New cabinet using this sub for live music? - Page 2 - AVS Forum
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post #31 of 55 Old 03-31-2014, 07:13 AM
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One MTL-4 stands up pretty strong against one Othorn, and it needs less power too. Ya, the Othorn digs lower and is the best bass cabinet I've ever heard, but the MTL sounds awesome for Reggae music (it's what the annual festival in Chicago uses) and Reggae is way more bass heavy than Spanish music. I think Spanish might be louder (good thing a higher F3 usually goes higher).

Everyone on this forum is so crazy obsessed with the F3 and ignores the more important frequencies. Lower frequency extension does not correlate to the perception of more impact/power. If I have s system digging below 40Hz, then I'm highpassing my kick drum so as to not lose the oomph....there's a magic spot in there and sometimes it only needs a low shelf cut. You trade off some weight but most music genres are negatively impacted by too much weight. Of course the bass freaks will disagree, but that's like saying the color of dark blue must reside in every painting before it can be considered a magnificent painting.

The PA should be seen as an instrument carefully tuned for the creation of art. Having cabs that dig super low requires more space and more amplifiers, which is a waste if the sound engineer is going to eq it out. That's really my only point here that I'm making way too briefly.
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post #32 of 55 Old 03-31-2014, 07:17 AM
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Originally Posted by MBentz View Post

... so crazy obsessed with the F3 ...
Agree...there is more to consider than f3
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post #33 of 55 Old 03-31-2014, 07:50 AM
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Originally Posted by MBentz View Post

Everyone on this forum is so crazy obsessed with the F3 and ignores the more important frequencies. Lower frequency extension does not correlate to the perception of more impact/power. If I have s system digging below 40Hz, then I'm highpassing my kick drum so as to not lose the oomph....there's a magic spot in there and sometimes it only needs a low shelf cut. You trade off some weight but most music genres are negatively impacted by too much weight. Of course the bass freaks will disagree, but that's like saying the color of dark blue must reside in every painting before it can be considered a magnificent painting.

Spot on.
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post #34 of 55 Old 03-31-2014, 02:32 PM - Thread Starter
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Ok so I know something is definitely wrong. I entered all the information the best that I know how and the result is a 1.86cf box? Something is wrong. Any thoughts? Here are some of the screenshots. Did I enter some of the parameters wrong or do I need to adjust the box specs manually? I adjusted the ports to resemble the marty cube ports but they are not necessary. Remember these are going to be used for live music.




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post #35 of 55 Old 03-31-2014, 02:59 PM
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Diameter 460 meters? Xmax 9.5 meters? Even Marty McFly didn't have a driver that size. rolleyes.gif

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post #36 of 55 Old 03-31-2014, 03:01 PM
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"Ok so I know something is definitely wrong. I entered all the information the best that I know how and the result is a 1.86cf box? Something is wrong. Any thoughts?"

that seems about right for those enclosure dimensions.

if you are going to mount an 18" driver, you need at least two dimensions to be about that large.

are you switching up internal dimensions with external dimensions?

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post #37 of 55 Old 03-31-2014, 03:04 PM
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you can change the units by clicking on them in winisd. that will scroll through the available options. as bfm notes, be careful to make sure that the units match the specs that you are using for the driver. 1134 for sd for example should be 1134 cm^2. xmax of 9.5 should be 9.5 mm. a lot of folks goof that up the first few times with winisd. well, at least i did. eek.gif
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post #38 of 55 Old 03-31-2014, 03:05 PM
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I'm guessing WinIsd does not have range error traps.
My antique manual Loudspeaker Design Cookbook doesn't agree biggrin.gif

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post #39 of 55 Old 03-31-2014, 03:16 PM
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The actual optimal net box size is 2.4 cu ft, giving a less than spectacular 72Hz f3. That's with a maximally flat response. A more logical alignment is an extended bass shelf, 5.6 cu ft with 36Hz tuning, for a 40Hz f3. It's not so flat, but at least it's useful.

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post #40 of 55 Old 03-31-2014, 03:20 PM - Thread Starter
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Thank you all for coming to the rescue, I am really trying to figure this out. Its a personal challenge for me. When I make something I like knowing why, how, etc. But with that said I do know my limitations and I know all of you have lives and are busy, so I really appreciate all the help. I made some changes and here is the new info. As far as the box dimensions, I see they change depending on the Volume that I enter, so does the vents. Am I to assume that I can change the shape of the box to make it more square or fit a certain parameter as long as the volume stays the same and the vent ports do as well? I tried to change the box dimensions on there and it doesn't do anything. Also the tunning frequency is that one of those things that is user preference? For example the marty cube, its tuned to 20hz, so I would enter 20hz there and it would tell me the port sizes I would need with that volume? My worry that I will choose the wrong combination of volume and tunning hz? Is that possible, could I choose say 8cf volume box and tune it to 40hz and it wont work out?



