TPA 311x D2 chip am...
 

TPA 311x D2 chip amps  

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ImCoKeMaN
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01/09/2019 3:33 pm  
So I haven't gotten into speaker building (yet?), but I've tried out a few of those little cheap amps (roughly $5-$10) from ebay to power some speakers I had.
They are actually not too bad, and great for a small speaker tester.  I've just been using them with ~19v laptop power supplies I've had around.
I started with this model, I think it was under $5 when I got it:
XH-M312 DC 12V-24V TPA3118D2 45W+45W Digital Audio Power Amplifier Board Amp Module
https://www.ebay.com/itm/DC-12V-24V-TPA3118D2-45W-45W-Digital-Audio-Power-Amplifier-Board-Amp-Module/322882705747  
The first one got fried, but second was good (seller sent replacement for free).  Unfortunately, it actually blew the sound card in my ancient computer I was using when it happend so now I use these as a usb fuse for testing them:
https://www.ebay.com/itm/1x-External-Virtual-USB-2-0-For-Laptop-Converter-Stereo-Sound-Card-Audio-Adapter/302387081316
I haven't done any testing to the quality of these, but at under $2 they work and I haven't had anything else fry.
While I was waiting on the replacement I stepped up a level and ordered one of these as well:
XH-M189 2*50W high-end digital power amp board DC24V TPA3116D2
https://www.ebay.com/itm/XH-M189-2-50W-high-end-digital-power-amp-board-DC24V-TPA3116D2-stereo-amp-c20-zh-/163652067126
 
I haven't gotten into any specific measuring equipment yet either, but these work well for small speakers in a house to a decent volume.
For outside use they don't seem to have enough power to fill a space as well as a full receiver, but I'm planning to upgrade to a 24v power supply to see how that works.

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123Toid
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01/09/2019 11:49 pm  

@imcokeman one thing I've noticed about some of those chip boards especially the TPA 3118 series is it will give you a plus or minus 3 decibels from 20 Hertz to 20 kilohertz. But it's not uncommon to see them very linear from say 100 Hertz to 20 kilohertz and then have a slow steady decline to down 3 decibels at 20 Hertz.  Meaning that sometimes those board amps can lack bass. Having said that, I really like them and I use them anyway. But if you ever wonder why you might be lacking bass, that might be an issue.  It's really hard to say without testing them though.  

Now if you can make it over before Tuesday,y can hear the Dinas.  😉  But Tuesday they are headed off to RMAF. 


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TVOR-Ceasar
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02/09/2019 2:59 pm  

Shame they're leaving tomorrow since I'll be passing by on the Turnpike heading home then. Oh well, one of these days, maybe. 

-Charlie


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ImCoKeMaN
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02/09/2019 5:28 pm  

@123toid

So about that, hard to say without testing them.  Want to put together a thread of how you test, and some basics for getting started?  Maybe a way to test the different components, like this chip amp, and drivers etc.  I know graphs don't say it all but there is a reason for them =)  


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Douglas Blake
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02/09/2019 7:53 pm  

@imcokeman

You probably don't want to hear this... but E-Bay is like the worst place to buy these boards. Many of them (the dirt cheap ones) are using counterfeit or recovered parts and are about as stable as balancing a rock on a nail. 

You would be much further ahead to pay the extra bit and buy from Amazon, since they have been actively weeding out the fakes. You stand a much better chance of getting a good board or min-amp there.  I've purchased over a dozen tpa3116 based mini-amps from Amazon and so far haven't had one bit of trouble with any of them.

There are a couple of things to watch out for... in particular 25 volt capacitors on boards running from 24 volt supplies. This is not enough safety margin for you to trust. I generally swap them out for higher voltage parts, 35 or 50 volts, rather than have capacitors exploding in the mini-systems I sell.

One example is the Linkfor/Proster Mini Amp  I reviewed here recently.

image

As you can see, these bulk capacitors are woefully underrated.  What I did was to remove the 3 x 470uf 25 volt caps and install a single 2200uf 35 volt part.

CapUpgrade

Use low ESR caps whenever you can. The provision for this is often right on the board so no hardware hacks required. The difference is not trivial and everything runs much better with the big guy installed.

Another problem in poorly designed boards is saturation of the output coils. This is pretty easy to spot, the coils will get warm, sometimes frighteningly so. The simple answer is to swap out the coils with better made parts.  The coil values for differing output impedances can be found in the spec sheets.

In terms of testing, you won't find huge differences between properly implemented TPA3116D2 amps.  You will get pretty much what the spec sheets tell you, since the whole thing is actually on a single chip. In fact, they should all sound the same.

That's not to say there aren't differences, but it should point out that poor performance is far more likely to be the result of weak bulk capacitors or cheapo output coils than because of the amp chip itself.

The Linkfor and Senucn amps I favour, actually get down to about 3hz and well over 30khz with very low distortion, typically under .1% ... other boards should do the same.

