SUPPORT FORUMS FOR DECWARE SPEAKER PLANS >> Housewrecker Support Forum >> 18" scaling?

Message started by Jeremy on 02/18/12 at 05:41:00

Title: 18" scaling?
Post by Jeremy on 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?

Title: Re: 18" scaling?
Post by Jeremy on 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....

Title: Re: 18" scaling?
Post by Jeremy on 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.

Title: Re: 18" scaling?
Post by Jeremy on 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.. :-? I may need to go back to the drawing board.

Title: Re: 18" scaling?
Post by Jeremy on 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.

Title: Re: 18" scaling?
Post by HT-EXT on 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.


Title: Re: 18" scaling?
Post by Jeremy on 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 :)

Title: Re: 18" scaling?
Post by Jeremy on 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.

Title: Re: 18" scaling?
Post by Jeremy on 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. >:(

I may start working on the box tomorrow, but my amp has not shipped and my 102" track aint here yet either ::)

Title: Re: 18" scaling?
Post by Jeremy on 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.

Title: Re: 18" scaling?
Post by Jeremy on 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 :-?

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.

Title: Re: 18" scaling?
Post by Lon on 03/17/12 at 13:41:11

Nice work.

Title: Re: 18" scaling?
Post by Jeremy on 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 :P

Title: Re: 18" scaling?
Post by Jeremy on 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....

Title: Re: 18" scaling?
Post by Jeremy on 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.

Title: Re: 18" scaling?
Post by Jeremy on 03/21/12 at 04:25:43

I put a third port in the bottom and found that it made me lose 3-4 decibels in the bottom range and gain 3-4 in the 50hz+ plus range. No good, 2x22" 4" ports is all the bottom box needs any more than that and you lose bottom end. I will keep posting the experiments as I go.

I currently have a 112db at 25hz and I am running off of the 120 15 amp outlet. The amp is clipping and I have to keep an eye on it not to over heat the speakers. Some sustained spikes in the 125+ db in the 30-35hz range. This really gets the house shaking nice. It is really deep bass that sometimes will have some subharmonics that hit hard and make things fall off of the shelf.

Title: Re: 18" scaling?
Post by Jeremy on 03/22/12 at 08:16:27

Hmm this is not turning out like I would like. I can not get any more output out of the box without the upper speaker vented open air. I had read about this in this forum but thought this could be alleviated with proper port size and tuning. In order to give the upper chamber a chance in needs to be closer to 10 cubic feet and and a 40" deep port that is 10"x12". It looks like it will be back to the drawing board. The design has promise and I can still spend a couple more days with it before I take the circular saw to it.....

Title: Re: 18" scaling?
Post by Jeremy on 03/23/12 at 04:05:42

Well.... I seem to have got something going with it. I kept my 8 cubic foot bottom, minus speaker and 22" of 4"abs ports. My upper 8 cubic feet minus  port volume of 24 3/4"wide x 4"high x 29"long. My center chamber is large enough but not critical. From 25hz to 85hz I am getting a 9db variation. With the gain turned up I am hitting 125-126 decibels all over that range and am right at the limits of my household wiring. I am popping the breaker box with extended run time. I can push 122db almost continuous. I am sure that with the wiring done and running my second amp I can push 130db at 45hz.

What is really nice about running center fire and 2 different ports is that you have different ranges that might conflict somewhat but begin to reinforce the harmonics of the building. In other words you get some huge rumble. My wife  could feel the bass in her chair watching tv in the next door neighbors house, not to mention they live 2 houses over and there windows where rattling to pieces.

I cant stress enough the need for a decibel meter. It is to easy to do something and not make an improvement and think that you did. I tested top and bottom speakers separately and combined using multiple variations of port size and number of ports. I really think that this is it and trying to get more output through dimensional changes would really sacrifice transition and balance.

Lining half the bottom chamber with foam got me 2db at 45hz and 3db at 50hz. The upper chamber it gained me 2-5 db. 2db from 30-60 and then went higher all the way up to 5db gain at 70hz. The upper box could have been bigger but I would have run into needing 3 sheets of 1"mdf for very little gain.

I have to go back in and radius some corners and glue the whole upper port together now that I know this design is a keeper. I need to finish beveling the edges of the center chamber which will stay open and mount my Lexan viewing port below the center chamber. Another days work ahead.

Title: Re: 18" scaling?
Post by Jeremy on 03/25/12 at 23:05:13

Well I am now running a dedicated line to my Crown xls 5000. I popped the new 20amp breaker today showing off to the local stereo shop owner. I guess a 25 amp is in order.

He was impressed enough to offer me work and has a couple of custom jobs for me starting on Monday.... :D

The gluing and beveling of all the port radiuses gained me 2-3db and I pegged my meter today at the 126+ db mark and did so hard. The shop owner commented on how he could feel the bass more than he could hear it until he got 40 feet away. Kinda strange, I think that maybe the sound waves could be so overwhelming close that the ear shuts down and at distance it becomes more audible because of separation of waves....?

