Port tube and terminal question.

[TonyW]

Hi, I'm getting closer to starting on the Vifa Tower design, most parts are on order.

Port tube, Straight or flared and should it be adjustable? I'm looking at a 3" tube ( I think).
Location of port; right now my plan is just off the bottom of the speaker a couple of inches off a corner and mirrored for each speaker.

Terminals; should I just go for a basic set of terminals or set it up for biwire (right now I only have one amp).

Tony

PS: This is my first speaker.

[Cal Weldon]

Alright Tony,

You're first, ahhh... there's nothing like it!

Terminals: You can get simple and end up cutting the box twice or get a bi set up and maybe not end up going that way. Only you can decide my friend.

Others can answer the port question better.

Welcome aboard the world of DIY.

"What a long strange trip it's been"

Cheers
Cal

[Timn8ter]

Since it's a parallel crossover you might as well use the dual cup. It's always nice to leave your options open and if you ever decide to sell them you can point out how cool that is. I'd go with the flared port if you have the room. With flared ports the length is the measurement of the center tube and the flared ends take up a lot of space. I didn't see the length measurement in the plans.

[TonyW]

Okay, biamp terminals it is! They are really not that much more expensive. By the way, is there any benefit to running a single amp and splitting the cable to the biamp connections, or did the guys at the stereo store see me coming a mile away with my B&W's?

Port. Dennis suggests on his site a 6" port length to start. The cabinet depth is 12.5". Enough room for a flared tube?

Tony

[Timn8ter]

By the way, is there any benefit to running a single amp and splitting the cable to the biamp connections, or did the guys at the stereo store see me coming a mile away with my B&W's?

Any benefit is negligible. I think it's like the "more watts is better" but it's "more wire is better".

I happen to have a 3" Precision Port with a 6" center tube that's 12" overall.

[TonyW]

Well, I guess that scotches that idea. I have 11" internal room front to back. The thought did occur to mount the flared port halfway out of the box, kind of like a trumpet horn, but I think I'll leave that experimentation for later. I don't see why it wouldn't work though. . .

Another question. I downloaded unibox and input the parameters for the vifa woofer in this design and the resulting linear excursion curve is 10 mm, 4 mm past max excursion. Is this bad, or did I just get dangerous by downloading software I know nothing about?

Tony

[asauer]

Yes, you can 'stick' your ports out of the box. I know it will slightly affect phase tuning, but I'm sure it is completely negligible. Although I have done this before, I'd use it as a last ditch effort, as I find it an ugly option to take.

[coolkhoa]

What about those knock-in binding posts? I don't know if they're easy to install (must align them square to the surface), and for biamping, it would mean 2 pairs.

[sreten]

Whether you use bi wire terminals or not also depends on the
way you build the crossover, you need to keep seperate earths.

The crossover will be better in the base of the cabinet
rather than the position shown in the Opal drawings.

My simulations of the cabinet and driver indicate that
the tuning should be between 28Hz and 38Hz.

38Hz is flat, and 28Hz is overdamped but with a nice shape
to utilise room gain. If pushed for a single frequency I'd say
31Hz is a good choice.
So I'd consider these frequencies also in selecting the port
for the job.

sreten.

[simon dart]

One option if you are struggling with port length is to put a bend in it.

I've used ordinary plumber supplies plastic waste which comes in several diameters so you can use elbows etc. Just spray it black with plastikote paint if the colour offends you.

It's a bad idea to jam the entry to the port tight to any internal suface, the port's air mass will couple less strongly with the box air volume and you'll get weak port output, leave at least a couple of inches.

Good luck,

Simon