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Author Topic: Sub woofer hookup help please :)  (Read 12825 times)

Cody Patterson

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Re: Sub woofer hookup help please :)
« Reply #10 on: December 23, 2011, 10:03:14 am »

In answer to your basic question, still need to know what your top boxes are (powered or passive), but:

Considering your apparent lack of pro-level skills (no offense intended), get a simple crossover, go from the l/r outs of the mixer into the XR, lo outs to the subs, hi outs to the tops, start off with crossover set at 100hz. Engage the HPF if the unit has one. If you have access to someone with experience get their help on-site (even if it costs a bit for one visit), it will be worth it.

I said multiple times that it is passive. So they mains are running out of a 3000 watt amp and the subs are powered so they don't need an amp.
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g'bye, Dick Rees

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Re: Sub woofer hookup help please :)
« Reply #11 on: December 23, 2011, 04:14:49 pm »

I said multiple times that it is passive.

Yes, but passive what?  Brand and model is the information being sought.
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Cody Patterson

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Re: Sub woofer hookup help please :)
« Reply #12 on: December 23, 2011, 04:18:53 pm »

Yes, but passive what?  Brand and model is the information being sought.

I don't know, the camp is an hour and a half from my house I have no way to find out sorry. I have figured out i do not need a crossover for the subwoofer since there is a built in crossover, but do tops need crossovers or can they just handle the low end frequencies?
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Re: Sub woofer hookup help please :)
« Reply #13 on: December 23, 2011, 04:43:20 pm »

I don't know, the camp is an hour and a half from my house I have no way to find out sorry. I have figured out i do not need a crossover for the subwoofer since there is a built in crossover, but do tops need crossovers or can they just handle the low end frequencies?


The accuracy and efficacy of the help you receive will depend on your supplying enough information. 

A cross-over is needed for both the subs and the tops.  It is an integral part of a complete system.  The crossover slopes need  to be of the same type as a rule.  This may or may not be the case with built in filters, but likely not if the speakers in question are of different brands and models. 

Just a word of caution:

Reply to the questions politely and patiently.  You'll receive good help here.  Cop and attitude, whine or expect everyone to do your work for you and you'll have to wait longer and wade through more to sort out your situation.

Now go and find out what brands and models of equipment you have if you expect the proper help.  Stop complaining.  It's up to you.
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Cody Patterson

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Re: Sub woofer hookup help please :)
« Reply #14 on: December 23, 2011, 04:46:39 pm »


The accuracy and efficacy of the help you receive will depend on your supplying enough information. 

A cross-over is needed for both the subs and the tops.  It is an integral part of a complete system.  The crossover slopes need  to be of the same type as a rule.  This may or may not be the case with built in filters, but likely not if the speakers in question are of different brands and models. 

Just a word of caution:

Reply to the questions politely and patiently.  You'll receive good help here.  Cop and attitude, whine or expect everyone to do your work for you and you'll have to wait longer and wade through more to sort out your situation.

Now go and find out what brands and models of equipment you have if you expect the proper help.  Stop complaining.  It's up to you.

In the last post I made there was no complaining no wining or anything, I said i was sorry that i did not know what type of speakers they were so where ever you came up with that i dont know im sorry. I got all i needed to know though, thanks!
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Re: Sub woofer hookup help please :)
« Reply #15 on: December 23, 2011, 05:22:35 pm »

In the last post I made there was no complaining no wining or anything, I said i was sorry that i did not know what type of speakers they were so where ever you came up with that i dont know im sorry. I got all i needed to know though, thanks!

No, I'm sorry.  It was not clear to me.  Perhaps the lack of punctuation confused me.

To help you understand a bit more about the process, here's an analogy.

Help.  I have a car that I need to fix.  I don't know what it is and I'm not going to go and find out, but please tell me how to get it running.

And no, you haven't gotten all you need to know.......
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Cody Patterson

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Re: Sub woofer hookup help please :)
« Reply #16 on: December 23, 2011, 06:12:06 pm »

Well since I don't have all I need to know then I guess I can't find out anymore, therefore right now I have all i need to know :P Thanks for the help I'm sorry im a noob with pro audio stuff.
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Re: Sub woofer hookup help please :)
« Reply #17 on: December 23, 2011, 07:02:23 pm »

Well since I don't have all I need to know then I guess I can't find out anymore, therefore right now I have all i need to know :P Thanks for the help I'm sorry im a noob with pro audio stuff.

