Subwoofers to pair with JBL 835sp 15" 3-way

Mason Joy

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Apr 2, 2021
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Thanks for reading. I have two (2) 15" 3-way JBL SRX 835sp speakers and I'm looking for a cardioid solution for the subwoofer. Unfortunately, it doesn't seem like JBL makes a cardioid subwoofer like QSC does (the 112c).

My question is: What other brand/model subwoofer(s) would pair well with the JBL 835s? This is generally for a small venue (I know the speakers are big for small venues, but they're what I have) and I want to keep the base more contained than the general kw118s do. Anyone have experience pairing cardioid subwoofers with JBLs? Stacking a couple JBL 828s for cardioid is simply WAY too space-consuming and they aren't, to my knowledge, able to be configured as a cardioid stand-alone subwoofer.

My other issue is that dual 12s just seem small compared to a 100lb 15" 3-way speaker.

Thanks in advance!
 

Brian Bolly

Junior
Jan 11, 2011
408
20
18
Baltimore, MD
Thanks for reading. I have two (2) 15" 3-way JBL SRX 835sp speakers and I'm looking for a cardioid solution for the subwoofer. Unfortunately, it doesn't seem like JBL makes a cardioid subwoofer like QSC does (the 112c).

My question is: What other brand/model subwoofer(s) would pair well with the JBL 835s? This is generally for a small venue (I know the speakers are big for small venues, but they're what I have) and I want to keep the base more contained than the general kw118s do. Anyone have experience pairing cardioid subwoofers with JBLs? Stacking a couple JBL 828s for cardioid is simply WAY too space-consuming and they aren't, to my knowledge, able to be configured as a cardioid stand-alone subwoofer.

My other issue is that dual 12s just seem small compared to a 100lb 15" 3-way speaker.

Thanks in advance!
If you already have SRX835s as mains, why go with another manufacturer whose frequency response, phase response, and ballpark output do not automagically match your mains? To me, having more "regular" boxes that can be configured how you see fit is more flexible from a system standpoint.

See the SRX 800 manual page 33 - they give examples of cardioid configurations using the SRX800 series subs. The preset guide also talks about it, and presets exist for cardioid configurations.

You can do a cardioid config with 2 boxes in an end-fire arrangement if you have the real estate. You can do a "pseudo" cardioid with 2 boxes stacked vertically, but it is not as effective as a 3-box stack or horizontal array (think of the ground as a mirror, although it is not perfect).

Keep in mind, whether with another manufacturer's all-in-one cardioid box, or with your own configuration - they need space behind them to work properly. Pushing a sub array with directional control against a wall negates any directional benefits gained in the first place.
 
Jan 19, 2011
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...

You can do a "pseudo" cardioid with 2 boxes stacked vertically, but it is not as effective as a 3-box stack or horizontal array (think of the ground as a mirror, although it is not perfect).

...
2 boxes is actually more linear in the rear at loud drive levels, but it doesn't get as loud in the front as 3 boxes.
With a 3 high stack you can run into a situation where the cardioid pattern collapses because the rear facing box starts to limit.
I figured that one out the hard way when the stage floor started to lift at an outdoor gig....
 

Mason Joy

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If you already have SRX835s as mains, why go with another manufacturer whose frequency response, phase response, and ballpark output do not automagically match your mains? To me, having more "regular" boxes that can be configured how you see fit is more flexible from a system standpoint.

See the SRX 800 manual page 33 - they give examples of cardioid configurations using the SRX800 series subs. The preset guide also talks about it, and presets exist for cardioid configurations.

You can do a cardioid config with 2 boxes in an end-fire arrangement if you have the real estate. You can do a "pseudo" cardioid with 2 boxes stacked vertically, but it is not as effective as a 3-box stack or horizontal array (think of the ground as a mirror, although it is not perfect).

