TPA3255 - all about DIY, Discussion, Design etc

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#3,443
drMordor said:
No, only need quality PSU
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I posted measurements earlier in the thread showing specifically that THD+N gets worse at higher supply voltage, so this is not a true statement. Generally speaking this is true for all class D amplifiers as the pre-filter output is constantly switching from rail to rail (or in this case from PVDD to GND) so it follows that the higher this idle switching voltage is, the higher the noise will be after the filter.

GeekySimar said:
A noob question here. Is there any difference in audio quality between 36V and 48V?

I am more concerned about audio quality rather than output power. So does voltage rating makes difference here?

Thanks
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My advice would be to use the lowest possible supply voltage for the amount of output voltage you need. With 8 ohm speakers that are low efficiency, you may opt for higher supply voltage just to get the output levels you need. Slightly higher THD+N is much better than clipping.

There's also the question of which board you have, and how hot it will run at the desired supply voltage. Some designs are under-engineered and get excessively hot even within the specified supply voltage range.

Cheers,
Owen
 
#3,444
opc said:
I posted measurements earlier in the thread showing specifically that THD+N gets worse at higher supply voltage, so this is not a true statement. Generally speaking this is true for all class D amplifiers as the pre-filter output is constantly switching from rail to rail (or in this case from PVDD to GND) so it follows that the higher this idle switching voltage is, the higher the noise will be after the filter......
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Hi opc,

I’ve looked back many months in this thread and can’t find the posted measurements with psu voltage and THD+N. This would be helpful info, can you link the posts your referencing? Thank you🙂
 
#3,447
turion64 said:
Lesters, is this because you are using 4 ohm speakers or will that LC alteration be noticeable on 8 ohm speakers as well?

Thanks, Pete
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Hi Pete,

I'm using 8 ohm speakers (JBL studio 230). Reason I disabled PFFB is because the output filter does not work in our default PFFB network values. It's a bit of work to replace each SMT (17pcs 0603) that's why I just disabled the PFFB.

THD is slightly higher than PFFB 10uH + 1uF.

THD of this config is 0.0024% at 5W 4 ohms.

But this is non-PFFB, with this THD result, it means that the inductor is really good.

Regards,
Lester
 
#3,451
:cop:
Salut Mamocel,
Ceci est un site en anglais, veuillez fournir une traduction google de vos messages en anglais.


Hi! JLesterP!
Your amplifier board is on my list for 2021! It looks very nice! Have a good day and a Happy New Year with your family! (This post is also for all DIY members)
 
#3,456
GeekySimar said:
A noob question here. Is there any difference in audio quality between 36V and 48V?

I am more concerned about audio quality rather than output power. So does voltage rating makes difference here?

Thanks
Click to expand...


Yes it does. The difference is easily visible in AP machine (THD) , spectrum analyzer (noise at switching frequency). As for sound quality , our team reports there is a small but audible difference between 51V and 38V (tested voltage) but its only a subjective opinion .
 
#3,459
BucketInABucket said:
Any ideas for a fanless ~36-48V PSU for the 3e board? I'm unable to get the Connex unit because I live in HK. Plan to have it be flexible enough to use with 4-8ohm speakers.
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I use the Mean Well LRS Series (LRS-200-24). The 24 volt one can be adjusted to about 29/30 volts which is adequate for most home listening applications. They also do a 36 volt and 48 volt version.

The 200 Watt one is fanless. The 350 Watt version has a fan but only comes on when it gets hot so basically never when using with an amplifier like the 3e board.
 
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