You'll get it figured out before too long.  It really will help when you can find out all the information required.  Just come back when you have it and it's game on.  You'll really enjoy getting to know what you need to know and then applying it.  You don't need to be sorry, you just need to supply the proper information to get more than general answers.

Good luck.
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Tim McCulloch

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Re: Sub woofer hookup help please :)
« Reply #18 on: December 23, 2011, 09:41:45 pm »

Well since I don't have all I need to know then I guess I can't find out anymore, therefore right now I have all i need to know :P Thanks for the help I'm sorry im a noob with pro audio stuff.

Hi Cody-

Have you ever asked your physician to diagnose an illness over the phone?  Can you imagine the diagnoses if you couldn't answer his questions?  "According to my careful prosthesis, this man... has... the plague!"  (from "Beat the Reaper", Firesign Theater)

So here's the deal with subs, crossovers, etc and why they are important.  I'm going to skip or gloss over or perhaps over-generalize some things you're not ready for (this is to ward off the other posters who will reply to say "that's wrong" or "you should have.....").

There are 2 kinds of filters used to make up crossovers, first is the "high pass filter."  Abbreviated HPF.  The purpose of this filter is to lower (attenuate) the amplitude of frequencies below a specified frequency; alternately you can think of it as passing frequencies above a specified freq..  The reason to use this filter is to regulate the spectrum being sent to a particular transducer or speaker, often to keep from destroying it.  For example, sending low freq program to a tweeter or compression HF driver will certainly destroy it; the HPF used for these devices is often above 1,000Hz.

Now we need a complimentary filter, the low pass or LPF.  It does what the name implies - it passes frequencies below a specified frequency.  Used together with the HPF, we now have a crossover...  Let's take a simple 2 way passive (externally powered) top box...  No HPF on the 15", but there is a LPF on it, somewhere around 1,200Hz.  The HF horn has a HPF, somewhere around 1,200Hz.  See how this works?  I suggest you look at the manual for one of the dbx analog crossovers (234?) as the explanation comes with good charts.

As said earlier, one of the reasons to filter the signal is to keep transducers from self destruction, but the primary reason is to keep them from operating in ranges that are unwanted, but not dangerous.  One of the reasons to not have transducers significantly overlap their frequency coverage is that we create time (phase) issues.  There is more below, but consider this:  for time (phase) problems to exist, identical sounds from more than 1 source need to reach a listener at different (no matter how slight) times, and those sounds need to be 0 to 6dB different in level.  As the difference in level becomes greater than 6dB, the time interference lessens greatly.  This is the primary reason you need a crossover between your subs and the top box.  You also gain more power handling in your top boxes when they are no longer asked to reproduce the bottom octave, but that's another post.  At any rate, if your powered subs have a filtered output for the top box, use it.  The JBL JRX subs have a little switch that makes the output XLR either full range or High Passed, for example.

By crossing over (but not with John Edward), we can limit the interaction of co-located transducers.  We can also match the relative levels between the LF and HF (in our example) in our design, so the HF (which is more sensitive) doesn't outrun the LF (which is less sensitive).

Concept to remember:  Everything in audio is about TIME.  Time is a measure of chronology; it is a measure of pitch (frequency) and; because it has a predictable velocity (the speed of sound, roughly 1130 ft per second) it can measure distance.  Very useful, this time thing.  Also note that ideally we want all sonic events to occur at the same instant and to arrive at the listener at the same time.  Note the word "events" is plural.

In your case, you have 2 sonic events, the sound leaving the top box and the sound leaving the subwoofer.  Because they are 2 separate sources they almost inherently have different time relationships to the listener.  Presuming the sonic events are simultaneous, the difference in distance between the speakers and the listener means the sound arrives at the listener at different times.  As pointed out above, minimizing the amount of signal overlap between the subs and LF helps control this, but does not correct it.  There is still significant energy in the "acoustic crossover."  The acoustic crossover region is the overlapping range of frequencies from BOTH transducers that have SPL within 12 dB or so (some designers use 24 dB) of each other.  We use small amounts of delay (on the earliest arriving signal) to match it up with the other transducer.  Now we have 2 subsystems (top box & subwoofer) that combine into a "system" that is time-coherent.

Now you have all the "whys".  When your head stops spinning (this turned out much longer than I'd planned) read it again.  Then get the brand names and model numbers for everything that makes up this rig so you can get their manuals online and provide links when you hit your next roadblock.

Have fun, happy holly-daze.

Tim Mc
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Re: Sub woofer hookup help please :)
« Reply #18 on: December 23, 2011, 09:41:45 pm »


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