recon440
Junior Member
Hi everyone,
I'm in the process of designing a new enclosure for next season and would like to get some advice.
To give some context, the vehicle in question is a 2001 LS430 which has a sealed trunk which only has a ski-pass, which is suboptimal for conventional bass-reflex designs. At the current power level (~1500W Fosgate T1500-BDCP) I was using two 12" Alpine Type R's in a 6CF ported alignment tuned to 37Hz. This setup had immense lows (30-35Hz) but fell flat on it's face above 45Hz due to the trunk and ski-pass acting like a poor 6th order, not to mention annoying trunk rattle. Here's a photo of that:
Next, I built a 4th order bandpass (1.8cf rear chamber / 3.8cf front chamber) and the output was somewhat better and more flat but the lows were not as powerful. To remedy this I modified the 4th order to a 6th order by porting out the rear chamber using a pair of 3"x12" PVCs. This gives a net tune of ~33Hz on the rear chamber and ~75Hz on the front chamber. Output from 30Hz to 80Hz is quite impressive and the box response pretty much the same as the Hornresp model to the ear. Now I'm looking to get even louder and the bottleneck is essentially the power handling on the Type Rs.
This is what the modelling looks like in Hornresp. Alpines @ 1000W in a 6CF vented (grey) vs Alpines in 6CF series 6th-order bandpass (black curve):
Below is what the box looks like now:
For this season, I am planning to go louder with more power (~4000W). I am targeting to be very loud between 35-100Hz for which I have two options:
- 2 x 12" DC Audio XL m2 (each 2200W RMS)
- 2 x 18" B&C 18SW115-8s Neos (each 1700W RMS, 3400W program power)
I actually have both sets of drivers as I am too impulsive and had to pick up a pair of B&Cs cause the price was too good (~350USD a piece brand new). The B&Cs are monstrous in terms of cone area with a motor size that is unassuming compared to ferrite offerings even though they house a 4.5" inside-outside would coil... LOL. Engineering and build quality is really impressive on these drivers.
The DC XLs are attractive in that they are compact and can essentially be retrofitted into the existing enclosure but the B&Cs are even more compelling to me for a few reasons: the wow factor of two 18s, the ability to run them outside of the bandpass as a bass-reflex as PA-sound rig, and the weight (~28lb a piece which is half of the XLs). The motor force on the B&Cs is impressive and on paper the only place where they fall short in comparisons to the XLs is xmax (14mm vs 26mm) but I don't think this is an issue due to cone area and the fact that they have a huge xmech of 60mm p-p which is atypical for a PA driver.
Obviously to fit the 18's I will be redesigning a box into two piece sections: the rear low-ported section which houses the drivers which will then sleeve into the front section which will be build to conform to the front aperture of the trunk. Optimizing these in Hornresp I am working with the following sections:
- Front chamber: 6.6cf tuned to 74Hz (front port 5cm long, ~75sq in)... preferably would like more port area but it's all I can do with the ski-pass. Port velocities even at 3000Ws are still <40m/s which is not bad.
- Rear chamber: 3.8cf effectively tuned to 40Hz (twin 4"*8" PVC) as a bass reflex, but drops to 36Hz when loaded into the 6th order alignment with the front chamber.
The sleeve looks something like this with the 3.8cf loading into it:
If I were to go with the DC XLs then I would just use the existing 6CF box that the Type Rs were using but with more power.
When I compare the B&C to the DC XLs, the B&C dominates everywhere on paper.
Here is a comparison of the B&C 18s (dark) and DC XL 12s (light grey) normalized to @ 3400W.
Even at 3400W I am within the rated xmax of the B&Cs of 14mm (black line) from 30Hz and upwards. In fact the xvar on the B&Cs is 16mm and with xdamage 60mm peak-to-peak there is no risk of unloading these things that hard even at 20Hz.
The main question is whether there is something I am missing because this all seems too good to be true. Has anybody else use pro-drivers for such an application? With current sims the DC XL's will generally be better <35Hz but with that being said I don't think that they can even remotely hang with the pro-drivers in terms of a wide broad-band response from 40Hz-100Hz, which for me is the sweet spot of bass and where real loudness is perceived. I'm not really interested in doing hairtricks. In fact I'm thinking the B&Cs should model closer to reality than the DCs due to the fact that their inductance is much lower thanks for the shorting ring (1.9 Le for the B&C vs 5.2 Le for the DC).
