Active Pickups - Mechanism

[AM1]

Aloha

How do active pickups actually work???

Regards

AM

[Fraktal]

Active pickups are kinda rare. Only a few brands make them: Most EMG pickups are active, and I have seen a few Seymour Duncan models many years ago. Most Pickups are passive, but when paired with a built-in preamp inside the bass, they advertise 'active', meaning 'active electronics', but most of the times, not necessarily 'active pickups'

There is not much difference between active pickups and passive ones. Active pickups have very tiny electronics preamps embedded inside the epoxy block, so you have the magnets, the coils and the circuitry everything inside a single piece. EMG proudly advertises this technology stating that, since the circuits are so close (inside) the pickup the sound suffers less degradation/interferences/whatever, in theory because the wiring is minimal. Though in my opinion, the most harmful thing to the signal from a pickup is not necessarily the wiring, but going through an integrated circuit. Every time the signal passes through an integrated circuit something is lost, the signal will degrade, even if minimally, and the IC will add noise, distortion, etc so I have never been seduced by active pickups.

The principle is the same than passive pickups+preamp, just everything tidier, smaller, more compact. I prefer a signal path with a minimum of integrated circuits on it: Passive pickups and NO built-in preamp (passive bass). We already have an EQ inside our amp/mixing desk/whatever, so there is no need to force the signal through another set of EQ filters and more ICs (the built-in preamp).

The best, cleanest, purest bass sounds I have ever heard came from 2 passive basses (passive '75 Fender Jazz bass MIA and a passive Warwick) plugged directly into a protools system. Makes sense when you realize the amount of ICs in that signal path are truly minimal. The sound was so in-your-face that we didnt need to process the sound at all, no EQ, no compression, nothing at all. It cut through the mix like a knife, amazing definition, full of detail, low-end, nuances, harmonics... You name it.

Edited December 16, 2008 by Fraktal

[AM1]

Hiya

Thanks for the explanation.

[quote name='Fraktal' post='355533' date='Dec 16 2008, 12:14 AM']There is not much difference between active pickups and passive ones. Active pickups have very tiny electronics preamps embedded inside the epoxy block, so you have the magnets, the coils and the circuitry everything inside a single piece. EMG proudly advertises this technology stating that, since the circuits are so close (inside) the pickup the sound suffers less degradation/interferences/whatever, in theory because the wiring is minimal. Though in my opinion, the most harmful thing to the signal from a pickup is not necessarily the wiring, but going through an integrated circuit. Every time the signal passes through an integrated circuit something is lost, the signal will degrade, even if minimally, and the IC will add noise, distortion, etc so I have never been seduced by active pickups.[/quote]

While I can see the logical basis of this argument, I can hear a noticeable difference between active and passive if I listen really carefully. When you say that something is lost every time the signal passes through an IC, what is it technically that causes that loss/adds noise??

[quote name='Fraktal' post='355533' date='Dec 16 2008, 12:14 AM']The principle is the same than passive pickups+preamp, just everything tidier, smaller, more compact. I prefer a signal path with a minimum of integrated circuits on it: Passive pickups and NO built-in preamp (passive bass). We already have an EQ inside our amp/mixing desk/whatever, so there is no need to force the signal through another set of EQ filters and more ICs (the built-in preamp).[/quote]

I take your point on the principle, i.e. passive pickups and preamp being the same. I do like the clean sound of passive also but am beginning to open my mind and see the "sound science" possibilities with active pickups and preamp/passive pickups.

[quote name='Fraktal' post='355533' date='Dec 16 2008, 12:14 AM']The best, cleanest, purest bass sounds I have ever heard came from 2 passive basses (passive '75 Fender Jazz bass MIA and a passive Warwick) plugged directly into a protools system. Makes sense when you realize the amount of ICs in that signal path are truly minimal. The sound was so in-your-face that we didnt need to process the sound at all, no EQ, no compression, nothing at all. It cut through the mix like a knife, amazing definition, full of detail, low-end, nuances, harmonics... You name it.[/quote]

That's really interesting as those are the two basses I am currently struggling to decide between, apart from the pure playability differences and sound, I like the fact that the Warwick can be played both passive and active, but the tone of the Warwick is less versatile than the Fender. Tough call!

tBBC of course loves the Warwick and heavily recommended it

Probably a long shot but I don't suppose you've got recordings of those sounds???

Regards

AM

Edited December 16, 2008 by AM1

[Fraktal]

[quote]While I can see the logical basis of this argument, I can hear a noticeable difference between active and passive if I listen really carefully. When you say that something is lost every time the signal passes through an IC, what is it technically that causes that loss/adds noise??[/quote]

Im sorry to deceive you but unfortunately Im no electronic engineer. The reason for a transistor (wich is the basic innards of an IC) adding noise and distortion has been explained to me once or twice by qualified people, though Im afraid I forgot the concepts behind it.

Still, I can speak from my experience, and this has been tested, I think, every single day of my life, since every day I listen to signals coming from some kind of IC. It doesnt matter how good a transistor is, even the best one will always introduce noise and distortion.

The noise might be easy to notice, most of the times being the infamous 'hiss' we all have suffered and hate. Distortion might be much less apparent, since human ear has a certain tolerance, a signal can have a bit of distortion, but under a certain threshold or percentage, you cant really perceive it, at least CONSCIOUSLY. There is always a fair chance you will perceive it subliminally before it becomes obvious. Whether that annoys someone or not, its up to each one of us: Some people are very sensitive to it, some others couldnt care less.

