Bus Pumping with 3 or more amps on a single supply

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#21
Oh ok, so I think I understand how the inversion works then and what I should be doing in a situation like mine with a fully active setup:

2x channels: Tweeter Left & Tweeter Right (invert the one channel)
2x channels: Midrange Left & Midrange Right (invert the one channel)
2x channels: Subwoofer 1 & Subwoofer 2 (invert the one channel)

That in essence should prevent any bus pumping from occurring. The capacitors are there as an extra safety net for any residual bus pumping or perhaps some pumping caused by a stereo, low frequency only playing on a single channel.
 
#22
That's correct although I don't think you need an inverter on the tweeter.
the midrange depends on the low cut crossover frequency . if above a few hundred Hertz no need there either .
Enough rail capacitance will absorb the much lower rail pumping energy of the mid and high channels .

Cheers,
Rens
 
#23
Fantastic, I really appreciate your assistance! 😀

One last thing, if I were to add a 7th amp channel and have 3x subwoofers. Would I then invert 2 of the amp channels and leave the 1 channel as is or how would one combat bus pumping with an odd number of amp channels.
In this case the subwoofers are most likely all receiving the exact same signal.
 
#24
sync

Hey

I recall some D chips having a "sync" signal/mode for precisely this reason ...

Ah, here are some lower power examples:

SSM2319 3W
class d sync 2319.png

View attachment SSM2319.pdf


TPA3100 20W
class d sync.png

http://www.ti.com/lit/ds/slos557/slos557.pdf

Cheers,
Jeff
 
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