TPA3255 - all about DIY, Discussion, Design etc

[drMordor]

I do LLC PSU and amp yourself

 

[drMordor]

It was a long journey to suppress plopping noise under all operational circumstances. Now that this seems to work I revised the pcb layout accordingly adding even more control circuitry.

My pcb

 

[bucks bunny]

Nice! Meanwhile my next revision has left production at JLCPCB. With some luck the next batch arrives during the following week. The last days I revisited the controller program code. After fixing some bugs it seems to work basically but is not tested in all scenarios until now.

 

[bucks bunny]

My actual pcb batch from JLCPCB just arrived at my house door. I uploaded the gerbers at June 17th in the evening. I would call this service unbeatable.

 

[drMordor]

My actual pcb batch from JLCPCB just arrived at my house door. I uploaded the gerbers at June 17th in the evening. I would call this service unbeatable.

i build amp
Testing

 

[bucks bunny]

i build amp
Testing

Looking forward to your results. I did not expect my pcbs arriving that soon so I ordered some missing parts on monday. Hope these will arrive tomorrow.

 

[hansueli]

Hei guys


Really happy. Got my 2nd TPA3255 board yesterday. Its the mono version of 3e Audios TPA3255. Works good. Unfortunately I am still waiting for my ADAU1701 DSP.


So no Subwoofer crossover....


Caps are stock... will be changed later.

 

[jimk04]

Where are you feeding the power to?

 

[hansueli]

Where are you feeding the power to?

The 3e Amp has soldering hole for power wires.

 

[jimk04]

I hadn't noticed those...great...can get another cap in where the green connectors are.!

 

[bucks bunny]

This morning the missing parts arrived so I could finish the actual prototype. I assembled a TPA3251 that I had removed once or twice from former prototypes. There was no problem recycling these so far. Powered up: It lives

 

[alonper]

Hi amigos,

New TPA3255 under my hands)
Let's start a little review with a 3h listening test.

Setup :

BRZHIFI TPA3255 amplifier
SMPS LLC integrated PSU
4 OP Amps DIP8 socket
Bluetooth QC. Chipset.
3-band equalizer

High end Floor speakers (Ribbon tweeter)
93DB / 100RMS / 8 ohms

Source :

HD Audio Quboz streaming
Jazz / WorldMusic / Classical playlist

Options :

AK4497 double dac.
Quad DAC ESS (V30).

A first sight : When I removed the top enclosure panel, I started to measure the LLC PSU that seems good. But something is weird, I measured it @ 40V. The Voltage can be adjusted to +/- 5%. (I already knew this before ordering). I have the same PSU in my other PSU enclosure. The Amplifier is provided with 4 OP amps... I guess 2 are dedicated to Equalizer ? It comes with 4 NE5532.

I removed those OP Amps and installed 4 TI OPA1656 instead. (improvement is huge, I really do not exagerate), I wonder if it because it uses 4 OP amps but it's even more noticeable than on my AIYIMA TPA3251, especially when it comes to volume gain.

So here the + and - :

Plus :

ANTI POP circuit yeahhhhhh )
4 removable OP amps
Equalizer works really fine ! you can clearly juggle between frequencies
Good looking design, full Aluminium enclosure (well ventilated)
Integrated LLC PSU
PCB seems good
Dead silence amplifier, no Hiss, no noise
the amplifier does not heat up even after 3 hours of listening

- :

PSU is only 40V ? I wonder why !
Because of this, the Amplifier do not deliver is best power
Volume Knob seems a bit fragile
Personnaly, I would prefer it without Bluetooth chip (subjective)
Only silver case, I would like a black one.
No PFFB


Sound quality :

With the 4 OPA1656, compared to the AIYIMA TPA3251. I found the Bass being sweeter, the fact you can juggle the equalizer is really fine and brings something very interesting.
With my ribbon speakers, I set the trebles forward, cymbals and fairly incisive percussion sound awesome. Medium are just fine, I left the Medium at 12:00
The amplifier is absolutely dead silence, no hiss, no noises, nothing to complain about )
So this is good alternative to the AIYIMA TPA3251.
Since the amplifier is completely different from the AIYIMA TPA3251, I can't say so much about the caps, electronic etc...

