PA and Subwoofers

[Deathwatch]

I have been playing the bass guitar for a little over 2 years now but never have seen the need to use more then my 15W Crate could handle. But now that I have just recently joined a band I desperatly need a stronger amp for gigs and such. Now a PA and some Subwoofers will probably be the least of my problems because I don't plan on buying these things just for a few free gigs but I would like to widen my understanding of them.
First off I don't see how you can have a PA and a Subwoofer and be able to control what sounds go through each, for instance I've heard people say that you need the low sounds to go through the Sub and the Higher sounds to go through the PA but how is this possible? Does it have something to do with an Amp Head?
Secondly just since this is Live Sound forum and I need to know, how much power will I need to be hear in a small venue as a bass player, also will I need something like a Amp Head.
Last thing would I be being stupid if I bought a Multi Effects Pedal and then buy a cheaper amp or should I just wait on the Pedal and buy the nicer amp?

 

[baba]

First off I don't see how you can have a PA and a Subwoofer and be able to control what sounds go through each, for instance I've heard people say that you need the low sounds to go through the Sub and the Higher sounds to go through the PA but how is this possible?

A crossover accomplishes this. It's typically a separate unit, but is sometimes incorporated in a multi function unit like a Driverack.

Does it have something to do with an Amp Head?

No.

Secondly just since this is Live Sound forum and I need to know, how much power will I need to be hear in a small venue as a bass player, also will I need something like a Amp Head.
Last thing would I be being stupid if I bought a Multi Effects Pedal and then buy a cheaper amp or should I just wait on the Pedal and buy the nicer amp?

For a small venue like a bar or small club, depending on the guitarists volume and band type, I'd say 300W to 600W. This doesn't have to be a separate amp head as you mentioned. A combo will work fine.

Definitely skip the multi effects pedal and get a better amp!

 

[albertofrog]

what your talking about is a crossover unit.

Take the signals from your mixing desk into the crossover (left input and right input)

the crossover has four outputs, two left and two right.

the lower frequencies go to the low outputs (left AND right)

and the higher frequencies go the high outputs (left AND right)

If you then feed the high outputs to a power amp, and then into your PA speakers,

you can then do the same with the low outputs - into another power amp and into your subwoofers/bass bins.

hope that helps.

reading it back, it sounds a bit confusing.....

 

[Deathwatch]

great thx, but one other question, if I use a crossover will I need something to give the bass a tone or will the crossover act as a preamp?

 

[baba]

great thx, but one other question, if I use a crossover will I need something to give the bass a tone or will the crossover act as a preamp?

Forget about the subs and crossover. They are both a function of the PA. You just need to play your bass and have an amp to play it through. If you go through they PA at a gig, you'll either stick a DI between your bass and amp, or mic your amp, or both....but the soundguy will typically take care of this.

 

[Deathwatch]

Just since we're on the subject of crossovers, would I need a crossover to connect to more then one amp, say I have an amp head and have 2 amp cabinets?

 

[MNAirHead]

Just since we're on the subject of crossovers, would I need a crossover to connect to more then one amp, say I have an amp head and have 2 amp cabinets?

Depends.. I'd start by saying don't do it without more homework.. this is where stuff gets broken, overheated etc.

Tim

 

[baba]

Just since we're on the subject of crossovers, would I need a crossover to connect to more then one amp, say I have an amp head and have 2 amp cabinets?

No need for a crossover to accomplish this. What you would need to do is just check the ohm and wattage ratings of the cabinets. If their combined load can be supported by your amp, you would just simply daisy chain the cabinets together and connect to your amp. If you go to do this, and aren't sure about your load, bring us your amp and speakers' ratings.

Just so you are clear on crossovers, the short story is this. They just take an incoming signal and chop it up into 2 or 3 frequency ranges: high and low or high/mid/low. They then spit these 2 or 3 signals out the back and send the appropriate one to the appropriate speaker. Where they divide these 2 or 3 frequencies can usually be controlled by knobs. This is almost always a PA function associated with the entire multi-instrument mixed signal. There is no need to this at your instrument level as instrument speaker cabinets typically have internal passive crossovers that do this and send the signals to the appropriate speaker and/or tweeter within the same cabinet.

 

[hbarcat]

Forget about the subs and crossover. They are both a function of the PA. You just need to play your bass and have an amp to play it through. If you go through they PA at a gig, you'll either stick a DI between your bass and amp, or mic your amp, or both....but the soundguy will typically take care of this.

+11

 

[gregoire1]

I may be misreading this but, it sounds like your confusing the purpose of a dedicated bass amp(like your crate 15) and a PA system.
When performing live, you can still use your small combo for yourself and band (if loud enuff), but a seperate signal will also go to the PA system, where its amplified to your audience. The PA needs the crossover with subs, probably not your rig.