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Bookshelf and Bass Management
#378443 06/13/12 12:11 AM
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Sorry I stole this from another site. But, would this not be true and accurate.

I think that's called Bass Management. And Bass Mangement is the key to this discussion.

If you have a receiver/pre/pro with a modern Bass Mangement scheme, and you have satellite speakers with sufficient mid-bass capability, (i.e., 60 Hz or so), then a system comprised of satellites and subwoofer(s) can sound at least as good, and often, better than a system comprised of "full-range" mains. Why is this??? Several reasons:

1. Most "full-range" mains are not really full-range. In order to be full range for HT purposes, the mains need to have sufficient output at 20 Hz. Very few large, floorstanding speakrs have any output at 20 Hz. Most are limited to the low 30's or high 20's, at best. So, what happens when you send them a "full-range" signal? The deepest notes are.......

LOST!

Let me re-iterate... they are not reproduced.

However, if you use Bass Mangement to "filter the low frequencies from the main channels and send them to the subwoofer", (and presumably the subwoofer has deeper extension than the mains), they
WILL be reproduced...
by the subwoofer.

2. (Sanjay's point") The best location for bass reproduction in any room is rarely the best location for the main speaker for the purposes of imaging and soundstage. For the main speakers to do their best at presenting the audio image locked up with the video image, the mains should usually be well away from boundary walls. However, bass is reinforced by boundary walls, and often the best location for bass reproduction takes the main speakers out of their best location for imaging and soundstage.

Siphon the bass off to the subwoofer and you free up the mains to be placed where they provide the best audio/visual "image". You can then place the subwoofer(s) where they interact best with the room and the listening position to provide flat, deep, clean bass.

3. Amplifier efficiency. When you use BM to re-direct the bass frequencies to the subwofer(s), you filter it out before the amplifiers. Since bass frequencies are the most power hungry part of the audio spectrum, removing them from the main channels and re-directing them to the sub(s), frees up the main amps to do a better job of powering the frequencies they are asked to reproduce. This allows the entire system, (speakers, amps and subwoofer(s)) to play louder and with less distortion.

Bottom line, if you have a system that consists of:

...true, full-range, 20 Hz to 20 kHz speakers...

...AND those speakers can be placed where they provide a perfect soundstage AND excellent bass reproduction,

...AND you have HUGE amplifier capabilty that can power those full-range speakers to limitless SPL's without clipping,

...then you don't need Bass Managment.

OTOH, if you're like the rest of us, Bass Management will be the best thing since sliced bead.


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Re: Bookshelf and Bass Management
axiom_man #378445 06/13/12 12:16 AM
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What I don't get and it was posted in another forum is

your subs may not be up on the front stage, your sub woofers maybe best in another location than the towers to produce the best bass. So there for why would I want deep bass coming from my tower mains up front, if it is better produced by a sub and that sub is in the side wall. And if I have two subs to even out the Bass, then wouldn't this have a negative effect on the low frequencies, coming from M80's up front and two subs on the side.

Would for movies it really be better to have great positioning soundstage and imaging from great bookshelf speakers and place the low frequency subs where bass is best produced ?


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Re: Bookshelf and Bass Management
axiom_man #378449 06/13/12 12:35 AM
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and then this guy shoots it all to H 3 dbl hockey sticks lol

Craig John posted a good argument for monitor + sub. In theory that would be correct, but as someone else already mentioned though, IMHO it's more of a personal preference. In my experience, I have started with a good monitor and sub system (Revel + Velodyne). The sound was good, but I had to spend a lot of time with integration. The bass from subwoofer would not blend very well with the sound from monitors. That's even with the aid of room correction software built into Velodyne, in addition to the bass management system from the processor. There is no problem with the amount and quality of bass. It's just that it wouldn't blend very well. The sound from bottom to top wouldn't sound very coherent. That's when I started looking for full range speakers. When I finally got a pair of Focal, they sounded much more coherent across the frequency spectrum.

In theory the subwoofer placement is much easier than the speaker placement. In practice, it depends on the cross over frequency and slope of the cross over. With typical installation with 80Hz cross over, the subwoofer may reproduce enough midbass and it will lose the advantage of being unidirectional. You will be able to point out where the subwoofer is located. That was the case for me at least, with 80Hz cross over. I ended up crossing over at 50Hz with better results.

As pointed out earlier, true full range speakers should reproduce down to 20Hz. Many of the floor standers do not reproduce 20Hz, thus technically are not full range speakers. But that is a technical definition, and not an indication of inferior sound as it may incorrectly infer. My Focals go down to 33Hz in anechoic chamber, and technically they are not full range speakers. The in room response probably extends to 25-30Hz. But the overall coherency from the treble all the way down to whatever low frequency it can reproduce is much much better than monitors + subwoofer system.

