RMS capabilities

[sqcomp]

Aside from the vented/ported space requirements and powerhandling/sensitivity changes of a speaker in a ported enclosure...the group delay idea is fairly new to me.

I'm wondering...in reality...are we going to hear a difference between a two properly constructed enclosures (ported and sealed), everything being equal, in the realm of response time?

If the amplifiers have good control...wouldn't the added "sensetivity" of the ported enclosure make it inherently more loose when dealing with equal sized woofers?

Then again, we have to wonder to what specifications the ported enclosure is built...I know darnwell I've heard some tight ported enclosures. *sigh* And then on the other hand, that "tightness" may have been from the added output amplitude rather than physical control.

The problem is that you MUST give something to get something. For the quick response of the ported enclosure, what do you have to have? A bigger, more elaborate enclosure (which is a given versus a sealed enclosure), or do we loose power handling and/or frequency response? What do we give up here?

That in itself is enough for me to stick with a sealed enclosure's benefits of space savings. Mind you, that's MY preference. A 15" woofer in one cube with plenty of power sounds just sexy to me...

Let us talk more on this specific subject though, its interesting.

[talnlnky]

Originally Posted by sqcomp

Aside from the vented/ported space requirements and powerhandling/sensitivity changes of a speaker in a ported enclosure...the group delay idea is fairly new to me.

I'm wondering...in reality...are we going to hear a difference between a two properly constructed enclosures (ported and sealed), everything being equal, in the realm of response time?

If the amplifiers have good control...wouldn't the added "sensetivity" of the ported enclosure make it inherently more loose when dealing with equal sized woofers?

You are close... the "loose/boomy/sloppy" sound is usually due to an over-accented low end, Usually due to a ported or bandpass box being tuned to high which results in a huge 6-10dB spike somewhere in the 40-60hz range. If you make the frequency response flat, slightly rolled off, or even with a small dB bump you will not get that bad "sloppy" sound.... unless the group delay is really slow.

Group delay is basically the time that the coil takes to get saturated and reverse its directions.... so... how long it takes for it to stop, and start. The quicker it can do that, the cleaner the sound. The T/S spec that you can check to guesstimate if the GD will be good or bad is the (Le). Also... tuning a sub low will also help keep GD spikes down.

Originally Posted by sqcomp

Then again, we have to wonder to what specifications the ported enclosure is built...I know darnwell I've heard some tight ported enclosures. *sigh* And then on the other hand, that "tightness" may have been from the added output amplitude rather than physical control.

It is about the design of the box... a properly designed ported box (for sq) will be indistiguisable from a sealed box in terms of transient response (tightness)... but it will have slightly more low end.... even if you do design the box to roll off and mimic a sealed box (Makes for a darn good sq box in cars). Once again, the naturally dB gain from a ported box doesn't make it sloppy, just louder... an exaggerated bump will make it sound sloppy (mostly due to a high tuning)[/QUOTE]

Originally Posted by sqcomp

The problem is that you MUST give something to get something. For the quick response of the ported enclosure, what do you have to have? A bigger, more elaborate enclosure (which is a given versus a sealed enclosure), or do we loose power handling and/or frequency response? What do we give up here?

True, there is no perfect enclosure... size, response, efficiency, all kinds of enclosures suck at at least one of the three.... kinda like Hoffman's Iron law for speakers. The main thing for keeping a tight response on a ported box is a tuning at or below 30hz & a sub with a relatively low Le. You can do it with a huge box, or with a very small box.... If you want to mimic the frequency response/ roll off of a sealed box you just make the box undersized. Like the box in my avatar. Its 2 Tangband 8" 740C Drivers... a normal box would be .75-1cuft per driver @ 30-35hz for car use... I changed it to .6cuft @ 28hz for each driver... rolls it off nicely starting at mid 30's due to the small box size, but the tuning is still low so it tries to play low still.... I might have some picks on my laptop of the response somewhere.

Originally Posted by sqcomp

That in itself is enough for me to stick with a sealed enclosure's benefits of space savings. Mind you, that's MY preference. A 15" woofer in one cube with plenty of power sounds just sexy to me...

Let us talk more on this specific subject though, its interesting.

I NEED to show you the joys of the software I have for box modeling... Box modeling is where it's at when it comes to designing a good sub stage. You'd shit bricks if you saw what you could do with the right software. I've found that many times, a big sub in a sealed box is no better than a smaller sub in a well designed ported box, and that the smaller sub will actually play louder down low.

I forget exactly what it is... but physics states that a speaker will need an ever increasing box size the bigger the speaker gets.... It has to do with the Surface area (SD) of the speaker & the Vas I believe. If you double the cone area, I think the speaker would require 4 times the box size....all other variables staying the same of course. I might be a bit off on that tho....

Regardless... in the space that you could fit a single 15" sealed woofer... I could probably fit 4-6 similarly spec'd 8" subs.... would have less cone movement, & probably higher efficiency... meaning... louder & less distortion.


Like I said... I really want to spend 30mins to an hour showing you the joys of box modeling and what crazy shit you can do with a driver. I've got a copy of a really nice program.