[Listening test] Maxcio Pm01 - wattmeter...and more!

Maxcio PM-01 - power meter (and more!)

Measuring (and killing) unwanted watts!

Product name: Maxcio PM-01 - wattmeter
Manufacturer: Ningbo Cowell Electronics Tech. LTD - China
Cost: ±25€
Reviewer: Lucio Cadeddu - TNT-Audio Italy
Reviewed: May, 2023

Introduction

Monitoring energy consumption is never an easy task, and for various reasons: manufacturers' claimed data are not always precise, and normally refer to max power absorption (which isn't always the case) and stand-by power consumption is rarely declared, or is incorrect.

One might need a device that constantly measures power consumption, dynamically, and that can monitor any device over, say, 24 hours. Such a device might help us understand how many watts our amplifer is delivering to our speakers, by means of a simple calculation. Here's how: take into account that a Class D amp wastes only 10-20% of power into heat, while a Class AB amp wastes 50% of power and a Class A amp wastes 75% of power. The rest goes to the speakers. Hence, if your amp is using 100 watts, it is easy to guess, knowning its class, how many watts are delivered to your speakers and, hence, how many REAL watts you need. Be prepared for huge surprises!

[Maxcio PM01]

Moreover, it would be interesting to know how many watts your HiFi systems uses while in stand-by mode or even while it seems completely off. Well, such devices exist, and this Maxcio PM-01 does exactly all of the above, and much more! It also measures the status of your mains (voltage and frequency), how many amperes your components are drawing from the mains, and how many kWh of your electrical bill are due to your HiFi.

This innocent device will not be welcomed by amplifier manufacturers and HiFi dealers, trust me.

Tech specs

Max power load: 16A/3680 watts (13A/3120 watts for UK version)
Mains frequency range: from 47Hz to 63Hz
Mains voltage range: from 180V to 250V
Accuracy: ±1%
EU, UK, US, AU plugs versions available

In use

Being designed for people who ignore the first thing about power and electricity, it is extremely user-friendly: just plug it into a wall socket, then connect the appliance you wish to monitor...and you're done. Just allow some time for the energy consumption to settle down. My smart TV, for example, absorbs some power during the first 15 seconds, then enters into intellingent stand-by mode, consuming 0 watts.

By means of the Function switch you can decide to measure watts, amperes, kWh or €/UKP/$. Of course, you need to use the switch Cost to enter the cost of a kWh, according to your energy supplier plan. The device offers the possibility to keep in memory previous measurements, and peaks (min/max). Data won't be lost once unplugged, because it uses an internal back-up Ni-Mh battery. The display backlighting is a useful feature when the mains socket is out of reach.

I've tested this device on any electrical/electronic component at home, and there have been various “surprises”. A preamplifier, for example, though appearing completely off (no stand-by led, no display) absorbs up to 8 watts, doing nothing.
My CD transport absorbs 2 watts while in stand-by mode, just to power a dreadful blue led. A Class D power amp, when switched on (without playing music!) absorbs nearly 20 watts. A soundbar absorbs 0.8 watts while in stand-by and 5 watts when playing (a little bit more at full volume).

In other words, if your HiFi system is complex, with many components permanently switched on or in stand-by mode, it might absorb from the mains enough power to keep all the lights of your house on 24 hours a day (!!!).

[Maxcio PM01 Schuko]

Now, if you wish to know how many real watts your speakers are needing, measure the power absorption of your amp while it is playing, then subtract the part of energy it wastes (as said before, this depends on its class, A, AB or D). Now take a good SPL meter and measure the sound pressure at the listening seat. This, together with the sensitivity datum of your loudspeakers, should give you another gross estimate of the amount of watts you really need. Trust me, it will be much lower than you'd ever imagine!

While you're there, connect this device to any other electronic component at home. You'll discover that:

the clock on your microwave oven absorbs up to 3 watts, and so does any other clock you may have on other ovens/similar devices.
A WiFi modem might absorb from 7 to 12 watts when swithed on (mine absorbs 0 watt when switched off). For this reason it is always a good idea to switch off the WiFi when not in use (at night, for example).
Phone chargers might absorb 7-8 watts when charging your smartphone, and still 2 watts when the battery is already 100% full. For this reason, it is not a good idea to keep a phone connected to the charger when its battery is full.
My Acer notebook (on Linux) absorbs 0 watts while switched off and connected to the mains, which become 20 when powered on, a little bit more (25) if the internal battery is charging.
My Apple MacBook Pro absorbs 25 watts when switched off and charging the battery, has a 65 watts peak when switched on and then oscillates between 30 and 40 watts when in normal use.
A room perfume dispenser has a permanent energy consumption of 2 watts.

Of course, your devices might be different, so test them!

N. B.: the PM-01 can manage loads up to 3680 watts or 16A (EU version) or 13A/3120 watts if it's the UK version. An overload warning will light up if you connect something that exceeds these limits.

Availability

It is easy to find it at the usual online stores (Amazon, Ebay etc.) for 20€/$/UKP, or for much less on Aliexpress, even under different brands. There are more sophisticated power meters out there, if you fancy, such as those that can be interfaced via Bluetooth with your smartphone, like this one!

Conclusions

This Maxcio PM01 is an extremely interesting and useful tool, that might help you both debunking some myths on real power output of amplifiers and saving costs on your electrical bill at the same time. Its cost will be rapidly written off in a couple of months thanks to the energy saving on your bills.

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