TI TPA3255EVM

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chips666

Member
Joined 2007
Klipsch RP-8000F and TPA3255EVM

chips666 said:
Thanks,

Chain is: Hqplayer > RME Adi-2 dac > TPA3255EVM > Klipsch RP-8000F (extreme toe in)

Enjoy...
Click to expand...

Hi,

After reading several threads and posts about TPA3255EVM
I think i will need to test output filter caps values 0.22uf, 0.33uf and 0.68uf to optimize output for my Klipsch RP-8000F
and also keep the 10mh coils since there is no optimal value like 12.5mh available and as far as i know that no other board uses 15mh coils
(Many thanks to ClaudeG for this information)

Will also bypass SE jumpers and caps from TPA3255EVM with a proper bypass wire and report

Enjoy ...
 
Dadbeh

Dadbeh

Member
Joined 2010
chips666 said:
Hello,

Bypassing op-amps on my TPA3255EVM was a succes
Installed final wiring and put cover back on
Difficult to put in words
I like what i am hearing :)

I can easily say the best free tweak i ever did :D

Enjoy...
Click to expand...

what i did was to pull out the 3 pin molex connector and solder shielded balanced mogami cable directly into the board for XLR inputs. god i hate Molex. always loose, always coming off. always flimsy specially when i have to make it.
 
Last edited:
C

chips666

Member
Joined 2007
chips666 said:
Hi,

After reading several threads and posts about TPA3255EVM
I think i will need to test output filter caps values 0.22uf, 0.33uf and 0.68uf to optimize output for my Klipsch RP-8000F
and also keep the 10mh coils since there is no optimal value like 12.5mh available and as far as i know that no other board uses 15mh coils
(Many thanks to ClaudeG for this information)

Will also bypass SE jumpers and caps from TPA3255EVM with a proper bypass wire and report

Enjoy ...
Click to expand...

Hi,

Output filter will remain as is - lead free solder is a pain in... :)

Enjoy... ;)
 
M

mboxler

Member
Joined 2011
chips666 said:
Hi,

Output filter will remain as is - lead free solder is a pain in... :)

Enjoy... ;)
Click to expand...

Those are a pain to desolder.

I no longer have my EVM :(, but as I recall the outputs from the chip are accessible using vias PWMA, PWMB, PWMC, and PWMD. I always wondered if one could solder custom filters to these vias and in turn connect the speakers to these offboard filters. Now you have a set of 4 ohm and 8 ohm outputs.

I realize these would be in parallel with in onboard filters, but with no connected load, very little current would be drawn.

Jus' wandering.

Mike
 
B

bisouxxx

Member
Joined 2017
Paid Member
chips666 said:
Hi,

Output filter will remain as is - lead free solder is a pain in... :)

Enjoy... ;)
Click to expand...

Hello,
I'm building a personal amp.
I have 2 3eaudio tpa3255 pbtl boards, supplied by 2 smps 48v 600w.
At the moment they are connected via RCA to a smsl A8 used as a pre amp. Maybe the problem is related to it?
The sound is quite nice but I feel there is not too much dynamic (very low bass) despite of the huge power I should get.
So I'm investigating what I could improve on those boards. Output filter ( they are 10uH a 1uF), or op amp bypass...

Thanks
 
C

chips666

Member
Joined 2007
Hello,

My friend has a 3e audio dual mono TPA3255
No problem with bass
He uses a big 10000uf cap on dc power inlet
If your dac has a preamp stage you dont need the smsl

Enjoy...
 

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B

bisouxxx

Member
Joined 2017
Paid Member
chips666 said:
Hello again,

Still enjoying my TPA3255EVM but also looking for possible further improvements
Went through 90 pages but did not find alot of information about the output filter stage concerning less components in signal path and/or optimizing for 8ohm load

Any advice is appreciated...
Click to expand...

Hellooo
I have the exact same configuration, boards and power supply.
I have no DAC at the moment that's why I use the smsl as a preamp. I think the problem is there.
I was about buying a topping D70 but I will probably buy the new audiophonics dual 9038q2m instead, with RPi option.

What are the big cells between supply/boards are for?
And about the op amp bypass?
 
E

ellisaudio

Member
Joined 2006
ellisaudio.com
Still enjoying my TPA3255EVM but also looking for possible further improvements
Went through 90 pages but did not find alot of information about the output filter stage concerning less components in signal path and/or optimizing for 8ohm load
Click to expand...

I can maybe offer some help here, but it depends on the configuration for the initial query. My notes will only be applicable if running the TPA 3255 in 4 channel.

When running the TPA 3255 in 4 channel, the board uses the 4 larger value electrolytics as coupling capacitors optimized for the drivers I was pushing (Accuton and Hiquphon). I replaced these with very high quality capacitors (electrolyics for the woofer) then bypassed with good metallized poly and then a .1uf Sonicap Platinum. This was expensive, and I did it in stages. In every stage the sound quality improved - even with the .1 uf Platinum bypass on the woofer. This was NOT cheap, but dang.... it really worked.

Also, of vastly lesser importance and significance. I increased the input voltage to to 56 volts and I think this improved sound quality too. The difference wasn't profound and could easily be debatable.

One more... I experimented adding various values of capacitance to the power supply input terminals for filtering and surge control. I added 15uf metallizeed poly - no difference. I added @ 200uf better quality electrolytic - no difference. I really think the TPA3255 is supplied with sufficient input capacitance.
 
L

larzman

Member
Joined 2006
home.comcast.net/~larzman/
454Casull said:
Does anyone know if replacing the stock 10 uH inductors with higher-quality 7 uH inductors will be problematic? TI themselves note that the Wurth 7443630700 is one of the best-performing candidates in terms of THD performance.

According to 4.6.2 here it should be OK: https://www.ti.com/lit/an/slaa701a/slaa701a.pdf?ts=1596000235446
Click to expand...

Thats a great L-C filter design App Note for the TI Class D chips. Yes, the 7uH Wurth inductor is the best from a performance perspective.

Thanks for posting the link
 
D

DPH

Member
Joined 2008
bucks bunny said:
I got excellent results with these inductors.
Meanwhile a new 10uH-Class-d-inductor from Würth is available with half size footprint that measures quite well.
Click to expand...

I'm interested, would you have the part # off hand before I go digging through their catalog? I don't run these amps hard enough for this to be anything more than specmanship upgrade, but that's never stopped us before. :)
 
Kay Pirinha

Kay Pirinha

Member
Joined 2011
bucks bunny said:
I got excellent results with these inductors.
Meanwhile a new 10uH-Class-d-inductor from Würth is available with half size footprint that measures quite well.
Click to expand...


Good to hear, basically. But are the ratings the same? Usually the power or current handling capabilities comply with the size in inductive components. They aren't that miniaturizable as, say, resistors or capacitors :rolleyes:.

Best regards!
 
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