Ok, I have four of those woofers. These are currently installed (as not original drivers) in two 2x15 manifold/bandpass type enclosures. Rear chamber something around 210 litres, tuned to 45Hz. Front chamber 60 litres / one end open (tuning freq over 100Hz or so). Cones are facing each other inside front chamber.
But here is the problem: any more than 300Watts of power, or anything if xmax of 6.5mm is exceeded, they start to make "farting" noise / cone flapping.
Using highpass at 50Hz, helps a little but as power is increased further, they will hit the bottom which is weird. Specs are saying 38mm max excursion before damage, but I could clearly hear loud bangs while cones are moving around 10-15mm max.
It looks like these enclosures are way off for these drivers. Or maybe these drivers don't like cone loading like this. Maybe P540's are more for midbass/midrange?
Maybe there is bad cone control over xmax, but my 18" drivers does never any farting sound even at triple xmax cone travel? Even my JBL 2206H (12") has no such an annoying problems when pushed hard.
Maybe I should test one driver in standard bass reflex to see if those "farting" symptons disappear. What else, is there any possibility to make tapped horn for these? Or something else like Cubo15? HD15 kick bin? I'm too tired for boring bass reflex 😀
I actually need kick bins because I have two 18" hog scoops and (not to be used at same time!) one 2x18" bandpass for very low freq.
For mid/highs, I have 4x RCF L12L750 and two 2" p.audio bmd750 + large horns.
But here is the problem: any more than 300Watts of power, or anything if xmax of 6.5mm is exceeded, they start to make "farting" noise / cone flapping.
Using highpass at 50Hz, helps a little but as power is increased further, they will hit the bottom which is weird. Specs are saying 38mm max excursion before damage, but I could clearly hear loud bangs while cones are moving around 10-15mm max.
It looks like these enclosures are way off for these drivers. Or maybe these drivers don't like cone loading like this. Maybe P540's are more for midbass/midrange?
Maybe there is bad cone control over xmax, but my 18" drivers does never any farting sound even at triple xmax cone travel? Even my JBL 2206H (12") has no such an annoying problems when pushed hard.
Maybe I should test one driver in standard bass reflex to see if those "farting" symptons disappear. What else, is there any possibility to make tapped horn for these? Or something else like Cubo15? HD15 kick bin? I'm too tired for boring bass reflex 😀
I actually need kick bins because I have two 18" hog scoops and (not to be used at same time!) one 2x18" bandpass for very low freq.
For mid/highs, I have 4x RCF L12L750 and two 2" p.audio bmd750 + large horns.
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Hi tonskulus
You could try to build Tapped Horn.
Last year I modified the SS15 design to better couple with a driver available at my country. It's a light cone one with good BL, but not so high B&C one, so the design may satisfy you needs.
I made the simulation with 200W once it reach your driver Xmax 6,5mm, but in fact hornresp overestimate the diaphragm displacement, so you can put more power without a problem. Almost all design the displacement was higher than the driver's spec. This will give you around a flat 123dB response with -6dB at 36Hz (500W would be 127dB)
I also made a comparisson for you: SS15MOD with your driver vs THAM15 vs SS15 @ 2,83V.
You could try to build Tapped Horn.
Last year I modified the SS15 design to better couple with a driver available at my country. It's a light cone one with good BL, but not so high B&C one, so the design may satisfy you needs.
I made the simulation with 200W once it reach your driver Xmax 6,5mm, but in fact hornresp overestimate the diaphragm displacement, so you can put more power without a problem. Almost all design the displacement was higher than the driver's spec. This will give you around a flat 123dB response with -6dB at 36Hz (500W would be 127dB)
I also made a comparisson for you: SS15MOD with your driver vs THAM15 vs SS15 @ 2,83V.
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I ran a quick sim of this driver in a 135 litre MLTL tuned to 50 Hz. It started running out of linear excursion at 360W. 35 liters of that was the vent too, so I suspect with a slightly larger Vb and lower tuning, the driver will start running out of linear excursion at a lower power level, which appears to be what's happening in your case.
The Xmech quote is a peak-to-peak one, and it's 36mm, which suggests +/- 18mm, and that's if the limit is the same in both directions of travel. It might not be. It could be +21/-15mm for example, which would explain your observations.
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Not according to my observations. The prediction is pretty close once the driver remains linear. That's not always the case though 🙂
It is, as indicated on post #2 but probably not the best trade off.
I must agree with kickbin because it's lets demanding in terms of diaphragm displacement and it was one of the targets from the original post to match with 18" hog scoops. If he want's 4 way system, that's it.
Thank you!
Yes, HD15 kickbin has been in my mind.. just not sure if these drivers has strong enough cone for such a duty?
But I can try it for sure 🙂
Yes, HD15 kickbin has been in my mind.. just not sure if these drivers has strong enough cone for such a duty?
But I can try it for sure 🙂
Something like a Cubo 15 or tapped horn will have approximately 1.5 times less excursion as a typical reflex, so that could make a bit of a difference, as to how much power the driver would handle.
On the other hand those RCF L12L750 shouldn't be doing anything under 150 - 200 Hz in my opinion, so a kick bin is the logical next step. Personally I would suggest something like a Cubo Kick 15 (naturally) or the Xtro kick section, they don't go as low as a HD15 but are usable higher up. The HD15 is said to sound funny over ~170 Hz and you might need your tops to cross a bit higher than that.
Alternatively you could use all 4 RCF L15P540 in a reflex setup aimed at kick instead.
Johan (aka Cubo)
On the other hand those RCF L12L750 shouldn't be doing anything under 150 - 200 Hz in my opinion, so a kick bin is the logical next step. Personally I would suggest something like a Cubo Kick 15 (naturally) or the Xtro kick section, they don't go as low as a HD15 but are usable higher up. The HD15 is said to sound funny over ~170 Hz and you might need your tops to cross a bit higher than that.
Alternatively you could use all 4 RCF L15P540 in a reflex setup aimed at kick instead.
Johan (aka Cubo)
Yes, well.. actually RCF event 6000 speakers has L15P540 woofers. Quite a big enclosure tho, >300 litres I think. So according to this, P540 should be ok in large reflex too..
However I really want to make something else than reflex. kick bins or smallsh "all-round" bass cabinets (cubo or similar, if this type of enclosure is ok for P540).
However I really want to make something else than reflex. kick bins or smallsh "all-round" bass cabinets (cubo or similar, if this type of enclosure is ok for P540).
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