Home » Sponsored » Pi Speakers » 3 Pi subwoofer build (Basic questions)
3 Pi subwoofer build [message #84832] Mon, 27 March 2017 14:22 Go to next message
Audiozipper is currently offline  Audiozipper
Messages: 2
Registered: March 2017
Esquire
Hi All,

I'm building a 3 Pi subwoofer which is my first attempt at a speaker build so I'm sure my questions are pretty basic. I'm thinking about adding some bracing to stiffen up the baltic birch panels of this 20 x 20 x 20 enclosure. I'm using 3/4 x 1-1/2 maple as the bracing and am planning to add them to the top, bottom and sides then bridge the top to the bottom and the two sides to each other. The total length of the maple is 111" with a total volume of 0.072 cubic feet. This Is about 2% of the total volume of the enclosure. The question I have is is it better to stiffen up the enclosure with the bracing even though the plans did not specify bracing or would reducing the internal volume of the enclosure by 2% negatively impact the design or sound of this subwoofer.


On a similar note the plate amplifier I'm using is a Dayton SPA 500. The back of the amplifier has a plastic covering to protect the electronics. The size of the cover is approximately 9-½ x 9-½ x 5". I was planning on cutting a hole in the back of the subwoofer and mounting the amplifier flush with the back panel. The plastic covering of the amplifier would then protrude into the subwoofer decreasing the internal volume of the enclosure by approximately 5%.


Would this negatively affect the performance of the subwoofer? Would I be better to mount the plate amplifier in such a way that it wouldn't protrude into the enclosure.


Can the length of the port specified for the 3 Pi sub be adjusted to compensate for a decrease in the originally designed internal volume of the sub?


Thanks for any help/advice,
Lee
Re: 3 Pi subwoofer build [message #84835 is a reply to message #84832] Mon, 27 March 2017 17:56 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17655
Registered: January 2001
Illuminati (33rd Degree)

Increase the box size to compensate for the displacement from the plate amp.

Braces are never a bad thing, though not necessary in this cabinet. But they sure won't hurt, and so while you're adding size for the displacement for the plate amp, do so also for the braces.

With the internal volume kept the same, the port length will also be the same.

Re: 3 Pi subwoofer build [message #84836 is a reply to message #84835] Mon, 27 March 2017 22:01 Go to previous messageGo to next message
Audiozipper is currently offline  Audiozipper
Messages: 2
Registered: March 2017
Esquire
Hi,
I forgot to mention that I already cut the panels for the enclosure and would rather not discard them and spend $80 on another sheet of baltic birch.

Thanks
Re: 3 Pi subwoofer build [message #84841 is a reply to message #84836] Tue, 28 March 2017 10:10 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 17655
Registered: January 2001
Illuminati (33rd Degree)

Well then, yes, you can shorten the port to adjust for the reduced internal volume. But this will reduce low-end extension.

Previous Topic: 3 pi plans and a woofer question
Next Topic: 4Pi Speaker variation
Goto Forum:
  


Current Time: Sun Feb 16 21:52:37 CST 2020

Sponsoring Organizations

DIY Audio Projects
DIY Audio Projects
OddWatt Audio
OddWatt Audio
Pi Speakers
Pi Speakers
Prosound Shootout
Prosound Shootout
Smith & Larson Audio
Smith & Larson Audio
Tubes For Amps
TubesForAmps.com

Lone Star Audiofest