Kill switch for active bass? Save batteries?

ericw · #1 07-26-2010, 08:19 AM

I'm looking to put an obp-2 in my yamaha. I'm going with the obp-2 as I can wire it with a single 9v and continue using the existing battery compartment. I'm going to set it up vol, blend, bass, treb, which leaves me room for one more control. I don't expect I would use an active/passive switch so I was wondering about putting in a kill switch.

If I did this in a manner as to disconnect the preamp from the output jack (break the green wire?), I believe it would stop drawing power from the battery - which would just be passive mode... is there a way to stop power draw AND silence the bass? And, would throwing such a switch while plugged into a powered-on amp/cabinet cause a pop similar to unplugging the bass or would it be a silent kill switch? Would it just be the bypass circuit with a DPDT on-off instead of on-on? I'm confused here...

Please help, if I could accomplish a silent kill switch that would let me leave the bass plugged into a powered amp without drawing power from the battery and audible output, I think it would be quite useful.

i_got_a_mohawk · #2 07-26-2010, 08:25 AM

You want to cut the black wire (-ve from the battery) from the circuit (just leave it open and disconnected).

I dare say with some preamps you might still get some sound through with no power. One way to test that with this one is to see if it makes any sound at all when there is no battery plugged in.

FunkMetalBass · #3 07-26-2010, 08:41 AM

The bypass switch will save your battery, so if that's all you wanted, you're done.

You could always go with a 3-position switch:
active preamp - preamp bypass - mute

Or with a 2-position switch (for the preamp bypass) and then a separate signal kill switch.

Also, you should always direct the signal to the ground.

ericw · #4 07-26-2010, 08:43 AM

Quote:

Originally Posted by i_got_a_mohawk

You want to cut the black wire (-ve from the battery) from the circuit (just leave it open and disconnected).

I dare say with some preamps you might still get some sound through with no power. One way to test that with this one is to see if it makes any sound at all when there is no battery plugged in.

I just worked through it a little more, comparing the two circuits. I think I need a dpst switch to break the blue wire and the black (battery -) wire in the first circuit. ? It seems your 1/4 inch plug from the instrument cable connect black wire from the battery to the ground, completeing the preamp circuit? So if I break the black (batt -) it would stop power draw. Blue wire is output from vol pot, so I want to break that wire to kill all audible output... anyone agree??

FunkMetalBass · #5 07-26-2010, 08:52 AM

Oops, the blue wire is the preamp input. That's where you'll want the switch to be.

plangentmusic · #6 07-26-2010, 08:53 AM

A battery cost 3 bucks and lasts for a year. Is this really a big concern?

Chasarms · #7 07-26-2010, 08:59 AM

It's almost certainly going to pop like h%$^ when you switch it. You might be able to buffer it with a capacitor, but I'm not certain that would even help.

ericw · #8 07-26-2010, 09:04 AM

Quote:

Originally Posted by Chasarms

It's almost certainly going to pop like h%$^ when you switch it. You might be able to buffer it with a capacitor, but I'm not certain that would even help.

Ok. No real benefit for me then. I guess I'll just go with the bypass circuit then.

FunkMetalBass · #9 07-26-2010, 09:12 AM

Quote:

Originally Posted by ericw

Ok. No real benefit for me then. I guess I'll just go with the bypass circuit then.

There's not much of a popping sound, and you can use some 1M resistors to calm down anything else.

Cutting the battery supply or preamp output would cause a decent pop, I expect.

**bass4worship** · #10 07-26-2010, 10:42 AM

Quote:

Originally Posted by FunkMetalBass

There's not much of a popping sound, and you can use some 1M resistors to calm down anything else.

Cutting the battery supply or preamp output would cause a decent pop, I expect.

Yes it would pop. I put many kill switches in my basses all pop.

i_got_a_mohawk · #11 07-26-2010, 11:09 AM

Quote:

Originally Posted by ericw

I just worked through it a little more, comparing the two circuits. I think I need a dpst switch to break the blue wire and the black (battery -) wire in the first circuit. ? It seems your 1/4 inch plug from the instrument cable connect black wire from the battery to the ground, completeing the preamp circuit? So if I break the black (batt -) it would stop power draw. Blue wire is output from vol pot, so I want to break that wire to kill all audible output... anyone agree??

That's why your bass doesnt drain the battery while it's unplugged

As said, if you just wanted it completelly cut, if there is no output without a battery, that would work. As has been said, you'll likely get a pop tho.

FunkMetalBass · #12 07-26-2010, 12:10 PM

The preamp bypass already shuts off the battery, by bypassing the preamp. The "pop" from the preamp bypass is pretty small when switching from active to passive, so I can't see the killswitch adding too much more.

That should work you just fine. Instead of going into a passive mode when you bypass the preamp, it simply directs the passive signal to the ground.

Note also that I got the colors backwards when drawing the wires. "To preamp" should actually be colored blue and "From Preamp" should actually be colored green.

**bass4worship** · #13 07-26-2010, 05:09 PM

Quote:

Originally Posted by FunkMetalBass

The preamp bypass already shuts off the battery, by bypassing the preamp. The "pop" from the preamp bypass is pretty small when switching from active to passive, so I can't see the killswitch adding too much more.

That should work you just fine. Instead of going into a passive mode when you bypass the preamp, it simply directs the passive signal to the ground.

Note also that I got the colors backwards when drawing the wires. "To preamp" should actually be colored blue and "From Preamp" should actually be colored green.

Thanks for the correct wiring, I've been killing the battery plus wire which causes a loud pop when switch on.

FunkMetalBass · #14 07-26-2010, 05:25 PM

Quote:

Originally Posted by bass4worship

Thanks for the correct wiring, I've been killing the battery plus wire which causes a loud pop when switch on.

Let me know if you notice a significant difference in the "pop" level. I imagine that shorting the battery signal would cause a considerable pop as well as take the chance of harming a preamp.

**bass4worship** · #15 07-26-2010, 05:43 PM

Quote:

Originally Posted by FunkMetalBass

Let me know if you notice a significant difference in the "pop" level. I imagine that shorting the battery signal would cause a considerable pop as well as take the chance of harming a preamp.

I always mute the amp before I turn on or off kill switch.