Mod to lower ACTIVE pups output to PASSIVE levels?

[rainsong86]

I have one guitar with the Dave Mustaine active pickup set and all of my other guitars have passive pickups. I'd like to install a mini switch that lowers the volume of the active set to passive pickup output levels.

Anyone ever heard of anything like this and know how to accomplish it? I don't want to use the volume pots for this, as it'd be moreso a quick (and exact) solo boost, and don't want to use a pedal.

 

[Van Noord]

Re: Mod to lower ACTIVE pups output to PASSIVE levels?

I don't sorry, but I know that with my Blackouts they are much louder than all my other pickups including my EMGs. It's kind of annoying.
I simply lowered the pickup height to a point where they don't lose their attack or feel but enough to lower their volume.

 

[Artie]

Re: Mod to lower ACTIVE pups output to PASSIVE levels?

A simple L-pad would do it. Two resistors. Give me a sec, and I'll draw it up.

Oops. Will have to wait 'til tomorrow. My electronic symbols are on another computer. But you can just "Google" L-pad. The math is the tricky part.

 

[rainsong86]

Re: Mod to lower ACTIVE pups output to PASSIVE levels?

Yea Van I'd imagine that's a good fix (altho might decrease sustain) if you want to keep the guitar at that lower volume level but I'd be playing the guitar most of the time with the switch throttling the active pups 5-10dB's and then I can switch the active pups to their normal level for a boost.

I don't know what value resistor in a mini switch would correspond to say the volume drop from a Mustaine active pickup to that of the Duncan JB it's based off of

 

[rainsong86]

Re: Mod to lower ACTIVE pups output to PASSIVE levels?

A simple L-pad would do it. Two resistors. Give me a sec, and I'll draw it up.

Oops. Will have to wait 'til tomorrow. My electronic symbols are on another computer. But you can just "Google" L-pad. The math is the tricky part.

That'd be very helpful and appreciated. I get impatient when working on guitars and would want the math to be right before having to desolder and solder over again. It's gotta be just right so that my pedals and amp get the same input levels as with my passive pup guitars.

 

[Artie]

Re: Mod to lower ACTIVE pups output to PASSIVE levels?

You could just temporarily wire a volume pot to your output. Turn it down to the level you want. Then, carefully, without moving the shaft, measure between wiper and ground and wiper and "hot". Replace with two resistors of those values. Or whatever standard values come close. I'll post a diagram tomorrow that will help make this more clear.

 

[Jacew]

Re: Mod to lower ACTIVE pups output to PASSIVE levels?

Yea Van I'd imagine that's a good fix (altho might decrease sustain) if you want to keep the guitar at that lower volume level but I'd be playing the guitar most of the time with the switch throttling the active pups 5-10dB's and then I can switch the active pups to their normal level for a boost.

I don't know what value resistor in a mini switch would correspond to say the volume drop from a Mustaine active pickup to that of the Duncan JB it's based off of

Make a box with two jacks and a terminal strip. That way you can easily try out different values for it.

You can also find the right amount of attenuation with volume pot. Then disconnect guitar and measure the resistance from middle lug to both sides. Those are the ratings you need for attenuator resistors.

It's pretty easy to connect those in a simple switch.

 

[Artie]

Re: Mod to lower ACTIVE pups output to PASSIVE levels?

Great minds think alike.

 

[rainsong86]

Re: Mod to lower ACTIVE pups output to PASSIVE levels?

Great minds think alike.

You two really know your stuff. Thanks for the replies

 

[rainsong86]

Re: Mod to lower ACTIVE pups output to PASSIVE levels?

It's an epi LP (display pic). Could I accomplish what you're both explaining by lowering the 25k volume pot to the sweet spot for a passive pickup level and taking measurements on that? I have an ammeter that's been collecting dust.

 

[Artie]

Re: Mod to lower ACTIVE pups output to PASSIVE levels?

That would get you into the ballpark. The problem is, the new added resistors will interact with the existing volume pot. That's why there's a formula to calculate the resistors and maintain the proper load impedance. Fortunately, active pups aren't as sensitive to the impedance mismatch that a passive pup would. So, that may work fine.

 

[Artie]

Re: Mod to lower ACTIVE pups output to PASSIVE levels?

So, here's the long answer. The purpose of an actual L-pad is to attenuate the signal without creating any additional electrical load. If you wanted to do the simpler "pot" method, I'd probably use a 1M of maybe 500k pot. To do the L-pad method, do this:



It's just a switch and two resistors mounted between the output jack and the wire that goes to the jack. Here's the formula for calculating the values. It's not really as daunting as it looks.



The formula in the 1st block is usually simplified by making the antilog(db/20) part "K". "Z" is just the input impedance of the amp. Usually 1 meg. That makes the formula:



Which, if punched into a modern calculator, would be this:



Or, you can just take values from this quik-'n-dirty chart I made:



These values assume a 1 meg input impedance and they aren't standard resistance values, so you need to pick whatever's closest. With active pups, the slight variation shouldn't be a problem. Note also that 6db would be cutting the signal in half. That's probably more attenuation than you want. 3db would probably be a good starting point.

Hope this helps.
Artie