2 pi surround speaker project - AVS Forum
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DIY Speakers and Subs > 2 pi surround speaker project
petew's Avatar petew 06:40 PM 06-03-2013
I've started a long delayed project to build new surrounds. My first post here on this subject was back in 2010. I move slow sometimes. I finally decided on Wayne Parham's 2 pi design, a bass reflex two way. The cabinets are about 15 x 21 x 8. Details here.

The drivers are an Eminence Alpha 10 midwoofer and a Vifa DX25 tweeter.

I haven't taken too many pictures so this will be brief.

Here's the result of two days of making sawdust. All of us were worn out.

I built the boxes out of some incredibly crappy import plywood that I have in stock. The panels are not flat by any stretch of the imagination. Also the veneer peels off like cheap shelf paper or something. The core is structurally sound though. I laid out all the joinery to avoid gluing anything to the face veneers. All the joints are simple rabbet cuts about 1/8" deep. The edges are getting a 3/4" roundover and then will get a liberal coat of Duratex. I haven't decided if I'm going to use grills or not. Likely will not. Here's a couple of shots of the boxes.

Nice void there, 'eh? That joint needs a bit of sanding flush before I attach the baffle too.

Rear corner after some sanding. I blew right through the veneer in places but the Duratex will cover a multitude of sins. I'll fill the voids with rock putty.

Simple terminal cups from P-E. I used the same ones on my subwoofer project and the quality is good.

Here's the boxes lined up in various stages of stuffing. They get the pink stuff on the back, bottom and port side. I used rigid insulation on the box furthest to the right but ended up ripping it out. Didn't want to deviate too far from Wayne's plans, which specify R-11 or R-13 fiberglass.

Here's a baffle and test-fit of the port. The port material comes from the place with the ez button (Staples). The little mouse ear cutouts in the tweeter hole are for the terminals. Clearance is tight.

A baffle shot with the drivers laid into place.

filtor1's Avatar filtor1 06:45 PM 06-03-2013
I look forward to your impressions Pete. They look great!
petew's Avatar petew 06:59 PM 06-03-2013
Thanks Filtor1

If I can stay on schedule...
Glue baffles and ports Tuesday
Roundover and sand Wednesday
First coat of Duratex Thursday
Second coat Friday
Build crossovers and assemble everything Saturday
Watch movies Sunday!
tuxedocivic's Avatar tuxedocivic 07:04 PM 06-03-2013
Nice work. That dome looks crushed?
petew's Avatar petew 07:14 PM 06-03-2013
Those vifa tweets are funky. They have some sort of surround molded into the fabric dome. I have an odd reflection off the ceiling that looks like a dented dome.

nube's Avatar nube 07:22 PM 06-03-2013
Hey, those monkey coffins look familiar! Coming together pretty quick after ripping stuff on Friday, especially given how big of a dent we put in that bottle of Crown!

You gonna paint the inside of the ports black?

Once those 2pi are done, I'll have to bring my Jack of All Trades 8 over to compare output and response.
NWCgrad's Avatar NWCgrad 10:37 PM 06-03-2013
I'm watching this as I need new surround speakers to run with my 4 Pi's. Nice looking build, except for the plywood but being so small I wouldn't think it would matter much.
petew's Avatar petew 07:15 PM 06-04-2013
On schedule...Tuesday glued baffles to boxes....

...and glued the ports into place. I coated the ports with glue so they won't soak up Duratex when I get to that point.

brian6751's Avatar brian6751 07:38 PM 06-04-2013
awesome. lots of clamps are handy tongue.gif

on a side note. i dont think youll have to worry about Duratex getting soaked up. its too thick
NWCgrad's Avatar NWCgrad 10:18 PM 06-04-2013
Wow, a lot of REALLY nice clamps, not the cheap Harbor Freight ones I use.
smokarz's Avatar smokarz 01:27 PM 06-05-2013
Nice. I built a pair of 1pi's last year for surrounds. I am sure you're going to like your 2pi's.

What exactly did you get at Staples to use for ports? I know Wayne advocates the use of paper ports, instead of plastic.

I am not quite sure what the reasoning is behind that, but hey the man uses so I guess it must work.

I am going to need ports material for an SEOS build, and like to take a look at this Staples stuff.

And yeah, great clamps.
tuxedocivic's Avatar tuxedocivic 01:38 PM 06-05-2013
Maybe poster tubing?

Paper probably is a little "deader". Just a guess.
nube's Avatar nube 03:00 PM 06-05-2013
It was paper mailer tube from Staples, cut to size. The exact tube with bar code and UPC code is in this pic:

smokarz's Avatar smokarz 05:59 PM 06-05-2013
Originally Posted by nube View Post

It was paper mailer tube from Staples, cut to size. The exact tube with bar code and UPC code is in this pic:

Thanks. I'll have to make a quick trip to Staples to pick up some of these tubes.
petew's Avatar petew 07:41 PM 06-05-2013
It almost feels wrong to use such a cheap chunk of cardboard for a port tube. At least it's not a TP core. It's just a standard 2" mailing tube. I don't think the surround waves will care one bit though.
petew's Avatar petew 07:53 PM 06-05-2013
Wednesday Project:
I ran roundover bit around the front baffles. I didn't take any pictures of the router work - too much dust.

