In Reply to: An argument for multiple subs posted by Duke on February 28, 2007 at 23:36:29:
1/4 wavelength cancellations are minor issues in subwoofer bass frequencies (under 80Hz.) but do affect the upper bass above 80Hz.
Remember how long the wavelengths are at these frequencies compared to the distance between the subwoofer and nearby walls (relatively close for most people).Standing waves are major issues at subwoofer frequencies (under 80Hz.) because they can cause easy to hear bass peaks and nulls.
Using left-right subs prevents a side-wall-to-side-wall standing wave that makes the bass more consistent across a couch. But don't confuse 'more consistent' with a flat frequency response that can never happen without bass traps/parametric EQ in the relatively small rooms that we use for home audio.
For two channel audio, subwoofers have to be located near main speakers (or between them if there is only one sub) for good integration with those speakers.
With two subwoofers in use, a bass note is played by four (two-way main speakers) to six (three way main speakers) different drivers in four different enclosures!
If you want a realistic reproduction of a bass note using two-channel audio, all the drivers involved with a bass note (the attack of the note comes from a mid-range driver or vass/mid driver!) must be located relatively close together -- not on different sides of the room.
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Richard BassNut Greene
Subjective Audiophile 2007
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Follow Ups
- Can't argue against two subs ... but your arguments for them are wrong - Richard BassNut Greene 09:24:09 03/02/07 (57)
- Re: Can't argue against two subs ... but your arguments for them are wrong - Craiger56 11:31:55 03/02/07 (0)
- reply - Duke 10:35:32 03/02/07 (55)
- I'll put on my thinking cap and offer a long-winded reply to the reply - Richard BassNut Greene 14:57:17 03/02/07 (51)
- Long-winded reply to, ah... your reply to my... um... reply - Duke 17:13:38 03/02/07 (50)
- scattered multiple subwoofer system - Richard BassNut Greene 09:27:01 03/03/07 (49)
- Re: scattered multiple subwoofer system - Duke 11:36:00 03/03/07 (48)
- The Welti paper is not worth the paper it is printed on if good bass at one seat is your goal - Richard BassNut Greene 09:45:03 03/05/07 (24)
- While I don't agree with some of Welti's conclusions... - Duke 10:08:59 03/05/07 (23)
- Welti averages 16 seating positions -- this is worthless for two-channel audio -- many are confused by his priorities - Richard BassNut Greene 11:19:13 03/06/07 (22)
- Re: Welti comments - twelti 15:48:53 03/11/07 (1)
- Duke caused the commotion by quoting your paper at a primarily two-channel audio website - Richard BassNut Greene 14:33:25 03/13/07 (0)
- The acoustics does not change in the bass region. - Duke 11:42:36 03/06/07 (19)
- If you think computer simulations in one virtual room results in conclusions for ALL rooms, you're a lost audiophile! - Richard BassNut Greene 10:07:21 03/07/07 (18)
- Acoustic principles don't change from room to room - only the specific application of those principles changes - Duke 10:32:08 03/07/07 (17)
- Did it ever occur to you that every so-called "expert" you cite has a DIFFERENT sub location recommendation !!!!!!!!!! - Richard BassNut Greene 08:38:46 03/08/07 (16)
- It is the data I am most interested in; I draw my own conclusions. (nt) - Duke 09:22:19 03/08/07 (15)
- It's the sound quality in a real room that I'm interested in -- not computer simulations never tested by real ears! - Richard BassNut Greene 09:52:24 03/08/07 (14)
- So... if I tell you that I've tried both and my way works best, will that convince you? - Duke 11:36:37 03/08/07 (13)
