TPA3255 - all about DIY, Discussion, Design etc

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Deleted member 148505

cdsgames said:
Regarding Avdd , since the beginning we understood that's a very important rail. I chose dedicated LDO to feed power to that rail. From what I remember , I read the noise on Cap pin (forgot what pin number) and experimented with different values of caps(tpa datasheet is substandard with ceramic small cap).220uF , 470 and 1000uF. I found a decrease on that rail (that most likely has the comparator and wave generator) from 23uV to 8uV. 220uF and 470uF were not enough I think that at 470uF we seen only 3-6uV of noise reduction.
(all this while playing a 1Khz file)



Further I crosschecked the reduction of noise with FFT and THD+N data. We see a small correlation. However I am convinced (by gut ), based on many subjective feedback's and the fact that analog to PWM conversion takes place on this voltage , that reduction of noise on that pin is VERY important for SQ. It just makes sense ...


In the end , I have used the LT3042 (or lt3045) LDO to power that rail along with 1000uF polymer cap(on decoupling pin) that gave us the best noise reduction..


Hence I was suggesting that 100 to 470uF might not be enough , but some caps are better than others in reducing noise.
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Can you show the capacitor placement on AVDD :D
 
daniboun

daniboun

Banned
Joined 2019
cdsgames said:
On Monday I will show my unit. It looks very ugly since I have done many tests on it. As we spoke privately Dani , I will also show publicly my last great "trick" and hopefully convince you all , that it was SQ and not THD my main goal. Because of that pursuit I was delayed...................................
I would say 2 months to market , but I have been wrong before.
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Thanks for this nice feedback.
Looking forward to see and test ) :)


I fear bankruptcy for the competition arrffffffffffffff ! Jlester / DrMordor / XRK good luck )
 
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454Casull

Member
Joined 2004
cdsgames said:
ok just to clear things up , TNT has seen a message from me posting my FFT...on drmordor GB. Honestly I did not realized (poor excuse)and posted without thinking. Its below my standard(or anyones here) and understandable that TNT lost patience. I have asked a moderator to remove my post and it was done .
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Huh, I tried to find that image a few days ago and couldn't. I even specifically remember posting something about that but couldn't find my own post for some reason. Now I know.
 
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cdsgames

Member
Joined 2015
I fear bankruptcy Jlester / DrMordor / XRK good luck )[/QUOTE]


Not at all . those designs are very competent and have good SQ. Price will also be a factor . At last , the ideas that everyone shared here , went into design of our amp. Example , it is bucks bunny that suggested a few months ago to decrease the tpa gain and increase the front end gain..
 
D

Deleted member 148505

daniboun said:
I fear bankruptcy for the competition arrffffffffffffff ! Jlester / DrMordor / XRK good luck )
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I think I need to create a cheaper PFFB version where 99.9% of the best sound is present. Gotta keep up lol.

cdsgames said:
Correction . Avdd is decoupled with 1uF in tpa3255 datasheet and we decoupled with 1000uF on that pin. Power to Avdd comes from Vdd that's where we used LT304x


We used dedicated LDO for Gvdd as well .
You will be able to see the cap on the pic of the board.
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I see, I assume that you put electrolytic decoupling close to opamp buffers as well. It's illogical if you put electro on AVDD and not on where the large contributor of sound which is the opamp buffers.
 
daniboun

daniboun

Banned
Joined 2019
Jlester > I think I need to create a cheaper PFFB version where 99.9% of the best sound is present. Gotta keep up lol.
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I think above all that you should gain from making yourself known ... by offering more accessible modules for the European market. On the other hand, can you explain the choice of LME49860 instead of OPA1656 ?

I would have proposed a module with the possibility of Bypassing the OP amps in fact) By the way, should be interesting to measure this option ?
A lower cost for better performance! To test )


I can offer you the opportunity to contact Audiophonics to see if they might be interested in your modules) send me private message if you want.
 
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chermann

Member
Joined 2017
cdsgames said:
Ok I will create it and update there.

.....

