# X Over Frequency Selector on Sub



## ryanstrong (Apr 14, 2016)

I have JBL sub with my 8" LSR monitors and it allows me select the cross over frequency that it engages at.

The frequencies you can select are:
50Hz, 80Hz, or 120Hz

I know there are variables but generally why would you choose one over the other?


----------



## Rob Elliott (Apr 15, 2016)

To my ears (on a Focal quad / sub setup - the 80Hz feels the most natural....but I am open to a change of heart


----------



## higgs (Apr 17, 2016)

Which sub do you have? I assume the monitors are the JBL LSR4300 series? What are your room dimensions LWH?

According to their website the LSR4328 monitors have a freq response ranging from50Hz to 20kHz at +- 1.5dB across that range. My gut feeling is that 50Hz (mayyybe possssibly 80Hz) would be a solid target for your sub. If you had the 6 inch monitors then it'd be reasonable to consider setting the sub at either 80-120Hz. Depending on room size (and a slew of other details I don't have about your setup) it's entirely likely that anything above 50Hz could be more than you need to make good decisions about your work.

Those 8 inch JBL monitors can easily handle material comfortably down to 60Hz, and since it doesn't look like there's an option for adjusting their crossovers, it doesn't make much sense to me to have the monitors and sub producing too much of the same frequencies. Ultimately the sound at your mix position and the mixing/EQ/level decisions you make from that position will reveal a bunch, but I'd be surprised if setting the sub's X-over to 120Hz would provide accurate results. But it's all up to your ears.

Oh hold on, aren't those the monitors that you can perform measurements and tweak with the RMC room mode correction? If so that'd be worth doing and getting the mic for them if you don't have it already!

Edited for poor and potentially confusing grammar


----------



## owenave (Apr 17, 2016)

I like to roll my sub off at around 50 or 60. I am using DynaudioBM15's and even other monitors I like to roll over as low as possible or the subwoofer sounds muffy from the mid Low bass if crossed over at 120 or higher.


----------



## ryanstrong (Apr 18, 2016)

higgs said:


> Which sub do you have? I assume the monitors are the JBL LSR4300 series? What are your room dimensions LWH?
> 
> Oh hold on, aren't those the monitors that you can perform measurements and tweak with the RMC room mode correction?



I have the JBL LSR 4300 sub, and 8" monitors WITH the room correction. I'm in a smaller but acoustically treated room. I've done the microphone to speaker RMC correction with the JBLs which is nice.

I've always struggled with lowend. Listening in my room I always want to bring the bass up louder and fuller - but when I take the mix out of the room the lowend in the mix is way overwhelming.

SO my thought with that is to have a higher crossover on the sub at like 80Hz that way when I listen I hear MORE bass and therefore will hopefully be more apt to lower it in the mix so that when I take it out to do a car test or whatever it works.


----------



## Nick Batzdorf (Apr 18, 2016)

It depends entirely on your speakers! This would be a good application for a sine sweep in your DAW and a dB meter. An iPhone one should be fine. Just try the different crossover freqs and see which one doesn't give you a lump when both speakers are firing (i.e. you don't want that).


----------



## Nick Batzdorf (Apr 18, 2016)

Thinking about it, you'd be better off sending pink noise when you look for the lump.


----------



## higgs (Apr 18, 2016)

Smaller rooms can be menacing with bass response. My room isn't particularly small (12' X 20') but ceiling height is ~ 8'. I've been gradually making adjustments to the room treatments to help with this obscene room mode that has been present at my listening position. At about 58Hz the bass was > 10dB higher there than other spots. I'm also sitting in/next-to a null where the bass seems to dip about the same amount at about 42Hz-46Hz. Two things have been instrumental in mitigating that mess: 1) repositioning the speakers, and 2) _adding_ more bass traps/treatment - it seemed counterintuitive to me at first.

Have you spent time turning your subwoofer or repositioning it just a few inches and then measuring? A few inches in rotation and/or a few inches left, right, forward, etc. can make all the difference. Adding more bass 'trap' treatment to corners and in an overhead cloud has actually increased the bass volume I perceive because it's helping to reduce the peak and lift the null (for lack of a better way to describe it). The result has been a smoother, more accurate and tighter bass response.

