Active/Passive question.

[lug]

I'll say the best my Bart MMC ever sounded was when I wired it direct when building a homemade. More "open" for lack of a better term. Could be entirely psychosomatic but that's how I felt after adding a preamp. Of course it could be the fault of the preamp as well (EMG BTC control). Too many varialbes to tell for sure.

[Groove Mama]

More on this topic, from notreble.com:

 

Passive vs. Active Circuitry?

 

by Damian Erskine

Wednesday, July 7th, 2010

 

Q: Im just getting back into the bass and theres something Ive always been curious about: the differences (as well as the different kinds) of passive vs. active circuitry. What are the main differences between them, why are there only active and passive circuits, and what does it mean to have either in a bass?

 

A: Although I am not the most tech-savvy of bassists (and Im sure many of you will comment back on this to add to what I say here) I think I can answer your question.

 

Essentially, an active bass just has the addition of an on-board pre-amp to give the user further tonal control. Active pre-amps require one (or two) 9-volt batteries although Alembic (who I believe came up with the concept for Phil Lesh of the Grateful Dead) has given the option of additional cables to power the on-board pre-amp.

 

Passive controls (by definition, a pre-amp is powered, therefore you would not speak of a passive pre-amp) are generally limited to volume control and tone shaping (tone knob). While you can shape the tone a bit, there is not nearly the flexibility as with an active pre-amp.

 

The pros and cons all boil down to personal preference. Personally, I like to have pre-amps available to me but Ive also added active/passive switches to all of my basses so I have the option of playing the bass passive OR active (the most flexible way to go, I think). Many pre-amps color the sound naturally even before you boost or cut a frequency. For this reason, many players (especially traditionalists) feel that the passive electronics deliver a more organic sound. This is true, Id say. Many pre-amps do give the user a more hi-fi sound, which is desirable by some. Personally, I prefer an organic tone, but sometimes you just need to boost one frequency or another to help compensate for a particular room or to help you cut through a larger ensemble without necessarily just getting louder.

 

Most active pre-amps will offer a boost/cut knob for 2-4 frequencies. Most will have a volume control and a pickup pan. In addition, to those two knobs, the most common configurations are:

 

2-band EQ = Bass Treble

 

3-band EQ = Bass Mid Treble

 

4-band EQ = Bass Low mid High Mid Treble

 

I personally find that Ill use low and high mids the most for shaping my tone to fit a band or stage. Therefore, I tend to go 4-band EQ (often using a stacked knob for my mids (meaning there are two knobs affixed to one knob space stacked on top of each other)

 

I hate to have to rely upon batteries, which is another reason to have a passive switch if you go the pre-amp route. There is nothing worse than your sound crapping out on you in the middle of a gig because your 9-volt died on you (has happened to me once, and Ive been very careful to make sure it doesnt happen again).

 

Now, if my battery dies or starts to sound bad, I can just flip my switch and finish the set passively.

 

In short, if it sounds good to you, its right for you. Just make sure that you explore the tonal possibilities and explore the quality of the sound coming from the instrument with or without a pre-amp and use your own judgement as to what will work best for what youre doing musically.

 

If youre slinging a P-bass in a country or blues band, I wouldnt bother messing with active circuitry. However, if youre playing many different styles of music and want one or two basses that can cover it all, a nice active pre-amp can certainly help with that!

 

[azucar4u]

Active is a thing of beauty, you can shape your sound right there on your bass. Now Passive is a thing you got to get use too you have to dile your sound on your Amplifier. When you started on a active bass it's kind of hard when you play a passive thats what i have run in to. and just till now i'm starting to get in to passive basses

[Mark Schmieder]

I don't use tone controls on my amp either. :-)

 

My tone controls are in my fingers.

 

Granted, on the rare occasion that I cover something from the 90's or beyond, I find that there's a certain bite that is hard to replicate without an active on-board or out-board pre-pre-amp.

 

My clarinets, flute, and saxophones don't have pre-amps on-board either; I do the tone-shaping with my mouth.

 

This isn't meant to be snotty; I merely take on the role of Contrarian when I see incorrect assumptions about what is required in order to generate a desired effect.

[Mark Schmieder]

Robb, thanks for the write-up on Anthony Jackson's setup.

 

I have had several gigs where we went Direct to Mixer from the basses' instrument jacks, due to too many reasons to go into here.

 

Other than for some limitations on total output (not a problem in most jazz settings), I did indeed detect wider tonal range.

 

Impedance is king. A good way to experiment with impedance differentials is to borrow a Summit Audio TD-100, which is my main pre-amp for passive basses (I sold my Avalon U5 passive DI after selling my last hybrid passive/active bass last year).

 

The interesting thing is that different impedance settings on the Summit's front panel controls show up the most difference in tone on my Tele-Bass, then the Jag-Bass, and hardly at all on my Bartolini-fed Dingwall Afterburner.

 

I don't have specs in front of me right now, so can't do the math to see how this correlates with Robb's findings, regarding the impact of plugging these directly into a mixer (which themselves may not have consistent impedances for their line inputs).

[Michele C.]

Lok what I found in my Yamaha B614F. I was not expecting good old transistors in a three band preamp, pretty effective too.

 

http://a1.sphotos.ak.fbcdn.net/hphotos-ak-ash4/301217_2260515185258_1019762213_2500604_1744009764_n.jpg

 

I did not like at all the preamp in my BB604, too many high mids and a strange sweepable (not really parametric) mid cut pretty useless to me.

This one really satisfies me and I think that the mid boost or cut changes the sound in a musically sensible way. Lows and highs are usable too.

I use the controls to adapt to different amplifications or shape the sound for different occasions, but leave the lows and highs alone, most of the times.

So, I guess it depends on how musical and usable is your preamp.

In the end, I would rather have a good passive, with an external preamp I like, than an active with a cheap or questionable preamp.