I cannot use 2 crown amps because they will not each run 2.4ohm bridged, I tried and they shut down. I have to do some research and see if I can run 2 amps in parallel to double the wattage my speakers see. This in theory could allow me to run the amps at lower gain and increase my signal to noise ratio. However I assume this will lower the resistance the amps see and could cause me problems there. More research needed.

PS: Strike that last comment.... The crown amps will run 2.4ohm in bridged and do so running cool. I only ran them for half an hour at moderate levels but they did not get hot. With all settings staying at my baseline testing, the only change running bridged mono I gained as much as 8db. 3-5 db where it counts down low. The speakers showed no signs of over travel and now my 10 gauge wire running to them is getting warm so it is time for bigger wire. GOD be willing I should hook the 2nd amp up tomorrow and now I will need a a db meter that goes to 140+

Title: Re: 18" scaling?
Post by Jeremy on 03/27/12 at 04:29:30

Well 2nd Crown xls 5000 hardwired in and I am no longer popping breakers. I think I may have come to the end of conventional exploring. Any questions feel free to ask them.

I have not reached 140 db as far as I know. I have pegged my meter and I am clipping both amps on 30 amp breakers and 12/2 wiring running directly to the amps and only them. I have to go larger wire to the speakers or double up my existing.

The local audio guys have been driving past me trying to show off their bass. I guess when they drive by the house when I am 80 yards from the road and their mirrors rattle they get impressed(or they hear the bass over their own).

I do have to say that the bass level are dangerous. Please resist the urge to stick your head in the center chamber, I tried it and my left eye wanted to pop out of my head and felt like it was going to. This is not something I would want to explain to my wife. Also 125+ dbs of 35hz and below causes all sorts of strange energy in the body. I felt levels of euphoria mixed with panic and pain all mixed together. It definitely hurts the ears, I mean it causes pain and I have to plug them when doing long exposure tests.

In order to go louder and deeper the box will need to be bigger and enclose better speakers and 220 volt amps running 7000 watts will be needed. I would have had to pay at least a $1000 a speaker to get more wattage and power output. And then my amps would not be enough. My pockets are not that deep so I will let the next guy do it, unless I win the lottery, or they go on sale ::) For now my home 12,000 watt entertainment center is done :D

Title: Re: 18" scaling?
Post by Jeremy on 03/31/12 at 02:07:57

Well it seams that not all is finished here besides cosmetics. I replaced my speaker wire with 4gauge from the amps all the way to the speakers themselves. I gained an absolutely unbelievable 13db at 15hz for a total of 109. I have 118db at 30hz, this is not a one hit wonder, this is continuous 30hz.

This I must add is at my test volume of minus -50db. I decided to make this my constant or control volume. This level keeps the amps running cool and max efficiency.

Like when a thunder clap strikes and the windows rattle and you are like wow that is awesome, this just keeps going and you expect it to end but it doesnt. I have a test cd that sweeps and it gets so crazy. The plates are now rattling off of the shelf's and  paintings on the walls are going crazy. The box is peaking with a continuous 50hz. I may have to sell something and buy the xxx18". They have nearly 3 times the vmax and it should get me more low db's.

I will keep updating and eventually post a spread sheet of various changes and db's gained from each change.

Title: Re: 18" scaling?
Post by Donnie on 03/31/12 at 02:32:12

Jeremy, This is insane! You are my new hero. I say go for broke and build a second copy. If one is too much, two must be even better. I need a Housewrecker because I hate my neighbors, that would teach them to not build a house across the road from a madman.

Title: Re: 18" scaling?
Post by Jeremy on 03/31/12 at 04:39:27

Thanks, I unfortunately dont have the space or resources to have a second one. In reality it would gain me 4-6db and would cost a cool $2800. I cant justify it and times are to uncertain to spend the money.... But what I can do is have a boatload of fun with this one trying to extract every last db I can. Oh yeah and I am taxing the 200 amp main power lines from the pole to the house, I guess the power company could always upgrade it ;D

I had 2 people trespassing into my back yard a couple of days ago and I was bass testing. I think they thought a party was going on because I had the whole system cranked to Domino. Every word out of there mouth was f#%& I cant believe the bass. It was if they where following the Pied Piper.

I noticed around 2 hrs ago that it did not sound as good as it had been with my favorite track. The speakers have come to their limits and I had to turn it down. I lowered my crossover to accept only below 50hz and turned my low pass on at 25hz. It sounded good but is limited by the excursion and the amps and the speakers. Ugh.... I really do need better equipment,but... One of my closest friends reminded me that what I have is complete overkill for anyone and anything outside of a stadium and this I can rest easy with :-?

I will keep tuning :)

Title: Re: 18" scaling?
Post by gexter on 11/06/12 at 22:21:55

Just wondering how your HW played out for you and what you settled on after tweaks and mods.
I have built a couple of the Decware subs in the past.
Just curious how things turned out for you on this monster. Someone approached me to build a HT sub to fill a large room and I was going to go with a horn but this 18HW might fit the bill and use up less room.
I have always wanted to built a HW this big ;)

All the best,

Title: Re: 18" scaling?
Post by GarretLC on 03/29/15 at 02:43:06

I saw that you resized the house wrecker and used RE subs. I want to know if you would suggest going the same route and use 18 in subwoofers

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