I did. This works provided your op-amp is capable to deliver the high audio level at really low THD. But I am not intrigued to invest here for squeezing some 5dB lower THD figures, it is not worth the effort imho.
You will hear a difference switching OP amps (in my case OPA1656, Aiyima TPA3251 Tilear 2.1). It is certainly measurable and this is why I asked Rhing to send the updated version to Audio Science review but still waiting for his feedback.... This would be the best way to check improvement.
I made some "human" test with Burson Audio V5I / OPA1656 / OPA627 / OPA1622 / OPA1612 / OPA MUSE01, they all sound differently. I would say that switching OP amps it is like changing Tubes : You can have surprising results when listening
Last edited:
I have speakers that can be bi-wired (a metal strap connecting the low pass section of the crossover to the high pass). With the strap removed, and if there were a way to access the point just before the LC filter's inductor, could one bypass the LC filter and wire straight to the low pass section of the crossover? It seems like the low pass current would be passing through far fewer components (an audio improvement?), and the high pass current through the LC filter would be greatly reduced.
Apologies for the rough drawing.
Mike
Apologies for the rough drawing.
Mike
Let's say 10 ft 12 awg, or 20 ft from OUT_A to OUT_B.
the inductance of the speaker will ruin this idea
I assumed the inductive load of the low pass crossover/driver would be in parallel with the capacitive load of the high pass crossover/driver, as far as the TPA3255 output pins are concerned.
Thanks for the responses.
Mike
Meanwhile I had some ideas for improvements that ended in additional iterations of the TPA325x-PBTL pcb-design. Actually that is the news:
+12V Sync-buck-regulator extended to “flybuck” providing +-12V symm supply for op-amps.
10pin IDC-connector added to connect via ribbon cable a new control pcb providing 4 operating status LEDs and another 10pin port for diagnostic measurments.
Replacing output inductors by latest Würth HIDE-series with small footprint.
PCB dimensions shrinked from 100x75mm down to 100x62mm.
+12V Sync-buck-regulator extended to “flybuck” providing +-12V symm supply for op-amps.
10pin IDC-connector added to connect via ribbon cable a new control pcb providing 4 operating status LEDs and another 10pin port for diagnostic measurments.
Replacing output inductors by latest Würth HIDE-series with small footprint.
PCB dimensions shrinked from 100x75mm down to 100x62mm.
Attachments
I was able to improve EVM of 6.67Khz/10W/4R (non PFFB) from 0.012% to 0.005%
With PFFB (while not tested) I would expect it to be 0.0025%, Our goal is to make it around 0.001 % at a max
What I did , is tryed over 20 inductors and ended up making a custom one. As you can see inductor influences distortion by quite a good amount .
With PFFB (while not tested) I would expect it to be 0.0025%, Our goal is to make it around 0.001 % at a max
What I did , is tryed over 20 inductors and ended up making a custom one. As you can see inductor influences distortion by quite a good amount .
There is no problem in downgrading from 2-4 Ohm to 8 Ohm.
Yes, DOWNgrading, as the current flow drops to 1/2~1/4.
Power dissipation drops as well so a small heatsink will do.
And with its small heat sink my design is suitable for 8 ohms and will overheat at 2-4 ohms.
Last edited:
hi. can you please share how you solved the popping noise through your linear power supply. thanks