What cross over to use, 80hz or 120Hz?

What's the frequency range of the subs?

Do you have a graph?

 

What are the tops and what are you crossing them over at?

 

It look looks like these cabs can run down to 80hz. IMHO the best course of action would be to try both 80 and 120hz and choose whichever sounds best. Given the frequency response graphs, I think 80hz will probably provide the flattest frequency response and best fidelity, but it may depend upon how loud you plan to push the system and how much bass you plan to run.

 

I believe in whatever sounds best. I’m guessing the higher xover will make the system sound seamless. However, crossing over lower could clean up the sound. A lot depends on who is mixing. Didn’t RCF help you out?when I did sound, I’d carry a noise generator to give me a great starting point just about every time.

 

That's the way I'd go. This dovetails the high-pass filters on your vocal channels. You don't want anything intelligible (vocals) coming from the subs.

Riis

 

I'd always start lower and only go up if you hear it's needed. Your full range speakers will be just fine down to 80hz. Your sub is already down 10db at 120hz. My guess is you'll hear something missing when you try 120hz.

 

My guess based on my own experience and the information you provided is that it probably would be 80Hz. But you’ll need to check it by ear. So I’d pipe some full range source into it and do multiple A/B comparisons. And do it over a few days since you might change your mind a few times before you settle on what settings you really prefer hearing.

You may also need to adjust things from your preferred settings depending on the room anyway. So trust your ears. And if the place fills up recheck multiple times in the course of the show. Having someone out on the floor whose ears you trust to provide feedback is helpful since an empty house soundcheck sometimes only puts you in the ballpark.

Luck!

 

I have usually preferred a 120 Hz crossover, because the natural dip at that point where the woofer ends and the midrange takes over is about where many smaller venues have a room resonance, so it cuts down on standing waves.

 

1st there are no rules, that's why most crossovers are variable.
It all depends on the speakers, amplifiers, and even the room.

If your speakers only go down to 80hz, what are you crossing over?
Answer: Nothing if you're set at 80hz.

Good luck,
Dirk

 

You are crossing over your tops at 700 Hz? Did you mean 70? Even if you set the subs to 120 you are leaving a 3 octave hole in the middle of your system.

 

Are you planning to mix the subs at the same volume level as the mains or are you going to crank the subs to get that chest thump effect?

Based on the graph, if you want the sub to be a smooth extension of the mains, I'd try 80Hz first. If you want the subs 10+ dB louder than the mains, I'd go with 120 Hz. Then I'd listen and pick what sounded best.

 

The charts for the sub don't quite make sense... The top chart says "Low pass 80 hz" so we can't see what they can do above that to determine if they have enough sensitivity in the 80-120hz region. But it may not matter:

According to the specs, the RCF's have an internal crossover between the low frequency driver and the high frequency driver at 700Hz--that's what the "700Hz" number means.

Their frequency response is listed as down to 45 Hz but the frequency charts in the downloads section of the RCF website shows they start dropping off rapidly below 80 Hz. If it were me I think I'd cross these over at 80 and see how it sounds. If you cross over at 120 I'm betting you'll get a bit of mud as you'll have both the subs and the tops reproducing the 80-120 hz range, but it might sound ok so I'd try it.

Tom

 

I'd keep it at 80Hz. Seems like the sub peaks at around 65Hz, and the tops can go down to 45Hz. Cut everything below 80Hz on the tops, and you'll still have most of your bass on tops.

You can always try both and see which you like the best.

 

Mmmmmm, there's this thing called 'slope" ...

I never had an issue with PA, but it's a welcome concept, the basis of love even, for things like the Pulteq EQ ...

 

Can you +/- 15Hz at 90 for the center and navigate for the room? How precise is the published data?

 

Let your ears be the judge and may the bass be with you.

 

all the online stuff i'm seeing is for the 705 AS MK2. that one shows as having 80 and 110Hz crossover settings.

with 12" tops i vote for the higher setting either way, and those tops will probably still far outstrip the subs if you let them (unless you've got like four subs to two tops)