6th order BP kick section

I agree with Mark, the driver should have a Qts around 0,3 and a lowish BL around 23, that makes the response nice and smooth. I think that the 0,2 Qts high-fs drivers that Johan mentions are more for pure horns without a front chamber. They'd make a peaky response in a BPH. I made a pair of 6th order BPH based on L15P200AK, but they were rather aimed at low extention.

As to 'real kick bins': they're all 4th order band pass horns, Turbo TMS, F1, HD15, so if you like that sound, go for it. They all have front chambers, otherways they wouldn't play that low. A straight 15" horn without a front chamber kicks like madness (think Martin MK1) and I can understand that people find that sound way better than a BPH, but then the only thing that makes it play lowish (70 Hz) is horn length.

It's not the group delay as it only displays how long it takes till the signal will be coming out of the system. It can be compensated by delay as long as the group delay over frequency diagram won't be a wild ride around the crossover frequency. It is the decay time of the resonator. A resonator is a very high Q system, that means energy will be stored in and then put out of the resonator, and this won't happen in an instant, especially the "puting the energy out" will take some time AFTER the original signal stopped and even AFTER group delay time has passed. What a resonator does to the original signal is NEVER a good thing, it's always a degradation. Below 60, 70, 80Hz it is acceptable, but still not great. Above 80Hz it's just ugly compared to real "kick bins".

Most double-12 tops are tuned to 80Hz or below, and crossed over around 120Hz. That's ok in my opinion, still there is coming some "noise" coming from the resonator. Stuffing the port for top usage comes to mind. Ported tops tuned to 100Hz or above are just flawed designs, I wouldn't like to use them at all.

I have had some problems in the past with Doppler effect in a design similar to this

I don't say you shouldn't try, just make sure the speed of air in the ports is as low as possible so there won't be a lot of air moving along with the mid and HF, atrough I am still not shure that this is the corect way to cure the problem after some recent tests.

This can also be observed when running stupid amounths of sub right next to midtops

above a certan limit everything starts to sound muddy when you unmute the sub section.



Edited by Mircea Bartic - 11 January 2011 at 9:40pm

I've found light cones work well in 6BP that need to reach mid kick bass/mid bass frequencies. I used the 18sound 18ND930 in 6bp (light cone for an 18) and measured -3b 47hz - 136hz. Sounded good crossed at about 120hz.

could another idea be to take the meyer aproach and relex load the rear chamber of the 12" section - they do this on the MSL4 to good effect, that runs down to 65Hz ewith just one 12" and 2" per cab

From what you say the B&C 15NW76 would be nice. FS 42, Qes 0,23, Qts 0,22, Vas 130L, Le 1,25mH and Xmax 8mm.
The simulation also looks good for rear chamber 60L at 70Hz and front chamber 20L at 140Hz. But measurements will tell.

I dont know what compression ratio you mean? For the porn horn I dont know. The porn horn plays down to 130Hz so I would cross over them around 130-160Hz must see. The low cut off for the bandpass would be arround 80Hz. I have 1000W availible to power the kick section.

I dont know how will a BP sound compared to a say USB, what you guys think?

Regards
Luka