I don't even know where to begin ...

kosmicwizard · #1 12-15-2008, 12:24 AM

I have tried to do searches and haven't found anything that answers my question. I know the negative aspect of active pick ups (dead battery means no sound), but what are the positives? And what if you don't want an EQ/preamp in your bass? So you put in active EMG's and get more amperes (I hope this is the right term) flowing up the instrument cord from the strings to the amplifier head, but then you kill the bonus charge because you plug it into the "Active" input jack on your head. Am I right or wrong? And what is the point of boosting something just to cut it? Thanks for your help in regards to this. Cheers.

bongomania · #2 12-15-2008, 12:37 AM

Signal transfer isn't just about how strong the signal is, it's also about how efficiently it can travel from point A to point B.

"Impedance" is a way of determining how efficiently a signal will transfer between two devices. A very low output impedance (the measurement at the output of the sending instrument or device) should ideally connect to a very high input impedance (the measurement at the amp or receiving device).

A preamp can sometimes boost the signal level (AKA strength) but more importantly it will always lower the output impedance of a bass, which means the signal can transfer more efficiently from the bass to the amp whether or not the level of the signal is changed.

One of the key ways this is heard is in high frequency content retained. A passive bass through a long cable to the amp will typically lose some highs along the way, and may even sound a bit "tired"; whereas a bass signal that is buffered by a preamp will have a lot more high frequency content and more perceived "energy" in the tone.

That said, the sound of a passive bass with no pre-amp buffering is a classic and beloved tone, so it's all up to personal taste and goals.

kosmicwizard · #3 12-15-2008, 12:40 AM

Makes sense to me thank you once again, Bongo!

BruceWane · #4 12-15-2008, 12:44 AM

EMG is pretty much synonomous with "active pickups", so you might want to check with them for all the details.......

http://www.emginc.com/company.asp

But some of the main reasons....... active pickups are extremely quiet, which is great for recording; also their design allows them to use much weaker magnets which exert much less force on the strings, allowing them to vibrate more freely.

Lots of other stuff at the link above.

And actually, active pickups do not necessarily put out a hotter signal than passive pickups. My 77 P bass is about as loud as my 5 string with EMG soapbars. Maybe even a touch hotter.

kosmicwizard · #5 12-15-2008, 01:56 AM

Thanks Bruce, I have been to the EMG site a couple of times but never read about the company/benefits of active pick ups before. I also was unaware that a preamp is actually inside the sealed pickup unit. I was possibly referring to active electronics? Where you can actually change/shape the tone of your bass before it even leaves the instrument. Cheers.

cdawzrd · #6 12-16-2008, 05:23 AM

"Active pickups" are pickups that have a preamp built in to them. MOST "active" basses have passive pickups, just like any passive bass, but then an active preamp, sometimes mistakenly referred to as "active electronics". The active preamp, whether it is inside the pickups (EMG actives) or as a separate preamp box (most active basses) buffers the pickup signal to provide a low-impedance output, and usually also offers EQ controls.

JTE · #7 12-16-2008, 08:39 AM

The active EMGs are made in a way that allows them to optimize the actual pickups without having to worry about how hot the signal from the wires is. Then they use the preamp to shape the ultimate character of the PUP and boost the signal. With passive PUPs you get more signal with more wire and/or different magnets. However, more wire doesn't mean a better tone (that's pretty subjective BTW), so more output could compromise the sound.

Active PUPs work around this by ignoring the need for signal level from the wires and magnets. They add it with the amp. They can also shape the sound of the system with the pre-amp. In fact the only way I like EMGs personally is when they feed a good passive treble cut circuit.

jte