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18" scaling? (Read 4718 times)
Jeremy
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18" scaling?
02/18/12 at 05:41:00
 
I went and did it.... I bought the best 18" speakers I could find for the money and I purchased 2 of them. So there is no turning back now.

Here are the theile numbers.

Electrical Q Value -Qes: 0.476
Mechanical Q Value -Qms: 3.214
Total Speaker Q Value -Qts: 0.415
Free Air Resonance -Fs: 16.742 Hz
Equivalent Compliance -Vas: 384 liters
One-Way, Linear Excursion -Xmax: 22 mm
Efficiency -SPL 1W/1m: 87.65 dB SPL
Effective Piston Area -Sd: 1210 cm^2
DC Resistance -Re: 1.4 ohm
Nominal Impedance -Znom: Dual 1 ohm
Thermal Power Handling -Pe: 1500 W
Force Factor -Bl: 14.56

I really need some help, I have never built a speaker box before. I am a contractor and have all the tool but never had to do any math like this. I purchased the hwk15 plans and just need help getting started.

I plan on using 1" mdf for the construction and it I can get away with a 24" wide box I may add a layer of 3/4" mdf to help cut back on potential losses. I am prepared for the 400lbs it will weigh. Any help guys on actual dimension running these 2  18"s both pointing up on there own baffle?
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Jeremy
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Re: 18" scaling?
Reply #1 - 02/19/12 at 02:24:23
 
Well I I guess I will get my 5 messages in my own thread. From all the box calcs I could do today calls for a port the size of the top of the enclosure. I read some of the past constructions threads running into this same phenomenon. They had better sound with the top off the box. Did I screw up purchasing these plans?

Time will tell....
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Jeremy
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Re: 18" scaling?
Reply #2 - 02/19/12 at 04:06:54
 
Well quite a few hours later I have determined that for this to be a true house/home wrecker it needs to be 21 cubic feet with my selected drivers. Nearly a flat response from 40-20hz and only losing 15db by the time I hit 10hz.  

The 15" plans by comparison are roughly 8 cubic feet. I already have a pair of 12" and 10"s for the 50hz on up bass. This is for waking up the neighborhood. I am going to need to purchase a crown xti-4000 to power this monster, maybe 2 of them.

If anyone wants to ask me any questions after this turns out just ask. I will give the dimensions to anyone that purchased plans to this forum. I optimized it to cut down on the amount of full sheets. 77" tall with 1" mdf double wall top and bottom.
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« Last Edit: 02/19/12 at 22:24:26 by Jeremy »  
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Jeremy
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Re: 18" scaling?
Reply #3 - 02/19/12 at 22:07:40
 
Drew up the plans and cut sheet.... 4.5 sheets of 1' mdf at around 130lbs a sheet.....?

This is not going to be portable that is for sure. Maybe doubling 1" is overkill. I seem to remember large rock bands having to use forklifts to move their speakers.

This current setup will weigh 720 lbs.. Huh I may need to go back to the drawing board.
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Jeremy
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Re: 18" scaling?
Reply #4 - 02/19/12 at 22:22:54
 
Well with a little quick math and because of the simplicity of my double wall setup, my external dimensions did not change. I just removed the internal pieces which can be substituted for corner bracing. This brings the weight down to just over 300 pounds without speakers. This is much more doable. It will however increase my internal volume, I can live with this. It will allow a larger port up top and longer ports on the bottom.
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HT-EXT
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Re: 18" scaling?
Reply #5 - 02/23/12 at 11:53:30
 
When it comes to building enclosures that most people would not dream of building you will find it hard to get replies.  I am not even sure what to tell you what will work and what will not with the HWK18.
Trial and error will be the only method to figure out the madness of HWK18 build but I bet you will be more than happy with the results.

Don't forget to post some pics.

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Jeremy
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Re: 18" scaling?
Reply #6 - 02/25/12 at 03:44:38
 
Wow, someone responded...!!!! I have settled on a 1"mdf and a crown 5000 amp. The speakers have still not been shipped and I am waiting on them.

I purchased a new 1500 watt front channel subwoofer amp and receiver. This powers my 2 12" for the 25-100hz bass. I also bought a digital preamp to tweak it all for optimum performance. I am waiting on my 102" track saw track to cut the mdf with. It is much easier to have sheets laying flat instead of trying to guide them on the table saw. I may try to use my 59" track in 2 passes.

