I have four Cobo 18 extended that were loaded with FaneXB's 1000w 8ohm they were ok but the bass was not quite deep enough so,
I have now upgraded to RCF LFX451- 18" 1800w 8ohm. The problem is the bolt pattern and the cut out hole are very different therefore; I may have to use clamps instead of m6 bolts and T-Nuts not having enough space to get a router and a drill in the cab to work on the baffle. Can I place another baffle on top of the existing one and what difference will it make to the performance and sound quality.
Mounting information: RCF LFX451
Overall Diameter: 465 mm / 18.3 inch
Bolt Circle Diameter: 442-447 mm / 17.4-17.6 inch
Bolt Hole Diameter: 6.5 mm / 0.25 inch
Front Mount Baffle Cut-out: 424 mm / 16.7 inch
Rear Mount Baffle Cut-out: 424 mm / 16.7 inch
Depth: 194 mm / 7.63 inch
MOUNTING Fane XB
Overall Diameter 19.1" / 485 mm
Width Across Flats 18" / 457 mm
Flange Height 0.465" / 11.8 mm
Baffle Hole Diameter F/M 16.52" / 420 mm
Baffle Hole Diameter R/M 16.33" / 414 mm
Fixing Holes 8x 0.275" diam on 18.425" PCD
8x 0.275" diam on 17.25" PCD
8x 7 mm diam on 468 PCD
8x 7 diam on 438.15 PCD
Depth 8.07" / 205 mm
Thanks in advance and I look forward to hearing from you,
Did you try the Fane with the magnet visible or magnet inside the chamber? That orientation has some influence on how deep the driver goes in Cubo 18 Extended, although most of it is due to Cubo 18 itself and not the driver. The RCF LFX451 is a good sub driver so it might change how deep it goes a bit but not by much. Because the RCF has good Xmax you can use o bit of EQ to get most out of
it but if you need much deeper bass Cubo Sub might be a better option for it.
I usually make a 18 - 30 millimeter ring on the baffle that has two sets of bolt patterns in it. It has 8 t-nuts for the new driver and spaced in the middle between those holes, 8 clean holes for the old driver. The ring is then mounted onto the baffle using hex bolt countersunk heads, so the ring surface is flush. The new driver can then be mounted with short bolts via the t-nuts. I like to countersink the t-nuts a bit, so that the entire bolt threat is used before exerting maximum (bolt clamp) force on the threat. The bolts are 17 - 29 mm plus whatever extra length is need for the driver, so they don't touch the baffle of the Cubo, this means they might need to be cut to length.
I've seen those clamps used before on heavy drivers, although I've never used them, they seem capable. So if implemented the right way that could be an relatively easy fix.
Please excuse me for the delay in replying to your response and thank you so, so much with all your help regarding the baffles and bolt holes.
In the end I made a double baffle and only used two of the four Cobo 18's with two specially adapted smaller cubo 15" cabs in a medium sized hall (they ROCKED and Tore the place down OMG happy days)
A friend of mine has finally completed building his Cubo 18's (hearing mine recently has given him a push) he would now like to extend them like mine. Can he place the 18cm extension board in the cab now the cab has been built or will he have to make new cabs.
Like you suggested in the last thread "Because the RCF RCF LFX451 has good Xmax you can use o bit of EQ to get most out of it but if you need much deeper bass Cubo Sub might be a better option for it" therefore I am now thinking about building some Cubo Subs to add to the arsenal but; I do not have a workshop, the weather is not so wonderful to build outside now and I am running out of time so, I'm considering buying some Mini Scoops, do you think there will be any compatibility issues?
After building 3 Cubo Sub's, which I love, I want to build a couple of Cubo 18's for the "portability" advantages. I scrubbed the thread but could not find recommendations of B&C drivers. Cubo, what would you recommend from the currently available 18" B&C drivers (
) ? Thanks.
Personally I favor lower Qes drivers in Cubo 18 Extended, so the 18PZB100 (ferrite, decent power handling), the 18NW100 (neo, high power handling) or the 18DS115 (cost no object, very high power handling). Considering you already have Cubo Subs, the 18DS115 might be a bit much.
The PD184C01 and Fane 18XB are quite similar in many ways (gap depth, voice coil overhang, Vas x Qes product). The main difference is the higher EBP and efficiency on the Precision Devices which makes it a bit more Cubo 18 oriented while the Fane XB is a bit more Cubo Sub oriented. However, because of the similarities in excursion they will both have similar performances in Cubo Sub as well as Cubo 18 (Extended for both). I expect the PD will pronounce the upper frequencies a bit (around 80 Hz) and thus the lower kick, while the Fane will sound a bit warmer and more subby.
So the PD184C01 in Cubo 18 for maximum output and the Fane in Cubo Sub for maximum sub oriented response. However swapping the drivers will also work.
- What (if any) delay should I put on my mid/top section? I've read though lots of posts and can't see any reference to horn length/necessary delay.
- I have it crossed at 40hz- 90hz. Does that sound right? I'm working with someone who likes/is fussy about 'real' low end... Could I go any lower than 40hz? I guess not. Could I boost 40hz through EQs on my DSP, if I dont push the driver that hard would this be ok? I'm running it with a QSC RMX1850 in bridge.
First you would have to look at your tops, if you have horn loaded tops with a long enough horn path, you might actually have to delay the subs Technically you're adjusting 33 cm (or about 1 ft.) of sound path difference for every millisecond of delay that you apply. Sound path differences depend on the exact design of the subs and tops but also spatial placement. The easiest way to set up delay is to play a sine wave, of the crossover frequency that you use, through your top and sub simultaneously. (in your case 90 Hz). This doesn't need to be played loud by the way.. If you reverse the polarity (red and black wire) on your subs, the best delay is the setting that reduces output to a minimum. Meaning that if you use the normal polarity during use, the sub and top will have maximum output at the crossover frequency.
40 - 90 Hz sounds like a good setting in combination with 1200 W if kept away from clipping at all times. Boosting 40 Hz with EQ, while also using a 40 Hz high pass isn't going to be very effective for boosting low bass. I would initially lower the high pass if you feel the E-18ELF does have enough excursion left (somewhere between 30 - 35 Hz). If you truly need more low end you can consider building a Cubo Sub instead or adding one to your current setup..