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post #41 of 55 Old 03-31-2014, 03:41 PM - Thread Starter
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Ok, new challange. He wants a dual 18" cabinet like the one on this picture. Would it be best to build on the inside 2 separate cabinets with their own ports or build one just like this one where they share the port? Is there an advantage of one over the other beside what I assume would be less material to build the shared volume cabinet.

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post #42 of 55 Old 03-31-2014, 03:50 PM
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"Would it be best to build on the inside 2 separate cabinets with their own ports or build one just like this one where they share the port?"

it will pretty much perform the same both ways.

if dividing the port into two, just make each port the same width, but half as tall. keep the same length for both.

personally, i think the slot port in between the drivers looks cool, so i'd go with that.

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post #43 of 55 Old 03-31-2014, 03:53 PM
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If you don't mind my asking: Why a dual instead of 2 separates?

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post #44 of 55 Old 03-31-2014, 04:02 PM
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With the port area you have the vent velocity is off the chart. With even 800w input you need no less than 60 sq in.

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post #45 of 55 Old 03-31-2014, 04:03 PM - Thread Starter
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Originally Posted by LTD02 View Post

"Would it be best to build on the inside 2 separate cabinets with their own ports or build one just like this one where they share the port?"

it will pretty much perform the same both ways.

if dividing the port into two, just make each port the same width, but half as tall. keep the same length for both.

personally, i think the slot port in between the drivers looks cool, so i'd go with that.

So in order to figure out the box volume would I double the volume, to say 12cft? As far as the vents, it was saying something like 4"x4"X19 or so but if I do vents that run across the front of the box, again like the marty they would be 2 vents at about 13"x4" X10", does that work? More pics.


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post #46 of 55 Old 03-31-2014, 04:04 PM - Thread Starter
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If you don't mind my asking: Why a dual instead of 2 separates?

Me? The guy has 5 of these subs and wants to make 2 dual cabinets and 1 single? I asked him the same thing and he said it looks better on the stage.
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post #47 of 55 Old 03-31-2014, 04:58 PM
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he said it looks better on the stage.
Ummm ok

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post #48 of 55 Old 03-31-2014, 05:03 PM
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New version of Powered Sub - Half Track... Gas, Diesel, Propane, or Hydrogen Powered.
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post #49 of 55 Old 03-31-2014, 05:10 PM - Thread Starter
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Ummm ok

I know I just finished explaining to him that maybe individual cubes might be better even if you stack them so that its easier to carry around. I think I talked him into making 1 cube to see if it sounds good and works then we can go from there. I think he sees the big bands having the dual subs and he wants to be like them.smile.gif
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post #50 of 55 Old 03-31-2014, 07:46 PM
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Quote:
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Ummm ok

I know I just finished explaining to him that maybe individual cubes might be better even if you stack them so that its easier to carry around. I think I talked him into making 1 cube to see if it sounds good and works then we can go from there. I think he sees the big bands having the dual subs and he wants to be like them.smile.gif

What about making a slightly larger cube say , 24 by 24 by 32 high. Then put it on caster's so you can wheel it around. Will have a little longer port and be about 7 cuft. Pair of those should rumble his shows.
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post #51 of 55 Old 03-31-2014, 08:12 PM
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I know I just finished explaining to him that maybe individual cubes might be better even if you stack them so that its easier to carry around. I think I talked him into making 1 cube to see if it sounds good and works then we can go from there. I think he sees the big bands having the dual subs and he wants to be like them.smile.gif
The stage look shouldn't even be a major consideration - but musicians often focus on the wrong things. ( Often noted on contract riders )
Having modules opens up placement and implementation options.

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post #52 of 55 Old 03-31-2014, 08:59 PM
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Originally Posted by cessna1466u View Post

I asked him the same thing and he said it looks better on the stage.
He needs to learn how to place subs, and it's not on the stage. Most do place them there, split left and right under the mains, but it's just as bad to do so in live sound as it is in home theater. Perhaps worse, as home theater seldom has power alley concerns.

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post #53 of 55 Old 04-01-2014, 08:15 AM
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So almost 9cubic feet per cabinet. That is a little bigger than the marty cubes I have. Not too bad, just have to find the right box style and port size. Again thank you for all the help. I now have something I can go to him with. I know he thinks he needs a folded horn design or the tuba design to be able to get louder sound from these but maybe some cubes with the right ports might work out better for him as far as storage and carrying them around.

