Quad 8's for punchy bass

[bw1313]

Hi all

I've built a pair of vented enclosures which contain 12" 300w RMS rated subs. The box vol. is 55L and box freq. is 35 Hz and is being powered by a 4 x 100w RMS amp which i have bridged to get Approx. 300w RMS to drive each sub.

The subs sound great with most types of music, but the problem i have is that i want a more punchy response when i listen to heavy metal. In particular to reproduce the quick double kick of the drums.

To achieve this i see three options:
1. Rebuild my 12" enclosures with a smaller box volume

2. Build an extra set of 3way XO floor stanging speakers which include two 8" woofers (I have little experience with XO to date tho)

3. Build a sub enclosure that uses 4 x 8" woofers.

The 3rd option seems the most interesting to me. Box size is not a big consideration as my main goal is reproducing a specific range of frequencies.

Any comments, sugestions or tips would be great.

Cheers

[joecarrow]

Hi BW1313,

I've studied the waveforms of bass drums in software, and the initial impact of the bassdrum has a lot of energy at frequencies over 200 hz. Your present subs might be OK if you have the rest of the system to go with them- the sound isn't all in subwoofer range.

I found that the initial attack (the slope of the transient signal) is practically an impulse, and after it starts to come back and go into resonance it does a couple of cycles with periods in the 200-500hz range, constantly lowering in frequency to a sustained tone anywhere from 40 to 150 hz. The bass drums I studied were samples from electronic music programs and clips from some of my favorite rap and rock songs.

What's in the rest of your system right now? If you're mating some 6" two ways with these subs, you could have a really satisfying system for a lot of movies and music, but be missing some of the visceral impact in the 75-300 hz range. The subs won't go high enough, and the hypothetical 6"s won't go low enough at serious volumes.

One thing to keep in mind is that if you're going for the "live concert" sound, the desired frequency response probably won't be flat, and some specific EQing is likely necessary to give you that in-your-face flavor. Some sort of graphic or parametric EQ would probably be helpful, and overkill with the headroom will let you get there without overstressing the components.

[bw1313]

Joe attached is the sub data.

In this room with this system I'm only running a set of floorstanders that consist of a 1" tweeter, 4" mid and a 6.5" woofer. They pump out some volume, but are not outstanding by any means. They are pretty rough compared to what i run in my main system.

[joecarrow]

Interesting... that XSL1236 has its upper limit listed as 2,500 hz. I don't know how sweet it will sound that high, but you might want to try increasing your crossover frequency from the sub to the main to something over 200hz, maybe as high as 400hz, and boost the level on the sub if no EQ is available.

If a little more EQ is available, then I'd want to give the subwoofer a highpass slightly above the tuning frequency to reduce excursion and improve headroom, and then give the sub a 2-4 db boost between 100(ish) hz and the crossover to the the mains.

If there's any quick way to try this it might give good results. I think my recommendations would give a good effect for metal, but would take some tweaking of the crossover point and boost to get the best effect in your room.

[thylantyr]

If you like heavy metal and want SQL, pm me .. I have ideas. :lol:

[Rudy Jakubin]

Glad to see someone with the same problem. I've been pursueing this for over a year now. The last 2 months have been the most productive. Playing around with an equalizer I got center frequencys at 60 120 & 180 to 240 that captures the bottom end of the drum attack. As joecarrow correctly observed it's more than just the lower octaves and they're respective harmonics, it's the grand total.
The quick solution would be a pair of line-arrays. I've attached a pic of my 5 1/4" aluminum array that can reproduce any drum kick with both - impact and clarity. The opening of "Smoke On The Water" will just floor you.
My pursuit as stated above was to reproduce the same affect with modular speakers i.e. Subs + MTM's or 3 -Ways. The normal point source type speaker systems.
What I've been doing lately is mating high Qts drivers in small sealed enclosures to mimic my equalizer settings. The graphs below will resemble 4th & 6th order bandpass boxes, but without the disadvantages of said designs (High Group Delay & Port Noise).
So far, so good. My 15" Aluminum sub with a Qts of 1.4 - 4 cu. ft. box /w plate amp (white line) is handling it very well. The yellow line is for a 12" Goldwood with a Qts of 2.0 in a 3 cu. ft. box.
The other 2 lines are for 2 drivers in parallel.
Well, I think I got the bottom end covered and it's on to the mid and top end.
If I had a Decx 2496 I could probably nail it.
So far this setup can play with any genre of music. I especially love the standup bass in jazz and pop songs, also the lower piano keys which seem hidden in a lot of songs like Diana Krall's and others are accentuated also.
Just need to get that attack nailed down in the mids and treble.

[bw1313]

Thanks Joe I got a little bit more of the sound i was looking for, but i have limited EQ to play with. My logic was pretty much on the same wavelength as yours, so my settings didn't change all that much.

I'm still exploring the 8" mid bass option, playing around with several drivers. I have been modelling a few options with various freeware enclosure packages to try and get a bit more punch around 100-200Hz range. Also going to check out a few other options, caus now we have a Peerles, Vifa and ScanSpeak dealer in Australia. It's interstate, but at least it's not international freight