Keep in mind, whether with another manufacturer's all-in-one cardioid box, or with your own configuration - they need space behind them to work properly. Pushing a sub array with directional control against a wall negates any directional benefits gained in the first place.
Those are all good points and I've been struggling to make this arrangement work. This is my first studio and the space is determined by the existing room size. The speakers are what I already have and my budget is running out so I need to figure out the sub configuration. The room these are in is 30x13 with a 12' ceiling so I know the 835s are way big for this space. Some 8" would be big enough. But they're what I have and budget wise, it's going to be too expensive and space-consuming to stack 3 boxes or buy 4 subwoofers to point 2 of them back (or 6 subs for that matter) so I'm looking for a cardioid subwoofer solution that I can mount each speaker on. I'll keep the power way down on these and at least I have an excellent setup for monitor speakers. So, as we all are aware, space in this room is going to be a key issue and the speakers I have aren't ideal. A a musician who has never had a studio before, there are a lot of questions that I've never come across so c'est la vie--I'm asking the expert community for help! So far, the QSC 212c is the top contender option that I can find for a 1-to-1 speaker-to-subwoofer pole mount configuration. I'd put the QSC 212s on their sides for better stability/safety, but I'm also wondering, if they'll reasonably handle a pole mount from 100lb monster speakers. And it's not like these speakers are easy to put on a pole anyway, so I'm considering building platforms for the JBLs. Anyway, I can get two (2) 212s for roughly $3.2K and keep the volume way down. I'm wondering if they will work will with the SRX835s. I'm wondering if they will keep up well with the SRX835s or if I should just bite the bullet and grab some JBL non-cardioids. Also, since everything is so large already, I want to maximize the use of space and I'm not a fan of speaker stands.

Re: "having more "regular" boxes that can be configured how you see fit is more flexible from a system standpoint." This is something I've considered. What would you go with in this situation? Is there a good option that would cost about the same as 2 QSC 212c's ~($3200). That's already stretching my max budget for subwoofers. What subs would be best for this situation? And do I need subwoofers at all or will that be certain overkill in a space this size? Since the speakers are 3-way with bass reflex, should I forgo the subwoofers altogether and just rent for outside shows?

Your last point is really good as well: will cardioid do anything at all in a space that size? Or am I on a wild goose chase and I should just get a single omni-directional sub and call it a day? I'd rather have one great sub than two cheap ones and potentially add another one later, but it may be a better option. Thanks for your advice!
 
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Mason Joy

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Apr 2, 2021
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2 boxes is actually more linear in the rear at loud drive levels, but it doesn't get as loud in the front as 3 boxes.
With a 3 high stack you can run into a situation where the cardioid pattern collapses because the rear facing box starts to limit.
I figured that one out the hard way when the stage floor started to lift at an outdoor gig....
Wow. The stage floor actually rose up due to the cardioid failure?
 

Brian Bolly

Junior
Jan 11, 2011
408
20
18
Baltimore, MD
Those are all good points and I've been struggling to make this arrangement work. This is my first studio and the space is determined by the existing room size. The speakers are what I already have and my budget is running out so I need to figure out the sub configuration. The room these are in is 30x13 with a 12' ceiling so I know the 835s are way big for this space. Some 8" would be big enough. But they're what I have and budget wise, it's going to be too expensive and space-consuming to stack 3 boxes or buy 4 subwoofers to point 2 of them back (or 6 subs for that matter) so I'm looking for a cardioid subwoofer solution that I can mount each speaker on. I'll keep the power way down on these and at least I have an excellent setup for monitor speakers. So, as we all are aware, space in this room is going to be a key issue and the speakers I have aren't ideal. A a musician who has never had a studio before, there are a lot of questions that I've never come across so c'est la vie--I'm asking the expert community for help! So far, the QSC 212c is the top contender option that I can find for a 1-to-1 speaker-to-subwoofer pole mount configuration. I'd put the QSC 212s on their sides for better stability/safety, but I'm also wondering, if they'll reasonably handle a pole mount from 100lb monster speakers. And it's not like these speakers are easy to put on a pole anyway, so I'm considering building platforms for the JBLs. Anyway, I can get two (2) 212s for roughly $3.2K and keep the volume way down. I'm wondering if they will work will with the SRX835s. I'm wondering if they will keep up well with the SRX835s or if I should just bite the bullet and grab some JBL non-cardioids. Also, since everything is so large already, I want to maximize the use of space and I'm not a fan of speaker stands.

