Thinking about installing a ACG EQ01 in my L2K

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Thinking about installing a ACG EQ01 in my L2K

Postby dade8283 » Mon Jun 04, 2018 6:10 am

Hello!

I’m really thinking about installing an ACG EQ01 filter preamp in my tribute L2000 bass. I’m a huge TOOL fan and love the Wal bass sound but don’t have 4K euros to spare, so this might be my best bet! I’ve read of several people online installing that preamp in a G&L L2000 with good success but I have a few questions.

First of, my plan is to (if possible) remove the entire stock preamp and switches so that it easily can be replaced later on if I would sell the bass or just charge my mind. I would just install the volyme/blend and LP filter pots so no drilling for a fourth hole! Secondly, I would like to be able to switch from parallel to series mode, preferably for each pickup seperately.

1.) is it possible to install two mini switches for series/parallell switching for each pickup or would this just complicate things? How would one go about doing this?

2.) what to do about the holes left from the switches? I would like to plugg them with something that’s not permanent and looks good with the transparent natural finish of the bass. Maybe som type of plastic pluggs exist?

Anybody here that has direct experience with this filter preamp?
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Re: Thinking about installing a ACG EQ01 in my L2K

Postby Ken Baker » Mon Jun 04, 2018 4:26 pm

dade8283 wrote:I’m really thinking about installing an ACG EQ01 filter preamp in my tribute L2000 bass. I’m a huge TOOL fan and love the Wal bass sound but don’t have 4K euros to spare, so this might be my best bet! I’ve read of several people online installing that preamp in a G&L L2000 with good success but I have a few questions.

First of, my plan is to (if possible) remove the entire stock preamp and switches so that it easily can be replaced later on if I would sell the bass or just charge my mind.


Clip the leads to the pickups, jack, and bridge ground. Clip as close as possible to the switch, jack, and the lug where the bridge lead connects. Remove the switch and pot jam nuts and the whole assembly should lift out.

I would just install the volyme/blend and LP filter pots so no drilling for a fourth hole! Secondly, I would like to be able to switch from parallel to series mode, preferably for each pickup seperately.


I'm not at all familiar with the ACG preamps, so will only talk about the passive circuit you can use to feed the thing.

1.) is it possible to install two mini switches for series/parallell switching for each pickup or would this just complicate things? How would one go about doing this?


Yes, though our circuits also provide single coil on the outer coils. Here's a passive circuit that does just that. This is an entire working circuit, so you'll need to pare out the bass, treble, and (maybe) the volume controls. Possibly even replace the pickup select switch with a smart blend. Click the image for a PDF.

Image

There is also some info here that you might want to read.

2.) what to do about the holes left from the switches? I would like to plugg them with something that’s not permanent and looks good with the transparent natural finish of the bass. Maybe som type of plastic pluggs exist?


Check online electronics suppliers for panel caps. They're little pop-in pieces that are usually available in black or chrome, maybe other colors, and in various diameters.

Ken...
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Re: Thinking about installing a ACG EQ01 in my L2K

Postby dade8283 » Sat Jun 09, 2018 12:04 pm

Ken Baker wrote:
dade8283 wrote:I’m really thinking about installing an ACG EQ01 filter preamp in my tribute L2000 bass. I’m a huge TOOL fan and love the Wal bass sound but don’t have 4K euros to spare, so this might be my best bet! I’ve read of several people online installing that preamp in a G&L L2000 with good success but I have a few questions.

First of, my plan is to (if possible) remove the entire stock preamp and switches so that it easily can be replaced later on if I would sell the bass or just charge my mind.


Clip the leads to the pickups, jack, and bridge ground. Clip as close as possible to the switch, jack, and the lug where the bridge lead connects. Remove the switch and pot jam nuts and the whole assembly should lift out.

I would just install the volyme/blend and LP filter pots so no drilling for a fourth hole! Secondly, I would like to be able to switch from parallel to series mode, preferably for each pickup seperately.


I'm not at all familiar with the ACG preamps, so will only talk about the passive circuit you can use to feed the thing.

