For audio (not video) is there really much information below
-3db at 43hz?
At 100 watt input, I should get approx 110db at -3db/43 Hz.
I think you're misunderstanding -3dB at 43Hz. This means that the sound output at 43Hz (and likely below) is 3dB quieter than the average for the speaker. Also, the fall-off usually increases as the Hz get lower, so it may be -9dB at 30Hz.
If the speaker is a conventional vented design it will be 24dB down at 21.5Hz. The SPL at 30Hz may be considerably further down than just 9dB.
I am highly dubious of the ATSW achieving 110dB at 43Hz.
A 6inch driver like AT 18H52 will run out of linear travel at 43Hz well before 110db SPL is reached and the roughly 200watts input needed to achieve 110db would handily exceed the 150watt nominal power rating.
Time for a sub.
Scotty
Scotty,
My lower Swan W12 drivers (2 per side) will be taking over at 100Hz via external crossover in a bi-amp setup.
The W12s are currently in a box not designed for them. I can alter the ports in the boxes to get -3db at 43 Hz or scrap out the boxes and build new 10cf boxes (huge) for a -3db at 30hz. SPL would then be approx 110 with 100 watt input at 30 Hz.
My plan is to build the ATSW's for the top end, modify my current bottom cabs for my W12 drivers.
I'm wondering if building new 10cf cabs for the W12s would be worth it for an extra 10Hz output down to 30 Hz.
Quote from: FnAudioDog on July 22, 2012, 04:14:28 AM
I'm wondering if building new 10cf cabs for the W12s would be worth it for an extra 10Hz output down to 30 Hz.
My opinion would be no, it is not worth building 10cf ported cabinets. You are using active crossover already, so you should seal the boxes and apply boost to get the low frequency response you desire. It will sound better.
The driver can take 300W peak during music playback, and are 90dB/W/m. So they cannot play 110dB at 30Hz without breaking. If you want that kind of dynamic headroom at low frequencies, you need 18+ inch driver and a big ported box, or sealed with 1000+ watts.
HiVi recommends sealed box of 75liters per driver. That's 5.3 cu ft for two drivers in same box. Sealed volume doesn't have to be exact. Try what you have now, you can adjust it with the crossover.
http://www.swanspeaker.com/asp/product/htm/view.asp?id=111 (http://www.swanspeaker.com/asp/product/htm/view.asp?id=111)
To answer your original question, there is not a lot of musical information below 40Hz, that's the lowest note on a bass violin or bass guitar. But there is a lot of information about the acoustic space below that, and there is musical information in bass drums, and organs if you listen to that. 40Hz+ is enough for most people, it is very low, especially if only -3dB at 43, that is pretty loud.
I agree with richidoo concerning the 10cf. vented cabinets, sealed and boosted is the best compromise possible with these drivers.
Unfortunately you didn't buy sub-woofer drivers. With only 7mm of linear excursion possible, your woofers will tend to run out of travel long before they exceed their thermal power rating.
Scotty
Hi Scotty, Richidoo, and Barry
Thank you all for your awesome advise. Your all spot on.
The "Key" sounds like equalization. My Swan W12s model at -3db at 56 Hz in a 5.3cf sealed box as Richidoo suggested.
I cannot EQ my lower cabs with my crossover i can only increase or decrease the volume.
Adding Marchand's WM8 "BASSIS" Bass Correction Equalizer
http://marchandelec.com/wm8.html (http://marchandelec.com/wm8.html) seems like it will put me right where i need to be. It will allow me to add boost at around 20-40Hz to give a flatter response. Adding the "Bassis" just before my bass amp will not effect the top cabs in any way.
I've had several ported cabs over the years and have not really
been happy with the bottom end.
I hate the thought of adding a component to the chain,but since it will only be effecting the bottom end (hopefully for the better) I think it will be good. The W12s are good drivers and I think they can handle the job.
Steve.
Linkwitz Transform will do what you want to do, it is DIY.
http://sound.westhost.com/project71.htm (http://sound.westhost.com/project71.htm)
http://sound.westhost.com/linkwitz-transform.htm (http://sound.westhost.com/linkwitz-transform.htm)
http://www.trueaudio.com/st_lkxfm.htm (http://www.trueaudio.com/st_lkxfm.htm)
You might only get 95dB at 30Hz with those drivers, but that's a lot for music. Sealed and boosted will also lower group delay so it will sound fast and clean. I bet you will be satisfied. ;)
I have permanently changed my name from FnAudioDog to WireNut
Quote from: WireNut on July 23, 2012, 12:20:01 PM
I have permanently changed my name from FnAudioDog to WireNut
I give up. Why a nut?
(http://upload.wikimedia.org/wikipedia/en/thumb/2/28/Why_a_Duck.jpg/300px-Why_a_Duck.jpg)