The "right" box will have dimensions that are based on "truck pack dimensions". This is a standard.

Typically, trying to hit as many dimension in multiples of 90" is a good thing. The most common are 22.5", 45", and 33", also referred to as 1/4, 1/2, and 1/3 "truck pack".

Port size can be calculated easily, most of the software programs will do this. The port area is based on an acceptable level of air velocity, typically 2-3% of the speed of sound. For pro audio designs, I've always gone at least 20% larger in area, which of course increases length too. Port noise in a home design at a few watts is one thing, pro audio designs spend a lot more time riding the ragged edge of disaster at their power limits typically, and larger ports make for less port noise.

Also, Baltic Birch plywood is the standard for good pro audio loudspeaker builds. 18mm would be my first choice, but 15mm could be used if you design nice internal bracing to keep the cabinet walls stiff. Bracing also is very important for overall cabinet strength, important when they're being moved and set up/down for a living. A pretty lightweight design could be had in 15mm with these neo woofers. For larger cabinets like these, good square cuts with straight edges are essential. I'd really recommend having a shop(wood supplier or otherwise) with a panel saw at least make the first or second cuts on the plywood stock first if you don't have a good table saw. Dado the top and bottom pieces to take the sides and baffles, as well as the first couple of major braces. It adds strength, but more importantly, makes it easier to assemble. Use pnuematic staples or finishing nails to pin pieces together as you glue up the cabinet(every 4-5"), and if needed, the occasional screw.

My preferred finish is Line-X. Period. The DIY Duratex/Polane types are okay, but Line-X outshines them all in toughness.

These will want a dolly to roll them around, or casters attached on a cut corner(See JTR Orbit Shifter Pro for an example), and handles-nice big recessed handles. Dual Neutrik Speakon panel mount connectors are the usual standard input, mounted on a nice recessed plate for protection.

Nice handle: http://www.parts-express.com/steel-bar-speaker-cabinet-handle--262-821

Nice input plate/dish: http://www.parts-express.com/penn-elcom-d028k-dish-two-ep-nl4mr-black-5-x-7--262-335

The best caster and standard for pro audio gear dollies: http://www.greatlakescaster.com/colson_caster_corporation___swivel_caster___4_x_2_polyurethane_on_plastic_swivel_caster-4.04109.929.php

The 3.5" version with 1.25" wide wheel is acceptable too, but the larger diameters roll over cracks and stuff better.

Tee-nuts for driver mounting, either 10-32 or 1/4-20, depending on the speaker basket holes.

Foam tape to seal the driver against the baffle.

Good old 12 gauge hook up wire for connections, and use the .187" quick connects on the Speakons. UL type 1015 stranded hook up wire, get different colors for + and -, and if using multi conductor Speakons(4 or 8 pin versions), don't repeat colors.

On the cabinet design, set back the front baffle an 1" to 2". You will want some kind of metal grill, either the round "waffle" style over each driver, or a full metal grill cut to size. On a large cabinet like these, a full grill will need to have a seat on all four sides. Good source for cut to size perforated metal grills already finished in black powdercoat:

http://www.reliablehardware.com/customspeakergrill-14diastaggered.aspx

Best regards,

John
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post #54 of 55 Old 04-01-2014, 08:19 AM
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Originally Posted by WVSyd View Post

The stage look shouldn't even be a major consideration - but musicians often focus on the wrong things. ( Often noted on contract riders )
Having modules opens up placement and implementation options.

Oh no, "looks" can be a very important consideration. I've had customers I built designs for who actually asked for a larger finished product because it is perceived as louder and better.

Same goes with line arrays. Doesn't matter if there are smaller, more economical, and better solutions, some clients want the "look".

Best regards,

John
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post #55 of 55 Old 04-01-2014, 09:15 AM
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I've had customers
Yeah so have I rolleyes.gif
Contract riders are full of demands.

Thought I qualified sufficiently in post #51: smile.gif
Sometimes what a client wants/demands has little bearing on actual needs.*
That can include optimum speaker placements.

Prosound includes stage presentation of fake speakers to create an awesome look with no bearing on sound.

Philosophically ( to me anyway )...How a speaker system looks is as important as how a lighting system sounds biggrin.gif
But the client pays so...the piper plays their tune.

* Bob McCarthy's Book: "Sound System design and Optimization" contains segments called "Perspectives".
These anecdotes illustrate numerous occasions in which the paying client was "misguided"
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