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PostPosted: Thu May 18, 2017 6:48 pm 
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Howdy all!!

I'm new to the BFM world of speaker cabinet building and I'm excited to making the magic happen over the next few days. I've been searching and reading all of your posts and it appears this is a very solid community. So far I've been able to find the appropriate wood here in Atlanta (that was probably the hardest part) in either 5x5 or 4x8 sheets, and purchased the largest Vs 15" driver I could find as is recommended in the plans. I only have a few questions if you all would be so kind to help me out:
1.) Should I go with the 24" or bring it up to 30" as one poster did for max bottom end?
2.) Are the reduces really needed and is there a more optimal position other than just mounting them up against the speaker collar?
3.) I've also build a couple of the Tuba 18s and I had a bit of trouble cutting the braces to fit exactly. Do you all have any suggestions for making the best cuts for braces accurately?

Thanks for your tips and lessons learned in advance.


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PostPosted: Thu May 18, 2017 9:52 pm 
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Welcome! 8)

1. 24" is already plenty wide, but if you insist on as wide as possible and still road worthy, then I'd stick with 27" max. 30"-36" is flippin' huge.

3. Dry fit the entire cab first with srcews, along the way carefully pencil mark where you plan to install all the braces on both the side panel and then squarely up the mouth panels. Disassemble, then use the marks to size all the bracing. Dry fit and screw each brace exactly to where you marked when everything was in place. Disassemble those pieces. Then start your glue up from there.

In essence it's the process of building the cab twice, once without glue then again with, but it'll be an exact fit every time with no dimension left to chance.

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PostPosted: Thu May 18, 2017 10:14 pm 
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Location: Warren, MI
MrCyr wrote:
Howdy all!!

I'm new to the BFM world of speaker cabinet building and I'm excited to making the magic happen over the next few days. I've been searching and reading all of your posts and it appears this is a very solid community. So far I've been able to find the appropriate wood here in Atlanta (that was probably the hardest part) in either 5x5 or 4x8 sheets, and purchased the largest Vs 15" driver I could find as is recommended in the plans. I only have a few questions if you all would be so kind to help me out:
1.) Should I go with the 24" or bring it up to 30" as one poster did for max bottom end?
2.) Are the reduces really needed and is there a more optimal position other than just mounting them up against the speaker collar?
3.) I've also build a couple of the Tuba 18s and I had a bit of trouble cutting the braces to fit exactly. Do you all have any suggestions for making the best cuts for braces accurately?

Thanks for your tips and lessons learned in advance.


.5.) Welcome to the forum, and to the addiction/G.A.S./Holy crap, what have I done? place! :twisted: :lol:

1.) This is completely dependent on you. Do you have the ability to transport, store and use a wide cab? Wide gets you more SPL, not more extension.

2.) When using the Lab12 or 15 driver, yes, absolutely. If there were a more "optimal" position, Bill would have put it in his plans. You do understand that he designed them around a different driver, and the reduced driver chamber was added to facilitate the use of the Lab drivers because of a huge price spike of the design driver, the Eminence KappaLite 3015LF.

3.) You should be following your plan instructions, which should tell you, to para-phrase, to cut the braces as you are building, so that you can cut them to fit. Cutting them before or after building the rest of the cab is asking for mis-fitting panels.

Why did you decide on using Lab 15s? Do you have some preconceived notion that the Lab driver is a better driver? The 3015LF is the driver the T48 was designed from and around. The Definimax 4015 is the "premium" driver.

_________________
I know money often seals the deal, but seriously, quality is an investment, not an expense... Grant Bunter
Accept the fact that airtight and well-braced are more important than pretty on the inside. Bill Fitzmaurice


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PostPosted: Fri May 19, 2017 4:46 am 
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Posts: 10
I seem to remember that Bill stated in the directions that we should go for the highest Vd driver we can find.

"Maximum output isn’t about watts, it’s about driver displacement (T/S spec Vd). The Kappa 15LF has 471cc Vd, the Kappa Pro 15LF 507cc, so the Pro is only slightly louder. The Lab 15 Vd is 968cc, so it’s equivalent to two Kappa 15LF, justifying its weight and price if you’ve got more money than pack space. When comparing various drivers don’t look at the watts, look at the displacement." In my original post I typed Vs and not Vd....ooops....damn phone.

So that's what I did. Size really doesn't matter as this one and all subsequent builds will be going in a couple clubs spaces. This one will be going in a smaller space of about 100 people. The other builds will be going in larger space with a capacity of 300.


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PostPosted: Fri May 19, 2017 4:56 am 
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Joined: Mon Nov 28, 2011 11:12 am
Posts: 5599
Location: Ilfracombe Queensland Australia
MrCyr wrote:
... and purchased the largest Vs 15" driver I could find as is recommended in the plans. I only have a few questions if you all would be so kind to help me out:
1.) Should I go with the 24" or bring it up to 30" as one poster did for max bottom end?
2.) Are the reduces really needed and is there a more optimal position other than just mounting them up against the speaker collar?
3.) I've also build a couple of the Tuba 18s and I had a bit of trouble cutting the braces to fit exactly. Do you all have any suggestions for making the best cuts for braces accurately?

