Home Theater Forum and Systems banner

1 - 20 of 26 Posts

·
Registered
Joined
·
65 Posts
Discussion Starter #1
I just spent about an hour messing with WINISD and got some decent results I think.

3.2 ft^3
18 Hz tune
2 4" round ports. 63" lenght, 107Hz port res.

I need a small-ish box. Idea is inverted mounting, with the basket out, gaining about .15 cubes, and looking cool as well. Up fireing, sub mounted on the bottom of the box, with aluminum legs holding the box off the base. Ports in the front.

I will upload the WINISD info tonight. but until then...

Transfer curve is about a 3.5db. -4db around 18hz to -.5db around 50hz.

700W input:
108db 18hz
109db 22hz
111db 30hz
112db 50hz

16hz & 27hz are the peak XMAX (21mm) for the speaker.

15.2hz is the peak of 26m/s for port speed. ave port speed is around 20-21

600W input will give me about 2mm less excursion and port speed drops to 24m/s max. and I only loose about 1-1.5db SPL across the board.


What do you think?
 

·
Premium Member
Joined
·
19,397 Posts
Your numbers are right. The ports displace .9 cu.ft. so the total internal volume needs to be 4.1 cu.ft. A 21 inch cube is 4.3 cu.ft. internal. Getting the ports in there will be fun! Remember that when using elbows the port length is determined through the center of the port. Post a build thread if you can. :T
 

·
Registered
Joined
·
104 Posts
Like Mike P said... those ports will be fun to get in there.
Should make for a solid little HT setup. What dims are you looking to do for the enclosure?

Thanks,
Scott
 

·
Registered
Joined
·
65 Posts
Discussion Starter #4
note sure... I will work on that today tonight. I could always do a slot port if the tubes will be too hard to snake in there.

good news... I won a EP2500 for $220 on ebay. Ill order the speaker when the check clears from my side job... aka wife doesnt see this money.
 

·
Registered
Joined
·
65 Posts
Discussion Starter #5 (Edited)
hang on a sec... 63" that is 31.5" long PER port right... lol

Slot port:
3X10
72.42" long

It would make a few 90deg bends but it would be easier.
 

·
Registered
Joined
·
65 Posts
Discussion Starter #7
Yeah I know it was per port... I was joking about shoe-horning these into the box.

I am looking at a 20"X20" by 22" high box. This will net me 4.02 cubic feet. (both 63" ports are .88 total and I am going for 3.2 cubic feet for the box) Remember I am inverting the woofer so I will save the .14 for the basket and motor.

I have to look at how tall a 4" X 63" long port with all the bends will be.

If the 4" dia 90 deg elbows are 4" high... I can make a 64" port in 3 straight legs and 2 180 deg elbows.... which will be around 18" tall or so... Minus flairs. it is close.
 

·
Registered
Joined
·
2,431 Posts
That's a lot of port. GL! I think that a slot vent may be easier. Actually how are your fabrication skills? You could try to use the power port design on it, to cut the vent length down.
 

·
Registered
Joined
·
65 Posts
Discussion Starter #11
I am reading that today... thanks for the idea


I was about to order the speaker today, but I am unsure of all the options. I PM'd FIaudio, and will await a reply. But in the mean time, can anyone explain the options list to me? Anyone have pics of the different dustcap colors?

BTW I am powering this with a EP2500, so I am not sure what VC to get. I am a bit confused on the operationa and wiring on this amp... A bit more than the car audio amps I am used to! lol

What VC should I choose? I might end up building another twin box/sub, since the amp has more than enough power. so I should look ahead for wiring 4 VC's i guess.

Ohh yeah, I was right at Xmax with 700watts input.
 

·
Registered
Joined
·
65 Posts
Discussion Starter #13
Yeah but if I hit X-max at 700w, in real world I dont see this setup taking 2400W!!!

BTW, how does this amp double the power going from 2ohm to 4ohm??? isnt that backwards?
 

·
Registered
Joined
·
2,431 Posts
To give you an idea of what you'd have to build with a power port design here's a few pics from my 18" RE XXX design. What you have is a big port and imagine a rod going straight through the center all of the way to both ends of the port where it will meet up with 2 inverted flares (cones, think of a funnel) one on each end. the ports will also be heavily flared to match the curvature of the flow guides(cones), so that there is a constant distance all of the way through. There would be a lot more work involved with this and making the cones is the difficult part, but I have the calculator spread sheet for designing these if you are interested. You mentioned having a base with legs on your box and you need extremely long ports. This design cut me from needing a 63" port down to about 36.5" with the same tune.








 

·
Registered
Joined
·
65 Posts
Discussion Starter #16
Actually could I get a copy of that calculator? I have access to a lathe and could pull it off. I wouldnt mind taking a look at it and figuring out what i would need to build to try that.
 

·
Registered
Joined
·
2,431 Posts
I looked at what you've got going on and you could get a 6" based power port to about a 41.5" straight length. You'd need a 2" center flow guide, 8" diameter flow cones and 2 " baffle spacings, with 1.25" roundovers on each end of the port. You'd still have to bend the port in the enclosure though.

You've got PM.
 

·
Registered
Joined
·
65 Posts
Discussion Starter #18
Well The power port idea is sweet. But I picked up a few carbon fiber side jobs that will take up alot more time in the next few months so I dont have the time to put into the fab work for a power port. I will slot port it and call it a day.

Side note... Would it be OK to build the EP2500 into the subwoofer box? reason being my TV stand cant take another 45lb piece of equiptment!

My idea is slot port it out the top. and box off a section of the enclosure for the EP2500 to slide into. I can add a intake/exhaust fan to it as well.

There shouldnt be any vibration or pressure problems that the amp cant handle are there?
 

·
Registered
Joined
·
65 Posts
Discussion Starter #19
design is finalized.

23"X23"X23" cube.

Top center is a 5" high 20.5"wide and 23" deep box which will hold the EP2500 and flush out the face plate. Back of that amp box will have 2 exhaust fans. Speaker leads will be routed inside the box. I will even look for a male AC power plug/plate to relocate the AC power cord to the lower corner of the box. same with the input connections. (need some help here)

the 3"X8"X58" slot port will exit the side of the box. 8" high and 3" wide.

Subwoofer will be inverted, firing up into the box from the bottom. The speaker is 6" tall, so I figure I make the legs 8-9 inches tall. Base plate for the enclosure will be 25" squared and have a nice edge routered all the way around, and should provide a nice stable foot print and weight distribution.


I have a question for the inputs for the AVR to the EP2500. What do I use! Do I wire up a TS/TSR 1/4" plug to a MONO-RCA and hook that up to the subwoofer pre-amp out on the Onkyo 805?
 
1 - 20 of 26 Posts
Top