7 Full Range speakers a bad thing? (1 Viewer)

[John-Miles]

Well im kind of resurrecting an old thread here, but I ended up just adding a beefy center channel to my set up last summer, so i haven't gone much further in exploring the rears and center channels for my set up.

Now the consensus seems to be that you dont want bass cancellation, and you want to make sure that your crossover is set properly no matter what set up you have, i guess what i dont know is around what frequency range bass cancellation occurs, and secondly, what is the practical difference between say a dipole speaker like the ADP-590 and a bookshelf or tower speaker, will the book shelf or tower fail to provide a full sound? im thinking that with a 7.1 set up the rears should be pretty full if for no other reason than that you have 4 of them.

 

[chuckg]

Let me try to clear up some of this....at least to me

"Full Range" is somewhat of a loose term. Speakers that are decently good enough to not require a subwoofer are full range. Speakers that would sound lacking without a subwoofer are not full range. Somewhere in the middle of that is a giant gray area where we'd all argue endlessly about whether speaker "Goomba" is full range or not.

For our multi-channel systems, it makes good sense to get all the speakers to be about the same, so that the "quality" and tone of the sound does not change as it moves around the room. For example, if your fronts are crossed over at 80 Hz, you probably won't be aware that some of the sound is coming from a different speaker, way over there in the corner. (the one we call a "subwoofer") However, if your rears are crossed over at 250 Hertz, it will almost certainly be possible to hear some of the "rear" sound coming from that big boomer.

Not good.

We want to have all of our speakers able to produce sound down low enough that the lowest parts (what they don't do well) is low enough in frequency that we can't localize it. (we can't tell where that sound is coming from)

That frequency is also pretty much a gray area, but THX and many others feel that 80 Hz is a good compromise. Does this mean that your sub is not doing 81 Hertz? Nope. Does this mean that your surrounds and fronts are not doing 79 Hertz? Nope. A crossover is a much more gradual thing, and the 80 Hertz is the center of the frequency range - lower than center freq is mostly from the sub. Above the center freq is mostly the surrounds and fronts. The farther you get from the center frequency, the more the sound is separated into different speakers.



Okay. Bass cancellation.

Bass cancellation happens because the sound piles up in your room, bounces around, and can knock itself out. Bass can also pile up and make loud spots. But bass is not the only place we get this problem - we get hot spots and dead spots at all frequencies! It just happens that most rooms cause a much more noticeable problem at bass frequencies. The loud or dead spots are also much larger for bass than they are for mids and upper frequencies.

Finally, the difference between the speakers you mention are more subjective and "fine tuning" than whether they are full range or not. If a speaker can produce sound with not much loudness variation ( + or - 3 dB ) from one-half your crossover frequency to the upper limits of hearing, then it is considered full range.


Whew. I hope that helps!

 

[John-Miles]

Thanks Chuck that actually helps alot, and to further add to this I was also thinking that the recommended dipole speakers the salesmen were trying to sell me wont work well cause of my room set up, i dont have the cast to build an exclusive room, so as it is my basement does double duty as computer room theater and laundry room, so i cant mount speakers on the walls as the theater is not equidistant, but i can have free standing speakers located properly.

you do make a very good point about the crossover being the same on all the speakers, and the more i think about it, the more I am thinking I would like to have the towers all around, this way i can set the crossover a bit lower than 80, cause if im not mistaken the 80 crossover recommendation is partially bourne of the fact that most set ups have small speakers for the rears and surrounds, so if i get the studio 60's on the rears and surrounds i should be able to set the cross over lower like 55-60Hz and get a bit more out of my speakers and not stretch the bass as much, alot of bass curves ive seen show the drop off around 70-80 on the sub in the upper range, so i would think a lower crossover like 60 might give me an overall flatter response.