Thanks for your tips and lessons learned in advance.


Indeed, welcome to the forum!

1. As DJP has said, it comes back to pack space. Answer your own question by doing a cardboard mockup of the various sized cabs to see what fits in what you plan to carry your gear in.
Sure the wider the better. There are also some cab sizes which maximise ply sheets, and 24" (actually 23 15/16" IIRC) is one.
2. Yes, they are required, and stick with the plans about location.
3. Radian has covered that perfectly.

About the lab 15. Yep, it has higher Vd, but if you go to the "protecting your driver" section of the plans, you will notice that both the lab15 and the 3015lf have identical voltage displacement limits.
So the extra VD is meaningless. Vd is useful when comparing to smaller cheaper drivers.
The lab 15 is quite a bit more expensive than the 3015lf, and weighs a lot more.
It's not to late to send it back, and buy a pair of 3015lf's for 2 cabs lol

Oh, you absolutely positively need a brick wall limiter to run these subs and protect the driver.
I'm sure it mentions the driverack series, or the Berry DCX2496, in the plans. Either will work. So will a DSP capable amplifier...

_________________
Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


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PostPosted: Fri May 19, 2017 5:37 am 
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I don't think we'll be over driving this particular Lab15 as it's only going to have a max of 650watts running to it from a little Crown 1005 setup in mono with the LPF set to 100hz. The space this is going in is only about 100' long and 45' wide so it should fill the room nicely. Currently there are just a couple EVs flying for sound in that space and the low end is pretty much non existent when it gets crowded (100 people). So portability isn't a concern, but hitting the low frequencies is a must hence why I'm looking for a low Fs and high Vd. The more air you move the lower you can go....generally.


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PostPosted: Fri May 19, 2017 6:45 am 
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MrCyr wrote:
I don't think we'll be over driving this particular Lab15 as it's only going to have a max of 650watts running to it from a little Crown 1005
:cop:
Amps are rated at a low THD. You can easily get twice the rated power in bursts at high THD. Limiting isn't optional, it's mandatory. The same applies to high pass filtering.


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PostPosted: Fri May 19, 2017 7:53 am 
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Location: Colonial Beach VA
If hitting the low frequencies is a must, maybe you should be building Tubas instead of Titans.

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PostPosted: Fri May 19, 2017 10:16 am 
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Ok we will limit it at 60v. Ya'll know better than me.


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PostPosted: Fri May 19, 2017 3:09 pm 
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Location: Warren, MI
MrCyr wrote:
The space this is going in is only about 100' long and 45' wide so it should fill the room nicely.


Then you need to be making at least 2 T48s. Horns work best in herds of 2 or more. Want to maximize output? Build 2, 36" wide T48 and load them with the 3015LF. By using a driver that is half as much $$$, you get twice as much sound. Study the placement sticky and follow it as much as you can.


MrCyr wrote:
I don't think we'll be over driving this particular Lab15 as it's only going to have a max of 650watts running to it from a little Crown 1005 setup in mono with the LPF set to 100hz. The space this is going in is only about 100' long and 45' wide so it should fill the room nicely. Currently there are just a couple EVs flying for sound in that space and the low end is pretty much non existent when it gets crowded (100 people). So portability isn't a concern, but hitting the low frequencies is a must hence why I'm looking for a low Fs and high Vd. The more air you move the lower you can go....generally.


This whole quote tells me that you are very inexperienced in running a sound system of any magnitude, meaning more than 2 trapezoid cabs on sticks. We all started there. Read this entire forum. We will not bullshit you, or pass along false information. We WANT your build, and you, to succeed. There is so much experience on this forum, willing to teach you the scientifically proven ways to maximize your results. All you have to do is listen, and follow the advice. It is a leap of faith, but in the end, it is an education that you can use until the day you die. But, we can only lead you to the well, it's up to you to drink.

Since this is for an install, tell us what you are trying to achieve. Be as specific as possible. A 100' x 45' venue will hold a LOT more than 100. Are you doing dance parties? What kind of music are you playing? Top 40/Pop, EDM, Hip-Hop/Rap, Modern Rock, Classic Rock, New Country, older Country,etc...

Do you understand that EQ, an electronic crossover and a hard-knee limiter are MANDATORY for any PA. The one good thing in your favor is that once the PA is set for the room, unless something in the room changes, you won't have to change it.

_________________
I know money often seals the deal, but seriously, quality is an investment, not an expense... Grant Bunter
Accept the fact that airtight and well-braced are more important than pretty on the inside. Bill Fitzmaurice


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PostPosted: Mon May 22, 2017 2:45 pm 
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Posts: 10
Sorry for not getting back sooner as I've been busy with the build. Dry fit is all done and the glue and screw fun has started.

I don't claim to be an expert on sound configuration...never have so I apologize for my ignorance. That's why with have a sound engineer for the two spaces.

