Marchaudio P422 Stereo Power Amplifier Review

[MAB]

In fact, lead time of proper AP filter AUX-0040 took 2 months.

At least 8 weeks I can't correct them...

We eagerly await your new measurements.
Thanks for working through this. We all learn.

 

[thin bLue]

We eagerly await your new measurements.
Thanks for working through this. We all learn.

Thank you for your warm and kind words!

 

[Phorize]

@thin bLue really appreciate the effort here. I'm wondering if it would be helpful to add a caveat to the first post to be really clear that the results are compromised for the reasons outlined in the subsequent discussion? As always there's a likelyhood that people just take things at face value.

 

[thin bLue]

@thin bLue really appreciate the effort here. I'm wondering if it would be helpful to add a caveat to the first post to be really clear that the results are compromised for the reasons outlined in the subsequent discussion? As always there's a likelyhood that people just take things at face value.

I'll do that immediately! thanks for the feedback!


Edit : It seems editing old post need some kind of permissions. I'll ask about that ASAP!

 

[thin bLue]

@thin bLue really appreciate the effort here. I'm wondering if it would be helpful to add a caveat to the first post to be really clear that the results are compromised for the reasons outlined in the subsequent discussion? As always there's a likelyhood that people just take things at face value.

The caveats are now applied!!

 

[thin bLue]

Some of QnAs with Marchaudio

(Image was too big, I just copied and pasted them)


Hi thin bLue

As mentioned I have been performing some tests on the Cosmos ADC and Topping D90SE DAC for use as a measurement system using REW software. These components are probably the lowest noise and distortion units available for “DIY” use. Here are some of the results.

The Topping D90SE DAC has a noise level of 1.2uV RMS (20Hz to 20kHz). The Cosmos ADC with inputs shorted as a slightly higher noise floor of 2.3uV RMS. When the D90SE is plugged into the Cosmos we measure a total noise level of 2.55uV RMS 20Hz to 20kHz.

If we set the signal to 4 volts RMS at 1kHz we see the following performance. This is very similar to that measured by other people using an APx555 analyser. A SINAD of 121.0 dB.

As a reference we have a Purifi 1ET400A amplifier using Purifis own Eval1 input board. We feed this from the Topping D90SE via 20dB inline XLR attenuator. This is to ensure the input noise floor is as low as possible.

The Purifi reference amp noise floor is 27.5uV RMS 20Hz to 20kHz.

With input signal set to provide an amplifier output of 4.475V RMS (nominal 5 watts into 4 ohms) the SINAD is 104.4 dB. Again very similar to what has been measured by others using an APx555 analyser.

So now for the P422. This amplifier is set with a high 26.5dB gain meant for 2v rms input RCA sources. Please note I subsequently found a problem with a test lead which caused the very minor 50Hz pickup.
Noise floor is lower than the Purifi reference at 25.9uV rms (20Hz to 20kHz).

P422 SINAD 4.475v RMS output again higher than the Purifi reference at 105.0 dB

I will test another P422 set to 20.5dB gain (4 volt XLR source) later today. This will show improved performance over the 26.5dB gain above.

So from these tests we can see that this combination of D90SE and COSMOS ADC, when carefully implemented is approaching quite close to the performance of the reference APx555 analyser. It is a long way ahead of the APx525 analyser.

One thing I would note is that I believe the 3rd harmonic readings are a few dB higher than they really are.

Best Regards
Alan


Hi thin bLue

I fixed the cable and produced more measurements with another P422 unit set at 26.5dB Gain and then at 20.5dB gain.

26.5dB gain setting noise floor is 25.3uV RMS 20Hz to 20kHz

SINAD at 26.5 dB Gain setting and output set to 4.475v RMS (nominal 5 watts into 4 ohms) is 105.0 dB

With gain set to 20.5dB the noise floor is 20.9uV 20Hz to 20kHz

SINAD at 20.5dB gain setting and output set to 4.475v RMS (nominal 5 watts into 4 ohms) is 106.7dB

So the real performance of the P422 is still slightly better than indicated above, we are still slightly impacted by the measurement system and would measure better on an APx555, but we are pretty close.

So I thinks the Cosmos and D90SE is the best way forward for your amp testing.

Feel free to publish these plots on ASR/Korean forums.

Best Regards
Alan


------------------------------------
+ Alan has shipped me dummy load for low power(5W) for free to help us provide accurate measurements.

Thank you to all the members of the ASR, E1DA(@IVX )'s Discord community, Speaker gallery of DCinside and Marchaudio for providing the necessary(critical) information and appropriate(essential) specifications.

 

[Thomas savage]

I have Alan's hypex implemented amps , they are excellent and you can trust Alan to be anal about everything he has control over .

The purifi versions I'd expect to be the same , the case is excellent and internationally the service is really good from my experience.

If I was to buy something else it would be from him . He's not here as a member , he was difficult and thats on me and him but part of that is why he's so good at what he dose .

He stands by what he thinks is proud and you can buy with confidence.

 

[thin bLue]

I received dummy load from Marchaudio today!

Marchaudio provided this for free and I'll use them for measuring several amps next time

Neutrik NC3MXX-B XLR

Canare 4S8 Starquad

Speaker Cable

This is placeholder text. To change this content, double-click on the element and click Change Content.

www.canare.com

Mogami NEGLEX 2549

MOGAMI® - High Quality Balanced Microphone Cables

Mogami Bulk High Quality Balanced Bulk Cables are recommended when extended high frequencies are important or where long cable runs may be needed.

mogamicable.com

Quality cables and connectors,
MOX resistors with sturdy Die-casted case


Thanks for supports Marchaudio.

When filter is available, we can measure reliable SINAD for Class-D Power amps!

 

[Holmz]

I received dummy load from Marchaudio today!

Marchaudio provided this for free and I'll use them for measuring several amps next time

View attachment 223254
View attachment 223256
View attachment 223258View attachment 223259

Neutrik NC3MXX-B XLR

Canare 4S8 Starquad

Speaker Cable

This is placeholder text. To change this content, double-click on the element and click Change Content.

www.canare.com

Mogami NEGLEX 2549

MOGAMI® - High Quality Balanced Microphone Cables

Mogami Bulk High Quality Balanced Bulk Cables are recommended when extended high frequencies are important or where long cable runs may be needed.

mogamicable.com

Quality cables and connectors,
MOX resistors with sturdy Die-casted case


Thanks for supports Marchaudio.

When filter is available, we can measure reliable SINAD for Class-D Power amps!

I use the Magomi 13 ga line for a speaker.
That looks like a 20 or 23 ga cable???

 

[theREALdotnet]

I use the Magomi 13 ga line for a speaker.
That looks like a 20 or 23 ga cable???

The “speaker“ cable is the Canare 4S8 (4x 16AWG), making for 13AWG effective gauge. The Mogami is the signal cable to the analyser.

 

[thin bLue]

I use the Magomi 13 ga line for a speaker.
That looks like a 20 or 23 ga cable???

As @theREALdotnet said.
Speaker cable is the Canare 4S8.

A -BA-Mogami-XLR-ADC
M -NA
P -NA-Canare-Resistors

I hope It'll help!