Re: "having more "regular" boxes that can be configured how you see fit is more flexible from a system standpoint." This is something I've considered. What would you go with in this situation? Is there a good option that would cost about the same as 2 QSC 212c's ~($3200). That's already stretching my max budget for subwoofers. What subs would be best for this situation? And do I need subwoofers at all or will that be certain overkill in a space this size? Since the speakers are 3-way with bass reflex, should I forgo the subwoofers altogether and just rent for outside shows?

Your last point is really good as well: will cardioid do anything at all in a space that size? Or am I on a wild goose chase and I should just get a single omni-directional sub and call it a day? I'd rather have one great sub than two cheap ones and potentially add another one later, but it may be a better option. Thanks for your advice!
That's a very small space with a whole lot of PA. The subs will give you some feel, but since you need some space behind the subs to make cardioid work regardless of which box(es) you choose, you're talking...25' or so of coverage? Who is going to benefit from the rear cancellation lobe, anyone?

You mention "studio" - if this is just a rehearsal space and you're already on a tight budget, skip the cardioid for now. Just do a single sub that plays nice with your system — so another JBL SRX 800 series, just for some last-octave feel — and call it a day. Then if you need subs for any future outdoor gigs, rent them on an as-needed basis.
 

Mason Joy

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Apr 2, 2021
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That's a very small space with a whole lot of PA. The subs will give you some feel, but since you need some space behind the subs to make cardioid work regardless of which box(es) you choose, you're talking...25' or so of coverage? Who is going to benefit from the rear cancellation lobe, anyone?

You mention "studio" - if this is just a rehearsal space and you're already on a tight budget, skip the cardioid for now. Just do a single sub that plays nice with your system — so another JBL SRX 800 series, just for some last-octave feel — and call it a day. Then if you need subs for any future outdoor gigs, rent them on an as-needed basis.
Since this is in a neighborhood, the cardioid will give me a better volume without shaking the neighbors/disturbing the family, and fill out the bass range. Yeah, the 835s are much bigger than I'd imagined and will handle the bass in this size space pretty well on their own, I think. But would adding a PRX sub or two be enough or should I just bite the bullet and just get a JBL sub? Since I was going to DIY more of the studio but now I'm injured, unless I want to wait another 6 weeks, my budget is going to hiring help instead of my sub, unfortunately. Maybe I should just stick with what I have for now and hold out until I can afford a JBL sub in the future. Is this what you'd recommend? I'm with you on the rental for gigs.
 

David Morison

Freshman
Aug 21, 2012
164
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Aberdeen, Scotland
Since this is in a neighborhood, the cardioid will give me a better volume without shaking the neighbors/disturbing the family, and fill out the bass range. Yeah, the 835s are much bigger than I'd imagined and will handle the bass in this size space pretty well on their own, I think. But would adding a PRX sub or two be enough or should I just bite the bullet and just get a JBL sub? Since I was going to DIY more of the studio but now I'm injured, unless I want to wait another 6 weeks, my budget is going to hiring help instead of my sub, unfortunately. Maybe I should just stick with what I have for now and hold out until I can afford a JBL sub in the future. Is this what you'd recommend? I'm with you on the rental for gigs.

Here's the thing, you haven't told us much about this space or what you will use it for, so right now you know more about the answer to that question than we do. (That being said, PRX subs are JBL subs, so the highlighted question doesn't even make grammatical sense, sorry.)

So, to try and help, what kind of "studio"? Dance? Rehearsal? Commercial Recording? Video/Film Post Production?
Who will be the primary users? You? Paying clients? Someone else?
What are you actually missing when you listen to the 835s in the room? Have you utilised the onboard EQ's etc to try and see if they can give you what you need without extra subs?

What you actually need (rather than want) may well be quite different based on these kind of things.

Also, don't get your hopes up that a nominally cardioid product will do much good wrt family & neighbours etc.
This is because, in small spaces, the distribution of low frequency sound has a lot more to do with the room modes than the sub itsself - even the sound coming out the front of a cardioid sub will hit other walls of the room and bounce around, which may largely negate the cardioid effect anyway. That sound may also leak out of the room quite a lot, depending on it's construction. Effective soundproofing at low frequencies is not trivial unfortunately.

