Yes - just recently, and the results are wonderful!
The full story is messy - originally I had a TPA3250EVM, and I did multiple modifications to this board before powering it up - only to find it was faulty. I assumed that one of my mods killed the board, but I now realise that the main problem was a faulty external 12V power supply, and the amp was probably OK.
Lesson learned too late.
I now have a 3e-audio TPA3251 board, and just recently bypassed the opamps to connect the outputs of my balanced DAC.
First impression was disappointment at the more gentle/subtle presentation - but as I listened further I realised that any bursts of treble were free of harshness, and any bursts of bass were free of "flabbiness" - it sounds like a cliche, but I really feel like some electronic "hash" has been removed. Bear in mind that my audio playback chain is now opamp-free - my DAC has a transformer output stage.
Recordings which benefit most are those which are on the slightly bright side (in my opinion that means most post-1990 recordings) - one particular album of mine, "Us" by Peter Gabriel (DSD ripped from SACD) is a revelation with the opamps bypassed!
Also I have the DSD files of The Four Seasons with Janine Jansen on violin - the violin doesn't sound much different - but the timbre of the cello (played by Janine Jansen's brother) is now beautiful.
Bad idea, because the onboard SE-diff converter circuit is already good, and your DRV134 SE-diff converter circuit is likely to little, or no, better.
Instead you might (?) benefit from changing the supplied opamps - but the EVM and 3e-audio boards have surface-mount opamps, so this change is non-trivial.
The "AIYIMA" TPA3255 amp has DIP8 opamps, and forum member daniboun reports that the OPA1622 is a nice replacement there -
https://www.diyaudio.com/forums/class-d/287470-tpa3255-diy-discussion-design-etc-174.html#post6083665
OK, so I think your question was best answered by forum member wxn one year ago -
https://www.diyaudio.com/forums/class-d/309813-wrong-tpa3255-72.html#post5677467
https://www.diyaudio.com/forums/class-d/309813-wrong-tpa3255-72.html#post5677467
Happy with your good English.
You can use DRV134 or a double OP-AMP as you like. DRV134 is a bit more difficult to get your hands on, a double OP-AMP requires more external components.
Your choice.
Just one question... Did you try the excellent TPA3251 board from AIYIMA.
This is the only board equiped with removable OP Amp. I own the 3E Audio and the AIYIMA TPA3255 also. The fact you can custom the OP Amp
opens up the possibilities of finding "your sound" Got some fantastic results with the AOP1622
Hi
Schematic ist nearly finished !!
Including PFFB and optional additional snubber
Single ended to symetrical converter ist realized with OPA1632.
Inductors ... I dont know.
I found 3 possibilities
BOURNS PQ2617BHA-220K ( Option number one)
WURTH ELEKTRONIK 7443642200
WURTH ELEKTRONIK 74435582200
I try to implement all Footprints
I need 22uH. Because i optimize it for 8 Ohms.
Same Footprint is also useable für 10/15uH inductors.( With more Isat/ less Rdc)
Filter capacitors are WIMA MKP types.
Stolen Idea for Zobel Network with NTC .. ( sorry)
Ist ist worth to separate the 12v supplies for VDD/GVDD ?
I use separated VDD/GVDD and OPV supply rails
Schematic ist nearly finished !!
Including PFFB and optional additional snubber
Single ended to symetrical converter ist realized with OPA1632.
Inductors ... I dont know.
I found 3 possibilities
BOURNS PQ2617BHA-220K ( Option number one)
WURTH ELEKTRONIK 7443642200
WURTH ELEKTRONIK 74435582200
I try to implement all Footprints
I need 22uH. Because i optimize it for 8 Ohms.
Same Footprint is also useable für 10/15uH inductors.( With more Isat/ less Rdc)
Filter capacitors are WIMA MKP types.
Stolen Idea for Zobel Network with NTC .. ( sorry)
Ist ist worth to separate the 12v supplies for VDD/GVDD ?
I use separated VDD/GVDD and OPV supply rails
Just one question... Did you try the excellent TPA3251 board from AIYIMA.
This is the only board equiped with removable OP Amp. I own the 3E Audio and the AIYIMA TPA3255 also. The fact you can custom the OP Amp
opens up the possibilities of finding "your sound" Got some fantastic results with the AOP1622
Hello . Tell me, is it worth buying this model of amplifier? Read the subject. Is there a lot of explosive noise when switching on or off ? With respect.
I might as easily ask: "did you try with a balanced source and opamps bypassed?"
And tube fans might as easily ask: "did you try with a tube preamp?"
etc, etc.
There are many pathways to find "your sound". The pathway I'm likely to follow next is APEX class-AB.
But your innovative opamp-swapping has not gone unnoticed nor unappreciated - in fact, in an earlier post I mentioned to forum member saddevil your use of the OPA1622 -
https://www.diyaudio.com/forums/class-d/287470-tpa3255-diy-discussion-design-etc-177.html#post6087586
Thanks for the offer but unfortunately I already bought mine.
After more digging I found a TI document (attached) on how to implement the PFFB and the graphs (p 43 and up) doesn’t seem to show a drastic difference w the added PFFB si it’s all good. Of course graph doesn’t tell you the sound difference. Very nice of you though.
BR
Eric