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[FAQ] The ultimate active / passive thread.


Jazz Ad

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Okay, so if I had a bass with one bassive bartolini J, an active EMG P, and a combination lightwave/piezo bridge, and I wanted an active EQ control on the Bart, a passive tone control on the EMG, individual passive mini-pots for controling each piezo saddle individually, a passive blend control between the piezo and lightwave, an active pre-amp to mix together the bridge/Bart/EMG signals, how would I do that?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(I'm joking....)

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Originally posted by Skippii

Okay, so if I had a bass with one bassive bartolini J, an active EMG P, and a combination lightwave/piezo bridge, and I wanted an active EQ control on the Bart, a passive tone control on the EMG, individual passive mini-pots for controling each piezo saddle individually, a passive blend control between the piezo and lightwave, an active pre-amp to mix together the bridge/Bart/EMG signals, how would I do that?


 

 

it involves putting a plastic bag over your face and going to sleep...

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Originally posted by Harpua

Good stuff. So on my bass I have active pups, an active 2 band eq, a pup blend, and what I believe is just volume (not gain). I can switch the active eq on and off as well, I almost always leave it on but I've wondered, what is the purpose of being able to switch it on and off, what's the advantage?

 

 

the major advantage is to be able to use the bass if the battery goes dead. If you were playing an active without the switch and the battery started to get weak, it would sound horrible. If it went dead, there would be no sound. Neither of these would be good in a live situation(duh). Also it makes it easier to conseve the battery rather than taking the cord whenever you stop playing. And it allows you to have an active and passive bass in one. Just like m&m's: candy shell and chocolate in the middle. Or not.

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Originally posted by Jazz Ad

Try to make a big on-topic post.


See it sink to 4th page over the night.

 

Sorry dude, I intended to bump this but I got sidetracked.

 

Once you're finished, I'll move this over to the FAQ forum, if it's okay with you.

 

And thanks for taking the time to do this. icon14.gif

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+1

spot on thread Jazz Ad

and loads of clarity

its good you split all the stages up into their respective active passive explanations.

makes it easier to understand emg design.

cheers:)

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Good thread Jazz. I'd like to make a few additions/clarifications if you don't mind:

 

The reason active pickups are lower impedance is simply due to having fewer coils of wire. This lowers their susceptibility to noise (those coils are essentially noise antennas), and also reduces their overall output. The reduced output is why active pickups require a preamp.

 

The preamp in active pickups is mounted within the pickup casing itself. This is done both for convenience and for noise reduction - the sooner along the signal chain that you boost the signal, the less oppurtunity there is for noise to get in.

 

It is quite possible to have a bass with active pickups that has passive volume and tone controls.

 

Another side effect of the fewer coils of wire on an active pickup is a more even frequency response - meaning the pickup has less 'character' and more accurately represents the sound of the bass.

 

Active pickups aren't particularly common. A passive instrument with an active eq is the most common active instrument. Don't assume your pickups are active just because you use a battery.

 

And on a related note, many amps have seperate active and passsive inputs. The active input simply has an attenuator to reduce the signal level of very hot active instruments so it doesn't overdrive the preamp. You should always try the passive input first, even if your bass is active, cause most basses aren't hot enough to really need the active input. If you use the active input when you don't need to, you're reducing your signal (and thus your signal to noise ratio and overal volume) for no good reason.

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Okay, here's a question that's more related to pickups, but it'll fit in here.

 

What determines the different tonal qualities of pickups?

 

For example. Take Fender - they use different pickups in their American, Japanese and Mexican Jazz basses, as well as custom shop and Squier. Yet the basic construction of the pickups are the same. I'd assume they have similar dimensions and specifications, and that the basic materials used are similar from one to the next. So why do the Custom shop pickups cost so much more, and why do they all sound different?

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Originally posted by bassaussie

Okay, here's a question that's more related to pickups, but it'll fit in here.


What determines the different tonal qualities of pickups?


For example. Take Fender - they use different pickups in their American, Japanese and Mexican Jazz basses, as well as custom shop and Squier. Yet the basic construction of the pickups are the same. I'd assume they have similar dimensions and specifications, and that the basic materials used are similar from one to the next. So why do the Custom shop pickups cost so much more, and why do they all sound different?

 

 

I don't know the technical differences, but I do know that there are a lot of subtleties that can affect a pickup and its performance.

 

I will assume that the quality control, the coild for the wire, the magnets are of higher caliber in MIA instruments. The characteristics of the conductive capabilities of the wire such as guage and what it is made of will affect its inductance, which is what causes a pickup to transform string vibration into electric energy.

 

Also, the number of windings, and the shape of the windings affect inductance as well. Magnets are measured by Gaus? which is reflects the loss of magnetism over time, so the quality of the magnets will affect inductance as well.

 

So, as my theory goes, to cut costs, Fender will user cheaper wire and magnets in the Squire and MIM stuff.

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Originally posted by degroove



I don't know the technical differences, but I do know that there are a lot of subtleties that can affect a pickup and its performance.


I will assume that the quality control, the coild for the wire, the magnets are of higher caliber in MIA instruments. The characteristics of the conductive capabilities of the wire such as guage and what it is made of will affect its inductance, which is what causes a pickup to transform string vibration into electric energy.


Also, the number of windings, and the shape of the windings affect inductance as well. Magnets are measured by Gaus? which is reflects the loss of magnetism over time, so the quality of the magnets will affect inductance as well.


So, as my theory goes, to cut costs, Fender will user cheaper wire and magnets in the Squire and MIM stuff.

 

 

Okay, so although the basic specs may be similar, your suggestion is that the actual components (and the quality of those components) will effect the tone. Interesting.

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Great thread.

 

It bears repeating too: even though basses with active electronics usually have more output than totally passive basses, there are some exceptions. I'm sure we've all played a bass with some jacked-up overwound passive pickup that had output up the wazoo.

 

Second of all, I think the worst kind of electronics to have are the really cheap actives. In my opinion, active electronics don't get very good until you start getting into mid-grade basses. The really really cheap instruments with active electronics usually have really cheesy preamps that don't do much more than induce noise.

 

Joe

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Originally posted by Skippii

Um...that's not quite true. You can use capacitors or inductors to do the same--that's how a 3-way crossover works in speaker cabinates.

But there is no way to make them adjustable, unless you use variable capacitors. Those are VERY expensive.

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Originally posted by bassaussie

Another excellent post there.


This is definately going to FAQ!


Jazzy - you said your first post was part 1 of 3. Where are the other two parts?

I think the 3 parts are definitely here by now. :)

Time for FAQ.

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