Nord Three SE 1ET400A Dual Mono Stereo Amp Review

[restorer-john]

It is clear that use of a single SMPS 1200 in a Purifi-based stereo amp will likely work well. On the other hand, it is also clear that using an SMPS 1200 per Purifi module is not a completely stupid design decision. It seems the negatives and positives of this choice are within the realm of debate - the specifications leave enough room to justify either one.

Possibly someone will ask Bruno his thoughts on this.

In some ways, using one SMPS 1200 could be seen as equivalent to using dual SMPS 600's. If someone has decided on a dual mono amp, the difference in price/efficiency/quality between dual 1200's and 600's makes dual 1200's an easy choice.

There's valid arguments both ways, but based on my experience with any and all SMPS supplies from a repair perspective, the fewer you have in any product, the better. You have twice as much opportunity for failure, but half as much stress on each.

Interchannel PSU modulation issues aside, there's no doubt the twin supplies will offer better performance where the amplifier was running low impedance loads at sustained high power levels. But it could all be academic, as the modules may "thermally limit" anyway, or the PSUs may overheat. And that issue is only likely to occur on a test bench, not in an audiophile's loungeroom.

 

[Labjr]

I wonder if ATI will start building amps using Purifi modules with a linear power supply?

When you think about it, why wouldn't anyone currently using Hypex modules start using Purifi instead? Bruno was pretty much the brains behind the products. I would expect him to take a lot of the business with him when he left Hypex. Evidently, he didn't sign a non-compete agreement.

 

[Audiocrusader]

It is clear that use of a single SMPS 1200 in a Purifi-based stereo amp will likely work well. On the other hand, it is also clear that using an SMPS 1200 per Purifi module is not a completely stupid design decision. It seems the negatives and positives of this choice are within the realm of debate - the specifications leave enough room to justify either one.

Possibly someone will ask Bruno his thoughts on this.

In some ways, using one SMPS 1200 could be seen as equivalent to using dual SMPS 600's. If someone has decided on a dual mono amp, the difference in price/efficiency/quality between dual 1200's and 600's makes dual 1200's an easy choice.

what makes it a smart design decision is ignorant audiophiles will automatically think " if 1 is good, 2 is better". And since most audiophiles fit into this category, it could likely result in higher sales numbers. Another bonus is since Nord is a direct seller, anything that increases the BOM, puts them at an advantage compared to companies who sell through a dealer/distribution network. Because the BOM multiplier to MSRP needs to be much higher for them. Due to this they likely wouldn't add the expense of a 2nd supply for the sole reason of exploiting ignorance. So Nord could have a 1 up on them for this reason.

 

[Audiocrusader]

There's valid arguments both ways, but based on my experience with any and all SMPS supplies from a repair perspective, the fewer you have in any product, the better. You have twice as much opportunity for failure, but half as much stress on each.

Interchannel PSU modulation issues aside, there's no doubt the twin supplies will offer better performance where the amplifier was running low impedance loads at sustained high power levels. But it could all be academic, as the modules may "thermally limit" anyway, or the PSUs may overheat. And that issue is only likely to occur on a test bench, not in an audiophile's loungeroom.

The thermal or current limiters within the amp modules will trigger long before a single supply, connected to 2 Purifi modules will even remotely begin to stress. And this is under ANY conditions. Music listening, or torture testing on the bench. End of story.

 

[Audiocrusader]

Purifi provides the input module as well, making the whole thing an assembly exercise. You don't need to know anything about electronics and design to build an amp with it. Not so at all with a DAC chip.

Please provide some examples of OEM built amps using the Purifi module which use the Purifi EVM input buffer/ I/O board. This board was built for OEM's to easily evaluate the modules. No difference than the ESS DAC EVM boards:

http://www.shawelectronics.com/dac-evaluation-boards.html

Do we see OEM manufacturers simply popping them in a case? I suppose they could if they wanted.

 

[amirm]

Please provide some examples of OEM built amps using the Purifi module which use the Purifi EVM input buffer/ I/O board. This board was built for OEM's to easily evaluate the modules. No difference than the ESS DAC EVM boards:

No it is different. An eval board for a DAC includes the DAC in it. The optional gain stage for Purifi is a separate board/module. I am sure if you put in a decent order for them, Purifi will supply them.

 

[amirm]

Do we see OEM manufacturers simply popping them in a case? I suppose they could if they wanted.

Usually DAC eval boards lack USB input so they are not usable in the market except for all in one low end ones.

 

[Audiocrusader]

No it is different. An eval board for a DAC includes the DAC in it. The optional gain stage for Purifi is a separate board/module. I am sure if you put in a decent order for them, Purifi will supply them.

