http://tangentsoft.net/elec/vgrounds.html
The designer of the pimeta explains at the beginning why he doesn't trust two batteries to discharge equally. The main concern is that when batteries near zero, which coud happen if you let the amp on with music playing too long (getting asleep, leaving the room, and so on), DC offset could go through the roof and destroy the headphones. There are some posts about that on headwize.
The designer of the pimeta explains at the beginning why he doesn't trust two batteries to discharge equally. The main concern is that when batteries near zero, which coud happen if you let the amp on with music playing too long (getting asleep, leaving the room, and so on), DC offset could go through the roof and destroy the headphones. There are some posts about that on headwize.
Yes DC offset is a big problem but only if one rail is A LOt higher voltage-vise i.e. one rail is disconnected. I have found that the effekt is not killing if your using a high impedance headphone(300ohm).
The dc output is about one rail at worst.
I think it´s still usable but with cauton. Somehow you have to monitor the batteries status.
If your using big sealed lead-acid batteries(4-7 Ah) the dc-offset is not a really big problem either. The amp draws about 40mA per batteri. That´s stereo. So with the 4Ah batteries you still have 100 hours use without any problem.
Caution though, my experience is limited to high impedance phones. But if DC is a problem you can use output caps.
The dc output is about one rail at worst.
I think it´s still usable but with cauton. Somehow you have to monitor the batteries status.
If your using big sealed lead-acid batteries(4-7 Ah) the dc-offset is not a really big problem either. The amp draws about 40mA per batteri. That´s stereo. So with the 4Ah batteries you still have 100 hours use without any problem.
Caution though, my experience is limited to high impedance phones. But if DC is a problem you can use output caps.
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