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Discussion Starter · #1 ·
I currently have a v - 12 cerwin vega speakers that have a sensitivity of 98 db


but im wanting to buy another one of these to use as my surround sound , and then buy three of the v - 15 series which has the 15 inch subwoofer instead of the 12 inch subwoofer . but it has a sensitivity of 102 db,


Does this matter adn what does this mean ,


will the 15 woofers make more bass than the 12 inch towers. ???/


or is it going to take so much power that I would be better off with the 12's
 

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the more sensitive the speakers are, the more easier they are to amplify because they can easily go loud with minimal amplifcation


and it doesn't matter, because you can adjest the volume level of the speakers..
 

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That said, what is the limit that's advised to increase the level of a speaker to match the levels of another speaker? I think I realize ideally we would drop the levels of the speakers that are too high (should one base the home theater levels upon the least sensitive as a starting point, and then decrease all the other channels respecitvely?).


Is there some amount of channel dB increase that leads to unacceptable distortion? Or is it merely related to the THD that's introduced in a processor, amp, or receiver at a certain volume level? Or does it differ too much from manf. to manf. to advise a threshold?
 

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Quote:
Originally posted by Eyleron
That said, what is the limit that's advised to increase the level of a speaker to match the levels of another speaker? I think I realize ideally we would drop the levels of the speakers that are too high (should one base the home theater levels upon the least sensitive as a starting point, and then decrease all the other channels respecitvely?).


Is there some amount of channel dB increase that leads to unacceptable distortion? Or is it merely related to the THD that's introduced in a processor, amp, or receiver at a certain volume level? Or does it differ too much from manf. to manf. to advise a threshold?
Just calibrate them all at 80 dBs. That should take care of eveything. Most of my speakers have different sensitivity also, and this works for me.
 

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Quote:
Originally posted by Eyleron
So if I needed to boost the surrounds by +10 to get 80dB and matched to fronts / center, that's okay? It's not introducing distortion?
Why don't you try it first :) I seriously doubt you'll be raising them even 1dB. I've ALWAYS had to lower my surrounds, and I was using 6ohm with 86 sensitivity, and my mains were 4ohm with 92 sensitivity. I just upgraded my surrounds to 8ohm with 89 sensitivity, and they went down even further when calibrating compared with my old surrounds.
 

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Discussion Starter · #7 ·
ok thanks guys for replying , but what about the sbuwoofer, will the 15 inch produce more than the 12 inch ,


i heard that it does


but ive also heard that that deosnt mean anything only that it takes more power to drive a 15


?
 

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If a 15", or 18", etc. sub didn't gain one anything over 12", then no one would by those bigger ones.


Ideally, theoretically, you want to be able to produce all frequencies of bass (between 0 and 100 Hz) at reference levels. And you want all those frequencies to be able to be produced at the same volume relative to each other, so that when the artist records a sound at 25 Hz at a certain volume, you HEAR that sound at that volume.


So, if you were to run a test tone sweep from 0 Hz to 100hz and measured it with a meter, you'd get the same volume of 80 dB all the way.


If your player and sound processor will give 15 Hz sounds to the sub, you may not "hear" them, but you certainly will feel them! And in the real world, when a torpedo strikes a submarine, there are many things to be felt, even if they are vibrations beneath the 20 Hz threshold of human hearing.


That's theory.


It appears that not many subs that most people can afford produce much response beneath 25 Hz. It's DIFFICULT to produce sounds that low! I forget the law, but the amound of power required goes up rapidly, the lower you go.


It appears to me that the main methods for getting more lower bass is:

*Increase the size of the driver...this allows for a greater volume of air to be moved.


*Use more watts of power.


Enclosure, porting technology, tuning, amplifier, etc. all contribute additional benefits / detriments.


It should be easier for a 15" driver to produce those 20Hz - 30Hz sounds than a "mere" 12" driver.


That said, one company's 12" sub may well outperform another's 15" sub, due to those other factors. For instance, Velodyne has one product that is 12" that goes to 15 Hz. Another of their 15" subs only goes to 25 Hz. You can bet the former (their digital drive) costs thousands of dollars.


We try to get subs that are more powerful not so much that we want 40 Hz to be incredibly loud (because that's easy), but rather so that 20 Hz is as loud at 40 Hz (that's incredibly difficult).


Enjoy!
 

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Discussion Starter · #10 ·
ok , i was just wanting to know about the loudness of the bass period , casue its the same set of cerwin vega speakers, and the same series, its just that one has a 15 and the other has a 12,
 

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Quote:
It should be easier for a 15" driver to produce those 20Hz - 30Hz sounds than a "mere" 12" driver.
Well, it's not quite that simple, but you're on the right track. You need to move large amounts of air to recreate the huge waves of really deep bass. The amount of air moved corresponds to the swept volume of the cone, which is a function of diameter and of excursion. You can move that amount of air with a smaller cone. You just have to move it farther along the axis (excursion). At a given frequency, the acceleration (and thus the force) that the voice coil has to apply to the cone increases with excursion. Bigger magnet, bigger voice coil, bigger amp. But a smaller box is possible.


The larger 15" cone has to move less far, which is good for the efficiency of the "motor" at low frequencies. But the cone itself is more massive and is supported farther from the center of mass. The larger cone tends to lose its stiffness at frequencies lower than the smaller cone.


In general, the larger cone does better at lower frequencies, but worse at higher. Plus the box is bigger. It's a compromise. If you want to cover 20-80Hz, a bigger cone is probably better. If you need to supply the bass for less capable satellites, say up to 150Hz, you would go with the 12" or smaller and give up the bottom 5Hz.


BTW, when I was younger, I built a folded corner horn (based on an old Jensen Imperial design) with a 15" Altec VotT driver in it. The bass was *awesome* even with a little amp. I could literally shake the building. But the thing was 6' tall, weighed 100 lbs, and had to sit in a clear corner to really work well. Some compromises needed to be made...
 
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