Lancelot Posted August 20, 2002 Posted August 20, 2002 If the cross over is fixed at the receiver's end, say at 80hz, will adjusting the cross over at the subwoofer's end alter the cross over to the sub itself?
Jag Posted August 20, 2002 Posted August 20, 2002 of course..... but you'll face a gapping hole below 80hz and the sub'c cross over. However, if your mains have good low freq extension, then its no such a big problem.
Lancelot Posted August 20, 2002 Author Posted August 20, 2002 So you mean that if the receiver's cross over at 80hz, and I set the sub's cross over at 60hz, there will be a gap in the range between 60-80hz right? Another question, even if I have full range front speakers, should I set them to "small" on the receiver, so that bass will be routed to the sub. Coz I was thinking that if the mains are set to "large", whereby the mains can only handle bass down to maybe 40hz, bass below 40hz that are supposed to be handled by the front speakers will be lost as the "large" setting on the receiver does not route the front bass to the sub.
desray Posted August 20, 2002 Posted August 20, 2002 My advice...if possible...try to set the mains (even if it's full-fledged dynamic floorstanders) to "small"...and the let the LFE adjustments to be handled by the Subwoofer. In this way, there's no need to worry about anything going below 40hz render it unable to be handled by the Mains. Anyway, if your AV Receiver or Amp has set it to 80 or 120hz crossover...then adjusting the crossover on the subwoofer itself will not yield any result. Best to set to the max if you wish to let the Amp/Receiver handles the crossover. While listening to music from CD source...if the Mains are floorstanders and well-endowed with built-in sub and tweeter to handle both LFE and midrange nicely then would suggest to forgo the LFE to be sent to the Main subwoofer instead choose S.Direct (if any) to let the Mains do the musical processing...More often than not, the music sounded BETTER...IMO. :D
Lancelot Posted August 20, 2002 Author Posted August 20, 2002 Desray, I get wat you mean..... thanks for your help! ;)
Jag Posted August 21, 2002 Posted August 21, 2002 This advise should get reasonable results...... but it tends to lend the bass a boomy after-taste. Try adjusting the subs crossover even lower if the sub sounds boomy.
Lancelot Posted August 21, 2002 Author Posted August 21, 2002 Yar..... agree with you, Jag. Some of the receiver's crossover is fixed and is abit high, may lead to the sound being too boomy.
Jag Posted August 21, 2002 Posted August 21, 2002 Coz boom is caused by too much subwoofer sound above 60hz (approx only). With my mains able to go down to 50hz, I can get fairly good bass down to 50-ish hz. My subs are set at approx 40hz.......large fronts and the rest set to small. LFE are routed to both mains and sub. So in the end, some good bass from my sub to 40s.....good bass from my mains down to 50s...... the 40-50 range is the cross-over for my system AND room (I have a measured room resonance at 44hz)
Lancelot Posted August 21, 2002 Author Posted August 21, 2002 So there's a gap between 40-50hz for the frontal bass portion?
Jag Posted August 21, 2002 Posted August 21, 2002 In theory there seems like a black hole between 40hz and 50hz. In practise, not at all. The cross-over filter on both the subwoofer and the amp is not a brick wall filter. Instead the filter has a gentle down slope. Thus the sub still rumbles at 45hz....but at a lower volume. At the same time, the main speaker still produces 45hz, also at a lower volume. If phasing is correct, the sub and main spkr will add up constructively and thus not having really black hole btw 40-50hz. Furthermore, my room resonance at 45hz, so only a relatively small signal is needed to excite 45hz harmonics. The idea is to synergise and balance the cross overs such that they integrate seamless..... as far as possible at least.
Lancelot Posted August 21, 2002 Author Posted August 21, 2002 I see..... thanks for the advice! ;D How do you know your room resonate at 45hz?
Jag Posted August 21, 2002 Posted August 21, 2002 I see..... thanks for the advice! ;D How do you know your room resonate at 45hz? After many beads of sweat moving the heavy sub around the room, no matter what position its in, a frequency sweep always produced an extreme peak at 45hz. A peak of sometimes +10db from reference.
Jag Posted August 22, 2002 Posted August 22, 2002 Set the sub's crossover to approx room resonance. Then set a notch lower. 40Hz works fine with me. It'll be different for you. The logic here is to mildly excite the room's resonance on the sub's gentle downslope. Even with mild excitation, the resonance will be pronounced strongly. The other lower frequencies will be produced by sub at full power, supplemented by the mains. Vice-versa for the frequencies above resonance. But this trick works only on large mains.
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