If One Sub is Good, Are Two Better? - Page 2

If people could experience a room like yours, it would be a real eye opener for many.

That's what I'm thinking. Everyone's "opinion" is based on their experience. I wonder if the single sub guys have heard multiple sub rooms?

Hmm...
Do i need/want 2 subs?
Thanks for the thoughts everyone.

Mike

My room is really sound deadened. (Former professional recording stuido) and while I feel the extra headroom from my dual 500watt single 15" powered subs is just peachy? I like the look of my front L/R speakers sitting on them on each side of the screen. No extra speaker stands needed.

Mike: need <> want

That's just your room, not everyone's. There are so many graphs showing output below 30hz from many people with one sub. It has to do with the room, not the sub.

Sorry, not buying it (and did you miss the comment about my having heard many sytems and rooms). I also think there is a big difference between generating a graph and actually listening - shoot, there are plenty of subs that make ridiculous claims about LF extension on paper but perform poorly in the room. I'll stick to what I have heard for myself, and when somebody can demonstrate even bass response down to 25hz. from a single 10-12" sub - THEN I'll adjust my thinking.

That's exactly what it says, and I'm not sure how that equates to the "full output" of the receiver. Perhaps what they wanted to say was along the lines of:

((full power for 1 channel + 1/8 power) x the number of other channels)

Which would give you 450 watts for your example, which would seem closer to what I'd expect.

I'd really like to know what the correct calculation is, because if the math is that sloppy, the rest is probably just as sloppy

-Fred

It's a useless formula to try to tell someone to buy a subwoofer based on amplifier power rating when you don't know box volume, driver efficiency, BL and XMAX of the driver. You also need to know the efficiency of the loudspeaker system, distance of the speakers to the listener, etc. Also, how loud can the rest of the speakers play? It makes little difference if a user is running a 100wpc receiver or a 1kwatt/ch amp while using Bose cubes for his speakers.

I have somewhat of a newbie question. Are all of the responses and curves people are talking about done with the gain/volume control on the sub/subs turned all the way up or at some other setting. Mine are set below half way. Should they be set higher? It seems I have more bass than i know what to do with.

FYI, for those that didn't see my earlier post, I have 2 12" 200 subs in opposite corners and the mains are 15" Cornwalls. Don't slay me too bad.

Another question. I was looking at the formula from he article. AVR watts + (1/8) AVR watts) x # number of channels.

What if your setup, like mine uses dedicated amps for the mains. I am running 2 Carver 1.0 bridged for 1000 watts each and the AVR is 95 per channel. How does the formula work then? Do you average it out across all channels?

You set the gain on your sub where it matches best with your system. Mine are set to about 1/3 volume for two subs, and closer to 1/2 volume for the third.

As for the formula, I wouldn't worry about it too much.

That's a rather horrid little plan. If you need to do that, you need to place 1" of fiberglass in front of the driver so you don't hear all the air slaps and mechanical noises which any sub will produce.

What? If you have one sub that rolls off at 30Hz, adding 15 more copies of the same sub ain't going to get you below 30Hz.

I didn't word that correctly. But you back up the point I was trying to make. There are subs proven to hit 25hz. The original poster says that it isn't possible with 1 10-12" sub and basically saying you need 4 subs to do it. I would argue that an SVS PB12-plus can do this and has done this in many rooms. Maybe not his room because of his room size, shape, sub location, etc. causes drop off too quickly.

when one sub is loud enough to fill the room, it needs digital sound processing to interact appropriately with the walls.
in this situation, a second subwoofer isnt necessary.
but generally, the amount of watts and cone size is of the larger scale (especially the watts and excursion)

but

if your subwoofers dont have the extensive sound processing..
i wouldnt, for a second, suggest that you dont use two subwoofers.
putting each sub in the corner and point it somewhat diagnally.. i would say get a second sub of the same make and model.. and i would even go as far as saying 'reduce the gain to half of what it was previously' to hear the immensive difference.