1.) is it possible to install two mini switches for series/parallell switching for each pickup or would this just complicate things? How would one go about doing this?


Yes, though our circuits also provide single coil on the outer coils. Here's a passive circuit that does just that. This is an entire working circuit, so you'll need to pare out the bass, treble, and (maybe) the volume controls. Possibly even replace the pickup select switch with a smart blend. Click the image for a PDF.

Image

There is also some info here that you might want to read.

2.) what to do about the holes left from the switches? I would like to plugg them with something that’s not permanent and looks good with the transparent natural finish of the bass. Maybe som type of plastic pluggs exist?


Check online electronics suppliers for panel caps. They're little pop-in pieces that are usually available in black or chrome, maybe other colors, and in various diameters.

Ken...


Sorry for the late reply and thank you very much Ken!

It’s either going to be the full ACG EQ1 filter pre or just installing a stacked volume/blend pot. I just found out that Noll Electronic makes a dual concentric stacked 500KB vol / 220KA+220KC blend pot that could potentially also give me some really cool tonal options while being cheaper aswell. It’s a tough choice and I Will also have to make shure that the very tall pot fits...

Here is a link. What do you think?
http://noll-electronic.de/potentiometer/ (Its under dual shaft multifunction)
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Re: Thinking about installing a ACG EQ01 in my L2K

Postby Ken Baker » Sat Jun 09, 2018 7:51 pm

dade8283 wrote:It’s either going to be the full ACG EQ1 filter pre or just installing a stacked volume/blend pot. I just found out that Noll Electronic makes a dual concentric stacked 500KB vol / 220KA+220KC blend pot that could potentially also give me some really cool tonal options while being cheaper aswell. It’s a tough choice and I Will also have to make shure that the very tall pot fits...

Here is a link. What do you think?
http://noll-electronic.de/potentiometer/ (Its under dual shaft multifunction)


It's your bass, so do whatever makes you happy. Please don't interpret that as me disapproving - I'm pretty neutral on that.

Things to consider after looking at those pots:

For passive or stock L-2000s, the volume control(s) should be 250KA. 500KA will make the bass a bit brighter than standard. A 500KA blend can have the same effect, though it would probably be less noticeable. A passive tone pot (really just a treble cut) should be 250KA with your cap value of choice, though .047µf or .1µf would be considered normal. 50K linear pots are used as a part of fully active circuits and just don't work well in passive circuits.

Regarding blend pots: look for a smart blend pot. A smart blend pot is different than your bog standard blend pot. When at the center detent both pickups are at full volume. Move off the detent and one pickup remains at full volume while the other is cut. Move off the detent in the other direction and the deal is reversed. This is the type of blend found in the M Series.

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Re: Thinking about installing a ACG EQ01 in my L2K

Postby dade8283 » Sun Jun 10, 2018 11:37 am

Ken Baker wrote:
dade8283 wrote:It’s either going to be the full ACG EQ1 filter pre or just installing a stacked volume/blend pot. I just found out that Noll Electronic makes a dual concentric stacked 500KB vol / 220KA+220KC blend pot that could potentially also give me some really cool tonal options while being cheaper aswell. It’s a tough choice and I Will also have to make shure that the very tall pot fits...

Here is a link. What do you think?
http://noll-electronic.de/potentiometer/ (Its under dual shaft multifunction)


It's your bass, so do whatever makes you happy. Please don't interpret that as me disapproving - I'm pretty neutral on that.

Things to consider after looking at those pots:

For passive or stock L-2000s, the volume control(s) should be 250KA. 500KA will make the bass a bit brighter than standard. A 500KA blend can have the same effect, though it would probably be less noticeable. A passive tone pot (really just a treble cut) should be 250KA with your cap value of choice, though .047µf or .1µf would be considered normal. 50K linear pots are used as a part of fully active circuits and just don't work well in passive circuits.

Regarding blend pots: look for a smart blend pot. A smart blend pot is different than your bog standard blend pot. When at the center detent both pickups are at full volume. Move off the detent and one pickup remains at full volume while the other is cut. Move off the detent in the other direction and the deal is reversed. This is the type of blend found in the M Series.

