Question 1

If the power going in to this unit is 32v 5amp = 160 watts. How is this unit rated 300 watts?

Accepted Answer

I tested the continuous wattage output using the 32v 5amp supply that comes with it.  I get 50 watts driving 8 ohm, 100 watts driving 4 ohm and 200 watts driving 2 ohm.  I tested with a scope and sine wave.  You get about 20 volts RMS before the sine wave starts to square off at the peaks.  The 50 watts at 8 ohms is surprisingly loud but my 8 ohm speaker is very efficient Electrovoice EVM15 in a Thiel box.

Question 2

I can't seem to fine the rms watts. does anyone know the true specs? power at 2 ohms, at four ohms. peak does not mean much.

Accepted Answer

I put it on an oscilloscope and fed it a sine wave across a 2 ohm, 4 ohm and 8 ohm load resistor.  Using the power supply that it comes with this unit (32V 5A) I see the sine wave start to clip right around 20 volts RMS.   It works out to  50 watts with an 8 ohm load, 100 watts with 4 ohm load and 200 watts with a 2 ohm load.

Question 3

What is the maximum voltage and current can be used as it comes with 32VDC at 5 amp.

Accepted Answer

The power supply current rating of 5A is not quite enough to get the maximum rated output, but it doesn't fall short by much. There are tradeoffs with duty cycle, thermal management, equipment life, program spectral characteristics, etc. but they don't really amount to more than giving precision to common sense. All you need to know is that you can always use a higher current supply without any concern. A 10A supply will run cooler, longer, and cleaner. It is the voltage that has to be in bounds and for this chip TI specifies the working range to be 24-35V and the maximum power to be 300 Wrms. If you want to upgrade get a 36V unit rated over 300 watts, e.g. Mean Well MW LRS-350-36 (9.7A) AND turn the voltage down to 35V or less.

Question 4

If using as a full-frequency mono amp to a passive speaker, can the RCA output still go to a powered sub with the frequency control for the sub only?

Accepted Answer

Yes,

ASIN	B07VHG2LR9
Best Sellers Rank	#32,193 in Electronics ( See Top 100 in Electronics ) #169 in Audio Component Amplifiers
Brand Name	Fosi Audio
Customer Reviews	4.3 4.3 out of 5 stars (808)
Item Dimensions	5.12 x 4.13 x 1.37 inches
Manufacturer	Fosi Audio
Maximum Output Power	200 watts
Maximum Supply Voltage	32 volts_of_direct_current
Minimum Supply Voltage	24 volts_of_direct_current
Model	M03
Mounting Type	Surface Mount
Number of Channels	1
Number of Items	1
Number of Packs	1
Package Type Name	Box" or "Case
Part Number	Ｍ03
Unit Count	1 Count
Voltage	220 volts
Warranty Description	18-month manufacturer

Fosi Audio M03 200 Watt TPA3255 Subwoofer Amplifier Mini Mono Channel Audio Power Amp for Home Theater Full-Frequency and SUB Bass Switchable with 32V/5A Power Supply

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