There's a free piece of software called Room EQ Wizard (REW) which you can use to measure the acoustics of your room and listening position. I picked up a USB measurement microphone on Amazon called UMIK-1 for which REW has calibration file available. I measured my mix position so many times, made incremental improvements, and measured more and on and on... 

Sorry if I'm repeating things you already know. But it was a good experience for me those months I put into my mix/composition position. Work, measure, treat, and repeat was the norm for quite a while. I bought panels and treatments Initially, then I started making my own from materials and with textiles that were better than what I was buying. It was pretty nice to have say over the size and quality of the corner traps and wall panels I made. My rear corner traps are huge and custom, and they're super effective because they were made for the space specifically to remedy the problems I ran into with bass mode and null. Anyhow, I'm happy to help in any way I can.


----------



## Nick Batzdorf (Apr 18, 2016)

All good advice from particle man, and I should have added that you're likely to see lumps in the room's response as well as reinforced bass due to overlapping speaker/sub areas.


----------



## germancomponist (Apr 18, 2016)

I never liked it to listen to such a system. No Sub here ... .


----------



## higgs (Apr 18, 2016)

Nick Batzdorf said:


> All good advice from particle man, and I should have added that you're likely to see lumps in the room's response as well as reinforced bass due to overlapping speaker/sub areas.


I beginning to wonder if this topic might be worth expanding into a thread (or threads) specifically for acoustics... Thoughts?


----------



## germancomponist (Apr 18, 2016)

In a well built room there is no need for a Sub!


----------



## higgs (Apr 18, 2016)

germancomponist said:


> In a well built room there is no need for a Sub!


Wellll, so long as you've got some good full range speakers.


----------



## Nick Batzdorf (Apr 18, 2016)

germancomponist said:


> I never liked it to listen to such a system. No Sub here ... .



Normally I agree, but my Blue Sky System One is designed with it, and it really is seamless.

Usually subs aren't integrated well, and it sounds like a separate speaker.



> In a well built room there is no need for a Sub!



A 6" or 8" speaker can only respond so low, and usually there's nothing much below 55 or 50Hz. Even my 12" UREI 809As don't do a whole lot once you get to 40Hz or so.

A good test is "Sk8er Boi" by Avril Lavigne. There's a boom-boom-boom-boom at... I forget the freq, but it's way down there, and normal speakers don't reproduce it. That's when you're glad you have the sub.

As an aside, we used to get readers' tapes when I was at Recording magazine. You'd be surprised how many of them had pops and piano thuds that people hadn't heard, because their speakers didn't show them at 50Hz.


----------



## ryanstrong (Apr 19, 2016)

germancomponist said:


> In a well built room there is no need for a Sub!


How would you know what the sub range feels like in a theatre or home theatre experience that use subs?


----------



## ryanstrong (Apr 19, 2016)

higgs said:


> Smaller rooms can be menacing with bass response. My room isn't particularly small (12' X 20') but ceiling height is ~ 8'. I've been gradually making adjustments to the room treatments to help with this obscene room mode that has been present at my listening position. At about 58Hz the bass was > 10dB higher there than other spots. I'm also sitting in/next-to a null where the bass seems to dip about the same amount at about 42Hz-46Hz. Two things have been instrumental in mitigating that mess: 1) repositioning the speakers, and 2) _adding_ more bass traps/treatment - it seemed counterintuitive to me at first.
> 
> Have you spent time turning your subwoofer or repositioning it just a few inches and then measuring? A few inches in rotation and/or a few inches left, right, forward, etc. can make all the difference. Adding more bass 'trap' treatment to corners and in an overhead cloud has actually increased the bass volume I perceive because it's helping to reduce the peak and lift the null (for lack of a better way to describe it). The result has been a smoother, more accurate and tighter bass response.
> 
> ...


Thank you so much for the response. I haven't done any scientific testing (meaning using analyzing software etc.), I've only done testing by ear moving things a bit here and there. I have bass traps and monster bass traps all around me corners, sides, and backs but I do NOT have any overhead. I may look in to that.