Thanks for any advice...
I'm in the process of designing a new enclosure for next season and would like to get some advice.
To give some context, the vehicle in question is a 2001 LS430 which has a sealed trunk which only has a ski-pass, which is suboptimal for conventional bass-reflex designs. At the current power level (~1500W Fosgate T1500-BDCP) I was using two 12" Alpine Type R's in a 6CF ported alignment tuned to 37Hz. This setup had immense lows (30-35Hz) but fell flat on it's face above 45Hz due to the trunk and ski-pass acting like a poor 6th order, not to mention annoying trunk rattle. Here's a photo of that:
Next, I built a 4th order bandpass (1.8cf rear chamber / 3.8cf front chamber) and the output was somewhat better and more flat but the lows were not as powerful. To remedy this I modified the 4th order to a 6th order by porting out the rear chamber using a pair of 3"x12" PVCs. This gives a net tune of ~33Hz on the rear chamber and ~75Hz on the front chamber. Output from 30Hz to 80Hz is quite impressive and the box response pretty much the same as the Hornresp model to the ear. Now I'm looking to get even louder and the bottleneck is essentially the power handling on the Type Rs.
This is what the modelling looks like in Hornresp. Alpines @ 1000W in a 6CF vented (grey) vs Alpines in 6CF series 6th-order bandpass (black curve):
Below is what the box looks like now:
For this season, I am planning to go louder with more power (~4000W). I am targeting to be very loud between 35-100Hz for which I have two options:
- 2 x 12" DC Audio XL m2 (each 2200W RMS)
- 2 x 18" B&C 18SW115-8s Neos (each 1700W RMS, 3400W program power)
I actually have both sets of drivers as I am too impulsive and had to pick up a pair of B&Cs cause the price was too good (~350USD a piece brand new). The B&Cs are monstrous in terms of cone area with a motor size that is unassuming compared to ferrite offerings even though they house a 4.5" inside-outside would coil... LOL. Engineering and build quality is really impressive on these drivers.
The DC XLs are attractive in that they are compact and can essentially be retrofitted into the existing enclosure but the B&Cs are even more compelling to me for a few reasons: the wow factor of two 18s, the ability to run them outside of the bandpass as a bass-reflex as PA-sound rig, and the weight (~28lb a piece which is half of the XLs). The motor force on the B&Cs is impressive and on paper the only place where they fall short in comparisons to the XLs is xmax (14mm vs 26mm) but I don't think this is an issue due to cone area and the fact that they have a huge xmech of 60mm p-p which is atypical for a PA driver.
Obviously to fit the 18's I will be redesigning a box into two piece sections: the rear low-ported section which houses the drivers which will then sleeve into the front section which will be build to conform to the front aperture of the trunk. Optimizing these in Hornresp I am working with the following sections:
- Front chamber: 6.6cf tuned to 74Hz (front port 5cm long, ~75sq in)... preferably would like more port area but it's all I can do with the ski-pass. Port velocities even at 3000Ws are still <40m/s which is not bad.
- Rear chamber: 3.8cf effectively tuned to 40Hz (twin 4"*8" PVC) as a bass reflex, but drops to 36Hz when loaded into the 6th order alignment with the front chamber.
The sleeve looks something like this with the 3.8cf loading into it:
If I were to go with the DC XLs then I would just use the existing 6CF box that the Type Rs were using but with more power.
When I compare the B&C to the DC XLs, the B&C dominates everywhere on paper.
Here is a comparison of the B&C 18s (dark) and DC XL 12s (light grey) normalized to @ 3400W.
Even at 3400W I am within the rated xmax of the B&Cs of 14mm (black line) from 30Hz and upwards. In fact the xvar on the B&Cs is 16mm and with xdamage 60mm peak-to-peak there is no risk of unloading these things that hard even at 20Hz.
The main question is whether there is something I am missing because this all seems too good to be true. Has anybody else use pro-drivers for such an application? With current sims the DC XL's will generally be better <35Hz but with that being said I don't think that they can even remotely hang with the pro-drivers in terms of a wide broad-band response from 40Hz-100Hz, which for me is the sweet spot of bass and where real loudness is perceived. I'm not really interested in doing hairtricks. In fact I'm thinking the B&Cs should model closer to reality than the DCs due to the fact that their inductance is much lower thanks for the shorting ring (1.9 Le for the B&C vs 5.2 Le for the DC).
Thanks for any advice...