Some classical music lovers with a very gifted and trained ear go to the extreme of listening exclusively vinyl discs through incredibly expensive valve amplifiers, because vinyl discs generate an analog signal with some harmonic distortion that is considered to be much more pleasant, natural and musical than that of CDs. Similarly, the distortion from valve amplifiers is generally considered to be much more pleasant, natural and musical than that of transistors, since it tends to boost even harmonics (valves) instead of odd harmonics (transistors). Not only that, but valve distortion is also much harder to perceive than transistor distortion, i.e. you need a much higher percentage of valves THD (Total Harmonic Distortion) to perceive it.

Some other people listen crappy quality, low bitrate, highly compressed MP3s through Ipods with their factory default earphones. To each their own.

In addition to noise and distortion, transistors also 'color' the sound, i.e. they boost some frequencies and damp others, yet another reason to use as few as possible in the signal path.

[quote]I take your point on the principle, i.e. passive pickups and preamp being the same. I do like the clean sound of passive also but am beginning to open my mind and see the "sound science" possibilities with passive pickups and preamp/active pickups.[/quote]

Thats alright, but as I said on my previous post, your amp or mixing desk or whatever equipment you are using to deal with the signal of your bass, already has an EQ, and most times a much better EQ than that of an active bass, so where is the point?

Preamp circuits were included in bass guitars because old pickups had low output. When you combine low output with a very long cable, you lose/dampen some frequencies due to the capacitance of the cable and also catch some interferences thanks to the cable working as an antenna etc. Modern pickups usually have high enough output so the built-in preamp of an active bass is not needed at all.

Manufacturers still include active circuitry for basses cos its a "feature" and that help with sales, even though you may not need it at all and never realize it. Have you noticed guitarists flee in terror away from active guitars? Active guitars are almost as rare as flying cows. Why does a bass need a built-in preamp, but a guitar doesnt? Its all just trends and shiny bits to sell stuff to the masses. A good passive bass gives you a perfect, pure signal with ZERO added noise/distortion/coloration. As a smart friend of mine used to say:"If it isnt broken... DONT FIX IT, FFS!". If a passive system works wonderfully, why introduce more complexity into it? You lose reliability and quality and increase costs. When I play with my passive basses I NEVER miss any feature from my active basses, and always enjoy a better sound.

[quote]Probably a long shot but I don't suppose you've got recordings of those sounds???[/quote]

Nope, sorry, that was a few years ago and it was a job for someone that paid for it, and he obviously kept the recordings and the rights.

[Paul S]

I can add nothing if a techincal nature to this discussion but I was in a position where I needed to buy a bass just a few weeks ago and from a standing start in terms of what I wanted. I basically didn't know. I thought I might want a Fender but had nothing set in stone.

After hours of noodling in the shop with nearly everything they had on the wall it became a playoff between a MIA Jazz and MIJ Jaguar. There was little to separate them in terms of playability - maybe the Jazz was a whisker ahead in build quality but it was also £150-odd more expensive. Not always the main criterion but it does come into play.

The Jaguar took it because of the huge range of sounds it makes - I play in a simple covers band so this is useful. Not everyone's cup of T I know but you can switch for neck only/bridge only/both in series OR in parallel (whatever that means - it sounds different - P-Bass VS Jazz? That's the spin, anyway). Then there is the secret weapon - a very primitive but highly effective active circuit with a 2 band equaliser operated by little rollers and still affected by the master tone knob (despite what you might read). So, as far as I can see (and hear) it has everything, tonally, you (or, at least, I) could wish for - a P-Bass or Jazz sound (arguably... different, anyway), with active boosting if you want it. Add to that a nice skinny Jazz neck and drop dead retro styling and I was smitten. Worth a thought, maybe.

[Musky]

Just to correct something here - active pickups are often quieter than the passive variety. Because they use electronics to boost the output level of the signal they can get away with using fewer winds on the pickup, and hence a lower impedance output. A lower impedance pickup is less likely to pickup noise and can have more treble content.

Proof of the pudding is, as always, in your ears. It has to be said that most people use passive pickups, but it's mostly down to taste.

Edited December 16, 2008 by Musky

[Fraktal]

[quote name='Musky' post='355678' date='Dec 16 2008, 11:02 AM']Just to correct something here - active pickups are often quieter than the passive variety. Because they use electronics to boost the output level of the signal they can get away with using fewer winds on the pickup, and hence a lower impedance output. A lower impedance pickup is less likely to pickup noise and can have more treble content.

Proof of the pudding is, as always, in your ears. It has to be said that most people use passive pickups, but it's mostly down to taste.[/quote]

Im sure you got a point there, but I have never heard any noise coming from my MEC soapbar pickups. No hiss, no halogen lamps hum, no interferences, nothing. Also, they have lots of highs and very often I have to attenuate the high frequencies. I must say that I replace the strings once a month, and that helps a lot with the highs, but still, new strings not only give you more highs, also a much more clean, stable, tight bass frequencies and defined mids, sustain, etc.

[Mr. Foxen]

[quote name='Fraktal' post='355578' date='Dec 16 2008, 05:32 AM']Have you noticed guitarists flee in terror away from active guitars? Active guitars are almost as rare as flying cows.[/quote]

That's not nearly true, loads of guitarists use EMG pickups, from Prince to Zack Wilde to Ben Chappell.