HTH,
David.
 
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Mason Joy

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Apr 2, 2021
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Here's the thing, you haven't told us much about this space or what you will use it for, so right now you know more about the answer to that question than we do. (That being said, PRX subs are JBL subs, so the highlighted question doesn't even make grammatical sense, sorry.)

So, to try and help, what kind of "studio"? Dance? Rehearsal? Commercial Recording? Video/Film Post Production?
Who will be the primary users? You? Paying clients? Someone else?
What are you actually missing when you listen to the 835s in the room? Have you utilised the onboard EQ's etc to try and see if they can give you what you need without extra subs?

What you actually need (rather than want) may well be quite different based on these kind of things.

Also, don't get your hopes up that a nominally cardioid product will do much good wrt family & neighbours etc.
This is because, in small spaces, the distribution of low frequency sound has a lot more to do with the room modes than the sub itsself - even the sound coming out the front of a cardioid sub will hit other walls of the room and bounce around, which may largely negate the cardioid effect anyway. That sound may also leak out of the room quite a lot, depending on it's construction. Effective soundproofing at low frequencies is not trivial unfortunately.

HTH,
David.
If only sound engineering was simple... c'est la vie! Yes, this is why I'm asking for advice. I'd estimate that about 90% of the time, this will be my home setup for rehearsal, recording and sometimes my home theater (yes, I know these speakers are far from ideal for a home theater, but I have other monitor speakers that are great for that already, and are the ones I'll use for mixing). I'll haul them outside maybe 3-6x/year MAX for live shows, generally mid to small venue (~50-300 people) but they'll mostly be used as monitors for rehearsal/recording. This room (~30' x 13' x 12' ceiling) is a soundproofed room, roughly 64STC, which is really good for singing and acoustic performances, but nowhere near what I would need to actually blare these. So I'm sitting on an overpowered system and wondering if adding JBL STX or PRX subwoofers to the SRX 3-ways would be a good idea or just a waste for the main space. I can always borrow or rent a subwoofer for the few events, or just rent an entire system altogether. The double 18" JBL SRX subwoofer is just a huge (but awesome) monster to put in a space like this. So, the questions are narrowing down to these 2. 1) Do I need a subwoofer at all? and 2) If I do add subwoofer(s) to this configuration, should I just stay with JBLs, perhaps the PRX, and call it a day? Or should I go with QVC 212c cardioid(s). I want the best sound that I can get with the config I have. Thank you!
 
The 835s play down as low or lower than many small subwoofers (the -3dB point is around 40hz), so unless you're running dance parties in that space, you probably don't need subs. And if you do want to add subs, you're going to need something beefy to go enough lower than your top boxes to be worthwhile - a double 18 or something horn-loaded would not be out of place for your top boxes.
 

David Morison

Freshman
Aug 21, 2012
164
12
18
Aberdeen, Scotland
Thanks for getting back to us Mason.
I would say don't bother adding anything just for the home use; as Rob says the 835's get respectably deep for a PA type main speaker already, and given you'll not be needing to get them anywhere remotely near flat out in that size room, you should have plenty headroom to EQ in a little more thump if you find you want that.
The one exception would be if you really want realistic LFE for movies, that genuinely does require deeper extension. Asking on a more home theatre style forum might be the best bet if that's your priority.
Completely agree with borrowing/renting for gigging out, given the frequency you think you'll be doing that.
Cheers,
David.
 

Jeff Babcock

Senior
Jan 11, 2011
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Ontario, Canada
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Completely agree with borrowing/renting for gigging out, given the frequency you think you'll be doing that.
Cheers,
David.
Especially now. My last gig was over a year ago and I still have no idea when the next one will be with COVID dragging on and on, mostly due to people who are unwilling to follow public health guidance. So unless the OP can find a good deal now (quite a few sound co's have gone out of business during the pandemic so there have been many auctions etc), there is no point.