4 CBe-18s or 6 SS15s

[scameron78]

well i had the money saved up to purchase drivers, but had to buy a new car. so i am currently saving again, but there is a chance i will be starting a new job and won't have access to some really good machines; CNC, panel saws..ETC...(i am currently an engineer for a wood working company). i wanted to start building before i leave this job. this build will be for live band applications only. most of the shows are indoors, but we do have a few outdoors. i currently have 2 amps i can dedicate to sub work both are QSC RMX2450s. thought about running 3 SS15s per side at 2 ohms (1200 watts per channel), which means using only one amp, or bridge and run 2 CB-18Es per amp. the SS15s will be loaded with Kappa Pro-15LF (or a driver similar in price) drivers and the CB-18Es will be loaded with either B&C 18TBX100, 18Sound 18LW2400, or cheaper drivers like Selenium 18SWS1100 or P Audio C18-650EL (would have to change amp set up).

i have modded the SS15s to use 18mm plywood (because that is what i have) and changed the outside design similar to kevinmcdonough post here THAM 15 - Touring Version! (and matching top) - Speakerplans.com Forums - Page 1

later on i'd like to build some tops that match the same dimensions as my bottoms. thought it would be an interesting challenge plus all the boxes would look identical. my SS15 design measures 22.5" H x 37.5" W x 26.69" D. the CB18s measure 22.75" H x 41.42" W x 27.36 D.

both set ups should work great, but i'm just torn between both designs. any thoughts?

[m R g S r]

How do the cb-18's sim? I'm guessing 4 will destroy 6 ss15's below 50hz...

[Djim]

Based on Stipe’s HornResp from #108 Post – thread: Speaker design project for Pyromusicals, both drivers will work. If Stipe’s model of the Cyclops Extended CBX18 is correct the average sensitivity within its bandpass is 101,9dB 1W/1m has an even higher efficiency as Jbell’s SS15 (average of 100.3dB 1W/1m with 3015lf). Use capable low cut filters at 38Hz!

[Djim]

Has anyone a link or actual drawings of the CBX-18 (CBe-18 are all around)?

[scameron78]

from my understanding the width is increased to 1152mm. not sure where the added dimensions occur for the internals.

quote from staiper off the speakerplans forum;
"In fact there are drawings for few slightly modified variants every made on specific demand.

1. Standard CB-18
2. Extended front CBe-18 (streetsounds version, 700mm deep)
3. Full extended CBX-18 (extended pathlength, front and mouth area) - made on demand for extra few hertz LF extension

+ there is also standard CB-18Light version plans for 15mm plywood (extralight version ... as much as it can )

Ofcourse it is possible to make to modify design to suit some new goals but all comes with some compromise .. If you want additional LF extension in compact size ..SPL suffers, If you want booth , max SPL and LF extension too cabinet size goes up rapidly.. etc

It is not big problem to make one "monster mega, giga, cyclops" but than size and weight will go much out of margins of regular "usability" and muscle and spines will hate em (however may be good for showing and shootouts)

I have thought about Cyclops idea to be good bass solution with "ideal" bandwidth for most jobs (flat ~40- ~130Hz), pretty easy manageable size and truckpack friendly. Any further increasing size (more than CBX-18 version) will go out of this goals."

[Djim]

Thanks for your reply Scameron78. I have my doubts about the HornResp Response of the CBX-18. To get such grafic response you will end with a cab way bigger as the real one.

Meanwhile I did my best to reverse engineer the CBe-18 to get a more realistic response from it. I still end up with a bigger volume (374litre in HornResp and the actually build one is less than 374Litre) than it is in reality.

Anyway, I hope this response helps in finding the answer to your question.

[scameron78]

yes very helpful Djim. i believe i am going to build the CBe-18. what are your HornResp inputs for this cabinet? i've been running sims but not sure my inputs are correct.

[Djim]

The problem in most models I have seen so far is that the volume in the cone is included in the front chamber. If you do so you have to make up the volume of the cone + the rest of the driver in the S4 area. Otherwise you will end with an extreme volume in your model that doesn't translate to the real thing.
The problem with HornResp is that it doesn't support more point within the path so for some values like S3 I used a more average value which is slightly lower. But actually it would be a great if Martin or Oliver could model it more accurate with a roll-out path.

Any comment is welcome.

[Djim]

I don't want to make you doubt, but a slightly bigger THAM (1/2 size of the CBe) loaded with 18Sound 18LW2400 can beat one CBe-18 in dual settings by 1,5dB in sensitivity (1W/1m) and about 4dB in max... and I still love the compactness/weight/performance of such system in quad-stack settings..... Never mind, just an idea to make your head go crazy

[scameron78]

Originally Posted by Djim

I don't want to make you doubt, but a slightly bigger THAM (1/2 size of the CBe) loaded with 18Sound 18LW2400 can beat one CBe-18 in dual settings by 1,5dB in sensitivity (1W/1m) and about 4dB in max... and I still love the compactness/weight/performance of such system in quad-stack settings..... Never mind, just an idea to make your head go crazy

any links to a cabinet? i am open to something smaller. right now i have the packing for the CBe figured out in the truck we use to haul the equipment. something smaller would make it easier.

what do you mean by dual settings; 2 THAM to one CBe-18?