Speakerbuilding Debut

[meuge]

It's up to you. I like PR or Sealed designs better, but ported will work, as long as you design the port correctly.

[formica]

The ported -vs- sealed debate is one of the oldest in the book and you have people on both camps. As with everything in audio design it's a question of tradeoffs... group delay versus bass extension.

I tend to prefer ported (PR and vented) designs for compact freestanding units... as they benefit from better bass extension, higher efficiency, and better power handling above tuning.

I don't think it's too advanced... you can learn it as you go along.

Due to published T/S parameters variances... a ported design based on these can also be a little off. To correctly build it, the subwoofer could be built and the port (PR or Vent) can then be adjusted according to the measured tuning.

Rob

[DrWho]

For the record, PR and ported systems are essentially identical...ported usually being the better choice when port noise can be eliminated (which gets hard to do in a small box with a low tuning).

Here are some things to keep in mind when modelling different drivers:

-cone excursion: keep an eye out for the max power and cone excursion graphs to get an idea of how loud your max will be (you can change the wattage going to the driver under the signal tab).

-port noise: winisd is cool because you can mess around with the port dimensions. Plug in your previously found max wattage and then go to the "rear port air velocity" chart. You want to keep this under 20ms as anything faster gets audible. Ideally you'll want to even get below 10ms, but that's pretty much impossible with cabinets this small.

-cabinet volume: don't forget to compensate for the volume of your ports. If you enter in say a 10 cubic foot cabinet for the driver and your total port volume is 1 cubic foot, then you will need to build a cabinet with a volume of 11 cubic feet. In other words, you have to manually compensate for the port volume because winisd doesn't.

Btw, I would like to second the suggestion for the AE AV15 driver because it performs nearly identical to the MKIII, but costs less.

[Zealot125]

I just need to make a simply clarification of my understanding of volume. When I say I want to make and enclosure of say 100 liters, then the 100 liters is the total amout of free air space INSIDE the walls of the MDF right? The 1" walls of the MDF should not count as volume right?

However, say I add a port with a volume of 1 liter according to the above statement that the volume is just the air space inside the material. I will have to compensate for the volume of air inside the port AND the volume of the material making the port since I will have to adjust the enclosure volume accordingly, right? Am I making sense?

One other thing, are there any other structures that go into the enclosure other than the port, amp, and walls? are there bracings that I have to take into account to adjust volume?

[Zealot125]

Does that AE AV15 have dual voice coils wired in series (4 ohms)? or am I reading something wrong, I want to make sure so I can model it correctly.

[Scp53]

I'd recommend the atlas 15(well actually, whatever replacement ascendant audio makes) from ascendant audio(although the others are good options too). i have it in a 24in cube with a 500 watt plate amp tuned to 20hz or so. i can get 115-118dB peaks in room clean at 2m away. imo its very tight and musical. a few highlights are it has an xbl motor(lowers distortion), adjustable q with the coils, and its BOTTOMLESS. this is just my two cents(and of course my biased opinion)...

[Jay481985]

the volume is counted as internal not counting the walls and internal bracing.

Same goes with the port. The port does not count as internal volume.

Bracing is meant for stability of the box. Say the wall was flexing, instead of that energy going to music and bass, it is convertered to flexing. Also the stiffer the cabinet the less likely it is to color or add nodes into the sub. Meaning the flex can actually externuate certain bass regions.

Also you might want to look into stuffing the subwoofer, no not like a turkey but you can add polyfill or fiberglass or wool to actually lower the responce of the subwoofer. Polyfill being the cheapest and probably best option.

[Zealot125]

OK thanks for the reply. So what shape/design should this bracing take on, are any rules involved in its designing? Also, if I add stuffing, do I have to add the volume of stuffing to the total volume of the box as well, or does it not work that way.

[Zealot125]

Ive been doing some reading and found that for ported enclosures, that drivers with a Qts of less than .4 are best. So, I have come to the conclusion that if I make a ported enclsure, then I am going to use the Dayton Titanic, but if I decide to use a sealed enclosure, then I am going to use the AE AV15.

[Scp53]

not sure what amp your were looking at but partsexpress.com now offers a 300watt and 500 watt bash amp for $150-300wt and $240 for the other. seems to be a good amp for the money. just a thought...