AUDIOPHONICS MPA-S250NC Amp Review

[Bernardo_G]

Do not confuse gain with power output. The Mission M778X has 31 dB gain, the Audiophonics has 25.6 dB gain. This means if you feed each the same input, the Mission will be louder. However, the Audiophonics is capable of higher output levels if fed more input voltage.

For example, let's look at feeding each amp 0.54 V which is the input sensitivity of the Mission.

Mission - 0.54 V input
Voltage Out = 0.54 x 10^(31 / 20) = 19.2 V
Power into 8 ohm = 19.2^2 / 8 = 46 W

Audiophonics - 0.54 V input
Voltage Out = 0.54 x 10^(25.6 / 20) = 10.3 V
Power into 8 ohm = 13.2^2 / 8 = 13 W

If you feed the Mission more than 0.54 V it will clip and not produce any more power, however if you feed the Audiophonics more than 0.54 V it will keep producing more power until you reach the input sensitivity of 1.66 V.

For example, at 1.01 V input, the Audiophonics will produce 46 W in to 8 ohm just like the Mission with 0.54 V input.

Audiophonics - 1.01 v input
Voltage Out = 1.01 x 10^(25.6 / 20) = 19.2 V
Power into 8 ohm = 19.2^2 / 8 = 46 W

To get 125 W into 8 ohm out of the Audiophonics you need to feed it 1.66 V.

Audiophonics = 1.66 V input
Voltage Out = 1.66 x 10^(25.6 / 20) = 31.6 V
Power into 8 ohm = 31.6^2 / 8 = 125 W

In case it isn't clear, to increase the input voltage to the amplifier you need to turn the volume on your preamp up.

Also, what are you feeding the preamp with? It looks like it only attenuates and does not provide any gain, so if you have a low voltage source in to the preamp you might not be able to get the full power out of the Audiophonics.

Michael

Michael, I still have a few questions; sorry but I'm trying to learn and see what would be the best options to make my gear work as expected.

Answering your question, it seems that my active preamp does not add any gain, it only attenuates. Given that, my questions are?

a) If I add an Eq between the preamp and power amp to bump up gain, is it an ok solution? Maybe one of those Loki equalizers from Schiit. If there's a better alternative, please let me know.
b) Is there a way to improve or increase input voltage fed into the power amp?
c) How did you calculate the Audiophonics power amp gain?
d) How to calculate input sensitivity? Is there a way to change it or improve it?

Thanks!

 

[rolfrander]

Michael, I still have a few questions; sorry but I'm trying to learn and see what would be the best options to make my gear work as expected.

Answering your question, it seems that my active preamp does not add any gain, it only attenuates. Given that, my questions are?

a) If I add an Eq between the preamp and power amp to bump up gain, is it an ok solution? Maybe one of those Loki equalizers from Schiit. If there's a better alternative, please let me know.

Probably, but you don't need to. If your volume is at 50%, you still have 50% to go.

b) Is there a way to improve or increase input voltage fed into the power amp?

Yes, but you might not need to.

c) How did you calculate the Audiophonics power amp gain?

It is shown in the measurements in the first post of this thread.

d) How to calculate input sensitivity? Is there a way to change it or improve it?

Input sensitivity is the input voltage that will drive the amp to max power. For the Mission, this is 0,54V (calculations shown already). As you have experienced, for the same input of 0,54V, the Mission produces more power than the Audiophonics. However, if you turn the volume knob more, the Mission will not produce more power, it will just produce more distortion. But the Audiophonics can handle up to 1.66V before distorting.

The input sensitivity is a result of the gain and the max power. Having more gain means less input sensitivity for the same power output.

 

[Bernardo_G]

Probably, but you don't need to. If your volume is at 50%, you still have 50% to go.

That's the thing... today I tested my system at 100% volume (kids at school, wife away at the office LOL) and sure it was loud but I feel it needs a bit more of grunt, really.

