TPA3255 Class D Amplifier and SMPS Part 1

Hi everyone, is it better to have a linear power supply with toroidal transformer vs a SMPS power supply to run a TPA 3255 chip?

No hubo 2da parte por k el tio se vacuno cntra el covi y manco

Splendid insights Michael; thanks. Working through your channel. Should you share the interest, post a series on custom, class d powered, FRFR guitar cabinet with integral power supply. cheers and thanks from WA state.

The biggest difference between AB and D class is wave form. AB have 100% sinusoide curve and D class have square wave form. You can google forward... Great video!

Got a question. Can you bridge this amplifier? If so how is it done?

hello, I don't understand your video, I only know Spanish, I'm using the translator, I wanted to know what the real power is without distortion and how much impedance was measured

Excellent write up sir, thank you.

I think if you are listening at moderate volume, there's very little difference between the 3255 and a class ab amp.
Most of the chinese factories try to squeeze everything into a small footprint, caps with little headroom n small heatsink so it kind of creates a constraint on a very competent chip.
Then again, it costs so little and could easily match up with AB Amos at 2~3 times that price

So, I did the math. I'm using this power amp, preceded with a tube preamp of my liking. And with 36V at 10 amps I have what I need in my living room in my home. What more could I want?

I'm so glad I found your channel!

Even i bought extra pairs of class ab amps ic for the future 😊

Sir it's still better to have class Ab amp like lm3886 and tda7294 ...

Just Bought the TPA 3255 Amplifier with 48v 7amp power. I will give you my own feedback soon but for now it sounds great😊😊

Your are excellent

Hi Michael, thanks for detail review, what is your comment of compare on sound quality of TPA3255 amplifier and LJM L20D amplifier?

Do take care of your health. We need more measurements.

You have a great caracter. Best wishes from the Netherlands

I think it's coming from the 12 V regulator harmonics

I've been working on some designs using this TPA3255 class-D chip and other similar class-D chips. Something I've noticed in simulations and testing is that when the devices are in BTL or PBTL mode they really don't like any imbalance in the audio inputs, by which I mean the inverting input needs to be exactly 180 degrees out of phase from the non-inverting input or you get strange overcurrent protection issues. I've started using an OPA1632 on the inputs to these chips to ensure that the non-inverting and inverting inputs are a perfect 180 degrees out of phase at all times and this has eliminated the over-protective overcurrent protection issues and some other noise issues I've had here.

I have a few different boards with the TPA3255 that I've used for testing while I design my own board. That particular board you have isn't one I have here but I'm certain the noise issues you might have are more to do with the TL072 chips on the input stage and the power regulator they are getting power from. Here in my designs I've been using a switching regulator to get the voltage to about 15 volts and then a linear regulator to bring it down to 12 volts for the audio circuits (and a 3.3 volt regulator for the LEDs and an OC and OT reset circuit) and this is also what the EVM from Texas Instruments does as well. That board you have seems to be using just a single switching regulator for 12 volts which is probably where most of the noise comes in. On the EVM from Texas Instruments the switching regulator is only used to bring the voltage down to an acceptable level so the linear regulator doesn't get too hot and a fast linear regulator is really what you need to get that power supply noise down flat.

I have had a cheap version of that since 2018 outputing to a pair of Monitor Audio Bronze 2. , it is great. :D The cheap version said the large capacitors are ELNA but I didn't trust that so I replaced them with Nichicons with higher values and relocate them to the bottom.

Fun to see you dipping your toes into some of the best of class D chip. I think you must have bought the most barebone card on the hole Aliexpress site hehe. The step down solution is quite awful on some of these boards. It also deliver the power to the opamps and the poor voltage quality to the op amps I assume is the reason for the hiss. If you have a balanced dac you should try to solder the balanced signals directly to the TPA3255. The 4 electrolytic silver caps on audio signal side of the pcb is the line in, so just solder the wire to them leaving the caps in the circuit(if you dont have dc blocking caps elsewhere). This way you skip the terrible op amp circuit and the sound will improve drastically. The chip impedance is about 20kOhm so it would be interresting to see a video of you trying a dirt cheap balanced dac connected to it this way. I have a highend dac connected to it directly and it works so much better than the stock SE mode.
That heat pad is way to thick! All of us modders use cpu thermal paste and direct contact which is so much better at higher power levels. I would not be surprised if the chip shuts itself down in your wattage test.. The heatsink solution is also a joke compared to what TI recommends so I usally put a temperature controlled fan on it. Anyways these board can become quite usefull with some small mods applied to them and thats why they have such a large following :) This chip series also has an interesting sound character which seperates it from other class D chips in a good way. Some prefer the 3251 because of the sound vs the 3255.

Hi Michael, hope you get better soon! You've been quite busy none the less. Strange, that noise issue. In my experience (ie PC speakers), most class D chips suffer from hiss, or rather a faint, annoying crackle. So I keep to class AB in my proper set. Maybe that is a power supply issue I now wonder. The hypex modules on the other hand are extremely noise and distortion free, but pricey! The TPA3255 is suppposed to be rather good. Look forward to your further measurements!