I’m deciding on whether to add a voltmeter to the front panel of the amps. As the battery voltage falls, they will need recharging – how will the listener know they need charging? One way would be to monitor a voltmeter as when the battery charge falls, so does its voltage.
But meters are expensive, the one I really like is £34 from Farnell and that doesn’t include VAT or delivery or the cost of putting it in – it’s square and only round holes can be drilled so making square holes is much more expensive. These moving coil meters are also quite deep (approx. 5 cm) so it would take up a lot of room.
I don’t like the idea of using an LED display (they are much thinner) as RFI is associated with diodes. There is an LCD display which is nice and thin but it doesn’t look too good to me and they are still £24.
Plus, with metering, there is all the switching involved, which pushes the cost up again.
I am starting to wonder if a meter is needed at all. Surely as the battery runs out of charge, the ensuing voltage drop will cause the volume to also drop and may also create distortion of some kind. Wouldn’t the listener hear the difference? And then turn the amp to Charge Mode?
I think I need to start building the first amp and see what happens before encasing it.
If you have any ideas / thoughts – feel free to air them!