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Amplifier Modules and PCBs For Sale

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Deleted member 148505

AlexScan said:
This is the Lester's sister the "instrument" Roger

How she find the TPA3255 PFFB Lester ?
Click to expand...

Haha she's not here so no human ear instrument. At first I noticed more details but overall sound is not so different compared to non-PFFB module, but after 2 hours of listening the amp got smoother and more natural, also the bass got better by tenfold compared to when I first powered it up. Any harshness from non-PFFB is removed on this PFFB module! (it's true, I'm not hyping haha), sometimes I get stunned by some music passages that I've already listened to before, few hours later I am playing it louder even though the speaker is just a meter away beside me. I only noticed that it was already loud when I went to other room.

I measured the input / output ratio and it is around 11.8 or 21.4dB. So you need around 2.71Vrms to get 32Vrms output.

In my non PFFB I need around 10 oclock volume knob on my usb preamp (I'm using FLAC files on foobar2000 player), now I am setting it to 12oclock to get the same loudness.
 
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Deleted member 148505

I re-run the THD measurement because there's a different value in the feedback compensation the last time I measured my amp.

This time the THD+N result is almost the same as the slaa78AA measurements.

Actually it is very near the limitations of my test setup:
QA400 + Soundcard interface(INA134+NE5532) + Line Driver SE mode (NE5532+THAT1646)
 

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Deleted member 148505

TLS205B0 is doing a good job in keeping the noise floor down.

My soundcard interface has a default -6dB attenuation so noise floor should be in around 40 uVrms.

With 28deg C room temperature, main heatsink temp is 38deg C. Inductors are cooler, 35deg C.
 

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AlexScan

Member
Joined 2011
JLesterP said:
TLS205B0 is doing a good job in keeping the noise floor down.

My soundcard interface has a default -6dB attenuation so noise floor should be in around 40 uVrms.

With 28deg C room temperature, main heatsink temp is 38deg C. Inductors are cooler, 35deg C.
Click to expand...

Great, the noise floor is similar than your measurement with the multimeter test probe... why without it is higher ?

No noise in speaker when it was no sound I guess ?
 
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Deleted member 148505

AlexScan said:
Great measurement !

Far better than IRcore350...

I think with APx555 Amir must measure better SINAD using differential input.
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Yes it's THD+N is not superior due to IRS2092's inherent high noise floor.
But IRCore350's sound is very good specially when I put OPA1692IDR on it. The background is not pitch black but the sound is very pleasing.

Too much treble for my taste when I put OPA1656.

AlexScan said:
Strangerly the noise is lower but the noise floor is higher, so the SINAD is worse...
Click to expand...

Probably a limitation on my setup, every wire that is being moved changes the result, using low end test measurement is actually frustrating.
 
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AlexScan

Member
Joined 2011
JLesterP said:
Yes it's THD+N is not superior due to IRS2092's inherent high noise floor.
But IRCore350's sound is very good specially when I put OPA1692IDR on it. The background is not pitch black but the sound is very pleasing.

Too much treble for my taste when I put OPA1656.

OK, another Versus is required Lester... IRcore350 OPA1692 vs TPA3255 PFFB LM4562 (or another one, try LT1364)

Probably a limitation on my setup, every wire that is being moved changes the result, using low end test measurement is actually frustrating.

Yes your right, I understand, but APx555 is very very expensive... try to re-measuring without the probe now and check the noise floor if is near -140dB
Click to expand...
 
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Deleted member 148505

I just ordered awhile ago some parts on Mouser to try for different feedback loop values and for additional Coilcraft VER2923-103KL.

Right now I'm using LM4562NA DIP IC, I like it =). I want to try different opamps but the IC socket will become abused and loose so I haven't pulled out the IC yet to preserve it.

I will re-measure next weekend :)
 
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Deleted member 148505

asuslover said:
JLesterP , there is a lot of buzz around these VER2923-103KL inductors , is there a benefit/improvement when you are them ?
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First thing that I noticed is that VER2923 inductor doesn't get hot at all when tpa3255 amp is idle.

VER2923 is actually overkill for TPA3255. I've been using the 22uH VER2923-223KL on my IRS2092 for years, a single inductor can handle clean 400W power.

The benefit is in TPA3255's high power performance as VER2923's inductance is very linear with high current output. Inductance won't change even on TPA3255's highest power.

Using those inductors will remove all your doubt if you are getting optimum performance on your TPA3255. I did get the same performance measurements from TI's PFFB application note when I used VER2923 inductors.

So if you are OC and want the best for your TPA3255, get the best inductor for it, otherwise if you are just listening on a small room, Sagami/ICE/codaca 17A Isat inductors will suffice.
 
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Deleted member 148505

asuslover said:
"Option A (54 USD) - Partially assembled and tested" is interesting for me , but I am not sure about the heatsink, is the heatsink available for sale separately ? Or can you share the brand / size /name of a good heatsink?
Thanks
Click to expand...

Heatsink is the same as the one used in TPA3255 EVM (attached pic), you just need a high performance thermal compound. I am including compatible screws for the heatsink in Options A and B.
 

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Deleted member 148505

Next on my line up is partially assembled LM3886 myref rev C. Maybe in 2021, I already created a prototype (attached pics). Sound is very good too. Last picture is the final design.
 

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