AUDIOPHONICS MPA-S250NC Amp Review

[Matias]

Does more power mean more current though?

Yes: P = U x I and U = R x I, so that P = R x I². If we make 2,5 x P, square root of 2,5 is 1,58 x I, that is, +58% more current.

 

[MacCali]

When you consider that many amplifiers with high levels of distortion are prized by some for their "musical" qualities, rest assured that it is much better to keep noise at bay than distortion

Thoughtful, I would of thought distortion is more audible. But I get what you mean, still trying to comprehend the difference.

 

[pma]

Does more power mean more current though?

Of course, when speaking about 2 ohm especially.

P = R*I^2

NC502MP is said to give 27A max and 450W/2ohm.

 

[MacCali]

Yes: P = U x I and U = R x I, so that P = R x I². If we make 2,5 x P, square root of 2,5 is the 1,58 x I, that is, +58% more current.

If it’s solvable by math I can definitely accept that. What is head room and slew rate though? I thought those were factors as well when driving low ohm speakers

 

[Talisman]

Thoughtful, I would of thought distortion is more audible. But I get what you mean, still trying to comprehend the difference.

In reality the distortion is very difficult to hear up to quite high levels, there are some tests here on the site where you can experiment for yourself what are the levels of distortion you can perceive. Moreover, the distortion is linked to the musical signal, therefore it masks itself quite well, while the noise is clearly perceptible in moments of low musical signal or for close listening and can really ruin the listening experience.

 

[Matias]

If it’s solvable by math I can definitely accept that. What is head room and slew rate though? I thought those were factors as well when driving low ohm speakers

These SMPS don't give much headroom for peaks, as we can see from the measurements. So if you are still worried that the 450W into 2 ohms of the NC502MP is not enough, there are always options like NCx500 with 700W or 1ET7040SA with 950W or NC2k with 2000W all into 2 ohms.

 

[MacCali]

These SMPS don't give much headroom for peaks, as we can see from the measurements. So if you are still worried that the 450W into 2 ohms of the NC502MP is not enough, there is always options like NCx500 with 700W or 1ET7040SA with 950W or NC2k with 2000W all into 2 ohms.

I got two M23’s o.o

Never too late to join the circus right? XD *referring to myself

 

[Acerun]

So if I was to go wiim mini, minidsp flex, this amp, 2 subs and the best speakers I can afford, I’d be all set? usage: small / medium living room

Minidsp have a remote?

 

[dweeeeb2]

Minidsp have a remote?

yep. I haven’t tried a minidsp but it seems the most practical way to run 2 subs and have dsp functionality. I realise its a very open ended question, Im fishing a bit to hear of any concerns about going this direction.

 

[JeremyFife]

Minidsp have a remote?

Yes. Basic, but works pretty well for my needs

 

[chych7]

The blue light on this amp is obnoxiously bright (mine is in a dark HT). One can disconnect the power button if the trigger is being used to turn on/off the amp.

 

[sealman]

The blue light on this amp is obnoxiously bright (mine is in a dark HT). One can disconnect the power button if the trigger is being used to turn on/off the amp.

Try these out! They work really well and you can double/triple up if you want less light.

Amazon.com

 

[chych7]

Try these out! They work really well and you can double/triple up if you want less light.

Amazon.com

Yeah I initially had some black electrical tape over it, but didn't look great and leaked a little light. Unplugging it was the answer for me.

 

[pma]

Just measured my NC252MP implementation, which has probably the best possible cooling with large, full-size 19" - 3U aluminium box with side heatsinks. I have just made a set of measurements with 2ohm resistive load.

Another view at distortion and maximum power of NC252MP into 2ohm load.

Measured with Arta, which allows for continuing after the amplifier collapse, but is scaled in [V] output voltage. We can see maximum output voltage of 22.8V at distortion of 0.71% and then the amplifier collapses. 22.8V makes 260W/2ohm. The maximum power into 2ohm is limited by the current protection implemented in the NC252MP module. It seems to be fully activated at 11.4A output current in case of my module.

 

[Endibol]

So if I was to go wiim mini, minidsp flex, this amp, 2 subs and the best speakers I can afford, I’d be all set? usage: small / medium living room

Yes, you are!

 

[Steve Rogers]

Anybody else having heat problems with this amp?
Mine is really hot to the touch and it's actually heating the room so much that it's uncomfortable (don't have AC). It's in a media unit but has plenty of room around it. I guess I'll try moving it on top.
I'm loving the sound but might have to sell it if I basically can't use it during the summer months.

i use it in Israel and have no heat problems, in fact the topping dx3 pro+ which preamps it gets hotter!

 

[Philipp]

Audiophonics remarks that This amplifier does not have a decoupling capacitor, so it lets the DC component of the signal through. Make sure your source has no DC component present at the output. The DC protection of the module switches on at 12VDC which is very permissive. amplifier does not have a decoupling capacitor, so it lets the DC component of the signal through. Make sure your source has no DC component present at the output. The DC protection of the module switches on at 12VDC which is very permissive.

What does this mean in other (simpler) words?

 

[restorer-john]

Yeah, I know they do but my point was more to _why_ they let this be audible on their products in contrast to most of the A/B class manufacturers.

A/B amplifiers are no better in general. It's not a Class D thing. To be honest, I don't think any brand of amplifier controls their startup/shutdown procedures better than Hypex.

Noises can be produced from the power supply, switching arcs, power relays, speaker relays etc. Some amplifiers have sophisticated multi stage muting, right from the inputs, pre and power stages. Others actually remove current from front end stages. They all make some noise.

The quietest designs used a lot of muting devices (FETs and transistors), but that also adds complexity, reliability and distortion issues. I've lost count of the number of 'muting transistor' problems over the years. Excess THD and failed channels are common. My bench test mule CD player is a Marantz professional machine where I had to remove the four (power up delay) muting transistors on the XLRs and RCAs as they caused a rise in THD from 0.002% to 0.0045%. They were unnecessary anyway as there is no turn on/off transient of significance.

 

[restorer-john]

Audiophonics remarks that This amplifier does not have a decoupling capacitor, so it lets the DC component of the signal through. Make sure your source has no DC component present at the output. The DC protection of the module switches on at 12VDC which is very permissive. amplifier does not have a decoupling capacitor, so it lets the DC component of the signal through. Make sure your source has no DC component present at the output. The DC protection of the module switches on at 12VDC which is very permissive.

What does this mean in other (simpler) words?

Any DC offset on the source device will cause an amplified offset on the output up to the limit (12VDC) of the DC protect monitor.

It means your source should be checked for nominal DC offset if you don't want audible pops and/or woofer cone offset (which isn't good for distortion or the magnet).

 

[Cincyret]

So if I was to go wiim mini, minidsp flex, this amp, 2 subs and the best speakers I can afford, I’d be all set? usage: small / medium living room

I have exactly this - Wiim & Flex in a small room - but with the Buckeye amp in a Ghent case. Also a Topping EX5 for headphone use. Only 1 sub though. I love my setup.