Howto: Make your L-2000/L-2500/ASAT passive

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Howto: Make your L-2000/L-2500/ASAT passive

Postby Ken Baker » Sun Sep 17, 2017 12:58 pm

Member Kostaboda wants to mod his L-2000 and ASAT to be passive. Sounds like a reasonable thing and a good target for a howto. Here you go.

Standard disclaimer applies. You're using sharp and/or hot tools in and around your bass. You're responsible if anything gets messed up when following this howto.

Starting off with Paul's excellent drawing I added a few red circles and arrows, though I did leave off the paragraph on the back of each one explaining how..... Nevermind. Click the image for a PDF.

Image

    1. Remove the battery.

    2. Carefully unstick the preamp board from the back of the pots.

    3. At location #1 on the volume pot, carefully snip off the lead that goes to the preamp board. Snip it off as close to the solder lug as possible without disturbing the other lead.

    4. At location #2 on the volume pot, carefully snip off the lead that goes to the preamp board. Snip it off as close to the solder lug as possible without disturbing the other leads.

    5. At location #3 on the preamp board, carefully snip off the red lead that goes to the battery clip. Cut the lead about 1/2" from the board.

    6. At location #4 on the jack, carefully snip off the black lead that goes to the battery clip.

    7. At location #5 on the jack, carefully desolder the lead that goes to the Active/Passive switch.

    8. At location #6 on the bass pot, carefully snip off the lead that goes to the Active/Passive switch.

    9. At locations #7 on the Active/Passive switch, carefully snip off the marked leads and either leave them hanging or remove if loose.

    10. At location #8 on the Active/Passive switch carefully desolder the lead that goes to the volume pot, leaving the lead hanging from the volume pot.

    11. Carefully remove the preamp board from the bass and store with all your bass paperwork.

    12. Carefully remove the battery clip and store with the preamp. Then remove any other loose leads that have been created and discard.

    13. Connect the lead that you disconnected in step 10 above to the jack lug marked with the circled #5.

That should do it. Obviously, the Active/Passive switch isn't doing anything. You can leave it in place or replace it with a pop-in hole cover.

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Re: Howto: Make your L-2000/L-2500/ASAT passive

Postby jim.i » Sat Dec 02, 2017 12:09 pm

So if i am understanding this mod (and entirely possible i am not), this differs from simply removing the battery by removing both battery AND preamp board, yes?

In "stock" mode, without battery, the preamp still is in the circuit, so perhaps adds some kind of flavor however slight to the output sound, yes?

If i got this right, how does the output sound differ between no battery/preamp in vs. no battery/no preamp?

Maybe this should be moved to Paul's Technicalities? If so Ken can you please do that.
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Re: Howto: Make your L-2000/L-2500/ASAT passive

Postby Ken Baker » Sat Dec 02, 2017 3:33 pm

jim.i wrote:So if i am understanding this mod (and entirely possible i am not), this differs from simply removing the battery by removing both battery AND preamp board, yes?


Correct.

In "stock" mode, without battery, the preamp still is in the circuit, so perhaps adds some kind of flavor however slight to the output sound, yes?


Correct again! Yes, the input of the preamp is hard connected to the signal chain and adds a tiny bit of loading to the circuit.

If i got this right, how does the output sound differ between no battery/preamp in vs. no battery/no preamp?


No battery/preamp is louder and cleaner (to my ears) than normal passive mode or no battery/passive. Series is HUGE. You're hearing JUST the pickups. OMG!

The only gotcha is that cable length needs to be 12 feet or shorter to avoid passive tone suck.

Maybe this should be moved to Paul's Technicalities? If so Ken can you please do that.


It could go either place, but this is where it started and is totally appropriate. It is, after all, Associated with an Experimental Bass. 8-)

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Re: Howto: Make your L-2000/L-2500/ASAT passive

Postby jim.i » Sat Dec 02, 2017 5:46 pm

Thanks Ken, very interesting mod. So, essentially the no batt/preamp L-2nnn ends up like the SB-1 or SB-2 ie passive with MFD pickup(s).
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Re: Howto: Make your L-2000/L-2500/ASAT passive

Postby Ken Baker » Sat Dec 02, 2017 6:34 pm

jim.i wrote:Thanks Ken, very interesting mod. So, essentially the no batt/preamp L-2nnn ends up like the SB-1 or SB-2 ie passive with MFD pickup(s).


Hmm.... Kinda maybe. About the only things in common with the SB basses is that both have MFD pickups and both are passive. Do a tone pot mod to an SB-2 and add a bass control to both the SB basses and they're essentially the same circuit. Still wildly different sounds though. The L Series in passive would still have coil switching and the huge pickups.

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