adding more cone area (especially at the opposite side of the room)
brings the output up to a high degree of obtainable listening.
you'll struggle less to hear the details of the previously winded (low blown) output.

its this same reason why i suggest listening to stereo music with the rear speakers turned on.
as long as the time delay is set for each speaker.. there wont be any obnoxious speaker locations standing out like a neon sign.
the extra cones will pour more output into the room... and the only time its not of any value is when the other speakers have extensive reflection calibration (usually done by processing, but can also be done somewhat by manually building walls and angles at the constructive points)

very simple and clear.. one speaker to do the job requires that speaker to be extremely more expensive.
it means more wattage and more excursion, and perhaps even a bigger cone.

take the three inch speaker example.
put one speaker in front of you and hear the output.
get an identical speaker and place them 2 or 3ft apart from eachother.. the output rises (usually the 3dB rise people have known about)
for that one speaker to sound just as good as the set of two, the power would need an increase and the excursion would need an increase.
that means more money to buy the speaker.
probably better to cut the workload in half and buy two.


they say put the subwoofer in the middle between the two side walls, because the output wont be isolated to one side of the room more than the other side.
and since your listening position should be in the middle of the screen anyways.. the output is forward and direct, compared to forward and sideways.

the intention is to get the sound appear as if it is stereo.. doesnt mean independent sound coming from the left and right channels.. it means having a speaker on the left and on the right, as if you were playing a mono track.
the envelopment of the sound is stereo.. has nothing to do with individual sounds from each speaker.

listening in stereo is less fatiguing because there arent any empty voids in the room.
like having a front left and right speaker, and a void behind you.
its like its dark and cold back there and you are forcing yourself to believe the musician is in front of you on a stage of some kind.
and that isnt the truth at all.. the musician is in a sound booth on a microphone with the output supposed to be going straight to your brain.
no front or back was intended.
if you want the musician to be in front of you, then you need a track that is intended to sound like you are in front of the stage.

soundbooth recording is ment to have the same sound go straight to your brain no matter if you look left/right, up/down, or forward/backward.
kinda like 'black' or 'nothingness' or 'lost in space'

but these tracks do have strong left/right fades.
some even have effects that are ment to go forwards/backwards.
i've even heard some that go from front left to rear right.
thats simply dolby.

DSP can compensate for a peak pretty well, but if you have a large null it is extremely difficult to compensate appropriately.

And that compensation would only work for one listening position, or is at best a compromised response curve for multiple listening positions. If you have two or more listeners, it is very difficult to have a response near uniform with one sub, even with DSP.

So it may "work" with one sub (after DSP) for one listener in an ideal position, but that's quite a compromise with respect to home theatre.

square and rectangle rooms dont have nulls.
when the walls meet at 90 degrees.. DSP's can compensate.
adding a piece of wall to the corner to use a 45 degree angle from wall to panel.. and another 45 degree angle from panel to ceiling.. those can create a null.
doesnt matter if its used on where the ceiling meets the wall, or where the two edges of the walls meet.

they add complexity to the reflections, and if the reverb isnt programmed for 45 degree walls (instead, the normal 90 degree walls) then the results will have dips at the null frequencies.

but using those corner panels can help 'unity' as they make the LFO's smaller.
depending on the phase of the reverb.. an LFO can be a spot in the air that contains audio, or it can be a spot in the air that doesnt contain audio.
large LFO's are used to get the same exact frequency response for two or three listening positions.
you have to rely on the sound coming from the reflections, as opposed to hearing the sounds coming directly from the speaker.
its the difference between pointing the speakers directly at the listening position, compared to pointing the speakers away from the listening position.

you might see speakers in each corner pointed to the listening position, or you might see two speakers in the middle between each side wall.. and those speakers are pointed at the wall with an angle.
you might also see the speakers almost in the corner, but instead of pointed at the listening position.. they are pointed at the wall with an angle.

if you want to get your home theater calibrated, you need to ensure that there is one giant LFO covering the entire seating area.
thats how you get the same frequency response in the middle seat or the left/right seat next to it.
using more than one LFO means the left/right speaker delay will be uneven for the LFO's in any 8 directions from the middle LFO.

with the subwoofer in the middle of the two side walls.. the delay is the same for each wall.. and the sound is straightforward, meaning less time delays necessary.
depending on the distance between you and the subwoofer, it may be better to point the subwoofer in the opposite direction.
with the cone pointed at the wall instead of the listening position, you get a wall to start the reverb.. and you will be listening to the reflections instead of the direct output.

right and wrong depends on the stereo(enveloping) sound you are trying to obtain.

