Active/passive switch on L2K

j_micho · #1 03-12-2009, 10:05 PM

When the Active/passive switch is set on passive, is the battery still delivering (or should I say "wasting") power?

I like to practice on passive mode at home to avoid changing batteries to often...so I'm just wandering

**Chef** · #2 03-12-2009, 10:14 PM

**Freddels** · #3 03-12-2009, 10:36 PM

That's good to know. So I could leave my ASAT plugged in so long as it's in passive mode?

Ken Baker · #4 03-12-2009, 11:11 PM

Sorry, Chef, but that isn't correct. The battery is delivering power even in passive mode.

The power circuit supplying 9v to the preamp is ON whenever a cable is plugged into the bass. Switching to passive mode only takes the preamp out of the signal path and does NOT cut its power. The actual difference in power used between active and passive modes is slight and it's not enough of a difference to be concerned about it.

The best way to conserve battery life is to be sure to unplug the bass when you're not playing it.

Ken...

sunbeast · #5 03-13-2009, 12:43 AM

Another thing worth noting is that there is a difference in tone in passive mode with the battery removed (at least in my '82 L2000). I had a low battery and was curious- I'd love to hear other peoples experience with this. Without the battery, the passive tone is much more percussive and middy, and gets more scooped with the battery.

I never really payed attention to the preamp circuit as I always leave mine in passive, but always assumed that the Active/Passive switch took the preamp out of the circuit- now I have reason to believe that is not the case...for now I'm just leaving the battery out!

Karl

quickervicar · #6 03-13-2009, 03:13 PM

Huh. I was under the same understanding as Chef for all these years. While I never got into the habit of leaving the bass plugged in, it has happened in the past.

spideyjg · #7 03-13-2009, 11:42 PM

Everything Ken said is right on the money.

Jim

DavePlaysBass · #8 03-14-2009, 02:37 PM

The preamp is always loading the pickups down whether you are in passive or active. The only difference in those modes is whether the pre preamp signal or the post preamp signal goes to the output jack.

Removing the battery may result in a different loading of the pickups and hence a different sound. In fact for a G&L passive purist, removing the preamp all together would be an option that may sound different as well.

And as we have discussed on here before, leaving the preamp in passive mode and removing the instrument cable can put a jolt of electricity into the preamp that will destroy it. It is more robust during plugging and unplugging in active mode.

sunbeast · #9 03-14-2009, 06:20 PM

I just looked at the wiring diagram and verified this- seems like an odd way to wire a "passive" option! I have been considering completely scrapping my preamp, but I may just switch out the active/passive switch with a 4PDT on-on-on (I just happen to have one still from my old L2500) and wire the bottom half of the switch to completely bypass the pre from the circuit in passive...I much prefer the woody sound of the passive mode without the preamp loading, but the pre does sound good on occasion. I may just switch out the preamp entirely for a Redeemer or some other simple low-imp pre.

Karl

Quote:

Originally Posted by DavePlaysBass

The preamp is always loading the pickups down whether you are in passive or active. The only difference in those modes is whether the pre preamp signal or the post preamp signal goes to the output jack.

Removing the battery may result in a different loading of the pickups and hence a different sound. In fact for a G&L passive purist, removing the preamp all together would be an option that may sound different as well.

And as we have discussed on here before, leaving the preamp in passive mode and removing the instrument cable can put a jolt of electricity into the preamp that will destroy it. It is more robust during plugging and unplugging in active mode.

fender3x · #10 03-16-2009, 12:31 PM

Quote:

Originally Posted by sunbeast

Another thing worth noting is that there is a difference in tone in passive mode with the battery removed (at least in my '82 L2000). I had a low battery and was curious- I'd love to hear other peoples experience with this. Without the battery, the passive tone is much more percussive and middy, and gets more scooped with the battery.

In my '94 ASAT, when the battery is low, it affects the passive mode. It's like there is a bit of a short, so it'll get staticy or cut out briefly. It plays fine with the battery out...but I wasn't really listening for difference in sound...I will now.

That scratchy, low battery sound even in passive, is a big part of the reason I have been planning to put in an external battery box. That way if it gets weird on my in a gig (which happened once), I can remove the battery quickly and keep going.

Quote:

Originally Posted by sunbeast

I may just switch out the active/passive switch with a 4PDT on-on-on (I just happen to have one still from my old L2500) and wire the bottom half of the switch to completely bypass the pre from the circuit in passive...I much prefer the woody sound of the passive mode without the preamp loading, but the pre does sound good on occasion.