You should also be aware that these chips were clearly designed for 24 volt operation. Using the too-common 19 volt or 12 volt SMPS brick supplies will rob them horridly of performance, leading to premature clipping which can result in excessive heat from the chip.  At 24 volts you should get a rather comfortable 35 watts of clean power per channel on 8 ohms (or 50w on 4 ohms) but at 19 volts you are all the way down to 10 watts, if you're lucky. On 12 volts you get barely 5 watts per channel out of them.

Don't underestimate these chips. They are fully capable of HiFi sound and in many cases deliver more power and better sound than high end systems from the 1980s. Just because they aren't 5000 watts per channel doesn't mean they are underpowered... Heck, most living room listening happens at less than 5 watts, anyways.

 


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ImCoKeMaN
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02/09/2019 8:13 pm  

@douglas-blake

No problem hearing eBay is not the best for this I definitely did this on a throwaway budget.  The one you linked is definitely reasonable, but still 10x the price.  I have a used reciever for more powerful use but figured it was worth checking these out.  I don't have an oscilloscope like you mentioned in your tests but would be happy to learn some ways to do at least relative type testing between 2 amps maybe.

 

Right now. I have the small one hooked to some old htib rca speakers.  Again throwaway  budget heh. So far I only have a 19v power brick though so I will be getting a 24v from Amazon. 

 

Thanks for all the info!


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Douglas Blake
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02/09/2019 8:28 pm  

@imcokeman

Amazon has bare boards too ... often they're actually the guts of these mini-amps sold separately.  Do a search for "tpa3116" and you should find dozens of them.

Power supply wise, I generally recommend This One or an equivalent 24v 5amp supply.

Oscilloscopes are cheap as chips these days ... Like This. Granted it's not something you go bragging about, but for infrequent, general purpose testing it gets the job done.

You may also want to consider a basic multi-meter ... Like This One  It's  good for a lot of general testing, voltages, resistance, etc. Again nothing to write home about, but handy to have around.

The really good stuff costs big money but this should get you off to a fair start.

 

 


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ImCoKeMaN
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02/09/2019 9:11 pm  

wow this looks like a horrible and awesome 24v psu option: https://www.instructables.com/id/Two-ATX-PSU-One-juiced-24-V-DC-PSU/   I have them lying around, but wouldn't want to die so probably just get the one off amazon hehe.

I was actually looking at pc psu more for an option to run more things off of one supply earlier like 5v for a raspberry pi but the 12v didn't seem enough for the amps.  Just trying to simplify and outdoor theater hookup, I'll just do a power strip though.

I have voltmeters, but may have to look into that oscilloscope.  

Thanks again!


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Douglas Blake
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02/09/2019 9:29 pm  
Posted by: @imcokeman

wow this looks like a horrible and awesome 24v psu option: https://www.instructables.com/id/Two-ATX-PSU-One-juiced-24-V-DC-PSU/   I have them lying around, but wouldn't want to die so probably just get the one off amazon hehe.

That's a terrible idea 😲 Think what happens if one of the PSUs wired in series fails.

I say you should stay with stuff that's made for the job you're doing.  

I was actually looking at pc psu more for an option to run more things off of one supply earlier like 5v for a raspberry pi but the 12v didn't seem enough for the amps.  Just trying to simplify and outdoor theater hookup, I'll just do a power strip though.

Try this option with the 24v brick ... you might have to do a little splicing of the power cord but at least it's all on one SMPS supply (hense a common ground). Just set the buck converter's output to 5 volts and you're in business.

I have voltmeters, but may have to look into that oscilloscope.  

Yep. Consider the mind-blow when you display your waveforms on a home theatre screen... LOL.

Thanks again!

Any time.


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ImCoKeMaN
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02/09/2019 9:40 pm  

Those little buck converters look cool, it says not to use with less than 10% load so I guess I'd pigtail the power supply, and put that in the line to power whatever device I have so it's only connected when in use. 

For now power strip still works, but if I get further and integrate things, I'm sure I'd want something like that.


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Douglas Blake
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02/09/2019 9:50 pm  

@imcokeman

Just add a switch between the 24v input and the buck converter ... or better still, hack the thing right into the Rasberry PI's power jack... it's small enough.

 


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Douglas Blake
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03/09/2019 1:56 am  
Posted by: @123toid

@imcokeman one thing I've noticed about some of those chip boards especially the TPA 3118 series is it will give you a plus or minus 3 decibels from 20 Hertz to 20 kilohertz. But it's not uncommon to see them very linear from say 100 Hertz to 20 kilohertz and then have a slow steady decline to down 3 decibels at 20 Hertz.  Meaning that sometimes those board amps can lack bass. Having said that, I really like them and I use them anyway. But if you ever wonder why you might be lacking bass, that might be an issue.  It's really hard to say without testing them though.  

That was an issue with the first generation TPA311X chips, the input capacitor could not be made big enough for full frequency response without destabilizing the chip. This has been solved by adding the NE5532 op-amps to the inputs, eliminating the capacitor altogether.

The ones I use get well below 20hz with no roll off ... most get down to about 3 or 4 hz before hitting the -3 db point.

 

 


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