I would say the floor stander speakers will have an edge in overall sound coherency in most cases. It's possible to configure a pair of monitors and a subwoofer to sound better than comparable floor standers. But it is not as easy as it seems. You would probably end up putting in dozens of hours tweaking the cross over frequency and other bass management system before you reach that state. For most people, who wouldn't spend more than 30 minutes to an hour for initial set up of the speakers, I bet the floor standers would sound better than monitors and a subwoofer.


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Re: Bookshelf and Bass Management
axiom_man #378450 06/13/12 12:36 AM
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as do a few others who made the case for floorstanding.


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Re: Bookshelf and Bass Management
axiom_man #378451 06/13/12 01:06 AM
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If you're watching movies, why on earth WOULDN'T you have a sub? I have M80s and use a sub for music and movies. Yeah, the M80s can get a lot of the bass, but not all of it. So that makes the argument moot.


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Re: Bookshelf and Bass Management
axiom_man #378453 06/13/12 01:34 AM
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I do have a sub actually Two subs.
For music it is 2 channel, no sub


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Re: Bookshelf and Bass Management
axiom_man #378454 06/13/12 01:44 AM
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Yes, Troy; what you quote in the first post is for the most part "true and accurate". The size of a speaker enclosure affects the bass tuning. It has no effect on the mid-range or treble, and if those drivers are the same in both, the performance above the bass will be the same, assuming that the crossover is the same. If a good sub is handling the low bass, the advantage of a larger enclosure in that area is a moot point.

The part that isn't entirely accurate is the comment in paragraph 3. about bass frequencies being "power hungry". There's no such thing, since power requirements are a function of loudness, not frequency. For example, 40Hz, 400Hz and 4000Hz at 80dB require the same power, and 4000Hz at 90dB requires 10 times the power needed by 40Hz at 80dB. It's true, of course that whatever power does happen to be needed for the bass handled by the sub doesn't have to be supplied by the amplification for the speakers.


-----------------------------------

Enjoy the music, not the equipment.


Re: Bookshelf and Bass Management
axiom_man #378455 06/13/12 01:49 AM
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I have heard people here say that low frequencies produced by subs may not be best up front. I may end up with the subs behind me or on either side wall or one up front and one in the rear. They say 80hz or so give or take a few. Yet, they also say the M80's produce great lower bass. So, why is it that 80hz coming from a sub is better elsewhere, but it is oh so great from the M80's in the front.
Such contradiction,
Yet, I am told you cannot hear the localization of lower frequencies, yet that it is best to have the M80's over Satelites because it give better bottom from the mains up front and fills the room.
Don't two great subs .... EP500/600's if place properly fill the room ? if you have two great subs, do you really notice the bass coming from the M80's that much ?
I thought if the sats and subs blended well you shouldn't notice any seperation ?
I thought if you had great detail, imagining, soundstage, clarity coming from the three up front then that's all you need. Everyone says low bass and crossing over at around 80hz to subs which can be placed anywhere, in a location that sounds best. where ever it is will fill the room and given it is unidirectional your not going to notice where it comes from, yet I am told well M80's give great bass up front.


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Re: Bookshelf and Bass Management
JohnK #378456 06/13/12 01:51 AM
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Originally Posted By: JohnK
Yes, Troy; what you quote in the first post is for the most part "true and accurate". The size of a speaker enclosure affects the bass tuning. It has no effect on the mid-range or treble, and if those drivers are the same in both, the performance above the bass will be the same, assuming that the crossover is the same. If a good sub is handling the low bass, the advantage of a larger enclosure in that area is a moot point.

The part that isn't entirely accurate is the comment in paragraph 3. about bass frequencies being "power hungry". There's no such thing, since power requirements are a function of loudness, not frequency. For example, 40Hz, 400Hz and 4000Hz at 80dB require the same power, and 4000Hz at 90dB requires 10 times the power needed by 40Hz at 80dB. It's true, of course that whatever power does happen to be needed for the bass handled by the sub doesn't have to be supplied by the amplification for the speakers.


Ok ....


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Re: Bookshelf and Bass Management
axiom_man #378457 06/13/12 01:59 AM
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I thought one of the biggest reasons people go with the M80's or floorstanding , is that you kill two birds with one stone.

Mainly so you don't need to seperate systems.
They are not neccessary the best for music but do a good job for movies to.
Saves you from buying a bunch of speakers.

SO, if you have two rooms same size side by side. One you go to wath movies and one to listen to music. What I am hearing is get the M80's for both rooms ?
For Movies the M80's and VP180 and two subs is the best you will get.
For Music M80's
Except, with the music room don't get subs


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