- Adding a third or fourth subwoofer may improve bass at your seat in your room ... or maybe make it worse! - Richard BassNut Greene 08:26:52 03/09/07 (12)
- Adding additional subs almost always results in smoothing. - Duke 09:29:21 03/09/07 (11)
- $10,000 says my one subwoofer + parametric EQ will be smoother than your three or four subwoofers in 9 out of 10 rooms - Richard BassNut Greene 13:40:32 03/09/07 (10)
- Depends on parameters of the contest - Duke 14:13:09 03/09/07 (9)
- Three or four "scattered subwoofers" all located on the floor = sonic disaster - Richard BassNut Greene 09:23:41 03/10/07 (8)
- not true - Duke 13:58:37 03/10/07 (7)
- Re: some comments - twelti 15:54:39 03/11/07 (6)
- Your paper applies to surround sound but many readers assume 4 subs are best for two-channel - Richard BassNut Greene 08:31:20 03/12/07 (2)
- Re: Your paper applies to surround sound but many readers assume 4 subs are best for two-channel - twelti 21:45:37 03/12/07 (1)
- My mind is open on a third or fourth subwoofer for two channel audio. You seem to have only conclusions. - Richard BassNut Greene 08:53:53 03/13/07 (0)
- Re: some comments - Duke 16:22:24 03/11/07 (2)
- Re: some comments - twelti 19:12:15 03/11/07 (1)
- "Heated exchange"??? - Richard BassNut Greene 09:12:33 03/12/07 (0)
- A more accessible source or two - Duke 14:18:30 03/04/07 (21)
- Earl Geddes' advice is for surround sound home theaters -- it does not apply to two-channel stereo - Richard BassNut Greene 09:52:37 03/05/07 (20)
- Not true - the acoustics does not change. - Duke 10:12:56 03/05/07 (19)
- A comparison of two subwoofer alternatives in one room proves nothing and Earl should be the first person to admit that - Richard BassNut Greene 11:38:55 03/06/07 (18)
- A mistake you consistently make - Duke 11:46:25 03/06/07 (17)
- Still clueless Duke (home theater computer simulations don't identify best sub location for ALL 2-channel audio rooms!) - Richard BassNut Greene 09:15:32 03/07/07 (16)
- It takes one to know one ... ;o) - Duke 10:13:33 03/07/07 (15)
- Average the frequency response at multiple seats "smooths" the bass (average enough seats and standing waves disappear!) - Richard BassNut Greene 09:47:21 03/08/07 (14)
- No, that's NOT what I'm saying. Average the output of multiple subs at any ONE seat. - Duke 12:56:05 03/08/07 (13)
- Duke Duke Duke Duke of Earl .... If I charged you for corrections to your posts, I'd be rich! - Richard BassNut Greene 09:24:58 03/09/07 (12)
- If we both charged we'd both be rich - and I could afford an equalizer and you could afford another sub! - Duke 10:19:41 03/09/07 (11)
- "I am suggesting an alternative that will offer a significant improvement throughout the room," = baloney - Richard BassNut Greene 13:58:53 03/09/07 (10)
- baloney - Duke 01:07:54 03/10/07 (9)
- Not only are you wrong about "scattered subwoofers" for two- channel audio, but your Mother also wears Army boots! - Richard BassNut Greene 09:40:57 03/10/07 (8)
- Time for some quotes - Duke 12:22:59 03/10/07 (7)
- Quotes can be BS too. Where are the two-channel audio listening tests with real human audiophiles? - Richard BassNut Greene 08:45:46 03/12/07 (6)
- "Quotes can be BS too" is not an argument - Duke 11:03:20 03/12/07 (5)
- You've got "experts" -- I've got "experts" But none of them agree on sub locations (the right answer is "I don't know!") - Richard BassNut Greene 09:14:57 03/13/07 (4)
- My turn to question - Duke 14:02:08 03/13/07 (3)
- I think I have just enough steam left to get in the last word - Richard BassNut Greene 15:10:18 03/13/07 (2)
- Show's over folks. Move along. - Duke 15:23:28 03/13/07 (1)
- They were all snoring after my third post ! - Richard BassNut Greene 08:49:18 03/14/07 (0)
- Duke - Craiger56 18:25:25 03/03/07 (0)
- Re: reply - David Aiken 12:53:22 03/02/07 (2)