It sounds like it may be worth while analyzing the frequencies in my listening position - I'm not entirely comfortable doing it as some of what you all were speaking about went a little over my head, but I'm sure its more simple then I'm making it out to be.


----------



## germancomponist (Apr 19, 2016)

ryanstrong said:


> How would you know what the sub range feels like in a theatre or home theatre experience that use subs?


I do not have to care about this... . O.k., listening to your mix in a cinema makes sence. But, if you do a good mix in your well treated studio, the result in a cinama can only be good or best!


----------



## pkm (Apr 19, 2016)

Nick Batzdorf said:


> All good advice from particle man, and I should have added that you're likely to see lumps in the room's response as well as reinforced bass due to overlapping speaker/sub areas.



The crossover should prevent any overlapping areas. That's exactly what it's for. The question is really which frequencies do you want coming out of the speakers vs. the sub and that depends on the frequency response of your speakers and your room.


----------



## Nick Batzdorf (Apr 19, 2016)

pkm - The crossover should prevent overlapping areas, but in this case the sub and speakers know nothing about one another. So you have to try and set the sub's crossover to the inverse of the speaker's natural roll-off slope. You have no control over the speaker.

That's the challenge! And it's probably a big part of why add-on subs are usually suboptimal. Hopefully one of the crossover frequency choices will work well.


----------



## higgs (Apr 19, 2016)

pkm said:


> The crossover should prevent any overlapping areas. That's exactly what it's for. The question is really which frequencies do you want coming out of the speakers vs. the sub and that depends on the frequency response of your speakers and your room.


I believe this subwoofer only has the 3 frequency values for roll-off at 50Hz, 80Hz, and 120Hz. The issue of there not being any crossover on the mains we think was causing some potential overlapping frequencies and lumps/build-up. Low freq response for the mains rolls off at a pretty gradual slope starting around 60Hz, and looking at the sub, it seems to have a sharper Q which isn't exactly complementary to the mains. So it seems as though we are (well, more @ryanstrong is, rather than "we") left with a decision. There will be overlap, so determining which crossover value produces the more favorable results is the key. Be it through slightly sciency means or personal preference - either is acceptable, a combination of the two would probably yield the most satisfying results.


----------



## pkm (Apr 20, 2016)

higgs said:


> I believe this subwoofer only has the 3 frequency values for roll-off at 50Hz, 80Hz, and 120Hz. The issue of there not being any crossover on the mains we think was causing some potential overlapping frequencies and lumps/build-up. Low freq response for the mains rolls off at a pretty gradual slope starting around 60Hz, and looking at the sub, it seems to have a sharper Q which isn't exactly complementary to the mains. So it seems as though we are (well, more @ryanstrong is, rather than "we") left with a decision. There will be overlap, so determining which crossover value produces the more favorable results is the key. Be it through slightly sciency means or personal preference - either is acceptable, a combination of the two would probably yield the most satisfying results.





Nick Batzdorf said:


> pkm - The crossover should prevent overlapping areas, but in this case the sub and speakers know nothing about one another. So you have to try and set the sub's crossover to the inverse of the speaker's natural roll-off slope. You have no control over the speaker.
> 
> That's the challenge! And it's probably a big part of why add-on subs are usually suboptimal. Hopefully one of the crossover frequency choices will work well.



I think either you are both misunderstanding how a crossover works and how a subwoofer should connect to your monitors, or I'm misunderstanding and the subwoofer that Ryan has doesn't have outputs to the monitors (which most do). Or for some maybe legitimate reason that I don't know, he is not connecting them that way.

What I would do: Plug your monitors into the subwoofer. Interface Out -> Subwoofer -> Monitors. If you're not doing that, that's just a high frequency roll off and not a crossover. The audio should pass through the sub before it gets to the monitors so the_ subwoofer_ can control which frequencies go to which speakers, just like how a studio monitor has an internal crossover to determine what signal goes to the woofer or the tweeter. That way you know the crossover is even and you're not getting any overlap.


----------



## higgs (Apr 20, 2016)

pkm said:


> I think either you are both misunderstanding how a crossover works and how a subwoofer should connect to your monitors, or I'm misunderstanding and the subwoofer that Ryan has doesn't have outputs to the monitors (which most do). Or for some maybe legitimate reason that I don't know, he is not connecting them that way.
> 
> What I would do: Plug your monitors into the subwoofer. Interface Out -> Subwoofer -> Monitors. If you're not doing that, that's just a high frequency roll off and not a crossover.



