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pre for active pickups

Discussion in 'Pickups & Electronics [BG]' started by denchiq, Apr 27, 2009.


  1. A guy I know asked me a question and I realized I wasn't sure about the answer. Does it matter what pre is to be installed for active pickups (EMG EDIT: DC40s)? At first sight, I said yes: the amplified signal from active pickups would need more headroom, hence input resistance is to be observed; 18V-powered pre seems to be a sure answer in any case. Then again, I wasn't so sure.

    By the way, what pre would you advise to get any close to Sean Malone's sound on a fretless? He uses Bartolini NTBT, does he not?

    Thanks,
    Denis
     
  2. spode master

    spode master

    Jan 21, 2007
    There is no such thing as an active pickup. If you put a pre amp in you want to have the load resistors selected to compliment the Z of the pickup, and its resonance.
     
  3. Care to explain?
     
  4. mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    This is wrong. All the original EMG series pickups are active (i.e. they have their own internal preamp and require a battery), and there are several active models of Bartolini and Duncan Basslines pickups.

    To answer the OP, as I understand it, the main difference with preamps to be used with active pickups and those to be sued with passive pickups has more to do with the pots used for volume/blend controls in the wiring harness than the with the preamp itself. Active pickups typically require something like 25k pots, and most passive pickups take 250k or 500k pots. If you're buying a preamp without volume/blend controls included, there should normally be no problem. Otherwise, ask the manufacturer if there are active and passive pickup versions of the wiring harness.

    The one exception to this that I can think of is Audere, which offers the Z-mode switch to modify the impendence that the pickup is hooked up to. That does not work with active pickups. Also, preamps with active blend controls (J-Retro) may not work--I'm not sure.

    Mike
     
  5. spode master

    spode master

    Jan 21, 2007
    Unless EMG is potting electronics into the pickup housing there is no such thing as an active pickup.

    A pickup is a passive device. Some I think I've heard called active only pickups, Are Low Z pickups. They are usually lower output and require more gain. That's why many companies sell pre-amps that are intended to be used with the LOW Z pickups, to boost signal levels closer to that of Hi-Z pickups. Most Low Z pickups could be run directly into a mic pre-amp but most bass and guitar cabs don't have mic pre-amps.

    Normally any pre-amp is used to buffer the pickup from the successive stages, keeping the load on the pickup stable and immune to loading effects caused by pots/tone/circuits and instrument cables.

    The output impedance of the buffer stage is normally quite low, so much smaller passive electronics can be used.

    I'm not certain but If a passive volume control (pot) was to be used for a LOW-Z pickup the convention would be to use a pot value that was ~equal to the Z of the pickup at its resonant peak.

    Normally the reason to use Low Z pickups is for extended High frequency response. And in the case of instruments like Alembic, allows them to push the pickups resonance out higher than what most pickups have, so they can use variable Low Pass filters (resonant or +Q) to allow the player to select where the pickup resonance and roll off happens.

    That's all I have to say at the moment. All an electro magnetic pickup is is a coil of enameled wire, CAREFULLY wrapped around a bobbin some pole pieces and some magnets. Hi Z use more turns of wire and sometimes smaller gauge, Low Z use less turns of wire and sometimes larger gauge.
     
  6. mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    Yes, that's exactly what they're doing--that's what EMGs have been known for since they first started making them over 25 years ago! They are low-Z with fewer windings for a wider frequency response, less magnetic pull, and less impact from long cables, and have built-preamps (requiring battery power) to compensate for the inherently lower output. (See http://www.emginc.com/pages/whyemg if you don't believe me...)

    Mike
     
  7. excane

    excane Banned

    Aug 23, 2005
    New York, NY
    +1

    This is exactly what EMG has been known for.
     
  8. sure thing. And I have mentioned the pickups in question are the EMG 40DC http://www.emginc.com/products/index/120

    As the manufacruterer says,
    In the EMG-40DC, we have succeeded in getting this extended range by utilizing an ultra low noise, low-impedance internal preamp, paired with ceramic loaded dual parallel coils that result in an extremely versatile unit
     
  9. Low-Z, Hi-Z, - are we talking about output resistance? Sorry if I misunderstand
     
  10. Skelf

    Skelf

    Apr 15, 2005
    Moffat D&G Scotland
    Builder AC Guitars.
    Hi
    The East pre-amps will work with EMG pickups as will the ACG pre-amps.

    Cheers
    Alan
     
  11. spode master

    spode master

    Jan 21, 2007
    Never looked that closely at EMG's stuff. I do remember seeing that they have a much wider frequency response for most of their bass pickups than guitar.

    Its interesting because it keeps EMG's pickups more proprietary, and black box. Less options for the tinkerer.