Both of those statements are absolute nonsense and categorically wrong.

Perhaps we have different definitions of "nulls".

If you have discovered a room shape in which colliding waves produce peaks without correspondingly producing valleys, I congratulate you.

If I am misunderstanding what you mean, please explain.

I think the experts are learning quite a bit from this thread.

I lurk these forums more often than I care to admit. This thread has been pretty entertaining!

That dear friend is the difference between true stereo and mono summed bass. (Just because you may have never heard it doesn't mean it doesn't exist.) Even mono bass being reproduced in multiple locations. Most home theater systems quietly destroy the bass by setting speakers to "small". I never do that. Every speaker runs full range. No bass mixing allowed!
Anyway if you understand these concepts, then its time to graduate to the bass of the Triton Two Towers from Sandy Gross.

He we go off on an advanced subject and completely miss getting the basics correct.
First all speakers should be able to reproduce the bass encoded to their channel, just as was engineered at the recording studio.
Only then will the multi-channel bass to be allowed to make its contribution to the soundstage, atmosphere dynamics and transients.
Adding a second subwoofer is then considered a refinement.

DSP is being incorporated into subwoofers now that the older ANALOG class D amplifiers are phased out in favor of DIGITAL class D amplifiers. It is far more precise to put the DSP in the subwoofer than in the receiver (I'll let you explain why).
So lets not put the cart before the horse?

This thread delivers.

We have multiple certified and experienced room audio guys taking the time to slap around the ones who havent bother with the Cliff Notes version of audio correction.

I need to go adjust a treatment...my wife didnt think it was in the right place and moved it...

well then we can agree, a hexagon shaped room will allow 3D audio.
sounds can creep up to seem as if the actor (or actress) is speaking right next to your face at 0/45/90/135/180 degrees on one side (and 0/45/90/135/180 degrees on the other side)

with that said, we can also agree, more folds in the walls means more angles of 'up close and personal' entrances.
and a completely round room would provide chance for an infinite amount of entrances of any 0-180 degrees per side.

and with that said, we can also agree, a completely sphere room would allow for an infinite amount of entrances of any 0-180 degrees per side (of the horizontal axis)
as well as 0-180 degrees per side (of the vertical axis)
thus allowing the sound to be 3D in all directions left/right and/or up/down.

getting 3D audio to become a standard (even the horizontal axis alone) seems to be extremely difficult.
adding half a sphere for the ceiling would do amazing and wonderful things for the current 'height' channels of surround sound.

mentioning industry standards,
the height speakers might not work when they are designed to work in square and rectangle rooms with 90 degree angles.

adding more folds in the wall (or even half a sphere) doesnt mean the audio processing is programmed to make the audio go into the correct direction.

thats why there is a need for receivers to transform the audio processing.
regular 3D mapping needs to be decoded then changed to work with the number of folds in the wall.

if you try to use a lot of folds in the walls with current surround sound, the audio will literally seperate when traveling the 3D matrix.
the reverb processor needs to know what is trying to be done, because it is a machine and the LFO's will deteriote (the audio signal splitting)

its all in the time domain.
when a sound moves 3D.. its the invidual changes per each LFO.
and that means, if your LFO's are large and there are dozens (or hundreds) of them in the room.. you would hear the sound transfer from one LFO to the next, kinda like a fly or bee moving from one bubble to the next.

