0.3 ohms.

 

And irrespective of the graphs you have produced ... many amps do not drive Quad 'statics well.

 

Andy