When I got done with the baffles I just had to do something to dress up the Easy Button Port Tubes. I raised the 3/4" roundover bit so only about 1/4" was below the router baseplate and ran it around the inside of the port tube.


Progress shot:


A little touch up with sandpaper and the Duratex treatment will hide the truth from all but the most experienced DIY speaker builder.
petew's Avatar petew 07:56 PM 06-05-2013
Scary power tools put away. Mess swept up. Time for some sanding. Time to crack a cold one.

And then some filler - and another cold one.

petew's Avatar petew 08:07 PM 06-05-2013
Originally Posted by smokarz View Post

Nice. I built a pair of 1pi's last year for surrounds. I am sure you're going to like your 2pi's.

I read through your pi build a couple of times. Good stuff!

I saw Star Trek Into Darkness in a commercial theater a couple of weeks ago. I realized my mishmash of surrounds really suck, so it got me off my butt to make dust. Looking forward to putting them through their paces!
petew's Avatar petew 07:30 AM 06-08-2013
Filling and sanding done.

First coat of Duratex goes down.

The crappy veneer has bubbled up in a couple of places. Need to sand down to solid wood and recoat those areas. Then I'll do the final rolled finish. The air is so dry here that the Duratex is dry to the touch within a few minutes. Might make it tough to roll out a smooth finish. Relative humidity is 37% now at 7:30 AM and headed down into single digits.
Gorilla83's Avatar Gorilla83 09:30 AM 06-08-2013
Looking nice, Pete. I think I'm going to have to pick up a 3/4" roundover bit soon, I think I will like it a bit more than the 1/2" I've been using.

Keep it up, listening soon!
WarrenBerry's Avatar WarrenBerry 07:16 AM 06-10-2013
Lookin good!
petew's Avatar petew 07:22 PM 06-16-2013
I always get behind schedule. But I'm getting close.

Crossovers under construction

Crossovers completed. The board will fit through the terminal cup hole. I wanted to have everything assembled on the crossover before installing into the cabinet

These things are simple. Three components.

Final coat of duretex, and the port holes are coated now.

I'll be listening to these tomorrow evening.
nube's Avatar nube 11:14 AM 06-17-2013
Lookin' pretty good. It'll be exciting to let 'em rip tonight. I think that calls for a tasty adult beverage or three!

I like the simple XOs. Is that vile pink stuff visible through the ports, or did you paint it black?
petew's Avatar petew 12:11 PM 06-17-2013
Originally Posted by nube View Post

Is that vile pink stuff visible through the ports, or did you paint it black?

I was planning to tack some black burlap over the pink stuff to pull it away from the ports. I thought about assembling one before work this morning but just a glance at the pink made me start itching.
tuxedocivic's Avatar tuxedocivic 01:04 PM 06-17-2013
I don't find fiberglass itches at all. Maybe it's made differently up here.

They look fantastic.
petew's Avatar petew 03:00 PM 06-17-2013
It's all in my head. I start itching if I drive by a construction site while the insulation crew is there.

I'm really happy with the Duratex finish. It's easy to use and looks good! I used decent quality 3/8" nap rollers to apply it.
nube's Avatar nube 09:13 PM 06-17-2013
Wow. After finishing those 2pi, hooking them up and manually calibrating them, all I can say is wow! The improvement over what you had before is astonishing. Elevating them a little bit in your theater really opened up the sound. The stage is expansive and enveloping, and the demos we watched/listened to were fantastic, especially the rebassed Avengers.

I can't wait til you get the new LCR built! Lest we forget that you have the LFE totally handled with, what, a hundred watts max to those subs, yet they sound/feel amazing and have perfectly flat response without any EQ?

How much did you say you had invested in the 4x 2pi surrounds and the 4x 15" subs so far?
petew's Avatar petew 10:03 PM 06-17-2013
Originally Posted by nube View Post

How much did you say you had invested in the 4x 2pi surrounds and the 4x 15" subs so far?

Under a grand. Excluding electricity, food and beer.
petew's Avatar petew 10:08 PM 06-17-2013
Here's a couple of action shots:

I am somewhat amazed at the difference good surrounds make. I listened to some acoustic music just now and the room came alive. I was transported to the venue. KD Lang in London.
smokarz's Avatar smokarz 08:34 AM 06-18-2013
Glad you enjoy them.

Those 1pi/2pi are very good for the money. Have you tried them in a 2 channel set up yet? I think you will be amazed what they can do for so little cash.
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