Battery Drain in Active Bass

So, both my basses are active basses, and require a 9 volt battery, and you have to have a working battery in them to get any sound to the amp. I also like to just leave the bass plugged into the amp, as I grab it multiple times in a day sometimes, and just play around with it.

If I leave the cable plugged into the bass, the battery drains pretty fast, maybe a couple of weeks or so. If I pull the cable from the bass each time I play, the battery lasts much longer, but I’ve had to go in and tighten the nut on the output jack (by opening up the cavity compartment) now on both the basses as it gets loose over time when the cable gets plugged in and unplugged. Also, I worry that the tiny solder joints will eventually come loose from doing this so much.

Anyone else have this problem? Just like the pedal thread, why don’t they just put an on/off switch on an active bass? I remember @Korrigan posting something about this once in a project bass thread, to just install one yourself. But, that’s not for everyone, plus, these are my “good” basses, the cavity is pretty full already, and this kind of surgery could get botched!

What do you all do?


I unplug mine and the battery lasts for months. Good question about the switch though! I like power switches.

Actually I wonder if I can just leave mine in passive mode with the cable plugged in. I bet that is more or less the same as turning the thing off would be.

I tend to move my bass around a lot though because due to humidity here varying a lot between seasons. I keep it near A/C in the summer and will keep it in a humidified room in the winter. So, keeping it plugged in isn’t even really an option for me.


Yes, I had to learn this one the hard way, @Vik… I thought something was wrong with my bass since the battery got drained so fast. Of course, it was because I had left it plugged in. I really like my TRB5Pii, but the fact that it “only” has active mode requires some “planning”, like remembering to unplug it every time I take a break, and - especially - always carry a spare battery with me. Mine is “howling” badly when the battery goes flat - quite annoying! Can’t imagine how that would be in the middle of a gig…

So, yeah, it’s a mystery why there isn’t an on/off switch - there’s gotta to be a good reason!?!


I didn’t know you had one of those! That’s an amazing looking bass.

one really nice feature of the TRBX504 and 604 is they have a LED that comes on when the battery needs changing.


Yeah, found one used here in CPH only a few months after I started playing and fell for it :grinning:Very nice bass! Play it almost exclusively at the moment! I guess I start to be able to discern the differences between an OK bass and a really good one (playing-wise)!

That seems like a really helpful feature! Oh, well, I guess in case I ever get to gig with this particular bass, I will just start off with a fresh battery, to be on the safe side!

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Not sure at all it would save the battery. There is a switch on the jack (or sometimes a stereo jack used as a switch), exactly as what we find in pedals, that turns the preamp on when the cable is plugged. I’m almost sure the preamp drains battery as long as the bass is plugged, even in passive mode.


I think that is probably right, especially as there is a circuit in there that ensures passive and active are always at unity gain (so you can switch back and forth at will without changing volume.) That wouldn’t work without the passive being a little active (because you can boost and cut the active eq.)

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or it means your active circuitry doesn’t boosts the signal level, to match the level of the passive mode, that’s very possible. do you have the shematics ?

edit : on the Yamaha website, they say that when the battery is dead, the bass switches itself to passive mode. that’s great !


I don’t have the schematics, I need to find them. Yeah they really thought out the active/passive thing. I wonder if others are the same way. It’s pretty cool to be able to switch back and forth without worrying about volume.

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