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Tops to sub ratio issues

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charlysays View Drop Down
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    Posted: 01 January 2018 at 2:22pm
firstly happy new year everyone :)

So I recently did a gig with four cubo subs and a couple of jbl 18s for kick. Cubos running 30-70hz- 6.8kw (though mostly I was running them at around -6db due to stuff falling off shelves and the cops turning up). JBL 18s running 60-120hz at up to 0db. JBL MP415 tops (BMS 4540 comps) running 120hz - 20khz running at around -6db. Rarely saw the limiters come on at all and the DBs were subtracted off the DSP output bands so the bins were basically ticking over all night.
I flip the phase on the cubos and use a fairly shallow slope on the filters to blend between the reflex kicks and the cubo subs, by and large they're in phase enough for the output to be better and clearer than just using the cubos up to 100- 120hz.

Anyway, I'd like more headroom on the midtops but cannot justify building or buying a pair of big tops, bi-amping etc. I've seen a pair of working JBL SP212 tops on ebay (1.75" coils on the CDs) and I'm wondering if these will give me more mid top headroom and if they will run fine on top of the MP415s? I'm assuming that because they're both a very similar design that they should be closely matched enough in phase terms to work OK?

Unfortunately MP415 tops are pretty rare, only seen one pair other than the pair I bought in 6 months (and they were a bit expensive and collection only) otherwise I'd just get another pair of these as I like the sound/ weight/ price ratio. Very smooth sound especially coming from using JBL JRX/ Soundfactor stuff which are horribly harsh.

So basically would the SP212 tops give me more headroom and work with the MP415s to give a similar result as a single pair of bigger tops is what I;m asking basically.
Cheers
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Conanski View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 02 January 2018 at 3:43am
Unless I misunderstand something your limiting factor seems to be the kick band.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote charlysays Quote  Post ReplyReply Direct Link To This Post Posted: 09 January 2018 at 11:53am
Originally posted by Conanski Conanski wrote:

Unless I misunderstand something your limiting factor seems to be the kick band.
 
True, though I could probably run the reflex bins which I use for kick with another 3db, or add another pair of reflex bins to add another 6db on top of that. Been running them too conservatively. Do reflex bins kick adequately?
I'm loath to build some specific kick bins as I basically run varying amounts of rig for different types of events and don't do a whole lot of events anyway. Sometimes just two tops and a couple of reflex subs (for a funk night in a small pub for example) up to a couple of cubo subs and two tops for a small rave party up to a maximum of 4 cubo subs.
 
So if I built some kick bins they'd probably get used about once per year.
 
In another thread where I was identifying ways to improve my sound it was suggested that there was not enough good quality mid range/ enough headroom in the mid range hence asking about getting another pair of tops though it seems there's a wide range opinion here.
 
I myself, like you don't feel that the tops are being overpowered if they're running on average at -6db.
I hear some say that tops should be able to do kick, run down to 80hz or so. If I had four tops to four cubo subs do you think there'd be adequate kick from those for me to be able to leave the reflex subs out of it?
Would tidy up the crossover and phase alignment too as I could cross them sharply with the cubo subs at around 80-90hz
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 09 January 2018 at 3:52pm
Are the tops biamped or is there a passive crossover between the 15 and horn? If they are passive then you still have loads of headroom in the comps and simply adding another reflex 15 will add more output and headroom in the low mids. Personally I'd lose the 18 reflex and go with a double 15 + horn vertical stack that runs all the way down to 80hz to meet the Cubos, and then biamp that.


Edited by Conanski - 09 January 2018 at 4:04pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote charlysays Quote  Post ReplyReply Direct Link To This Post Posted: 13 January 2018 at 4:26pm
Originally posted by Conanski Conanski wrote:

Are the tops biamped or is there a passive crossover between the 15 and horn? If they are passive then you still have loads of headroom in the comps and simply adding another reflex 15 will add more output and headroom in the low mids. Personally I'd lose the 18 reflex and go with a double 15 + horn vertical stack that runs all the way down to 80hz to meet the Cubos, and then biamp that.


Passive X-over yes...
So a couple of 1X15" cabs to go under the 1X15 tops would work as well? Then loose the reflex 18s.
As I said I wanna keep using compact tops as they seem loud enough and work for both small discos and also more bass heavy nights.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 13 January 2018 at 5:32pm
Originally posted by charlysays charlysays wrote:

So a couple of 1X15" cabs to go under the 1X15 tops would work as well? Then loose the reflex 18s.