God be willing I should have it completed in under a months time. I am just waiting on everything. Maybe I should make the whole box round to assist moving it around the house Smiley
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Jeremy
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Re: 18" scaling?
Reply #7 - 03/04/12 at 00:28:58
 
Amp is now on the way and speakers have been shipped. I made a pair of 5 way 15" speakers for my midrange. They do pretty good to about 55hz and then dont like much power. They will however drive a person out of the house. They are old school JBL d130's, I bought 3 of them for $50 at a yard sale. The same week I was given another jbl e130 in perfect shape. I have been busy.
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Jeremy
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Re: 18" scaling?
Reply #8 - 03/05/12 at 23:39:29
 
Mx18 REaudio Speakers are here.... They are an absolute work of art.

I have tried uploading pics and it will not allow it. I resized the pics to 65kb and tried 3 times now. Angry

I may start working on the box tomorrow, but my amp has not shipped and my 102" track aint here yet either Roll Eyes
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Jeremy
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Re: 18" scaling?
Reply #9 - 03/12/12 at 06:13:12
 
Started on the box and it sure is heavy. Standing inside the speaker box is a strange feeling. My amp has still not shown up and the company is claiming the tracking number is messed up. The box is large enough that torsional loading starts to happen and I have to support it in sections. It should only be a full day of work until I can test the box and speakers, I will just have to use a smaller amp.

Once again I cannot attach pics and they are only 47k.
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Jeremy
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Re: 18" scaling?
Reply #10 - 03/17/12 at 06:55:04
 
Well this is taking much longer than I thought. But I guess good things come to those who wait. I was able to fit one 18" in place and ran one channel to it at around 200 watts. I have the box nearly rough finished and can honestly say it has been allot of fun. I went with 1"mdf and corner braced much of it. I ended up deciding it needed 10,000 watts of power running to it to really wake it up. with the one speaker resting in its cutout I heard deeper notes in one of my favorite songs that I had never heard before, for deep base you need a big box. I hope to approach 140 db in the 16hz range, I really want to shake the house off its foundation.

I bought a separate breaker box to wire in the 2 dedicated 20 amp circuits. The Crown  xls 5000 requires a 20 amp plug.... more work and more money. This is going to end up costing around $3k to complete with speakers amps and materials Huh

PS: I have a days work done on the box after that pic was taken and I have to port the bottom and figure out how I want to do my lexan for viewing. Then I should be able to run 1500 watts to it and fine tune it with stuffing and port changes. Then it should get carpet and all the other goodies.

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« Last Edit: 03/17/12 at 06:58:33 by Jeremy »  
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Lon
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Re: 18" scaling?
Reply #11 - 03/17/12 at 13:41:11
 
Nice work.
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Jeremy
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Re: 18" scaling?
Reply #12 - 03/18/12 at 07:35:23
 
I got the bottom ports in today and braced them to the floor of the box. I am running 2 4" ports 20" in length. 5" ports where going to cost me twice as much and I can always run a third port if it sound like it needs it.

This pic was from yesterday. God be willing I should be able to get the speakers mounted tomorrow and get the lexan mounted. I like the look of rounded edges so I may do all the outside box edges to make it more pleasing on the eye and less prone to damage. I hope I gave enough setback to all the screw heads to do it, the carbide will cut through them no matter Tongue

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Jeremy
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Re: 18" scaling?
Reply #13 - 03/20/12 at 00:42:03
 
Well it sucks bad....however. I took the front lexan cover off the the top speaker and it came to life. It needs a port of 102 or 10"x10". I have to cover up the top speaker (so I dont drop something through the cone) and cut a new port on the top or make a death box style port. With the front top lexan off it is awesome and makes the 12"s sound like toys with no depth of field. I dont know if the bottom needs another port or not. Any ideas on determining this?

I have worked with allot of stereos and my 12"s have scared me before when they came on and I was half asleep. Today I was running the 18"s through there paces and turned my back on them. Dont turn your back on the 18"s in the house wrecker. The bass hit so hard I thought the box was falling on me....

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« Last Edit: 03/20/12 at 04:57:09 by Jeremy »  
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Jeremy
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Re: 18" scaling?
Reply #14 - 03/20/12 at 21:09:09
 
Well I have yet to hookup both amps and I am clipping the 5000 watt. I watched Batman begins last night and when he starts tripping on the blue flower and the bass hits with his hallucinations....well it was like being there. I havent done anything with the top porting other than leave the glass out. I am contemplating what to do.

I would like to be able to vary upper chamber dimension along with port length and diameter. I could remove the whole top and make something that could slide internally adjusting volume and port size.
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