With the monitor and sub system he has I wouldn't advocate that approach. Digging into the manual and back diagrams for the JBL LSR4300 mains + sub system will shed light on the proper way to connect ryan's monitor system - it's not exactly 3 wires and done.

As an aside, the Interface -> Subwoofer -> Mains setup, gives priority to the subwoofer in terms of the signal's integrity - I'd call that a last resort as opposed to good priority. Just because it's an available option doesn't mean it's the way 'a subwoofer should connect to monitors.' I'd always default to assigning the signal's integrity to the full range speaker and treat the subwoofer as the last-link/afterthought, or more favorably as an LFE or .1 (in the 2.1 / 5.1 sense). That LFE approach is the whole selling point of the JBL LSR setup. I believe we all understand what each other is saying and what each other means.

Here's the issue as I see it: after some back and forth in this thread, the problem was revealed to be more about wonky bass response at the listening position and less about semantics.

EDIT to fix a grammar snafu


----------



## pkm (Apr 20, 2016)

higgs said:


> With the monitor and sub system he has I wouldn't advocate that approach. Digging into the manual and back diagrams for the JBL LSR4300 mains + sub system will shed light on the proper way to connect ryan's monitor system - it's not exactly 3 wires and done.
> 
> As an aside, the Interface -> Subwoofer -> Mains setup, gives priority to the subwoofer in terms of the signal's integrity - I'd call that a last resort as opposed to good priority. Just because it's an available option doesn't mean it's the way 'a subwoofer should connect to monitors.' I'd always default to assigning the signal's integrity to the full range speaker and treat the subwoofer as the last-link/afterthought, or more favorably as an LFE or .1 (in the 2.1 / 5.1 sense). That LFE approach is the whole selling point of the JBL LSR setup. I believe we all understand what each other is saying and what each other means.
> 
> ...


Great, glad to know we're understanding each other. Sometimes it's hard to tell via text. There are just two problems I see in your reply. 

1. I'm not sure what kind of signal degradation you expect from a simple crossover circuit, but I would doubt that it's substantial in any way.

2. LFEs are not supposed to be an extension of the low end of your main monitors, but a totally discrete channel. If you want that, great, but then we're not talking about a crossover anymore, and overlap doesn't matter nearly as much because the speakers are getting different signals and can be mixed to taste.

I looked at the JBL sub and it looks like it does both discrete LFE and bass extension equally well (if you're using the matching monitors at least) and it is recommended in the manual to connect the monitors through the sub.

That's how I see it anyway, but I'm open to hearing why I'm wrong .

But point taken that we're off topic now!


----------



## ryanstrong (Apr 20, 2016)

Since the JBL system is all networked in with a network cable I believe it's intelligent in that whatever frequency it crosses over at it EQ's the Mains accordingly.

I did a test with this and I think this is accurate.

I set the crossover at 80hz, muted the sub and JUST listened to the Mains. The mains didn't have as much lowend coming out.

I then set the xover at 60hz, muted the sub and JUST listened to the Mains and they were now producing much more lowend to my ears.

SO it sounds like it has a much more intelligent crossover. Throwing the Room Mode Correction on top of it smarten/complicates it further.


----------



## higgs (Apr 20, 2016)

ryanstrong said:


> Since the JBL system is all networked in with a network cable I believe it's intelligent in that whatever frequency it crosses over at it EQ's the Mains accordingly.
> 
> I did a test with this and I think this is accurate.
> 
> ...


Great news! I'm curious to hear how your mixes come out now. Keep us updated


----------



## Nick Batzdorf (Apr 20, 2016)

> I think either you are both misunderstanding how a crossover works and how a subwoofer should connect to your monitors,



I'm pretty clear on how a crossover works, but I you're right about the second part: I didn't realize his sub has outputs to the speakers.

As to a passive crossover degrading the signal... well, I'd listen, but I doubt it's going to be noticeable that low. These days almost all monitors are powered, but twarnt always that way.


----------

