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Pre-amps


ForrestS

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I've never owned a bass with a pre-amp in it. Don't know much about them either. I picked up a Musicman Stingray 5 at a guitar shop and another customer made mention about the pre-amp in it (this is my first time hearing about them). So my question is what are some pro's and con's when having a pre-amp in the bass and why is it necessary or why is it not.

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before all the "i wont use a preamp because what if the battery goes dead while your playing" boys come marching in........

pros for me?, hotter signal to the amp for that slight amount of distortion ( some call it crunch )
EQ control on the bass if you need to tweek while playing to add/remove more bass/treb/mid
instant tone change while going from pluck to pick to slap without worrying about reaching for the amp controls.

cons?
battery that you have to check every now and then.
cheap preamps hiss when the treble is cranked

uh, thats about it until the battery-haters come in and whine up a storm.

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In GENERAL...

Preamp somewhat negates signal interaction with cable/amp. Preamp also usually lets you boost bass/treble (also mid if three band) as opposed to cutting only with passive setups. As mentioned above, some can add noise.

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The only time you absolutely have to have a preamp is if you're using a piezo pickup. Other than that it is personal preference.

Make sure you unplug it when you're not using it. A battery that would last 6+ months of normal use can go dead over a weekend if you leave it plugged in. Slightly annoying, but no different from effects pedals, etc.

Basses with 9V preamps usually have a more compressed sound than passive instruments. 18V ones less so. That can be a plus or a minus depending on what you want to sound like.

Edit to add:

Quote Originally Posted by lug View Post
Preamp somewhat negates signal interaction with cable/amp.
That's true. Just like on guitars, different volume pot settings on passive basses will impact tone. With a preamp the tone will be almost the same regardless of the volume setting. (assuming a clean amp)

Another positive/negative is that active basses usually have hotter output than passive ones. If you want to drive your amp harder it is a plus. If you want a clean sound and your amp doesn't have a db cut or high/low gain inputs it can be a negative.
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Quote Originally Posted by lug View Post
In GENERAL...

Preamp somewhat negates signal interaction with cable/amp. Preamp also usually lets you boost bass/treble (also mid if three band) as opposed to cutting only with passive setups. As mentioned above, some can add noise.
Rickenbacker 3000 series basses, such as my 3001, have boost/cut bass and treble controls on passive basses.
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Quote Originally Posted by isaac42

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Rickenbacker 3000 series basses, such as my 3001, have boost/cut bass and treble controls on passive basses.

 

Hence the "In GENERAL..." part. biggrin.gif So, how did the "boost" on a passive bass, transformer maybe?
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I'm an EE. If Rickenbacher is calling this a "boost" then it is actually be a pre-emphasis design, where the EQ flat out is actually a -6dB pad and the "boost" simply nulls the pad at selected bandwidth. "Boost" usually implies gain greater than unity, which isn't possible in a passive system without an energy source or feedback network. And it is very difficult to prevent passive filter circuits from interacting with impedance changes, IE volume control, cable capacitance, and input impedance of the amp all will impact the operation of the boost/cut.

It may be labeled "boost" but it has none of the benefits of a preamp.

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Quote Originally Posted by amimbari View Post
cheap preamps hiss when the treble is cranked

You mentioned a hissing noise on the treble? Is this a byproduct of wear and tear? A pre-amp problem or a pot problem?.... Well, you said it's with cheap pre-amps so I guess I answered my own question..
Also, what effect can a low batter have?
ie, some old effects pedals sound better (in some peoples peoples opinion) with a low battery.
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Quote Originally Posted by lug View Post
Hence the "In GENERAL..." part. biggrin.gif So, how did the "boost" on a passive bass, transformer maybe?
Quote Originally Posted by The Real MC View Post
I'm an EE. If Rickenbacher is calling this a "boost" then it is actually be a pre-emphasis design, where the EQ flat out is actually a -6dB pad and the "boost" simply nulls the pad at selected bandwidth. "Boost" usually implies gain greater than unity, which isn't possible in a passive system without an energy source or feedback network. And it is very difficult to prevent passive filter circuits from interacting with impedance changes, IE volume control, cable capacitance, and input impedance of the amp all will impact the operation of the boost/cut.

It may be labeled "boost" but it has none of the benefits of a preamp.
I never claimed that it had the benefits of a preamp. and of course you're correct that it does not have greater than unity gain, but boost is not as firmly defined. With the bass and treble controls in the mid position, the response is essentially flat. Turn them up, and response increases. To me as a technician, sure, that's reducing the attenuation in that frequency band. But to me as a player, it's a boost.

http://www.rickenbacker.com/pdfs/19504.pdf
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Quote Originally Posted by ForrestS View Post
You mentioned a hissing noise on the treble? Is this a byproduct of wear and tear? A pre-amp problem or a pot problem?.... Well, you said it's with cheap pre-amps so I guess I answered my own question..
Also, what effect can a low batter have?
ie, some old effects pedals sound better (in some peoples peoples opinion) with a low battery.
The hissing noise is probably caused by a cheap lower-quality op-amp chip. Presumably "brand name" onboard preamps use better quality, quiter op-amps. The current drain for on-board preamps is very low, the battery can last for months of normal playing if one remembers to unplug the cord from the bass when you're done playing. But, when the battery starts to die, you'll know it, and it most definitely doesn't sound better. The output level will drop off, then it will start distorting, and not really in a musical way. I thought my amp was dying at first...

Generally, active basses (those with a preamp) have more output, and a more "hi-fi" sound with a broad frequency response. For some basses, including the Music Man you just bought, the preamp is very much a part of the basses' tone.
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Quote Originally Posted by isaac42 View Post
I never claimed that it had the benefits of a preamp. and of course you're correct that it does not have greater than unity gain, but boost is not as firmly defined. With the bass and treble controls in the mid position, the response is essentially flat. Turn them up, and response increases. To me as a technician, sure, that's reducing the attenuation in that frequency band. But to me as a player, it's a boost.

http://www.rickenbacker.com/pdfs/19504.pdf
I view my L2000 the same way. Even though it's cut only (bass and treble knobs are before the preamp), bass and treble knobs set in the middle seem "right" and pegged seem "boosted". I've never had another "cut only" bass that I didn't max the tone pot out.
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