Ken...


No worries! I appreciate your advice, that´s the whole reason I´m asking it here :)

Okey, that makes sense. The L2000 is plenty bright as is and I really have no reason the make it even brighter. So you´re telling me that the above volume/blend pot probably isn´t a good choice?

I have no clue if it is a "true blend" pot or not. All I know is, that it seems like that there´s only to companies making and selling a stacked dual concentric volume/blend pot (without being a costom order), one of them is MEC/warwick (EXPENSIVE!) and the one I linked from Noll Electronic, soo not a lot of options. I think the one from Noll is for one of their own bass preamps..
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Re: Thinking about installing a ACG EQ01 in my L2K

Postby Ken Baker » Sun Jun 10, 2018 4:24 pm

dade8283 wrote:Okey, that makes sense. The L2000 is plenty bright as is and I really have no reason the make it even brighter. So you´re telling me that the above volume/blend pot probably isn´t a good choice?


I think I'd keep looking. You might look to StewMac for the parts you need. They are US-based but do ship internationally.

I have no clue if it is a "true blend" pot or not. All I know is, that it seems like that there´s only to companies making and selling a stacked dual concentric volume/blend pot (without being a costom order), one of them is MEC/warwick (EXPENSIVE!) and the one I linked from Noll Electronic, soo not a lot of options. I think the one from Noll is for one of their own bass preamps..


As to brands, look for Bournes and Alpha.

Ken...
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Re: Thinking about installing a ACG EQ01 in my L2K

Postby bigtone23 » Wed Jun 13, 2018 11:07 pm

Couldn't you put a 470K or 510K resistor across the outer terminals of the 500K pot to make a virtual 250K? I know it changes the taper to more linear-esque, but does bring the resistance down.
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Re: Thinking about installing a ACG EQ01 in my L2K

Postby Ken Baker » Thu Jun 14, 2018 8:18 am

Edit to add missing words and (maybe) add some clarity to my weird equation below.

bigtone23 wrote:Couldn't you put a 470K or 510K resistor across the outer terminals of the 500K pot to make a virtual 250K? I know it changes the taper to more linear-esque, but does bring the resistance down.


Good idea, incorrect value. You'd need two 1M resistors,

I've done this to make a 500KA dual concentric pot a 250K dual concentric pot. You're right in that it messes up the curve a little, but it works. The 500K pot being altered should be audio taper.

Using Ohm's Law and the "reciprocal of the reciprocal" formula for calculating an effective resistance from unequal resistances in a parallel network:

Individual resistances expressed in ohms, NOT K-ohms or Meg-ohms.

1/((1/1000000) + (1/1000000) + (1/500000)) = 250000

Using a calculator ("AC" - Clear All, "MC" - Memory Clear, "M+" - Memory Plus, "MR" - Memory Recall)

AC
MC
1÷1000000=M+
1÷1000000=M+
1÷500000=M+
1÷MR=250000

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Re: Thinking about installing a ACG EQ01 in my L2K

Postby dade8283 » Sun Jun 17, 2018 2:14 am

Thanks for the info guys! I emailed Noll Electronic and asked if it was a "smart blend" pot or not.

If I´m gonna go that route I´m also going to replace the bass and treble pots since they´re scratchy and thought I´d take the time and replace the caps aswell. Somebody clearly has been messing around in there before and I´m not 100% the caps are all up the spec/right value. Maybe that´s the hole reason I don´t like the sound on that L2K I got... I´ve got the right value pots put I´m having a real hard time finding all the right caps, especially the 222k and the 201k. The other two I could find here in the EU but only ceramic. Where do I find those and what do I search for? My understanding is that they´re polyester/mylar.
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Re: Thinking about installing a ACG EQ01 in my L2K

Postby Ken Baker » Sun Jun 17, 2018 7:18 am

At the extremely low voltages in a bass passive circuit, pretty much any cap of the correct value should do. Poly is preferred, obviously, but disc ceramic should also be okay. In fact, ceramic may be all you can find for the 200pf (201k) cap on the volume pot. The 222k (.0022µf) should probably be easier to find.

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