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[JustinSummerlin]

Hi all!

I'm the guitar player for a small church plant in Chattanooga, Tennessee.  Someone just donated a passive sub to us (a JBL JRX 100) and we have 2 active 15" Mackie Thumps as our speakers.  We're going to borrow an amp from someone for a production we've got going on tomorrow.  How exactly can I wire this up.  Our resources (read: money) are limited.  We don't have a crossover and I really don't think we can buy one.  We have a snake.  I have the speakers both coming out of their own outputs on our snake.  I can't remember what type of mixer we have. 

What can we do to get this subwoofer hooked up and working properly?

Thanks!

[Sammy Barr]

Without a crossover the speaker will run full range and probably not help much.  If you can't borrow a crossover, use a post fade aux out and only put bass guitar, kick drum and key in the mix for the sub. That might give you a bit more bottom end. But in truth if you don't have a way to separate  mid highs from sub frequencies the end result may not be worth the effort. Good luck.

[JustinSummerlin]

Without a crossover the speaker will run full range and probably not help much.  If you can't borrow a crossover, use a post fade aux out and only put bass guitar, kick drum and key in the mix for the sub. That might give you a bit more bottom end. But in truth if you don't have a way to separate  mid highs from sub frequencies the end result may not be worth the effort. Good luck.

Ok, so how should it be hooked up in both of the ways you mention... with or without a crossover?

Also, I think we only have one auxiliary channel on our board and it's being used for our monitor.

Don't some amps have some sort of built in crossover (I haven't seen this amp yet so I don't know if it will)?

[g'bye, Dick Rees]

Hi all!

 We're going to borrow an amp from someone for a production we've got going on tomorrow. 

Thanks!

Borrow a cross-over with it.

[JustinSummerlin]

Borrow a cross-over with it.

Ok, so how should it be hooked up in both of the ways you mention... with or without a crossover?

Also, I think we only have one auxiliary channel on our board and it's being used for our monitor.

Don't some amps have some sort of built in crossover (I haven't seen this amp yet so I don't know if it will)?

[g'bye, Dick Rees]

Ok, so how should it be hooked up in both of the ways you mention... with or without a crossover?

Also, I think we only have one auxiliary channel on our board and it's being used for our monitor.

Don't some amps have some sort of built in crossover (I haven't seen this amp yet so I don't know if it will)?

Trying this without a cross-over is probably a waste of time.  It'll just sound bad.

Yes, some amps have cross-over capability, but you're not likely to be getting one of those to run your JRX sub....which, by the way, is a crappy box and hardly worth the trouble. 

I'd go without the sub if you don't have a cross-over.  Forget the "aux feed" and other assorted kludges as well.  If you can't do it properly, don't muck about.

[JustinSummerlin]

Trying this without a cross-over is probably a waste of time.  It'll just sound bad.

Yes, some amps have cross-over capability, but you're not likely to be getting one of those to run your JRX sub....which, by the way, is a crappy box and hardly worth the trouble. 

I'd go without the sub if you don't have a cross-over.  Forget the "aux feed" and other assorted kludges as well.  If you can't do it properly, don't muck about.

Thank you for your help, but I still don't know how to hook up the sub no matter WHAT kind of equipment I have.  If this person who is letting us borrow an amp also has a crossover that we can use, how do we hook all of it up?

[Brad Weber]

The JBL JRX100 is a model series, not a specific model.  If it is a passive subwoofer in that series then it's probably the JRX118S.  That box does not have any internal crossover or summing.  The TH-15As also have no crossover or settings for use with a sub, the only adjustment they have that might be relevant to use with a subwoofer is the 80Hz 'contour' shelving filter.
 
So if you currently run the TH-15As stereo then you need both a crossover between the mains and sub along with a way to sum the stereo mains signal to mono for the subwoofer.  If you don't have the equipment to do that then it's probably better to just work without the subwoofer.  Maybe sit the JRX sub out just to make people think it's being used, I'd be curious how many then comment that the system sounds better or has more low end.
 
People may not want to comment on the possibilities with a borrowed amp and possibly crossover unless they know what they are.  There are so many potential possibilities on what may or may not be possible or how you may be able to apply them that it would make little sense to try to address them all or potentially address something that may then not be applicable.  Let us know what you can borrow and maybe then people can address how you might apply that equipment.

[g'bye, Dick Rees]

Thank you for your help, but I still don't know how to hook up the sub no matter WHAT kind of equipment I have.  If this person who is letting us borrow an amp also has a crossover that we can use, how do we hook all of it up?

Full range signal out of the mixer INTO the cross-over.  LF out of the cross-over into the sub amp, sub-amp connected to the sub.

HF out of the cross-over to the Mackies.  Set the cross-over somewhere between 80 and 100 to divide the full-range signal into sub and mid-hi speakers.

[JustinSummerlin]

Full range signal out of the mixer INTO the cross-over.  LF out of the cross-over into the sub amp, sub-amp connected to the sub.

HF out of the cross-over to the Mackies.  Set the cross-over somewhere between 80 and 100 to divide the full-range signal into sub and mid-hi speakers.

Well, that was much less complicated than I thought it was going to be.  Thanks for the info!

[g'bye, Dick Rees]

Well, that was much less complicated than I thought it was going to be.  Thanks for the info!

Cross-over : frequency dividing device.  that's all

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