TPA3116 D2 mono amplifier as a stereo system?

Groetjes,

42 degrees Celsius hints a problem with a too low switching (carrier) frequency. With a multimeter (without amplifier power), measure the value (approximately) of R2 and R3. If R2 has a value less than R3, the TPA3116 is most likely set up as a "slave" and the frequency is too low. In such case, I suggest you to swap the two resistors around and cut pin 16.

your dutch as well? => groetjes

On both versions of the boards R2 measures ~ 43k and R3 ~100k so this is the case. I will mod. 1 board and report the temperature back. Thank you and "groeten terug"
 
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I did the mod and temps of the coils and heatsink seem to settle at 25C now after 20 minutes.
It looked so easy from your picture on my huge computerscreen; but I managed to get them on ..... hope they don't get any smaller, or maybe drink more next time; for a steady hand. :p

Thank you very much, I will mod my other boards. I suspect all these boards have this problem, not just yours and mine.
 
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I did the mod and temps of the coils and heatsink seem to settle at 25C now after 20 minutes.
It looked so easy from your picture on my huge computerscreen; but I managed to get them on ..... hope they don't get any smaller, or maybe drink more next time; for a steady hand. :p

Thank you very much, I will mod my other boards. I suspect all these boards have this problem, not just yours and mine.


I actually find it is a fine board (when corrected). What is weird is why it includes two obvious mistakes. The mistake with the resistor values causing it to be in “slave”-mode could be a mistake in production. But, running a batch with a repeated component value error is seriously negligent. Why the “SYNC”-pin is grounded I simply do not understand the reason for. Configured as “master” it is an output and should not be short-circuited. Configured as a “slave” it is an input but expects a clock for synchronizing of the switching frequency. It must be a misreading of the datasheet or a PCB layout error.
Yes, also I do not like working on SMD resistors. They stick to the tip of the soldering iron. And, these two resistors are even not among the smallest you find.
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Please let me know your problem or the posting where the problem is described.

I was trying to follow your advice. I need a correct schematic for the decoupling board for running one 24v 6a power brick with 2 mono TDA3116 boards. A full schematic with preamp and and buck convertor power would be great also, but I really didn’t notice much of a difference between my dual NE5532P preamp and straight from an iPod. I’d rather build one than buy one and guess at the quality of the components or stability of the circuit.
 
I was trying to follow your advice. I need a correct schematic for the decoupling board for running one 24v 6a power brick with 2 mono TDA3116 boards. A full schematic with preamp and and buck convertor power would be great also, but I really didn’t notice much of a difference between my dual NE5532P preamp and straight from an iPod. I’d rather build one than buy one and guess at the quality of the components or stability of the circuit.


Hi “1152”,

My suggestion for the system.
The three 5A diodes (ordinary silicon) serve to decouple the other units from the supply rail if one unit suddenly pulls a lot of power.
I would use a linear LM317 based voltage regulator and not a step-down Buck converter because the pre-amp consumption is low and the linear regulator has less noise.
Try without a specific “-”-wire between the LM317 voltage regulator and the pre-amp. Your signal ground, connected to the two TPA3116 modules, will provide the connection. I am afraid you may form a harmful ground-loop if you also draw a specific “-” power wire.

You write: ”I really didn’t notice much of a difference between my dual NE5532P preamp and straight from an iPod”. With a perfect pre-amplifier, the output sounds exactly like the input (your Ipad). Nothing is changed. Did you mean that the sound level was the same with or without the pre-amp? In such case you may increase the gain in the pre-amp.
 

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Hi “1152”,

My suggestion for the system.
The three 5A diodes (ordinary silicon) serve to decouple the other units from the supply rail if one unit suddenly pulls a lot of power.
I would use a linear LM317 based voltage regulator and not a step-down Buck converter because the pre-amp consumption is low and the linear regulator has less noise.
Try without a specific “-”-wire between the LM317 voltage regulator and the pre-amp. Your signal ground, connected to the two TPA3116 modules, will provide the connection. I am afraid you may form a harmful ground-loop if you also draw a specific “-” power wire.

Yes, a bad hum happened before. Would this be like a virtual ground?

You write: ”I really didn’t notice much of a difference between my dual NE5532P preamp and straight from an iPod”. With a perfect pre-amplifier, the output sounds exactly like the input (your Ipad). Nothing is changed. Did you mean that the sound level was the same with or without the pre-amp? In such case you may increase the gain in the pre-amp.

My preamp is basically a “Classic 47” headphone amp with only a volume potentiometer. 12v battery power to avoid noise. The gain is set before clipping when the volume is turned to full. I may or may not build a better preamp. What would you suggest?

Thanks FF! I’m on a different path at the moment (and a bit under the weather), but I will get started on your suggested schematic soon.
 
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Now we al least we have a clue why they are the cheapest. :D Even configured wrongly I have not noticed the problem or lesser SQ while listening to it for about a week, feeding a sub woofer.


