And also, how important is phase accuracy to getting competent sound? For myself, I have never, ever worried about phase - it can do what it likes in a system,
- and such has never helped or hindered me getting the quality I was after ...
Hi,
Have you ever reverted + and - from a bass speaker? Have you seen that coil/diaphragm is moving vice-versa? You can also test this with a 1.5V battery and you'll see it easily.
Here's good example from my bedroom: after placing my subwoofer with backside to my chair I realised that bass can be heard with much more weight in the other half of the room than I intended to, hence I switched 180-degrees phase-shift switch from the sub to correct this. Now bass sounds bigger and with great weight, like it should be.
Here's a 20 kHz sine-wave on a headphones amplifier:
vs.
Left - original circuit, right- LowPassFilter modified by DIY.
Same as above, but with a 100 kHz test signal:
vs.
Left - original circuit, right- LowPassFilter modified by DIY.
You can see on the above pics that phase is visible shifted. Blue is the original audio signal, red is what the amplifier gets through the headphone-out 6.3mm jack plug. Is any sound difference after modifying the LPF? I say YES, higher treble sounds better now and more detailed...it's hard to explain, but after all, the phase shift difference is audible, at least in my case.
Let' continue with some square signals too.
Here's a 20 kHz square test signal:
vs.
Left - original circuit, right- LowPassFilter modified by DIY.
Here's a 20 Hz square test signal:
vs.
Left - sound gets through the HighPassFilter filter of the amplifier, right - audio signal was applied after the 2.2uF/250V input caps (input caps are usually there to prevent DC-voltage inject from DACs or other audio sources).
Low-bass has more kick and weight when the input caps are bypassed. Not recommended to inject audio signal without input caps connected, but probably doubling their capacitance resolves the phase shift. However, 4.7uF caps costs more than 2.2uF, so this is why most manufacturers consider not to spend lot of money on this.
L.E.: The 100 kHz sine-wave phase shift also shows us the
speed of the amplifier itself. With LPF removed signal is almost perfect with almost no phase-shift.