I highly doubt any OEM is going to just pop the same input board in their amps as the EVM and will be provided to the DIY market. The reason they make the modules devoid of a buffer is to allow OEM's the opportunity to differentiate their products from their competitors.

 

[Audiocrusader]

Usually DAC eval boards lack USB input so they are not usable in the market except for all in one low end ones.

I was referring to the ESS EVM boards with USB interface. Hence the reason for the link. However any EVM board with I2S inputs (all of them) can easily be used with one of the USB interface boards readily available on the market.

 

[Audiocrusader]

You're debating semantics. Bruno designed the Hypex power supply modules? Are you not aware of that?

More misinformation. Bruno did not design the SMPS's at Hypex. The owner Jan-Peter van Amerongen, hired a completely different engineer who specializes in SMPS design to engineer their SMPS. Where does everyone around here obtain their information? Wet finger in the air?

 

[Labjr]

More misinformation. Bruno did not design the SMPS's at Hypex. The owner Jan-Peter van Amerongen, hired a completely different engineer who specializes in SMPS design to engineer their SMPS. Where does everyone around here obtain their information? Wet finger in the air?

So what! Which power supply was in the amp Purifi sent to Amir for review? THE HYPEX! GET IT!

 

[Audiocrusader]

So what? ASR is supposed to be a place people come to to acquire accurate information. So if you must put a wet finger in the air for answers, this may be the wrong place for you.

 

[Thomas savage]

Dial down the tension please , yes we want accurate information but no we don't want it delivered with obnoxious behaviour.

Thanks

 

[phoenixdogfan]

So, are the Purifi amplifier modules for sale to DIYers yet? If so, what do they cost?

 

[maty]

This is what audiophilia came to. To branding switches. Pls discuss the musicality of different brands of switches! Pls do!

Build quality, implementation....

Always looking for the worst interpretation of my words.

 

[JimB]

I highly doubt any OEM is going to just pop the same input board in their amps as the EVM and will be provided to the DIY market. The reason they make the modules devoid of a buffer is to allow OEM's the opportunity to differentiate their products from their competitors.

FYI, about a month ago, Purifi confirmed to me that they would make the two channel OEM eval input buffer board available for DIY. I requested a SIMPLE adaptation of it for single channel use (cut off the side). They might look into that, later. Or not.

 

[TomJ]

Amir, can I ask a couple questions about EMI and RFI noise in class D amps with switch mode PS?
- Would a 2nd SMPS in the amp increase the EMI noise emission onto the AC line (mA leakage current)?
- Does it matter that class D amps put RFI on their output terminals (eg 900mV for ICEpower)? Does that just dissipate, or can it have any effects on the crossover networks in speakers?
Thanks!

 

[restorer-john]

Amir, can I ask a couple questions about EMI and RFI noise in class D amps with switch mode PS?
- Would a 2nd SMPS in the amp increase the EMI noise emission onto the AC line (mA leakage current)?

I would put that question to @March Audio as well. That is his area of expertise I believe. The Hypex modules have are trimmed at the factory for self osc frequency AFAIK (there's are pot onboard), but whether the SMPSs can beat/interfere or cause issues with EMI when located together, I have no idea.

A good question.

 

[March Audio]

I would put that question to @March Audio as well. That is his area of expertise I believe. The Hypex modules have are trimmed at the factory for self osc frequency AFAIK (there's are pot onboard), but whether the SMPSs can beat/interfere or cause issues with EMI when located together, I have no idea.

A good question.

It is a good question.

In theory, yes a second SMPS in the same box will increase the conducted noise level that ends up back on the mains. Is this an issue? If it falls below the required test limits (CE FCC etc) then no, I dont see it as one. When people raise the point about conducted mains noise affecting their other audio equipment, my answer is always that the other equipment should be designed to not be affected. Mains noise is a given, we have dozens of SMPS PSUs around our houses. Considering this should be part of competent design practice.

Leakage current is a different issue so we shouldnt confuse the two. Again it has maximum permissible limits for safety. Under normal circumstances I would say this is not an issue with having 2 PSUs together. Should be tested though to see the current level however.

The switching frequency in any competent class D design will have no impact whatsover on crossovers or tweeters. I am going to do a class D FAQ which demonstrates why this is so.

 

[TomJ]

It is a good question. In theory, yes a second SMPS in the same box will increase the conducted noise level that ends up back on the mains.../QUOTE]

Thank you, very helpful. As a consumer, how would I know whether an audio product’s SMPS complies with regulatory specs like those you mention? I don’t see anything about that in vendor product sheets or any independent testing online.