question about active pickups

[Marcos - Munky]

I readed in a magazine that active pickups have a preamp inside the guitar. It's only this, common pickups with a preamp? If yes, what is a good and simple preamp to use, and if is no, how I can get a sound like the sound of active pickups?

[petemoore]

Actives [I think for the  most part] attempt to mimic the sounds of popular pickups like humbux adn singles..I don't know why [I suspect it must be marketting...retail vs mfg cost...]]
 The only thing active pups can boast that regulars can't [AFAIK] is impedance and being able to run cables and 'heating' up your amp sound with boosted signals.
 AfAIC tell coniasuerres [like me] don't like the sound as well as great quality wound pups. Of course I haven't tried all the new ones ... and I really DID like the sound of the wires and battery in an Ibanez .... uh Ibanez ... ARTIST ... now I remem. Yupp I liked that stufff...but I think you can do well/get close to that with reg pups and an onboard [guitar]booster and pedals.
  I just use the Dimarzio's and 1 monster cable to the first impedance booster ...an LPB...not having a problem with noise/tone loss/impedance problems AFAIC tell..
  So I tried this active [bridge humbuck on LP] ..I installed it and uninstalled it in less that a few hours...when I turned the vol up in the guit the amp would bark an overload bark upon attack of any bass string....of course we know it could be anythig like the particular amp etc...I exchanged for a wound Seymour and that bridge position wiring should still be  happy for whoever using  it...I am hoping the new owner of my disposessed LP [stolen] paid the thief something for his troubles and provides a happy place for the guitar I was working with/on. Karma will hit hard ... those who least expect it...lol.

[Marcos - Munky]

Thanks. Then, what is best, a preamp or a booster like the LPB?

[D Wagner]

Munky,

Check out this preamp from Don Tillman.  Easy and effective

http://www.till.com/articles/GuitarPreamp/

Hope this helps,

Derek

[Marcos - Munky]

Thanks. What I use, a preamp or a booster?

[Mark Hammer]

Preamp = booster
Buffer = booster/preamp with gain of 1

There IS no such thing as "active pickups".  Anything that advertises itself as an active pickup is just a pickup with a preamp.  The preamp can do many things, though.  

The preamp will match the impedance of the output of the guitar to what the amplifier needs to see.  This provides better performance from the guitar and amplifier, especially when using long or poor quality cables.  Plug your guittar into your amplifier with a 20ft cable, then plug it in with the shortest effects patch cable you have and listen to the difference.  That is the difference between having a buffer/impedance-matcher and NOT having one (short cables = very crisp and well-defined tone; buffering lets long cables behave the same way).  

As Les Paul showed many years ago, you can get VERY clear, crisp tone out of a pickup if you make it a low impedance coil.  The problem is that such coils need very powerful magnets to produce a reasonable signal level.  Without any boosting, low impedance pickups can be too weak to drive amplifiers properly, so "active electronics" are sometimes used to make a clear but quiet pickup seem like a lopud and clear pickup to the amplifier.

Another way in which active electronics are used is for noise reduction.  Balanced microphone lines use a ground that is separate from + and - leads.  When the two leads of the microphone reach the input preamp, any common or shared noise they pick up is electronically cancelled at the preamp.  In the same way, active electronics can be used to make single-coil pickups a bit quieter, by maintaining a ground/shield separate from the two ends of the coil.

Again, it is not the pickup itself that is active - all guitar pickups are passive.  Rather, there are electronics on-board to assist the pickups in sounding their best, whether in terms of bandwidth, noise, or level.

I have one guitar which has had a gain-of-4 preamp in it since long before you were born, and a few others without any preamp.  There are advantages and disadvantages.  Because the on-board power source will usually be a 9v battery (though there is no reason why a person could not use those little 12v batteries, or a stack of five 3v lithium batteries for 15v, etc.), it is not a good idea to aim for too much gain, because you can quickly run out of clean headroom.  It is also not a good idea to aim for too much gain because it starts to become difficult to get a clean sound out of anything.  For instance many phasers that use FETs cannot handle a big input signal, and boosting normal pickups can push the phaser FETs too hard.  The same thing goes for some delay pedals, and certainly it may be difficult to get compressors to behave well when the signal is too hot.

On the plus side, the same way that a clean booster pedal can make a simple amp come alive, so can an on-board preamp.  My main amp is a little 5W Princeton with an 8" speaker and it can be surprisingly loud when I use the preamped guitar, with a very nice overdrive.

On the negative side, I made a Tube Screamer that sounded awful when I used it with the preamped guitar but sounded just like the classic TS when I used it with a non-preamped guitar.

So there are advantages and disadvantages.  If you have a few guitars, though, keeping one of them with an on-board preamp isn't such a bad idea.  Don Tillman's single-FET preamp, or the different ones at JD Sleep's site, are all good candidates for an on-board preamp, as are some of the ones at Tim Escobedo's site.

[Arno van der Heijden]

I was wondering, do the pickups used in active pickups differ from 'standard' pickups?

Does anybody have an idea what's inside EMG-81 and 60 pickups (the ones used by Metallica and such)?

[Mark Hammer]

As I understand it, yes.  The most common difference would be that they are "underwound" resulting in a somewhat extended bandwidth but less signal output.  Best place to pose this question is on the pickup makers forum at Ampage.

[Marcos - Munky]

Thanks, Mark, this helps a lot. I'm thinking to build the LPB booster with a volume control, and use a switch to get active and passive sounds.

[Marcos - Munky]

I'm thinking, isn't better to put the booster in a box and put the box as the first effect of the pedalboard?

[Ed G.]

Like Mark said, the EMGs are underwound. They're very underwound, and I don't remember what the numbers are, but its benefit is that it results in a very quiet pickup. It gives higher bandwidth like he said, and the preamp can be tailored to mimic different frequency responses and output levels. It basically needs the preamp to have a usable signal because the output from the raw pickup is so low..

[Nasse]

I have no more knowledge that what is said about "active" pickups and their properties. I quess altough they have benefits the reason that they are not very popular is that common amps and pedals are tailored for "ordinary" pickups.

But I trow in another idea or question: I dont remember having seen or heard about commercial "active" or "electronic" switching of pickups. I have been dreaming about two, three or even four pickup guitar with totally electronic switching systems. If pickup combinations and serial/parallel and coil split could be done by electronic switching instead of mechanical switches and their limitations... maybe a Strat with push buttons instead of five-way selector...or footswitch that chances your pickup combinations and your multi-effects at same push. Of course someone has done this? If someone gets commercial success of this great idea send me some cash or few guitars at least

[Mark Hammer]

Then what you want is a Bond Electraglide (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2558313767&category=2384#ebayphotohosting).  Scroll way down and watch the slide show and be amazed.

This was a wonderfully clever guitar that came out in the early to mid-80's and once you saw one you never forgot it.  Way too advanced for the time.  sadly, the inventor/developer Andrew Bond passed away in 1999.  His son Ashley Bond is apparently quite willing to provide information and answer questions about it.  It is not in production since the 1980's but he is justifiably proud in trying to keep the memory of his dad's work alive.

[Arno van der Heijden]

Is it possible to reverse engineer these preamps? There must have been someone who's done this?
What would they look like? Fets/opamps?

[Nasse]

My friend had Music Man guitar at late seventies. It had fet based active preamp, I believe. It had helluva nice distortion when cranked. I think I once saw the circuit somewhere when surfing around. I may have some early dementia if I did not see it. If such thing is designed around some obsolete or not so easy obtainable fet then you must do some tweaking anyway. How about some jfet preamp design or minibooster?