Sacar , I have designed the AMP with a front end that has selectable gain . So you can have gain of 10db (min) , 13db , 17db and 20db (total)
.....
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Hi experts


I played some time ago with the TPA3255chinese boards. i am a little bit confused with the select able gain what you wrote. i rechecked the datasheet and i found just that what i know ---> 21.5dB gain
How is it possible to set the gain of this amplifier?


chris
 
D

Deleted member 148505

daniboun said:
On the other hand, can you explain the choice of LME49860 instead of OPA1656 ?

I would have proposed a module with the possibility of Bypassing the OP amps in fact) By the way, should be interesting to measure this option ?
A lower cost for better performance! To test )


I can offer you the opportunity to contact Audiophonics to see if they might be interested in your modules) send me private message if you want.
Click to expand...

I'm using Nichicon Muse BP for the input caps, it adds bloom to the sound and sparkling highs which is not compatible with OPA1656 sound. Haven't tried OPA1656 after that. I will try the OPA1656 again for Elna Silmic II caps.

Pete (Turion64) is right, selection of opamp requires synergy with the input cap.

LME49860 with 22uF Nichicon Muse BP has the bass that you are looking for.

All modules with socketed opamps can be easily bypassed. We just need a preamp with ultra low noise supply and correct opamp circuit implementation.

Thanks for the audiophonics help, I will prepare for it sometime in the future.
 
daniboun

daniboun

Banned
Joined 2019
I'm using Nichicon Muse BP for the input caps, it adds bloom to the sound and sparkling highs which is not compatible with OPA1656 sound. Haven't tried OPA1656 after that. I will try the OPA1656 again for Elna Silmic II caps.
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Drmordor modules are using Elna Silmic II caps for buffer, I was really surprised to see how MC33272 + Elna Silmic II work well together.... far away better than OPA1602 and OPA1642 with Elna Slimic II caps for instance.

I guess rolling appropriate OP amps depends a lot on the Inductors as well + synergy with the input caps. You will find some measurements in 360 Customs site about this.

My last improvements on DrModor Module :

 
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wealas

Member
Joined 2017
chermann said:
Hi experts


I played some time ago with the TPA3255chinese boards. i am a little bit confused with the select able gain what you wrote. i rechecked the datasheet and i found just that what i know ---> 21.5dB gain
How is it possible to set the gain of this amplifier?


chris
Click to expand...

PFFB reduces overall gain and you can control how much by changing the feedback. TI app note here:https://www.ti.com/lit/pdf/slaa788
 
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sychan

Member
Joined 2019
daniboun said:
Hi amigos,

Just to share ) TAS3251 with internal DSP, quick test at home (video)
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Is this one of JMF11's NeatAmps? That is an interesting project, but it is hard for me to get a feel for the final outcome. It would be nice to have a great amp that plugs directly into my RPi without messing around with a DAC. The HiFiBerry Amp100 looks great in terms of plug and pla but the specs are underwhelming.
 
daniboun

daniboun

Banned
Joined 2019
Exact ) I met JMF11 a few weeks ago.

We have tested his TAS3251 vs TPA3251 with OPA1656 + updated inductors vs Dual Mono Infineon Merus
It was a super interesting listening session anyway )

The main interest of the TAS3251 is precisely to integrate a DSP) otherwise you might as well opt for a TPA3251....
As you can see, this TAS3251 does not have any OP amps, the signal is processed in the chip

My next challenge is : to propose to "la maison du haut parleur" (very famous shop in France), via an expert's opinion, a comparison between my future Purifi amp with a custom buffer VS the new Dual Mono Gan DrMordor VS the TPA3255 DrMordor.
I expect a lot from Drmodor Gan dual Mono modules.

Everything is already on the way... January should be an interesting month)
 
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sychan

Member
Joined 2019
JMF11 shared his opinion of the comparison, and it seemed that the NeatAmp was a good match for his tastes. How about for you? How did it sound compared to the other TPA3251 amps you have like the Aiyima or the 3e-Audio? Your Aiyima is heavily modified, any sense of how it sounds compared to a vanilla Aiyima?
 
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