My emotional brain (GAS) says that I might need to upgrade my power amp but my wallet says "oh no, here we come again!!!" LOL

 

[rolfrander]

That's the thing... today I tested my system at 100% volume (kids at school, wife away at the office LOL) and sure it was loud but I feel it needs a bit more of grunt, really.

My emotional brain (GAS) says that I might need to upgrade my power amp but my wallet says "oh no, here we come again!!!" LOL

what is your source, what is feeding your preamp?

 

[Bernardo_G]

what is your source, what is feeding your preamp?

A Schiit Modi DAC for laptop streaming and CD and a Vincent Audio PHO-300 for my Pro-Ject turntable

 

[IamJF]

A Schiit Modi DAC for laptop streaming and CD and a Vincent Audio PHO-300 for my Pro-Ject turntable

Strange. The Schiit Modi is specified with 2Vrms on the output - this will already overload the power amp. Are your sources (Laptop) on 90-100% volume?
What's your preamp again? When you pull it up 100% it should overdrive your power amp even when it's just a passive preamp ... this should be VERY loud.

 

[soundaholic]

I am currently looking for an amp to drive my LS50 Metas (having a KC62 sub for them, too). Would the AUDIOPHONICS MPA-S250NC be sufficient or is this eventually even too much?
In fact, for flexibility and optical reasons, I'd prefer the AUDIOPHONICS AP300-S250NC, which as I see should be the same just with XLR and RCA out. Or would anybody expect a measurable difference to the MPA-250NC?

 

[TheBatsEar]

I am currently looking for an amp to drive my LS50 Metas (having a KC62 sub for them, too). Would the AUDIOPHONICS MPA-S250NC be sufficient or is this eventually even too much?

You can kill the LS50 with the power of the NC256MP module. But that is true for many, if not most other power amps as well. You will have to learn to not set your volume to 100% ;-)

In fact, for flexibility and optical reasons, I'd prefer the AUDIOPHONICS AP300-S250NC, which as I see should be the same just with XLR and RCA out. Or would anybody expect a measurable difference to the MPA-250NC?

I would expect them to measure the same, maybe with tiny variations due to cable layout and such. Nothing anyone would be able to notice.

 

[Kimbrough Xu]

I bought this amp, based on the glowing reviews I've seen here and on some other sites. After several hours of testing I have very mixed feelings about it.

Call me newbie or whatever but I find this amp seriously under-powered for 125W per channel at 8 Ohms; I have it connected to a Ladder Bach preamp and JBL Classic L82 speakers, and it's quieter than my previous integrated amp, a Mission 778X, which is 45W per channel. I also had an old Technics integrated amp from the 80's (don't remember the model, though) which was something like 75W and boy... that thing played LOUD!!

Yes this amp produces very clean and clear sound, very detailed; everything is beautifully presented and you can hear nuances in the music, but honestly I'd like a bit more of muscle. I don't know if I'm doing something wrong with the amp or I just got a dud unit.

Any recommendations are most welcome; thanks!!

It is not the power, your amp has a lower gain, use a preamp with higher output voltage, such as 4V, to connect to your amp.

 

[OldManMatt]

The Ladder Bach should be able to push the amp... especially with it's balanced outputs. I only say "should" because no where can one find any tech specs on the preamplifier. Last time I looked I couldn't find any specs, and I scoured the internet.
That is never a good sign.

The preamp has been out a little while now though...maybe there is some info somewhere. Or maybe in the manual?

 

[Chromatischism]

The Ladder Bach should be able to push the amp... especially with it's balanced outputs. I only say "should" because no where can one find any tech specs on the preamplifier. Last time I looked I couldn't find any specs, and I scoured the internet.
That is never a good sign.

The preamp has been out a little while now though...maybe there is some info somewhere. Or maybe in the manual?

Is it as simple as connecting a multimeter to the output?

 

[OldManMatt]

Is it as simple as connecting a multimeter to the output?

Yeah I believe so. Switch the meter to AC and connect the leads to the negative/positive of an RCA cable plugged into the preamp output. To test the balanced im guessing pin 2? Since I'm guessing it's best that you get confirmation from someone more knowledgeable than me.

