http://www.dpsinsider.com/forums/topic/subwoofer-science-repost Bongiovi Acoustics DPS Community en-US Tue, 22 May 2012 02:46:27 +0000 http://bbpress.org/?v=1.0.2 q http://www.dpsinsider.com/forums/search.php http://www.dpsinsider.com/forums/topic/subwoofer-science-repost#post-4 Thu, 10 Dec 2009 20:44:38 +0000 Joey Butera 4@http://www.dpsinsider.com/forums/ <p>Re-post from the old KD-S100 forum: <a href="http://ibongiovi.omgforum.net/consumer-audio-electronics-f6/sub-woofer-science-t35.htm#158" rel="nofollow">http://ibongiovi.omgforum.net/consumer-audio-electronics-f6/sub-woofer-science-t35.htm#158</a></p> <p>If I may add to the crossover conversation:</p> <p>Many consumer audio products do use the subwoofer to recreate frequencies well above 80Hz. Most home audio surround systems have tiny speakers that can only get down to about 250Hz so they tune the subwoofer up to take over where the small speakers leave off. Keep in mind, our ears can really only localize (place in the stereo image) frequencies 1000Hz and higher. For most situations our subwoofers are "invisible" and our ears place the sound where the higher frequencies are generated. I'm of the opinion that if you have a bi-amped system (the head unit's amps with a separate sub amp) then by all means share the load as much as possible. That is why SUB 01 sounds pretty thin with no subwoofer. I made that profile with the capabilities of the KD-S100 in mind and eeked out every ounce of power from the unit at the frequencies it is most efficient. Remember, it takes MUCH more power to reproduce low frequencies compared to highs. I tune my subs like this:</p> <p>1) listen to the sub all by itself at full range (no crossover). I usually use Skinny Puppy or some other electronic music with very clean bottom for this.</p> <p>2) sub enclosures (especially ported ones) are tuned to a specific frequency for which they are most efficient. 40-80Hz I consider subharmonic frequencies (808 kick drums, "quad" or rumble) 80-100Hz are "kick" frequencies (they are high enough to "knock" you in the chest with the bass drum). 100-200Hz are "bass guitar" frequencies where you hear actual notes the lower instruments play. So you should hear the "note" your sub is tuned to very clearly. As long as the sub has no built-in passive crossover, you should be able to hear muffled voices and plenty of other sounds as well.</p> <p>3) Usually the speaker and enclosure will generate harmonics or other "notes" above the note it is tuned to. I listen for those by trying to notice muddiness in bass lines, boominess in the voice or a general honky sound. I then begin to turn the crossover frequency down until I get to a "sweet spot" where most of the voice is gone and the bass line and kick drum clean up nicely. The "Slope" control is how sharp (in dB per octave) your crossover affects the signal from the crossover frequency on down. This in turn affects the harmonics (higher slope number = more pronounced upper harmonics) so that control can be used to as well to shape the sound of your sub.</p> <p>4) After this process, the sub should sound big, ballsy and tight and very musical all on its own. I find my 12" sub in the studio sounds great at about 150Hz when used in conjunction with my NS-10M studio monitors. We have our Bryston crossover (or the sub's internal one) set to a 6dB/oct curve to keep the subwoofer's tone natural and to blend it into the low end of the NS-10. I designed VAR SUB 01 with the sound of NS-10's in mind to kind of re-create that particular studio sound in the car. The high mids are fairly well pronounced and the bass is rolled off at about 100Hz. The DPS processing is quite aggressive in this profile which should allow for very nice performance on low cost drivers. I find the best drivers are your standard paper cones with a decent magnet.</p> <p>5) Once the subwoofer sounds good, turn it all the way down and turn on the speakers in the cab. Set the KD-S100 with no bass or trebel boost. Play the same songs and find the approximate listening volume you normally use. It will sound bright and weird now so slowly turn the sub back up until you reach that magical "sweet spot" where the music "comes back together" and the sub is a natural extension of the cabin speakers. If at all possible to do safely, try this whole process while someone else is driving for you on the highway. Road noise is a HUGE factor in car audio that most people never take into account while tweaking their systems in the driveway. Your ears will automatically take the road noise into account as you tune your vehicle so when you are happy at 50mph, you will be happy in the parking lot! Also keep in mind that the subwoofer output is the only output on the KD-S100 that has no DPS processing.</p> <p>I'm trying to speak in musical term instead of engineering terms because in the end, that's all that really matters. It does take some time and patience to get the hang of this stuff and hey, it's also totally subjective! If anyone has any other techniques, I'd be happy to hear them. </p>