Cubo 18

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13 years 3 months ago #12555 by Cubo15
Replied by Cubo15 on topic Cubo 18
The original idea of comparing directly against an 18" reflex is, that some manufacturers inflate their figures, some don't, some use "tricks", etc. That way it's difficult to "see" on paper what exactly you've got. An 18" reflex is pretty standard, if not standard. Some might do a little more then others but as far as my experiences goes they are all pretty much in the 96 -99 dB/W/m region and 97-98 dB/W/m in the flat working range. This should give an easy reference for most if not all experience levels.
On the other hand, I do most commonly measure indoors, in a fairly large space (450 m'3 / 16,667 cu. ft.) I tried it outdoors but that was quite a hassle. So here I actually need the reflex as a reference, to excite the same room nodes (a blanc).

As I do live in the middle of a city, measure-ing outside would require a large car, a long drive, a generator, nice weather, a friendly smile to alarmed law inforcers (or a permitt). As I said before, working on it, but that smile, its so hard ;)

Personally, for Cubo Sub I would use lowish to medium Qts 18" or 21" drivers (0.20 -0.35). However, if it works in Cubo 18 and most of the times Cubo 15, it will work in Cubo Sub.

When the final measurements appear they will be the usual: 18Sound 18LW1400, Void Acoustics V18-1000, Eminence Kappa 15LF and another yet to be named 18Sound 18" driver. Love to get my hands on a 21". Currently adjusting Cubo 21 plans to fit the PD 2150 (I do the talk, Xoc1 the walk). As soon as I get my hands on a 3015LF I will try that one too, as it sims fairly well (minding it's an lightweight 15").
After measurements I'll be able to make a list.

Best regards

Cubo

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13 years 2 months ago #13139 by Carlos
Replied by Carlos on topic Cubo 18
Cubo 12 by CarlosWith the magnet inside the chamber of the Cobo 12 can we increase the chamber volume for speaker displacement, and if so how much can we increase it by as far as height is concerned? Your help would be an asset to my project. ThanksCarlos

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13 years 2 months ago #13149 by Cubo15
Replied by Cubo15 on topic Cubo 18
Hi Carlos,

I'm not entirely sure I correctly understand your question.

An increase in chamber volume will increase sensitivty at the lower end of the response in exchange for an overall lower sensitivty climbing higher as frequency rises up to a maximum of 140 Hz. Increasing the height of the cabinet also increases the horn path length and changes the horn expansion profile. It would be easier to predict performance based upon a given height then to predict a maximum.

Best regards Cubo

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13 years 2 months ago #13177 by Carlos
Replied by Carlos on topic Cubo 18
I plan to build a pair of Cubo 12 but i like the look of the seeing the speaker cone with the magnet in the chamber, so i would like to enlarge the chamber volume to maintain a lower tuning and better low frequency, my question is, how much will i have to increase the volume and will this work out ok?Thanks, Carlos

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13 years 2 months ago #13192 by Carlos
Replied by Carlos on topic Cubo 18
Just some added note. With the increse in volume of the Cubo 12 chamber i would want to keep the horn volume the same size. Thanks.

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13 years 2 months ago #13197 by Cubo15
Replied by Cubo15 on topic Cubo 18
The average 12" driver takes up about 5 liter and holds 1 - 2 liter inside the cone. The chamber therefor will be ~7 liter smaller. Because the horn volume is now 7 liter larger it will influence the result a bit more. leading towards higher efficency and less low bass. Best would be to make the chamber ~10 liter larger (instead of 7 liter) to compensate for this increase. Keeping the horn the same means the cabinet has to be made 6 cm higher or wider or deeper. If you need any help on this let me know per e-mail.

Best regards

Cubo

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13 years 2 months ago #13201 by Carlos
Replied by Carlos on topic Cubo 18
This info is sweet music to my ears,i will do a full scale drawing and send a sketch off to you for approval. Thank you!

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13 years 2 months ago #13217 by
Replied by on topic Cubo 18
Does anybody knows how much trimite / Warnex structure paint it takes for 2 cabinets?

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13 years 2 months ago #13221 by bee
Replied by bee on topic Cubo 18
a guess would be about 3L for 2 coats

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13 years 2 months ago #13378 by nickyburnell
Replied by nickyburnell on topic Cubo 18
Got one of these built, pics later.XB going in, will report back soon.

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