Neither did I notice a different SQ. It was only when I realized it got quite hot compared to my 3 other TPA3116 boards I started looking for the cause. Else, it has good components for a cheap board and the possibility for a balanced input.
 
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My preamp is basically a “Classic 47” headphone amp with only a volume potentiometer. 12v battery power to avoid noise. The gain is set before clipping when the volume is turned to full. I may or may not build a better preamp. What would you suggest?

Thanks FF! I’m on a different path at the moment (and a bit under the weather), but I will get started on your suggested schematic soon.


Hi "1152",
Also I use a good headphone amp as pre-amplifier. This way I am sure the pre-amplifier can drive any power amp I throw at it.
The only downside is it consumes quite a lot of power because it is designed to handle a 32 Ohm load.

I see three reasons to use a pre-amplifier stage:
- inclusion of a volume potentiometer and eventually tone-controls,
- need for amplification of the source signal,
- impedance adaption before the power amplifier.

I do not use tone-controls. If needed, start with a source selection switch eventually using signal relays. I would use a 50Kohm (stereo) potentiometer or attenuator (with fixed resistors) at the input of a pre-amplifier. Following that potentiometer I would put a NE5532, LM4562 or OPA2134-based buffer stage with a gain of 2-3 times. These OP-AMPs can handle down to 600 Ohm at the input of the power amplifier. Supply: +/-15Vdc. No more than that - the more you add, the more you distort the source signal.
 
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Nothing personal, but I think it's a big mistake to think you don't want tone controls. I use a 4 section Baxandall circuit I designed and built. That way I can create just the right loudness compensation curve for the level I'm at, plus deal with any room acoustics to some extent. I find it to be a vast improvement over "flat". Plus, well designed opamp circuits are way more than good enough for any level of Hi-Fi anymore. Same with digital. It's no where near the weak link of any system.

Back to the original subject; I had very good luck with some 3116 boards I got from Parts Express (and bad luck with some other 3116 brds. always test them on the bench before using in a system), but I'm concerned that they may not be dead quiet in my main triamp'd system in my living room, where I would want that. There's a tiny bit of "hash" sound in my other project (boom box) which may have been more because of the bluetooth anyway. Haven't ruled it out yet, but need more experimenting on that. Any thoughts?
 
I’m still in the middle of and wrapping up other project. I was even sourcing and ordering part I needed the other day when I got pulled away. While I cannot answer, I will say that decoupling WILL improve the quality of sound. “Crest factor” is a key term here. My amps were only $4 each, but if you took the time to DIY they would come out more expensive. It should be worth it.
 
Bluetooth and me usually don’t get along. I tested yet another model of bluetooth headphones, an upgrade from ones previous. The previous model still did everything right even on really bad mp3 files. Put me to sleep. I think the only real problem that cheap amp boards with good layout and decent components has been the bluetooth.

You’re right about the tone controls - even with a clean source and tripath I find myself rolling off trebel on some tracks to get the ping and cymbal crash, but cut the excess hiss in the vocals. I was told this happens with current. Otherwise “dead-quiet.”
 
Do you hear any audio difference with that power line decoupling capacitors ? I am asking because it is at least 2 times more expensive than tpa3116 board :)

Yes, you need sufficiently large and sufficiently good decoupling capacitors. The price has always been an issue but any reputed brand would add good size decoupling capacitors though it would add to the price. It is actually not that the capacitors are terribly expensive - it is today possible to buy very cheap amplifier boards due to SMD assembly and because such boards do not include the necessary decoupling but only a minimum, use marginal chokes and often do not add the necessary heatsink. With a transformer you will need in the order of 4700uF-20000uF, with an SMPS 1000uF-10000uF depending on the reaction speed of the SMPS.
Using a good amplifier without the necessary decoupling is like driving a good petrol car on 88 octane gasoline.
 
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All poweramp boards of any kind should have 0.1uF ceramic caps across where DC power enters the board. All the class D (or whatever) boards I bought needed these to be added. They can't hurt, and will probably help (with noise and/or stability). Value isn't critical, voltage rating should be significantly higher than voltage will ever be, in case there's a turn-on transient.

When putting bypass caps across the AC line (great idea, I always do this), put the cap from hot to cold, not from either of those to earth ground (the green wire). I use 0.01uF 3kV ceramic caps there.

Another thing that's wise to do, is to put a Zobel across the speaker, when using switchmode (class D), or transformer coupled outputs (tube amps), so the amp sees a fairly low impedance above the audio frequency range, where speaker impedance's go way up. Not doing this makes the amp more likely to blow itself up when overdriven.

A Zobel in this case is an R and C, in series with each other, put across the speaker terminals. I usually use a 20 ohm 5 watt R in series with a 0.2uF polypropylene cap. Those values are approximate, but it seems to work well. Lots better than nothing.