TPA3255 - all about DIY, Discussion, Design etc

[Mello4]

The audio pop that occurs on audio systems is typically from a DC offset suddenly charging or discharging a capacitor in the signal chain, when powered on or off. Sometimes this is related to power sequencing issues. If the output power switches get power after the signal chain capacitors have settled or power down before the low level signal chain, then the pop may not occur. It only takes a few mV of DC offset to cause the pop. Speakers are not supposed to be exposed to DC offset.


In the old days, some op amps had high DC offset and with 10uF signal chain coupling capacitors, this can be a problem.

 

[daniboun]

You are included in the percentage of population that doesn't like PFFB sound.

Too much negative feedback kills the full bodied midrange sound.

You can fix it by reducing negative feedback of PFFB. Ask dr. Mordor for R_fb and R_fb_ground values for reduced PFFB.

Problem with non-PFFB TPA3255 is that it has a harsh 'sss' and 'cchh' sounds.

So with PFFB config, we want to get the best sibilance / highs while maintaining the full bodied midrange sound. (This is what I'm doing these days)

-----------------------
If Dr. Mordor's amp uses SLAA788A values, This one also helps in improving the sound

Reduce R_op-fb (depending on opamp feedback resistor)

Set cutoff frequency to >= 450kHz
RC Low-pass Filter Design Tool

You can disable PFFB via the appropriate Jumper ) easy
Should be nice to give a try you're right ! 🙂

 

[Deleted member 148505]

Dear friends,
I bought an amplifier board from DrMordor.
I think that it doesn't fit to my speakers.
It's completely new, worked for 1 hour.
If someone wants it, it can sell it for half the price.
Please let me know and I can send it in 24 hours.
Thanks.

I bought from 3eAudio and it had more body than this one.
Strange.
When can I buy an Hypex Ncore built board?

Keep it if you can modify the amp. It has more potential than the 3eaudio module, removal of the 4 caps on the input is already an advantage. With couple of tweaks on the PFFB network, will make it fuller sounding than regular (non-pffb)

 

[drMordor]

I use the improved PFFB, out of 46 amps sold, only the first person said he didn't like the sound. Maybe reason source?

 

[daniboun]

I would say the same... nothing to complain with pffb.
Works fine in both amps Jlester and drmordor modules ;-)

 

[utking]

Dear friends,
I bought an amplifier board from DrMordor.
I think that it doesn't fit to my speakers.
It's completely new, worked for 1 hour.
If someone wants it, it can sell it for half the price.
Please let me know and I can send it in 24 hours.
Thanks.

I'd love to take it as i'm looking for an amp like this 🙂

 

[bucks bunny]

Paradigm Prestige 95F input impedance drops below 4 ohms at the upper range. The Class D output filter may need optimization: Paradigm Prestige 95F loudspeaker Measurements | Stereophile.com

TI TPA3255 Application note....LC Filter Design (Rev. A)

Fig.1 Paradigm Prestige 95F, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

Interesting, yes this may be a real issue. I would measure frequency response of output loaded with this speaker.

 

[UAN]

I use the improved PFFB ....

Thank you for sharing your work.
You can find out what the supply voltage of the op-amp is on your boards.


Best regards, UAN.

 

[drMordor]

+-12

 

[UAN]

That is, bipolar +/- 12?

No, unipolar, polarity C89!

 

[ilan5555]

Hi, strange
Are you sure that everything is correctly connected
I have the blackboard and i am really happy with it
Maybe it needs more time to settle
Goodluck
Enjoy...
🙂

Yes.
I took it to a technitian to connect it and we tested it.
It's simply too bright with lack of texture (for me).
I prefer the 3eAudio much better.
I tried to change opa and it's a bit better but it's not what I need.
Thanks.

 

[ilan5555]

You are included in the percentage of population that doesn't like PFFB sound.

Too much negative feedback kills the full bodied midrange sound.

You can fix it by reducing negative feedback of PFFB. Ask dr. Mordor for R_fb and R_fb_ground values for reduced PFFB.

Problem with non-PFFB TPA3255 is that it has a harsh 'sss' and 'cchh' sounds.

So with PFFB config, we want to get the best sibilance / highs while maintaining the full bodied midrange sound. (This is what I'm doing these days)

-----------------------
If Dr. Mordor's amp uses SLAA788A values, This one also helps in improving the sound

Reduce R_op-fb (depending on opamp feedback resistor)

Set cutoff frequency to >= 450kHz
RC Low-pass Filter Design Tool

I told DrMordor that I had a problem but he never told me what to do.
I also not a professional so I don't know how to fix it.

I'm done playing games and asking for favors.
I prefer to sell it and loose some money.
If someone wants it, I will happily sell it.

 

[drMordor]

Yes)
PSU onboard, any voltage))
C89 separated chip, 3,8V on input

 

[bushellj]

Dear friends,
I bought an amplifier board from DrMordor.
I think that it doesn't fit to my speakers.
It's completely new, worked for 1 hour.
If someone wants it, it can sell it for half the price.
Please let me know and I can send it in 24 hours.
Thanks.

Hi ilan5555

Did you receive my PM earlier today ??

Thank you. James.

 

[ilan5555]

You can disable PFFB via the appropriate Jumper ) easy
Should be nice to give a try you're right ! 🙂

I don't know which jumper it is.

 

[drMordor]

I told DrMordor that I had a problem but he never told me what to do.
I also not a professional so I don't know how to fix it.

I'm done playing games and asking for favors.
I prefer to sell it and loose some money.
If someone wants it, I will happily sell it.

I think the problem is not with the amplifier. Or a source, or wires.
I can get the money back, return the amplifier to me.

 

[utking]

I told DrMordor that I had a problem but he never told me what to do.
I also not a professional so I don't know how to fix it.

I'm done playing games and asking for favors.
I prefer to sell it and loose some money.
If someone wants it, I will happily sell it.

I sent you a pm yesterday, but perhaps you don't really want to sell it? 🙂

 

[ilan5555]

Keep it if you can modify the amp. It has more potential than the 3eaudio module, removal of the 4 caps on the input is already an advantage. With couple of tweaks on the PFFB network, will make it fuller sounding than regular (non-pffb)

As I said before, I'm not a professional as you are so I don't know to fix it...
But thanks!

 

[ilan5555]

I use the improved PFFB, out of 46 amps sold, only the first person said he didn't like the sound. Maybe reason source?

I use a Denafrip Pontus II with Denon 8500 as a Preamplifier only.

 

[ilan5555]

Hi ilan5555

Did you receive my PM earlier today ??

Thank you. James.

I will check immediately.