NC252MP (class D) vs. A250W4R (classAB) burst measurements into 4ohm//2.2uF load

[ZolaIII]

@MaxwellsEq and what do you think hoy SMPS are regulated? The same way with capacitors but there capacitors aren't isolated from most heat by design as they are on good iron core or triodal one's. Main thing that makes difference is voltage pump integration and fine rail regelation and semeles fast switching between them and then it's class H/G we are talking about. Not everyone whose ignorant when we discussed it cuple years back so we finally have designs based on plane D class chips like TPA 3255 and A-B class one's emerging still in budget category that are reshaping market regarding performance metrics at least.

 

[levimax]

Thanks again. I guess this begs the question : Cost vs Failure Rate?

Are there any reasons not to use SMPS?
(Transient plus long duration, high output power requirements etc...?)

I am kind of old school and would rather sacrifice a bit of (possibly inaudible) SINAD for reliability when it comes to amps.
Failing power supplies are a no no for me. Unless they are cheap and easily replaceable.
My 2c.

Thinking about SMPS vs Linear (besides the weight and heat issues) is mostly about regulated vs unregulated. Unregulated will tend to have more "headroom" i.e. short term output higher than continuous output or "sag". Regulated will keep the rail voltage steady which lowers distortion but will also not have much if any difference between peak and continuous output. Regulated supplies are "better" from a engineering and measured performance point of view and my understanding is that Class D is more sensitive to rail modulation than Class AB so they usually use regulated SMPS supplies. Cheap and easy linear supplies are good enough for many audio applications especially Class AB amps and their reliability and repairability are well know. Since SMPS supplies need orders of magnitude more engineering their reliability is designed in and can vary from short life junk to lifetime reliability and everything in between.

 

[pma]

Thinking about SMPS vs Linear (besides the weight and heat issues) is mostly about regulated vs unregulated. Unregulated will tend to have more "headroom" i.e. short term output higher than continuous output or "sag". Regulated will keep the rail voltage steady which lowers distortion but will also not have much if any difference between peak and continuous output. Regulated supplies are "better" from a engineering and measured performance point of view and my understanding is that Class D is more sensitive to rail modulation than Class AB so they usually use regulated SMPS supplies. Cheap and easy linear supplies are good enough for many audio applications especially Class AB amps and their reliability and repairability are well know. Since SMPS supplies need orders of magnitude more engineering their reliability is designed in and can vary from short life junk to lifetime reliability and everything in between.

That is not correct and is only an opinion. Hypex SMPS power supplies are unregulated and their output voltage changes with mains voltage. Their output current is limited

and that is the reason why output power of the amplifier that is supplied from them is limited. Class D modules work very well with linear power supplies as well, which I have tested and shown many times, namely with A07, UCD180 and 1ET400A.
Plus, there is a current limitation in class D modules itself, which is usually set higher than that of the SMPS.

Hypex Switch Mode Power Supply Family

A Hypex SMPS is a high efficiency, switch mode power supply specifically designed to be used in combination with our UcD®, NCORE® and NCOREx® modules.

www.hypex.nl

If you wanted to speak about SMPS with output voltage regulation, then rather look here:

MEAN WELL Switching Power Supply Manufacturer

MEAN WELL offers a comprehensive power solution with our versatile series of power supplies. You can use this product overview tool to find product information and datasheet of all MEAN WELL products, such as RS, LRS, UHP series for industrial application, HLG, ELG, XLG, HVGC series for LED...

www.meanwell.com

But those are not so good for audio amplifiers, rather are intended for industrial control systems.

 

[levimax]

That is not correct and is only an opinion. Hypex SMPS power supplies are unregulated and their output voltage changes with mains voltage. Their output current is limited

View attachment 472596

and that is the reason why output power of the amplifier that is supplied from them is limited. Class D modules work very well with linear power supplies as well, which I have tested and shown many times, namely with A07, UCD180 and 1ET400A.
Plus, there is a current limitation in class D modules itself, which is usually set higher than that of the SMPS.

Hypex Switch Mode Power Supply Family

A Hypex SMPS is a high efficiency, switch mode power supply specifically designed to be used in combination with our UcD®, NCORE® and NCOREx® modules.

www.hypex.nl

If you wanted to speak about SMPS with output voltage regulation, then rather look here:

MEAN WELL Switching Power Supply Manufacturer

MEAN WELL offers a comprehensive power solution with our versatile series of power supplies. You can use this product overview tool to find product information and datasheet of all MEAN WELL products, such as RS, LRS, UHP series for industrial application, HLG, ELG, XLG, HVGC series for LED...

www.meanwell.com

But those are not so good for audio amplifiers, rather are intended for industrial control systems.

