Need Help Porting Speakers

[horn player]

Hello Everyone,

IN the early '90s, after a failed attempt to buy back the Cornwalls I sold in '87, I started building some speakers to try to capture the sound I missed so much. They were never completed because I ended up buying more Klipsch speakers and lost interest in them. Now I'm getting nestalgic and would like to finish them. They are towers, 46.5" tall x 18" wide x 16.5" deep approx made of .75 in thick cabinet grade birch plywood. I figured 6.1 ft3 internal volume in each cabinet less speakers. I bought Eminence 15" cloth accordian edge woofers for them, with 4" VC and 96 OZ mags. The Thiele small parameters are listed below. I experimented with putting one on a riser with a make-shift port underneath and leaving the other sealed - and I definitely like the ported sound better.

I have lots of 6" ID schedule 40 plastic pipe to use as ports if that would be a good idea. I thought about having a friend machine some of the pipe so I could make an adjustable length port, or else cutting various lengths close to the theoritical correct length and trying them. I could also do an underneath shelf port. Could some of you well versed in this field plug in these specs and suggest what the port internal volume should be, and any other pertinent info I could use to finish these speakers? Also, I was thinking of sacrificing some Heresys for the horns and xover, or using some JBL horns and drivers crossed over at 800 HZ. All suggestions would be greatly appreciated!!!

02-PART # 15418

05-RE OHMS 5.17 13-FS HZ 30.70

06-LE MH 1.11 14-MMS GMS 64.40

07-QM 6.15 15-CMS mm/N .4176

08-QE .200 16-RMS NS/M 2.0197

09-QT .200 17-VAS LTRS 430.11

10-XMAX MM 1.60 18-SD SCM 856.34

11-BL TM 17.74 19-EBP 150.5

12-EFF % 5.88 20-SPL dB 99.7

[horn player]

I have conflicting specs regarding these woofers - may need to figure with these woofer specs as well - I received both of these sets of specs from Eminence:

Imp 8 ohms

Rdc 5.2 ohms

res 35 HZ

Qm Nom 3.58

Qe Nom .29

Qt Nom .27

VAS 7.5 ft3, 212 liter

eff 98 db

flux density 13 Kilogauss

VC 3"

Mag 95 OZ

[j-malotky]

Horn

I considered making a ported cabinet for my HT center channel. I have a friend who use to be an engineer at another speaker company I wont mention the name here and he is a somewhat Klipsch fan... And he was going to calculate the port requirements for me. I then found a pair of K22's and Heresy cabinets and abandonded the port project.

The questions he asked me was what woofer I was using. When I told him either a K22 or K24 he told me I could not port those properly. Would have to make sure the woofer was one that likes to be ported.

The other question he asked me was what frequency I wanted the port tuned too??? Its kind of like a pipe organ, you can tune your port to what ever frequency you need a boost. You need to know the limits of your speaker to properly add a port to aid in its performance.

Good luck on your project.

JM

[cornwaller]

Hornplayer,

I would suggest that you go to the 2 channel forum and post this for HDRbuilder. He is the speaker encloser guru, as far as I know.

You might want to post this in odds and mods also.

Cornwaller

[Al Klappenberger]

Paul,

I am in the process right now of building a ported bass for a pair of K24 woffers. The box calculates to about 4.3 cubic feet with a 6.1 inch long 4 In diameter prot. The tuning frequency comes to about 29 Hz. With a box this size none of these dimensions is extremely critical. I will be using the resulting speaker as a way to "store" the old high end parts I took out of my Belles!

Al K.

P.S.

I should admit that when I say "I am building..", I mean I am having a cabinet shop build it for me! I can't do that sort of thing with just the hand tools I have!

[DRBILL]

Well, you are terribly brave. Unfortunatly, the wheel has already been invented. I sincerely wish you the best of luck. Let us all know what you find. Accidents sometime result in flashes of light that transform everything.

Father Bill+

[jnorv]

If you are going to build speakers, you need to buy Dickason's book, "Loudspeaker Design Cookbook". It is $40 and I think I got mine from Parts Express.

Jim N

[Al Klappenberger]

Jim,

I have the Dickason "Cook book". I wrote a computer program from the chapter on vented boxes and desinged it from that. The desing was also config=rmed fro am downloaded program I got off the internet called winISD. It's pretty good.

Al K.

[horn player]

Thanks for all your comments, they are all appreciated. I did get a design guide for ported enclosures from an Altec engineer back when I initially started this project. At the time (if my memory serves me correctly), after plugging in the parameters, I couldn't tune to below 40 hz without loosing a lot of decibles, but that didn't seem right. I figured I was doing something wrong. As far as what frequency to tune to - I would want the lowest possible at -3 decibles.