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Double Bass Battery voltage and pre amps

Slaphound

Slaphound

Jun 16, 2003
2,988
1,235
59
Staten Island, NY
#1
I have the K&K Rockabilly preamp. It takes a 9v Battery. The last gig I noticed that the output from my upright was low and sounded like garbage. I changed the battery in-between sets and problem solved. Got home and tested the batteries. The one I replaced read 8.6 volts. The new one 9.6 volts. It was brand new so I expected that. But 8.6? Shouldn't the preamp have worked better at that voltage?
 
#3
I'm ashamed to say I have not been very scientific about measuring (and logging) voltages in batteries I discard. I assume every unit draws current and performs at lower voltages a little differently.

The big issue for me would be: how much play time did you get from your preamp? I have noticed (but again, not methodically documented) how some units seem to need fresh batteries more often than others. My fDeck HPF-pre seems a bit on the hungry side at twice a year when I use it a lot. But that's not that big a deal. Even three or four times a year would be acceptable for me on a workhorse unit. (More than that and I might start to frown.)
 
#4
Your Rockabilly pre is almost identical to my K&K Dual Channel Pro ST, which is rated by K&K at "about 60" hours. I try to casually keep track of that. Anywhere between 45 and 55 hours I'll change the battery. No use gigging with the pre-amp not working optimally.

The biggest battery related inconvenience for me is that when the output cable is plugged in, the battery is in use, whether I realize it or not. I really wish they had a switch instead. But then, if they did, people might forget to turn it on or turn it off, so I can understand the design choice K&K made.
 
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#5
That video helps a bit. But now here. I've got an example of what I'm trying to figure, although it might not matter. I had two 1.5 Volt batteries in a recorder that died. I measured the voltage and they were used up to 1.32v each. The Recorder died at that voltage but they were good enough to replace the two dead batteries I had in a metronome I'm using. So. Good for one and not another. I've got a fresh 9.46 volt in the fridge for the next gig and I've got a 9.26v in the pre now. I'll be finding out soon how low a battery in the K&K will work at. Plus I'm using the 'wrong way' to test a battery with a multimeter. According to that video..

I think measuring time in hours might be a good way for me to know but It must be hard to always recall or record how much time you practice. I sometimes just start practicing and never really know how long I've played or what time it is.
 
#6
Slaphound said:
It must be hard to always recall or record how much time you practice.
Click to expand...

True, I usually just go by the length of the gigs that I use my pre for. Most often in practice I'm just playing acoustically.

Plus, I've got another gig option: a mounted dynamic mic that I can send clear to my amp or to an FOH (so no batteries). So for gigs that are using sensible volume, there's no pre or batteries involved. My piezo/pre-amp system is pretty much for gigs where I'm competing for sound space with drums, electric instruments or other really loud instruments.
 
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