Interesting and I stand corrected but am still a little unsure about the terminology. My understanding is that a "regulated supply" tries to maintain the voltage on the rails in a tight range regardless of the load. If these hypex SMPS supplies are current limited, and assuming mains voltage is constant, then they would maintain a constant voltage on the rails and limit current. Is that right? If that is right then it seems like a current limited SMPS behaves more like a "regulated supply" than a traditional linear supply?

 

[pma]

I have a good news. I have now measured my implementation of Purifi 1ET400A, which use SMPS400A180, 2x46V Hypex SMPS module, with 2.2 ohm load. SMPS400A180 has lower supply voltage than is allowed for 1ET400A, however results are excellent.

First, let's see the proof that those power supply modules are unregulated:

I. Burst testing

time record of the 1kHz 10cycle sine burst into 2.2 ohm load

We get 389W / 2.2 ohm burst power from only 2x46V power supply.

The spectrum:

at about 1% distortion.

II. Continuous sine wave test

We get 309W into 2.2 ohm with distortion 1% approx., from only2x46V power supply. This confirms that the 1ET400A module handles low impedance resistive load much better than the NC252MP. With the power supply used, 1ET400A gives 200W into 4 ohm load and 300W into 2.2 ohm load at 1% THD and 1kHz. So this amp is closer to "ideal" voltage source.

 

[MaxwellsEq]

I have a good news. I have now measured my implementation of Purifi 1ET400A, which use SMPS400A180, 2x46V Hypex SMPS module, with 2.2 ohm load. SMPS400A180 has lower supply voltage than is allowed for 1ET400A, however results are excellent.

First, let's see the proof that those power supply modules are unregulated:

View attachment 472670

I. Burst testing

time record of the 1kHz 10cycle sine burst into 2.2 ohm load

View attachment 472673

We get 389W / 2.2 ohm burst power from only 2x46V power supply.

The spectrum:

View attachment 472674

at about 1% distortion.

II. Continuous sine wave test

View attachment 472676

We get 309W into 2.2 ohm with distortion 1% approx., from only2x46V power supply. This confirms that the 1ET400A module handles low impedance resistive load much better than the NC252MP. With the power supply used, 1ET400A gives 200W into 4 ohm load and 300W into 2.2 ohm load at 1% THD and 1kHz. So this amp is closer to "ideal" voltage source.

I am very impressed with my 1ET400A.

 

[peng]

We get 309W into 2.2 ohm with distortion 1% approx., from only2x46V power supply. This confirms that the 1ET400A module handles low impedance resistive load much better than the NC252MP. With the power supply used, 1ET400A gives 200W into 4 ohm load and 300W into 2.2 ohm load at 1% THD and 1kHz. So this amp is closer to "ideal" voltage source.

I am not sure why this even needed to be confirmed by such tests, isn't it very obvious the 1ET400A module is much more powerful than the NC252MP whether the load if 8,4 or 2 ohms based on published spec sheets? I like any tests lol, but I thought it would be a little more interesting if the 1ET400A is measured against the NC502MP.

 

[peng]

I am very impressed with my 1ET400A.

Me too, but recently, mine (a VTV amp version) is making that unwelcome pop noise that sounded like a spark occurring on turning on, even just by flipping the toggle switch from standby. It would only do it occasionally, say 1 out of 6 to 10 times. When I first got the amp from VTV, it was doing that almost every time, but after I tightened up the grounding screw (to the chassis), it stopped, so this time I open the box to check that first, found the screw was still tight, but I made sure it was making good contact anyway. Still it would pop occasionally, though the pop sound was never scarily loud, like it was when I first received the amp. Any idea what else I can check? I also have a NC502MP from buckeyeamp, that one doesn't pop after I fitted the standby toggle switch and use that only with the main power switch on all the time.

 

[Mort]

Mr. Dead Horse, u have been beaten again.

 

[pma]

I am not sure why this even needed to be confirmed by such tests, isn't it very obvious the 1ET400A module is much more powerful than the NC252MP whether the load if 8,4 or 2 ohms based on published spec sheets? I like any tests lol, but I thought it would be a little more interesting if the 1ET400A is measured against the NC502MP.

Why? Because many amplifiers do not meet manufacturer specs. Like Topping B100

Topping B100 RCA amplifier test review

And it has to be checked and published.

 

[peng]

Why? Because many amplifiers do not meet manufacturer specs. Like Topping B100

Topping B100 RCA amplifier test review

And it has to be checked and published.

Of course they need to be (or at least nice to be) checked and published, but your "confirm....." something that should have been easily predicted as the specs are very different, and that both Hypex and Purifi amp modules have many of their amps measured on ASR, with results close to their published specs, and the duts are not new products. Just thought that comparing the two seems a bit like comparing/measuring a Bryston 4B SST3 versus an Anthem MCA225, such that I could have bet 10:1 the that the Bryston would handle low impedance load regardless of resistive or reactive much better than the Anthem amp could. To be clear, do appreciate and thank you for your work, and hoping you would compare something more comparable next time.