That's a cool alternative. Would love to see the diagram for it if you put one together.

pauldebass · #11 03-25-2009, 06:36 AM

sorry I'm a late comer to this thread. When I bought my L2000 from the factory in the Leo days, Dale the shop manager told me to make sure to turn the a/p switch off as it would drain the battery if left on. I didn't get the impression it mattered whether u left it plugged in like other basses. Most basses use a stereo jack so the active gets turned on when plugged in. I don't know about new G&Ls but mine doesn't. Does anyone know of a bass that can use the preamp when in passive. every bass I've seen except G&l looses the tone control when the bass is switched to passive.

millahh · #12 03-25-2009, 08:40 AM

This is intriguing. I'm going to have to try this out tonight. Seems like it would be an easy enough mod to just have a switch that breaks the circuit with the battery.

Ken Baker · #13 03-25-2009, 10:07 AM

Quote:

Originally Posted by pauldebass

sorry I'm a late comer to this thread. When I bought my L2000 from the factory in the Leo days, Dale the shop manager told me to make sure to turn the a/p switch off as it would drain the battery if left on. I didn't get the impression it mattered whether u left it plugged in like other basses. Most basses use a stereo jack so the active gets turned on when plugged in. I don't know about new G&Ls but mine doesn't. Does anyone know of a bass that can use the preamp when in passive. every bass I've seen except G&l looses the tone control when the bass is switched to passive.

You might open the cavity and see how many wires lead to your jack. If only two and active works as Dale told you, then you have a bit of an odd duck.

Whether or not a bass set to passive has EQ available depends on the EQ controls and where they lie in the circuit. If the Active/Passive switch is between the EQ circuit and the preamp, then passive EQ should be available. If the preamp in question has active EQ (and the usual low resistance pots), then these controls would be separate from the passive side and would not be available in passive mode.

For example, we know how the standard G&L circuit works. I've modified my L-2500 with an Aguilar OBP3 preamp and I use an Active/Passive switch. This preamp has active EQ with 50 ohm pots that are connected directly to the preamp, so I only have the volume control available in passive mode.

The nice thing about the Active/Passive switch I'm using is that it completely isolates the signal from the preamp when set passive. I'd imagine the same wiring setup could be used with the G&L preamp, but Active w/Treble Boost would no longer be an option.

Ken...

wyleeboxer · #14 03-25-2009, 11:27 AM

For what its worth, last week I took my battery out as I always use it in passive, series both pups on mode anyway with bass rolled off about 30%. Big difference in tone, I had to bring my on-board bass knob back up to 100% and the bass still did not have the scooped, low end and higher output that it had when the battery was in. The bass sounds more jazz like now, which makes me wonder if the monster L2000 tone we always hear about is actually associated more with Pre-amp then the pups?

**Chef** · #15 03-25-2009, 12:06 PM

huh...gotta try that with my old L2Ke at some point...

sunbeast · #16 03-25-2009, 01:14 PM

Quote:

Originally Posted by Chef

huh...gotta try that with my old L2Ke at some point...

If its the potential "mud-monster" that mine can be sometimes, then I think you may be pleasantly surprised- I've had my battery out for awhile now and much prefer the tone. I'm really interested to hear the difference with the pre completely removed from the circuit- If it makes my L2000e sound more like my old L1000, then I wouldn't think twice about it (taking the battery out brought it much closer on its own). I'm in the middle of a move right now, but plan to rewire the active/passive switch early next month when I'm somewhat settled in my new place. I especially dig the extra percussiveness that I get with the battery removed- I couldn't get alot of the fret growl before that I can now because of the scooped nature of the sound.

Karl

**Chef** · #17 03-25-2009, 01:39 PM

Did this briefly at lunch and didn't notice a whole lot of diff...but, this was just batt out, not "in and out, a/b'd."

wyleeboxer · #18 03-25-2009, 01:44 PM

I first tried a/b'ing with battery in/out using my tascam bass trainer and noticed a bit of a difference, but it wasnt until I pluged into my amp for practice that I noticed the significant EQ changes I had to make to the amp, including the gain.

spideyjg · #19 03-25-2009, 02:14 PM

I flip and flop way too much to leave out the active option.

Jim

**Chef** · #20 03-25-2009, 02:32 PM

yeah, me too, really
just wanted to try it