Questions about MINIBOSS PLAYER PLUS

[ovi]

I'm a total beginner and after about 15 years without any option to listen to music except headphones or some tiny Bluetooth speakers I went with this neat solution below. Its good enough to sound pleasant to my ears and perfectly fits my current tiny room of <20 square meters.

I would just like to get a better understanding of all that is involved with DACs, amps and speakers. I've read a lot online, but most info is way too technical, with lots of formulas and stuff. I just want to get a better basic understanding not become a professional audio engineer if you get what I mean.

I am currently using a RPI zero w with a MiniBoss DAC PCM5122 32bit 384kHz and a Volt+ AMP + a stepped attenuator to power a pair of Monitor Audio Bronze 100 speakers.

The amp can deliver 2x50W @4Ohm while the speakers are rated at 8@ so from my basic understanding that cuts the power in half to 25W (Yes I know those are maximal theoretical values, right?)

So when I stream audio to this device, I can listen at low volume and at a high enough volume for the room size. I know the amp is underpowered for the speakers, but it works for me. I'm wondering why I see a base power consumption of 3.1W when the amp is idling (nothing is playing) and up to 4.2W when playing at about 80% of the volume (can't go higher or the neighbours will complain). The device I used to measure plugs in between the power source and the plug and its accurate (tested with a lamp with a 60W bulb, and it showed 60.1W).

So here are my first two questions:

1. If 2x50W @4Ohm translate to 2x25W @8Ohm, and I'm listening at about 80% (20W) why do I only measure 4.2W being drawn from the plug?
2. If the amp says 2x50W, why does it only come with a 19V 3.15Amp (60W) PSU? Wouldn't it need a 100W PSU to deliver 2x50W?

 

[muslhead]

How do you know you are playing at ~80% volume. Your measuring device says otherwise.
Are you talking about where you have the volume knob set at?

 

[fpitas]

1. If the amp says 2x50W, why does it only come with a 19V 3.15Amp (60W) PSU? Wouldn't it need a 100W PSU to deliver 2x50W?

Inexpensive amps are often very optimistic about the continuous output available.

/See how tactful I am?

 

[ovi]

How do you know you are playing at ~80% volume. Your measuring device says otherwise.
Are you talking about where you have the volume knob set at?

Yes, that is what I meant. I have set the stepped attenuator to max (it goes from 1-24) and while streaming I have set the volume of mopidy (the streaming app) to 80% (can't go higher due to neighbours).
Do you mean to say that the last 20% would push my consumption from 4.2W towards the 25W?

Additional question:
The volt+ amp says: “90% power efficiency” – if I read this right, when I am measuring 4.2W it actually means the amp outputs 3.78W to my speakers? They “sound” pretty loud in a room < 20 square meters. I'm just confused and trying to understand the situation, not unhappy with this setup.

 

[ovi]

Inexpensive amps are often very optimistic about the continuous output available.

/See how tactful I am?

Let's leave the quality, performance and marketing aside, say you have a “perfect” amp which should deliver 2x50W – would it need a 50W PSU or a 100W PSU?

 

[fpitas]

Let's leave the quality, performance and marketing aside, say you have a “perfect” amp which should deliver 2x50W – would it need a 50W PSU or a 100W PSU?

Obviously, it takes a sufficient (100W) power supply.

 

[ovi]

In that case it looks like this amp was never meant to output 2x50W as this is their power recommendation.

Power Supply Required: 16-24V (we recommend 19V), 60-90W

 

[fpitas]

In that case it looks like this amp was never meant to output 2x50W as this is their power recommendation.

If you try a larger supply, and demand the full 100W, make sure you don't overheat the amp.

 

[ovi]

If you try a larger supply, and demand the full 100W, make sure you don't overheat the amp.

Thanks, I will make sure to follow your advice.

Like I said, I'm happy with the current loudness and quality at most I'll wait for an opportune moment when the neighbours are away and slowly turn the volume higher just to check what the power meter indicates and if it goes further up towards 25W