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PA Speakers and Subwoofers questions

mcapote

mcapote

Sep 9, 2009
1,591
5
Miami Florida
#1
ok I was wondering because i never really had to get into my own PA system until recently.
1) PA speakers and Subwoofers when paired are the subwoofers generally set to cut out at xHz (40-50Hz for example) and the PA designed to cut in around the same and go up to whatever the tweeters go to? If so is this a standard point or do you need to find this out for each the sub and pa cabinets to make sure they are compatible?

2) are these generally 8ohm PA and 8 ohm subs so they provide a 4ohm load together? seems like the PA speakers and subwoofers Ive been looking at don't seem to list impedance just wattage. but most amps list 4ohm bridgeable or 8ohm bridgeable etc.
 
#2
You are not running the subs and PA tops on the same amp channel. You will need a crossover that will split the signal, usually somewhere between 100hz-180hz, and then each signal (hi and low) go to separate amp channels then to the speakers. Most tops are 8ohms and subs will be either 8 or 4 depending on the model.
 
#3
so they dont use internal crossovers? active crossovers are required? and going through the crossover means an 8ohm top and 8ohm bottom means and 8ohm load correct? just trying to figure all this out before we start spending more cash. right now we have a small powered PA just for mics at practice but we are thinking of running a couple 1k amps with a couple PAs and subs for shows and running everything through it and using the powered as a monitor for the singer.
 
#4
mcapote said:
so they dont use internal crossovers? active crossovers are required? and going through the crossover means an 8ohm top and 8ohm bottom means and 8ohm load correct? just trying to figure all this out before we start spending more cash. right now we have a small powered PA just for mics at practice but we are thinking of running a couple 1k amps with a couple PAs and subs for shows and running everything through it.
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A cab with multiple drivers will use an internal crossover for the various drivers, but separate subs and tops will need an external crossover and separate amp channels. You can use one amp and string the tops together (8ohms each = 4ohm load) on one channel and the subs together on the other channel (as long as they are 8ohms) and the amp would be fed with an external crossover. This would give you a mono system, however.

The easiest route is to use powered speakers and you do not have to worry about all the outboard stuff. Most powered subs have a crossover built in to feed an XLR out to the PA top. They are also much easier to setup. That's the way I would go.
 
#5
well I was actually considering building cabinets myself, and was looking at how existing cabs were run. I thought of powered cabs, but because my actual bass system is pretty much a 2 channel amp along with cabs in building, its not too far off from a PA system really. Im a hands on guy I just like building this stuff, but at the same time would like to have it quality.
 
#6
I have 2 way tops I feed with either a powered mixer or an amp. The amp has a cross over built in. I use that to protect the subs when I run that amp. Otherwise I daisy chain the 8 ohm subs and tops together, the subs have a crossover built in. My mixer can do a 4 ohm load per channel. When I use an amp just for subs I feed it with a line out or monitor out and I can still run 2 tops/mains off my mixer on each channel.

All my speakers are 8 ohm. You can build your subs with a cross over inside and they will work. There are several possibilities. Amp/w crossover...stand alone cross over, subs with a cross over.
 
#9
You can pull this off rather easily with (2) modestly-priced power amps, an external crossover, and mains and subs of your choosing. Suggest you use the amps in bridged mono...daisy-chain your mains together as well as your subs. Powered enclosures are great but hard to come by on the secondhand market. I kinda prefer the separate components as it gives me the latitude to swap, re-assign, upgrade, etc. as necessary.

Riis
 
#10
Zooberwerx said:
You can pull this off rather easily with (2) modestly-priced power amps, an external crossover, and mains and subs of your choosing. Suggest you use the amps in bridged mono...daisy-chain your mains together as well as your subs. Powered enclosures are great but hard to come by on the secondhand market. I kinda prefer the separate components as it gives me the latitude to swap, re-assign, upgrade, etc. as necessary.

Riis
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Be careful bridging amps and daisy chaining speakers. Be sure you know your amps ohm load in bridge mode( 4 OP). Carry on!
 
#11
konodl18 said:
Invalid Link Removed

Go there.
Read it all.
Read it all again.

There is sooooo much to learn.

Derek
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JohnMCA72 said:
Don't, unless you really, really, REALLY know what you're doing (if you did, you wouldn't have posted what you did).
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+2!

you have a long way to go before you start building stuff, or even buying stuff, really.

"I have this car, I think it has a v6 in it, and I want to install a v8 myself. is that hard?"
 

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