Here we have a good TPA3255 Amplifier, with anti Pop at startup which is really appreciated. I really like the fact the SMPS LLC PSU is integrated.
The enclosure size remains compact while preserving a sober solid design.

As a reminder, this is my 5th TPA32XX and I am still waiting for my TPA32XX based on 360 Customs design. So I will be able, later, to compare it to the top end TPA32XX.
For the moment, I am loving it as I still love my AIYIMA TPA3251.
I paid it about 90 euros, it is a bargain as well )

daniboun, thanks for sharing! your tiny project inspired me to order the same unit - I would like to do the op-amp modification you did, since I am a newbie and this is going to be my first little project - I have no idea what to order - do I need to order 4 X OPA1656 SOIC package? or I need to order a breakout-board with them?, in addition, I couldn't find a good picture of the PCB so I don't really know how to recognized the NE5532.

+ last question - is that the only modification you did for the amp?


Thanks!
Alon

 

[drMordor]

I assembled a TPA3251 Powered up: It lives

Good job)))

 

[jimk04]

My second setup up with better psu. 3e 2 channel 3255.

35volt 500VA transformer into monolithic rectifier. Bank of 14 2200uF and 0.1uf film.

Runs at just under 50V.

Sounding very nice...lots more gain than the Teac tripath that I was listening to before.

I feed it into a Salas Dcg3 preamp.

I am monitoring the amp temps as the heatsink on the chip and inductors are pprox 37 to 40 degrees....(measured on a hot day here...28 ambient).

See if the additional voltage has changed the SQ in any way. Was running this amp at 40V previously.

 

[daniboun]

This morning the missing parts arrived so I could finish the actual prototype. I assembled a TPA3251 that I had removed once or twice from former prototypes. There was no problem recycling these so far. Powered up: It lives

Sounds good ! Can you share some measures of your prototype ?
Thx

 

[bucks bunny]

Sounds good ! Can you share some measures of your prototype ?
Thx

I can do so later. But do not expect any really news - my prototypes perform similar to the TI-EVM and there is not so much I can do about that. Instead of squeezing the last zero out of THD numbers I focus on an extra power management that enable battery operation and suppresses popping sound on power up / down using a microprocessor. I can add some postfilterfeedback also - but in a different way than TI do propose. This will be my power building block of high-efficient mobile instrument amps in the ballpark of 30~100W mono.

 

[vitopro]

@jimk04
Can you tell me part number of wima output cap? Are they LS15? I founded only 22 LS

 

[albunicolae]

Yes this one ) Chinese boards are not using PFFB. You will find it only on high ends TPA32XX boards amigo

Thank you.

I ordered also this amplifier Finished Hifi TPA3255 stereo amplifier 300W+300W digital power AMP support BT 5.0|Amplifier| - AliExpress as per your recommendation.
First impressions it sounds amazing even out of the box. I will do some more testing.
What i found very useful is that the potentiometer for high tone adjustment has a switch on/off for the tone correction.

I am planning to replace also the 4 op-amps with opa1656.

 

[jimk04]

@jimk04
Can you tell me part number of wima output cap? Are they LS15? I founded only 22 LS

0.47uf 100v MKS

MKS2D034701E00KSSD

 

[daniboun]

Thank you.

I ordered also this amplifier Finished Hifi TPA3255 stereo amplifier 300W+300W digital power AMP support BT 5.0|Amplifier| - AliExpress as per your recommendation.
First impressions it sounds amazing even out of the box. I will do some more testing.
What i found very useful is that the potentiometer for high tone adjustment has a switch on/off for the tone correction.

I am planning to replace also the 4 op-amps with opa1656.

The OPA1656 update is really worth while.
You will hear the improvement !