Hi I'm running two av123 UFW-10's and they just don't seem to give me the deep lows I can hear and feel. My fronts are Av123 Rocket RS760's and they have a really good bass response and sometimes I have to really listen to tell where they leave off and where the 10's begin. Is this a sealed enclosure thing or what? I used to remember 10's vented hitting pretty hard. I've been looking into purchasing a CHT 18.1 the vented one to be placed in the rear of the room 8' behind the main listening position. My question is would a 15" vented sub work just as well to provide the room shaking bass and would a vented and sealed sub arrangement work?
Also any suggestions on other subs will work fine. If you have one you'd like to part with let me know too.
Thanks guys
edit: I changed the crossover from 40Hz to 80Hz and it sounds a little better. Audyssey had the Fronts/Center RSC200 (bigfoot) at 40HZ
You have asked a question with no answer by cone diameter alone. The size of the woofer cone is only one of many factors that determine the output of a sub and virtually nothing to do with low frequency extension.
Output from the cone is a function is cone area and stroke, which within the linear operating range of the driver is xmax. So max output is a function of cone area and xmax. So you can have a high xmax driver of 8" that has more output then a low xmax 18. In addition the flux density of the driver has to be taken into account. The higher the greater the output. However there is an inverse relationship between flux density and bass extension, which is unfortunate.
Low frequency extension is almost entirely a function of the driver free air resonance Fs. So a low Fs 8" driver will have lower bass extension than a high Fs 18.
So Fs essentially marks the floor of the low frequency extension.
Now in a sealed alignment the entire output is a function of cone area and stroke.
The low frequency extension is usually around an octave or more above Fs and rolls off at 12 db per octave. However if there is sufficient stroke, equalization of 12 db for octave can be used to maintain flat response to the Fs region. This requires a lot more amp power and a much more expensive driver, with a long stroke and obviously a larger cone area helps.
In a vented enclosure (and I will include PR alignments here, as they are virtually identical to ported alignments, with a slightly steeper roll off), most of the output at tuning comes from the port (PR) and not the driver. In fact the driver virtually stops still. Below tuning cone movements rapidly increase, but despite the motion output falls to zero at 24 db per octave quickly, so the cone motion becomes quickly useless as the driver decouples from the box. Equalization to extend bass response is useless and just results in driver destruction.
After all this we have the question of bass quality which is essentially a function of total system Q. Basically this means the bandwidth of resonant reproduction. If you build a driver with a heavy cone, highly compliant suspension and relatively low flux density, you have a high Q driver. The sound will be sloppy and not at all well defined. However all things being equal it is easier to get bass extension. The driver with the tight suspension and high flux density, will have a more accurate and controlled bass, but roll off will occur well above F3.
Now total system Q can never be lower than the driver Qts. It is easier to control total system Q in a sealed alignment and get it close to driver Qts.
Now a total system Q of 1 or over sounds very sloppy with a bass that oozes like goo all over the sound field. Most people fine a total Q of around 0.7 acceptable, but it is too high and will be perceived as resonant reproduction.
At a total Q of 0.5 or less reproduction is considered to be essentially non resonant. Total system Qts in this range can only be achieved by sealed, aperiodic transmission line, horn, infinite baffle and and open box dipole systems.
The only ported arrangements that give the designer good control of total Q are second order couple cavity systems, but they have significant problems of their own and are used less and less frequently. The main problem being that all direct output from the cone is sacrificed and they are band pass in nature and roll off above and below tuning. The lower Q, is the narrower the bandwidth. In my experience they are only useful in supplementing speakers that have an F3 at least an octave below the upper F3 point of the band pass sub. Crossover must be acoustic usually.
A Q4 ported box will always be a resonant system and never low Q without killing the resonance and therefore driver augmentation.
Only damped aperiodic TL and horn systems can achieve driver augmentation and low Q.
I'm a frequent concert attender, and have just come back from a fine SPCO concert at the Ordway St. Paul.
Every time I return from a concert I'm convinced that the vast majority of sound reproducers have far too a high total system Q with highly inaccurate bass.