    I have played with some of the alembic low Z guitar pickups. I built my own pre amps and filters. Very versatile great for clean and saturated lead.
     
  12. mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    Cool!
     
  13. Stealth

    Stealth

    Feb 5, 2008
    Zagreb, Croatia
    How exactly would you describe a saturated lead? For some reason my brain can't form the exact sound. :meh:
     
  14. spode master

    spode master

    Jan 21, 2007
    Somewhere in between Brian May, Dimbag Daryl, Alan Haldsworth, John Christ, Zak Wylde, Guitarist from Mastodon.... Etc

    Nice and hard clipped
     
  15. DaveAceofBass

    DaveAceofBass Supporting Member

    Feb 20, 2004
    Charlotte, NC
    This is not a very researched statement. EMG is not the only type of active pickup, they're just the most well known. As the OP said, Bartolini, Seymour Duncan, Alembic, and others make active pickups--with preamps in the housing. Note that MTD has used active Bartolini pickups for a long time in their USA basses (although I think they recently switched, but I'm not sure). Active pickups have less turns of wire and therefore have a supposedly wider frequency response.
     
  16. spode master

    spode master

    Jan 21, 2007
    Although EMG apparently does pot its pre-amps into the pickup which makes them active only.

    I Think you are confusing active with Low impedance.

    I'm sure others have potted the pre-amps into the pickup casing.

    That said I don't see any compelling reasons for potting the pre amp into the pickup. I know companies can make their pickups very easy to set up, without routing the body or complex wiring, and they can conceal the circuit from someone that might reverse engineer it or tinker with it. But if any component on that potted pre-amp goes bad, you have to throw the whole baby out with the bath water.

    Low impedance pickups which typically have less turns of wire and wider frequency response, normally require active electronics (vs passive) to bring the pickup signal to a usable level before sending to amplifier.

    I own an Alembic Bass, with Anniversary electronics. The pickups are Low impedance, and it has a modular electronic components that have quick connect pin configuration. But the pickups are not active.

    I also have an Alembic hum canceling "Strat" style, and "Gibson" style. They have no active electronics embedded in the pickup.

    I doubt that Alembic ever made a pickup with the pre-amp potted into it, as they seem to be quite fond of modular and serviceable configurations.

    I also have a Les Paul Triumph Bass with Low Z pickups. It originally had a matching transformer in it, instead of a pre-amp.

    Can't speak for other manufacturers I'm sure someone else has potted the pre's into the pickup.

    I'm pretty sure a majority or Low impedance pickups use active pre amps, but a minority of pickups are "active".
     
  17. I have a pair of EMG P style Pickups in my fender. it takes 9V and has no preamp. the pickups are each wired to a volume pot and from ther they both go into a tone pot (not sure the capacitor size) and to the input. this would lead me to believe that there is such thing as a active pickups.
    so if they have an internal preamp, could i hook these things to a typical preamp? (obp-3)
     
  18. mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    I'm afraid you're the one who's confusing "low impedence" with "active", since only a few posts ago you were claiming "active" pickups didn't even exist.

    Aside from the Les Paul Triumph you mention (long out of production, though Les Paul was the first to appreciate the benefits of a low-Z pickup) and Alembic, I can't think of any low-Z bass pickups that don't have built-in preamps.

    Mike
     
  19. spode master

    spode master

    Jan 21, 2007
    Well I must say my understanding of electronics is better than my knowledge of, what pickup manufacturer's offer.

    Seems that a majority of the Active pickups except EMG are specifically guitar pickups. Bartolini apparently has Active Guitar pickups, but I can't find active bass pickups on their site.

    So Ok for the most part an "Active pickup" is has a Low impedance pickup, with an integral pre-amp in the same housing.

    Interesting that the Seymore Duncan AHB-1's claim wider band response, yet they have their resonances set to 750Hz, and 540Hz. Thats Darker than most Passive HZ humbuckers...

    ...Go figure.

    I like user serviceable parts, myself.
     
  20. Stealth

    Stealth

    Feb 5, 2008
    Zagreb, Croatia
    While we're on the topic of active/passive vs Hi-Z/Lo-Z... Let's see if I can sum this up right.

    Basically, Hi-Z pickups have more turns or thinner gauge wire, while Lo-Z have less turns or thicker gauge wire? If I remember resistance, it's supposed to go down the thicker the lead (wire), but it goes up the longer the coil is.

    On the other hand: actives include an internal preamp in the pickup which then goes to (active or passive) controls, while passives don't have one yet still go to (active or passive) controls.

    Correct me if I'm wrong, please. I want to make sure this sums it up more or less.
     

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