[tomagardner]

Since I have a subwoofer, I just stuffed the ports of the front XLs and they seem to be more dynamic. What exactly does stuffing the ports do to the output sound? TIA, Tom

[ggunnell]

Tom, I'll blather general inananities until Mike shows up
You are going to raise the resonance frequency of the cabinet, probably into the 60-150 Hz area, which you may interpret as a more dynamic sound.   You loose reinforcement from the port down low, obviously

[DSK]

Since I have a subwoofer, I just stuffed the ports of the front XLs and they seem to be more dynamic. What exactly does stuffing the ports do to the output sound? TIA, Tom

Tom, there are far more qualified people to answer this than me. However, FWIW, from all my reading it seems that sealed enclosures will lose extension and possibly fullness in the lower bass, but have better transient response, group delay and tonality. The bass may be interpreted as 'leaner' as a result but may actually be more accurate and will usually integrate better with a good, fast subwoofer.

[pacifico]

wouldn't be wise then to offer a sealed version of the xl?

Also would the alternative of placing speakers deep into the room work at this as well?

[opnly bafld]

wouldn't be wise then to offer a sealed version of the xl?

Also would the alternative of placing speakers deep into the room work at this as well?

Mike does offer a sealed version, foam port plugs.

Moving ported speakers does affect the sound, but plugging the port changes the tuning and other things as already mentioned, that placement will not change.
The ACI Owners Manuals explain effect of port plugs.
Lin

[Lkdog]

Mike seems to typically recommend stuffing the ports, or using the RCA 85hz or 65 hz filters on all ACI monitors if one has a subwoofer.
Stuffing ports will roll off the monitors at a higher point than thier rated bass unplugged (60hz appproximately instead of 42 hz or whatever).

I do think he implied  that plugging the ports may make them slightly easier to drive yielding a more smooth presentation from them.
The ACI monitors are not the most efficient speakers, but that seems to be typical of monitors.

FWIW I have the ACI Jaguars (most recent and last version) and have always used the plugs. HAve not listened w/o them to hear the difference.
I use an ACI Titan subwoofer with my Jags. I set the overlap between the two at around 65hz.

As far as a sealed version-then I think a lot of other things come into play  as far as bass response, efficiency, extension, crossovers, etc. Mike can address that as the expert as I would be talking out my ass in that arena.

When you move speakers farther into a room from the back wall, this typically reduces bass also.

[DSK]

The thing I wonder about (and this is regarding all speakers, not specifically directed at ACI) is this ...

A particular woofer or midwoofer will have its own set of T/S parameters and some will be suited to ported enclosures only, some to sealed enclosures only and some are well suited to both. However, if a ported enclosure is designed to get the optimum performance from a given driver, then even if that driver is also suited to sealed designs, simply plugging the ports *may* yield improvement but will unlikely be the optimal sealed enclosure size for that driver to attain a target Q of say 0.7071. So, I would think that a purpose built sealed enclosure, designed from the T/S parameters, would outperform the ported version with the port stuffed. Now, just how much sealed enclosure size variance is required to be audible ... I have no idea.

[opnly bafld]

Typically with a driver that will work well both V and S, the recommended vented enclosure will be larger than the sealed one.
With sealed encloures once the volume is large enough for the driver to produce the sound (qtc) you want, the volume can be increased without affecting the sound much.  IIRC, it will lower the qtc. Making the bass leaner and easier to integrate with a sub. YMMV
Lin

[Mike Dzurko]

Typically with a driver that will work well both V and S, the recommended vented enclosure will be larger than the sealed one.
With sealed encloures once the volume is large enough for the driver to produce the sound (qtc) you want, the volume can be increased without affecting the sound much.  IIRC, it will lower the qtc. Making the bass leaner and easier to integrate with a sub. YMMV
Lin

You nailed this quite well! We just made it though graduation, etc. by taking almost two full days off and now I am SO behind, I'll try to get back soon with more details, including some graphs if I get a chance to run them.

[opnly bafld]

Thanks Mike.
When I saw you had replied, I thought I should look and see how wrong I was.      
BTW my Emeralds are still making me .
Thanks,
Lin

[DSK]

Why does a larger box = lower Qtc? I would have thought that a larger box means less resistance/impedance seen by the driver, therefore less damping, therefore higher Qtc and looser/woollier bass?

For instance, my sealed servo subwoofer can be set (via toggle switch) to a Qtc of 0.5, 0.7 or 0.9 ... with 0.5 being very quick, tight and 0.9 being slower/looser etc.

[opnly bafld]

DSK,
I can give you an example, it will be easier than trying to explain.
If you take an NHT 12" driver designed for sealed enclosures and calculate qtc vs. vb(box volume) here is what you will get.
Qtc 1=vb 77 ltrs    
qtc .707=vb 272 ltrs  
qtc .65=vb 429 ltrs  
qtc .6=vb794 ltrs
As you can see, qtc goes down slowly as box size increases dramatically.
But once you get to the point where you have IB everything changes.
Lin

[DSK]

Lin, Thanks but I already understood that a larger sealed box means a lower Qtc and that the numbers supported this. What I was hoping was that someone could explain why (preferably in layman terms) as I've never seen an explanation and thus never quite understood the concept.

[Mike Dzurko]

Think of it this way: the smaller the volume of air in the cabinet, the harder the driver has to work to overcome this "spring".