Battery selection. What battery do i need?

Irving

Joined Jan 30, 2016
403
A single TPA3116D2 chip is 50W into 4ohm @ 21V, two bridged is 100W but THD is 10% (horrible). its 0.1% at 25W (50W bridged). Thats continuous output so average not peak, [ V^2/R = (21*.7)^2/4 = 50W ] but realistically you wouldn't want to run it above 25W if you want to listen to it. Looking at the datasheet and the suppliers pictures on Amazon the heatsinking is marginal, barely good enough for continuous output and badly compromised airflow due to row of capacitors blocking flow at one end. The 24v/2A from the supplier's blurb is running the board at 2 x 25W a channel which is where TI recommend it for general use at <1% THD.

If you really want good sound at 200W, look elsewhere....

BTW 200W into 4ohm speakers is 16A average... thats about 30min on your proposed battery pack...
 

Audioguru again

Joined Oct 21, 2019
1,488
Amazon and its sellers know nothing about electronic products.
The amplifier uses a Texas Instruments TPA3116 IC. Its datasheet shows an output of 33W into 8 ohms or 60W into 4 ohms per channel at 1% distortion, when powered from 24V.
 

Irving

Joined Jan 30, 2016
403
The TI TPA3116 isn't a bad chip, used correctly. They've used 2 on a small board with a marginal heatsink and are exaggerating its capabilities. Its classic Chinese manufacturing. What makes me laugh is the branding "Don't click me unless you're an expert" - I agree with you, I doubt the drop-shipper has a clue!
 

Thread Starter

Mattumber92

Joined Jun 26, 2020
9
Okay thanks you all for the input I'll look for a different better chip. Do y'all have any recommendations? I am able to build my own circuits too so if there is a schematic for a better amp I'd love to have some more input.
 

Audioguru again

Joined Oct 21, 2019
1,488
This amplifier is sold on all the Chinese sites. It has only one TPA3116 amplifier IC, not two of them.
Texas Instruments make many amplifier ICs and have datasheets showing schematics and fairly truthful output powers. Look on their website then see if the Chinese make amplifiers with them.
 

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Irving

Joined Jan 30, 2016
403
Whatever circuit you build, you must consider the whole thing holistically. Starting with "how much output power do I really need and how am I going to resource that" before considering the finer details. As I've shown, you need to run the math both from the physics as well as financially as there are several trade-offs to be considered. One of the biggest considerations is "how long will I own this and how often will I use it" vs "how long will I run it for when I do" vs "what depth of discharge on the batteries (and therefore battery life and ongoing operating/replacement cost) am I prepared to accept"? That's a massive financial trade-off which will impact total cost of ownership RE up front vs ongoing costs as well as most other decisions, and is a discussion you've not mentioned yet.
 

Audioguru again

Joined Oct 21, 2019
1,488
You found an amplifier schematic from India that does not have a single word about its output power, speaker impedance, distortion or any other audio spec.
In his website and You Tube videos the author writes that he is not an engineering student but he likes it.

With a 24V supply, the amplifier output swing might be 23Vp-p then is 8.13V RMS. The output power in a 4 ohm speaker will be only 16.5W, if it works.
 

Irving

Joined Jan 30, 2016
403
This amplifier is sold on all the Chinese sites. It has only one TPA3116 amplifier IC, not two of them.
Texas Instruments make many amplifier ICs and have datasheets showing schematics and fairly truthful output powers. Look on their website then see if the Chinese make amplifiers with them.
Interesting... that board appears to be the suppliers version of the TI reference board in the datasheet, but the boxed version, and that shown on the OP's link with the row of caps down the side and larger toroidal filter inductors is different, but probably still only the one chip. I was being generous and assuming they'd used two chips, bridged per channel...

Anyway, that power input connector will melt at more than 5A or so...

 

Audioguru again

Joined Oct 21, 2019
1,488
Interesting... that board appears to be the suppliers version of the TI reference board in the datasheet, but the boxed version, and that shown on the OP's link with the row of caps down the side and larger toroidal filter inductors is different, but probably still only the one chip. I was being generous and assuming they'd used two chips, bridged per channel...

Anyway, that power input connector will melt at more than 5A or so...

In my post #25 I show a photo of the same amplifier with the little heatsink removed. It shows only one TPA3116 IC.
Its two outputs are already bridged so you cannot bridge them again. Its datasheet shows you can parallel its 2 channels to get 100W into 2 ohms.
Sure the power input connector will melt, it is very cheeeeep!
 

Irving

Joined Jan 30, 2016
403
In my post #25 I show a photo of the same amplifier with the little heatsink removed. It shows only one TPA3116 IC.
Umm, not quite...

The top pic is the same amp as in my post #30, but the bottom pic is a different board with smd inductors rather than wound toroids, and no row of bulk caps along one side. That lower board is, mostly, being correctly marketed as 2 x 50W.

There are several examples of similar boards with 2 devices, e.g. this one, that use 1 chip for subwoofer @100W and 1 for L & R @ 50W

https://ae01.alicdn.com/kf/H9498251b05f14fd393db2407f991749c9.jpg


I'm fairly sure, judging by the number of 220u bulk caps that the OP's K1002 board has 2 chips, each providing a 100W channel. That said, the power connector isn't up to the job of driving 200W - it really needs a screw terminal like the above.

Its all moot anyway without a sensible battery solution.
 

Audioguru again

Joined Oct 21, 2019
1,488
Hi Irving, you are correct. The amplifier has two TPA3116 ICs.
A seller on ebay is trying to cheat with the wrong photo.

All the Chinese places wrongly say 100W per channel into 4 ohms with a 24V supply.
Texas Instruments correctly says into 2 ohm speakers.
 

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sparky 1

Joined Nov 3, 2018
184
3) $5.00 TPA3116 with good heat sinks. For the money not much worry. Bigger aluminum enclosure with fans and connectors.
While the data sheet runs them at 32V they should do alright on 12V like 50W each but gets better with a fan.
If you build a DC/DC converter you might later step up to a few 300W boards and a way to keep them cool, DC/DC is good idea
When you add it up altogether each component plays a part a good speakers and speaker box that looks presentable and can operate high power
can be heard further away TPA3116 response is engineered to do bass but most of less expensive amps power is less than advertised.
 
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Audioguru again

Joined Oct 21, 2019
1,488
1) TPA3116 with good heat sinks. Bigger enclosure with fans.
2) While the data sheet runs them at 32V they should do alright on 12V like 50W each.
3) You might later step up to a few 300W boards.
4) TPA3116 response is engineered to do bass.
No.
1) The IC amplifier is class-D switching so it does not get hot. The amplifier module has a heatsink and does not need a fan.
2) Texas Instruments recommends a maximum supply of 26V. With a 12V supply, the power into 2 ohms is only 30W per channel at 1% distortion, or 15W into 4 ohms per channel, or 7.5W per channel into 8 ohms per channel.
3) 300W is impossible. With a 24V supply the TPA3116 datasheet shows 120W into 2 ohms per channel at 1% distortion.
4) Its high frequency response is shown to be excellent to 50kHz.
 
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