Class D Amp board heat-sink

Thread Starter

Surtsey

Joined May 8, 2022
15
I purchased a cheap Class D Amplifier board but I'm concerned about over-heating. If I put 20v into this will it need a heat-sink? There seems to be provision to secure cooling to one of the chips but there is no guidance stating a heat-sink is
bluetooth21.jpg
 

MrSalts

Joined Apr 2, 2020
2,376
There is likely no need for a heat sink. A transistor on a class D is either on or off and the fast transitions through the switching process generates little heat. Turn it on, crank it up ant quickly touch the ICs - if you get a blister, they need a heat sink. Anything is usually better than nothing.
 

MisterBill2

Joined Jan 23, 2018
13,141
The photo is ppretty, but where are the power devices that would be heat-sinked? The picture does not show us useful information in that aspect.
Also, how much power is the amplifier supposed to deliver? And what are the power requirements?
And a pule is that the "diagram" shows no input connection.
 

MrSalts

Joined Apr 2, 2020
2,376
Your device may just be the Bluetooth receiver. If there is no output power ratings, then you'll likely need to connect this receiver to an amplifier. Was it called a class D amplifier by the seller? Post a link to the listing.
 

Thread Starter

Surtsey

Joined May 8, 2022
15
To answer all the questions:

The quoted power output is 50w + 25w + 25w.
There is no 'input' because its Bluetooth.
The power requirements are 12-20v DC 3-5 amps. I plan to power it with 20v DC 4.5 amps.
If you look at the chip between the capacitors there are holes drilled either side, suggesting a heat-sink fixing point.
 

Audioguru again

Joined Oct 21, 2019
5,183
The amplifier IC does not have a metal pad on top for a heatsink.
50W is for the subwoofer and it is probably 50 Whats Peak with severe distortion but is actually about 15 real Watts.
25W is for the stereo outputs which are actually about 7.5 real Watts each.

With music or speech the average output is a max of (15+7.5+7.5)/10= 3W and the class-D has an efficiency of 80% or more then the amplifier IC will not need a heatsink unless you play three loud continuous tones at full blast.
 

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crutschow

Joined Mar 14, 2008
30,803
So in summary, the scientific consensus is that, if it doesn't get hot enough to burn your finger when playing music at your normal listening level, then you don't need a heat-sink.
 

Audioguru again

Joined Oct 21, 2019
5,183
The Texas Instruments TPA3116 class-D amplifier IC I showed needs a heatsink attached to its top metal pad when it delivers 25 real Watts continuously to 4 ohm loads when its supply is 21V.

What is the part number marked on the Chinesium amplifier IC?
 

MisterBill2

Joined Jan 23, 2018
13,141
OK, the device IS NOT a "class D amplifier board." It is a bluetooth receiver with amplifiers included. Does the TS have the transformer that is intended to power it? The size of the transformer will be a clue as to the actual real power output.
 

Audioguru again

Joined Oct 21, 2019
5,183
Of course the 3-channels amplifier (stereo, plus sub-woofer) is an efficient class-D. The max power supply is 20V at 5A= 100W.

If it is class-AB and is not bridged then with a 20V supply the outputs would be 5W stereo into 8 ohms plus 10W sub-woofer into 4 ohms then the heating would total 20W.
It might produce 10W stereo per channel into 4 ohms plus 20W onto 2 ohms for 40W of output and heating.
 

Audioguru again

Joined Oct 21, 2019
5,183
A class-AB amplifier near max low distortion output produces almost as much power in heat as it does making output power into a speaker.
A class-D amplifier is efficient so its heating is only 10% to 15% of its output power.

The thread title says Class D but if it was stated by Amazon or in a Chinese ad then it is a guess because they know nothing about electronics.
The photo shows only one amplifier IC. A TPA3116 IC has a metal tab on top for a heatsink and has two amplifiers. The wording for the amplifier shows a 3rd output called Bass. Post #6 says, "50W + 25W + 25W".
Many amplifier boards have one TPA3116 amplifier for stereo and a second TPA3116 with its two channels in parallel for the 2-ohms sub-woofer.
I do not know of a 3 channels or 4 channels class-D amplifier IC.
 

Thread Starter

Surtsey

Joined May 8, 2022
15
The Jury's in . . .

I can confirm by the lack of output on the mono bass channel and suspicious burning smell @ 20v it does require a heat-sink! the stereo channels still work.
 

MisterBill2

Joined Jan 23, 2018
13,141
That must have been playing fairly loud? What speaker impedance was used? And how did it sound before the failure? Is there any visible sign of failure?
So others can learn from this experience without repeating it.
 
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