people who are in the market of LFO's really need to know how big or small the LFO's are.
and also,
how well they blend together.
it might appear that there arent any LFO's in the room thanks to chorus, but if you remove the chorus.. you'll see the resolution of the LFO's (how many and how big)
they are identical to dots per inch with optical/laser computer mice.
identical to the pixel count in todays new high definition televisions (or computer monitors.. or telephones.. or handheld video games)

more simply means the 3D sound is more accurate.. as it begins in the right place and ends in the right place.
although, some people probably wont mind some bloating.

anyways.. more speakers in the surround setup can compensate for a lack of folds in the walls.
but the only way the audio can get up close.. as if the audio literally walks forward from the wall.. is going to come from the speaker (it comes from a speaker or a wall)

that should make those excessive speakers, in the surround setup, a lot more desirable.

i can only imagine what some of you have as far as subs in the trunk of your car. some of you here talk about having 2 12 to 15 inch subs for your ht system. what do you have in the trunk of your cars? 2 12 to 15 inch kickers blasting 1000 watts or more or what?

i guess some of you here most still have all of your hearing left and want to make sure you take some of it away with these huge ht systems blasting 1500 watts at almost full volume right?

i'm not certain most people will appreciate the word 'refinement'
and putting the details out into the open gives people a chance to know without needing to translate a definition.

to clear some confusion, it can be said (and asked) whether or not a piece of bass should come from a subwoofer or from a rear surround speaker.
the answer is clear, quick, and simple.
if an explosion goes off from behind the camera.. listening to the explosion from in front of you is stupid.
it completely doesnt match the screenplay.
thats why all speakers should be full-range.
dedicated subwoofers are stupid.. like hearing audio ment for the left channel and hearing it from the right speaker.

yes, that does mean each speaker needs to have enough power to fill the room with audio.
what i said about adding a second subwoofer to get those details louder and clearer, that doesnt include the location of the subwoofer being accurate.
because even if you have the subwoofer up front and the reverb has been calibrated.. if the audio effect tries to make the sound appear as if its behind you, the soundwaves will be heard as they make their way to the rear of the listening position.
it sounds like 'positional glare'
the rear audio isnt isolated, and you will hear the audio coming from in front of you.
again with the hearing left channel audio from the right speaker.

how annoying is it to see a vehicle travel from left to right on the screen.. but the audio from the speakers goes right to left?
it should be enough to give you a headache.

I come to the speaker threads to try and learn some things but I always end up laughing. A lot of you guys are so full of yourselves and stuckup compared to other areas of avs. Its hysterical. I know a lot of people here really know what they are talking about but the dosnt make you god. Also, it is possible for two or more people talking about the same subject to have 2 or more completely different thoughts/ideas/outlooks and even cold hard facts and both be correct. People have different schools of thought, plus theirs old school and new school ideas and technology. With some things there is only one, absolutely correct answer; but more times than not there is more than one right answer.

Yes and you won't find it anywhere else, as our economic system revolves around sales. The actual systems audio performance doesn't matter. If fact the steering is to always keep to the consumers buying more gear. Are we up to 14.1 systems? And now multiple woofers?
The primary rule to preserve the bass is to always run the speakers full range. Is this always practical? Yes

Here is a way to prevent bass mixing with just front speakers, like in my family room.
Use ONLY a left, center and right speakers with a subwoofer. In the receiver still set speaker configuration to 5.1 and all speakers to large. It is critical to have the center channel as much dialog is located there. Otherwise the whole channel gets mixed into the left and right and bass possibly redirected to the subwoofer.
If you don't have a subwoofer, still set the receiver to say that you do.

Summing or mixing of the bass creates a new lobotomized mix with hidden gain riding and limiting. The results can be unpredictable. As always I recommend simpling and getting the basics correct.
While it is true that lower bass becomes omni directional, anyone can still tell where is coming from. As good subwoofer moves considerable air. Can you tell the direction of a fan? However a fan only blows in one direction!
So the last basic is to place the subwoofer right under the center channel to anchor the soundstage.