I'm pretty certain this subject has been discussed here on ASR...you can try searching for it here or just Google it. Or maybe someone with more technical knowledge will chime in on this.

 

[IamJF]

Play a 400Hz tone and connect your Multimeter between pin 2 and 3.

 

[Sokel]

Play a 400Hz tone and connect your Multimeter between pin 2 and 3.

For an XLR output voltage?
Isn't it 1-3 and 2-3?
1 is always ground/shield,2 is hot and 3 is gold.

Edit:There's always the correct way with 3 conductors+shield where the shield goes to the outer (forth) pin of the XLR cable connector.

 

[Fahzz]

I've had this amplifier running off a Denon AVR 3700 for a while, then it stated cutting out occasionally, and then the 12v trigger stopped working, and then the amp stopped working entirely. Replaced all relevant cables with new ones including the trigger cable. It was time to upgrade the AVR anyway, so I got a real good price on a brand new 4800. Hooked everything up, including the Audiophonics, using the front pre outs and 12 v trigger. It was working perfectly for 1/2 hour. Turned the system off through the AVR, tried to turn back on, and the problems have reoccurred. The LED on the amp lights up with the trigger, but no sound from the fronts. Double checked the AVR speaker set up and music should be playing but it's not. Surrounds, center, and sub work fine when playing 5.1 content, just no front speakers.
Audiophonics has been responsive, but they don't think it's their amplifier. Anyone in the group have any ideas what the issue might be?

 

[IamJF]

Isn't it 1-3 and 2-3?

No.
1 is ground
2 is +
3 is -

Your signal is between + and - and has no relation to ground! (Imagine an output transformer). That's one of the main benefits of symmetric - no ground loops possible (when done right).

There is no fourth pin of the XLR cable. There is a case connection but be careful what to do with it.
There are PDFs from RANE and Grimm Audio/Hypex about the Pin 1 "problem" and how to deal with it - good basic knowledge.

 

[Sokel]

No.
1 is ground
2 is +
3 is -

Your signal is between + and - and has no relation to ground! (Imagine an output transformer). That's one of the main benefits of symmetric - no ground loops possible (when done right).

There is no fourth pin of the XLR cable. There is a case connection but be careful what to do with it.
There are PDFs from RANE and Grimm Audio/Hypex about the Pin 1 "problem" and how to deal with it - good basic knowledge.

AES specification say that pin 1 should be connected with XLR shell .I know that it's rare to see that as one must make sure that all chain is in order,and the chassis ground is not also connected to the audio reference ground for example like with old stuff.

But in some cases (measuring,microphones,etc) is critical as nothing must stays unshielded,specially when it is inside the connector that the bare connections needed it most.
Half solution is a small cap (100pF or so) between them so you can maintain grounding up high at RF and a high impedance path for the current.like the special ready made Neutrik.

https://www.neutrik.com/en/neutrik/products/xlr-connectors/xlr-cable-connectors/emc-series

(Right about the XLR voltage of course )

 

[Bernardo_G]

It is not the power, your amp has a lower gain, use a preamp with higher output voltage, such as 4V, to connect to your amp.

Well, this proves the point that I need to upgrade either the preamp or the power amp in the future; my hope was to make work what I already have without incurring in higher costs.

In the meantime, I'm using a Schiit Magni Heretic that I had laying around between the Ladder preamp and the Audiophonics power amp. The Heretic is set in High Gain mode with volume maxed out to "punish" the input of the Audiophonics (it adds 15dB gain if I'm not mistaken), and then I use the Ladder as a preamp to connect my DAC and phono preamp, and I control the volume with the Ladder as an attenuator only.

So far, it sounds killer!!!

 

[IamJF]

AES specification say that pin 1 should be connected with XLR shell

https://pin1problem.com/

This is the way.

 

[Sokel]

https://pin1problem.com/

View attachment 374438

This is the way.

I'm talking about the cable,shielding it all the way means that the XRL's shell should act like a Faraday cage too,protecting the bare soldered conductors.
Extreme maybe but that's the principle.