Yes exactly and if at all possible use the exact same 15" driver that the MP415s have so that output characteristics match as closely as possible. That could prove to be the hitch in this plan as I don't know what luck you will have finding another JBL 2033H. Actually I just had a thought on that, you have 2 boxes so as an experiment stack the MP415 boxes with the bottom box upside down so the 15's are closer together, it won't matter that the CD/horn is there because it won't produce any output with an 800hz crossover so you don't even need to disconnect it. I'm also going to suggest you use steeper crossovers for this.. like LR24.
15's in general have as much output and power handling as an 18" above 100hz so you won't be giving up any output in the range the 18" was covering, and if you extend the crossover up to say 800hz on this box alone you gain some low-mid output and minimize the downsides of running two large drivers in parallel up into midrange frequencies. So just to be clear the extra 15" runs from 80-100hz up to 800hz, and the MP415 box also runs from 80-100hz and up so there is an overlap in output, hence the need for identical drivers in boxes tuned to the same frequency.
Ideally this type of thing would be done with a large 2" CD and both of the 15's would be crossed at about 800hz, that configuration with the right type of horn produces much better vocal clarity and definition and a large gain in output and headroom but also at the expense of some topend sparkle.. but that is easy to fix.

On another note you could try the same thing with the 12" box you just acquired, I believe you said you only have 1 box right now but the 2206 is a lot more common.




Edited by Conanski - 13 January 2018 at 5:41pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote charlysays Quote  Post ReplyReply Direct Link To This Post Posted: 29 January 2018 at 5:59pm
Originally posted by Conanski Conanski wrote:

Originally posted by charlysays charlysays wrote:

So a couple of 1X15" cabs to go under the 1X15 tops would work as well? Then loose the reflex 18s.


Yes exactly and if at all possible use the exact same 15" driver that the MP415s have so that output characteristics match as closely as possible. That could prove to be the hitch in this plan as I don't know what luck you will have finding another JBL 2033H. Actually I just had a thought on that, you have 2 boxes so as an experiment stack the MP415 boxes with the bottom box upside down so the 15's are closer together, it won't matter that the CD/horn is there because it won't produce any output with an 800hz crossover so you don't even need to disconnect it. I'm also going to suggest you use steeper crossovers for this.. like LR24.
15's in general have as much output and power handling as an 18" above 100hz so you won't be giving up any output in the range the 18" was covering, and if you extend the crossover up to say 800hz on this box alone you gain some low-mid output and minimize the downsides of running two large drivers in parallel up into midrange frequencies. So just to be clear the extra 15" runs from 80-100hz up to 800hz, and the MP415 box also runs from 80-100hz and up so there is an overlap in output, hence the need for identical drivers in boxes tuned to the same frequency.
Ideally this type of thing would be done with a large 2" CD and both of the 15's would be crossed at about 800hz, that configuration with the right type of horn produces much better vocal clarity and definition and a large gain in output and headroom but also at the expense of some topend sparkle.. but that is easy to fix.

On another note you could try the same thing with the 12" box you just acquired, I believe you said you only have 1 box right now but the 2206 is a lot more common.




So I've picked up another pair of tops... which would probably fit into your plan very well as they are passive and also bi-ampable.

They are JBL SP225-9. Same 131db max spl as the mp415 but the comp is 4" diaphragm vs the 1.5" mp415 diaphragm, 1.5" outlet vs 1" outlet.
Woofers are JBL 2226h (so very easy to find more of if I wanna build these 15" single boxes).

I got them for £100 the pair. One has a blown woofer (tested CD and it's fine). May be some damage to the crossover in the one with the blown woofer but we'll see.
Certainly they were so cheap I couldn't say no.
Otherwise they're in good shape apart from the grills which need straightening, sandblasting and re-painting. With that done they'll look fresh.

They're a bit weighty... but this is due to the comp which is massive and almost as heavy as the woofer.

I believe they should be able to produce clear sound at a higher SPL than the MP415 (and the peak SPL of the MP415 is plenty for all my gigs).

They're really install speakers but have lots of m5 threads on them so I could easily weld up an adapter so I can still put them on pole mounts. At 38kg each they're well within the safe working load of my stands.

Cheers for the tips and I'll do some testing with these.
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