True bypass for active electronics

[Axtman]

Many active basses have a passive switch that only works if the battery is charged. What's the point?! To me a passive switch is to be used when the battery is dying.

The following basses NEED a battery to work in passive mode.
Fender Power Jazz Bass Special
Lakland 55-01
G&L L2000
Fender Precision Bass Lyte

The following basses have true bypass and DO NOT need a battery.
Carvin LB75

Please list the basses that you know in either category. An easy way to find out is to remove the battery and see if the bass can still play.

Thanks!

 

[cmlax21]

My Hohner B Bass 6 is true bypass and the passive works if the battery is dead even though it doesn't sound as good.

 

[line6man]

I'm a but confused on why a bass would be designed to use the battery in passive mode?

By definition, passive means that there is no power source required.
The active/passive switch should be configured to reroute the signal that goes to the preamp straight to the output jack instead.

If the bass does not work that way, then you should probably rewire it so that it does.

 

[Axtman]

Exactly Line6man! But it is true. Take the battery out of any of the basses that I indicated above and the bass will not play at all in passive mode. Don't ask me why. It's silly.

BTW most of the time the passive switch will kill the tone controls and you will only be able to use the balance "blend" control and volume control.

 

[M0ses]

Yeah that's totally backwards. I'd rip that thing open and whip out the soldering iron.

 

[line6man]

BTW most of the time the passive switch will kill the tone controls and you will only be able to use the balance "blend" control and volume control.

That's the point actually.
Passive mode removes the preamp from the circuit, leaving only the passive volume and blend controls in the circuit.

 

[rogypop]

Many active basses have a passive switch that only works if the battery is charged. What's the point?! To me a passive switch is to be used when the battery is dying.

The following basses NEED a battery to work in passive mode.
Fender Power Jazz Bass Special
Lakland 55-01
G&L L2000
Fender Precision Bass Lyte

The following basses have true bypass and DO NOT need a battery.
Carvin LB75

Please list the basses that you know in either category. An easy way to find out is to remove the battery and see if the bass can still play.

Thanks!

fender jazz bass marcus miller, with right wiring which was
done on later models

 

[hrodbert696]

Sorry if anyone minds me zombifying the thread, but anyone care to update the "true bypass" list? Are all the Carvin active/passives true bypass like the LB75 (looking at the Icon series at the moment)? Any others?

 

[stflbn]

* Anything with Active EMG pickups is skrewd if the battery dies.

 

[SGD Lutherie]

This is an old thread, but it makes no sense. I have the schematics for the G&L L2000, the active/passive switch does indeed totally bypass the preamp. This is also true of the other basses on the list.

So unless the OP was plugging them into a low impedance mixer input or something they will indeed work in passive mode with no battery.

To be honest, unless you want passive mode so the bass sounds different, there's no reason to worry about your battery dying. I've been using active basses since 1977, and I have broken strings on gigs, but never had a battery fail.

All you need to do is check them from time to time. I used to change my batteries every month when I changed my strings.

Now I don't gig as much, so I don't change my strings so frequently, and my batteries still don't go dead even though I play at home all the time.

Also, while we are on the subject, "true bypass" is not always a good thing for effects pedals. It's more of a fad. If you use a bunch of pedals, and they are all true bypass, when they are switched out of the signal path, your tone will be duller sounding because of all the extra wire in your path. Having even a single buffered bypass at the beginning of the effects chain keeps your tone sounding the way it did coming out of the bass.

This true bypass thing got started when effects makers were being cheap and used SPDT switching in things like wahs and fuzzes. They would leave the input of the circuit connected, and switch the output. If the circuit had a lower input impedance, that made the tone dull. Using a DPDT "true bypass" fixed that situation by removing the load from the circuit. But modern buffered circuits avoid this problem, and help you retain your tone through your patch cords. This is less important with active basses, since they are already buffered.