Space Size:
I took a my tape measure in there it's actually 78'x35' (my guess wasn't far off). The max capacity of the room is 100 people and that is nut to butt. 75 is a crowded night and on average 50-60 is the typical Friday/Saturday nights with a high churn rate. 15'x 45' of that space is bar space with the bar extending another 10' into the room at one end. So not much room left for dancing there, but people get down. Spaces is very limited for addition speakers. It's a whiskey bar that tends to get a little crazy from time to time. Here is the space https://www.facebook.com/edgewoodspeakeasy. So as you can see there isn't a great deal of room for Tubas and multiple 48s. The DJ both has been modified from the picture seen and has been lifted about 4' up off the floor to prevent drunk people from spilling drinks on stuff.

Music:
Live Performances, Top 40, House Music, Reggae, Spoken Word, Hip Hop...even country and jazz from time to time.

Equipment
There is a dbx drive rack and a 16 channel EQ in there managing two 300 watt Behringers (located behind the bar) currently running a dual ported 12" sub that is very small and built into the small dj booth on the bottom of the floor (not pictured). The other Behringer is running the two JBLs (horn, and 12") suspended from the ceiling 14' high firing at 30 degrees or so (best guess) down at opposite ends of the room. The reason for the drive rack and the amps behind the bar is because two many different DJs were messing with it and popped some speakers.

Thanks for any tips or hints in advance.


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PostPosted: Wed Jun 07, 2017 4:30 pm 
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Posts: 10
Got some db numbers from the room. Various speaker placement was used just to test db from 35' away (the other end of the bar). The 18" had a grill rattle really bad at 90-110 Hz that I think was throwing off. When shooting across the floor the undulations in the old wood floor did weird things to bass with dead spots and concentration spots of base all over the floor...was so interesting. Anyway here are the Db numbers

Drive Rack 100Hz roll off

Test Old 18" Titan 48 Titan 48 Titan 48
Freq Mackie Floor Raise 20" Corner Loaded
30 69 64 70 78
40 83 92 90 96
50 85 84 90 97
60 94 85 100 96
70 95 97 98 106
80 99 96 102 108
90 102 103 104 108
100 102 99 106 100
110 96 95.5 97 98
120 92 99 94 85

On the build I should have thought about corner loading and placed the speakon connector in a different spot. This was just a prototype to see if these designs work. From what I can see they work pretty well with just one Titan 48 replacing an old Mackie 18. I'm sure I'll get flamed for something.


Last edited by MrCyr on Thu Jun 08, 2017 8:20 am, edited 1 time in total.

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PostPosted: Wed Jun 07, 2017 4:31 pm 
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Joined: Mon May 15, 2017 3:32 pm
Posts: 10
Well that didn't post well.


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PostPosted: Wed Jun 07, 2017 4:38 pm 
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Joined: Mon Jan 21, 2013 9:30 pm
Posts: 223
Location: San Rafael, CA
MrCyr wrote:
Well that didn't post well.

You can get fixed character widths by using the "code" tag:
Code:
Test   Old 18"Titan 48   Titan 48   Titan 48
Freq Mackie Floor Raise 20" Corner Loaded
30   69    64   70   78
40   83   92   90   96
50   85    84   90   97
60   94   85   100   96
70   95   97   98   106
80   99   96   102   108
90   102   103   104   108
100   102   99   106   100
110   96   95.5   97   98
120   92   99   94   85


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Built:
1 Omni-15 Tall Boy
2 DR250s
2 Titan 39s


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PostPosted: Thu Jun 08, 2017 5:10 am 
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Joined: Mon Nov 28, 2011 11:12 am
Posts: 5599
Location: Ilfracombe Queensland Australia
MrCyr wrote:
Got some dp numbers from the room. Various speaker placement was used just to test db from 35' away (the other end of the bar). The 18" had a grill rattle really bad at 90-110 Hz that I think was throwing off. When shooting across the floor the undulations in the old wood floor did weird things to bass with dead spots and concentration spots of base all over the floor...was so interesting. Anyway here are the Db numbers

Drive Rack 100Hz roll off

Test Old 18" Titan 48 Titan 48 Titan 48
Freq Mackie Floor Raise 20" Corner Loaded
30 69 64 70 78
40 83 92 90 96
50 85 84 90 97
60 94 85 100 96
70 95 97 98 106
80 99 96 102 108
90 102 103 104 108
100 102 99 106 100
110 96 95.5 97 98
120 92 99 94 85

On the build I should have thought about corner loading and placed the speakon connector in a different spot. This was just a prototype to see if these designs work. From what I can see they work pretty well with just one Titan 48 replacing an old Mackie 18. I'm sure I'll get flamed for something.


Numbers work out fine when you quote your post lol. It only seems to frop into the onscreen format after posting.
Nah we're not into flaming. What we are into is trying to help to get the best possible result you can out of your build.

What would really help to determine what your measurements mean would be some more info.
To get these results, is the limiter lighting up on the Driverack?In other words, are you pushing the T48 to 50V?
How far away from the corner was the T48? Was the mouth to the corner?
Did you leak test the T48 to complete your build?
What slope is set at 100Hz? eg LR24? That's the Low pass, but what is the high pass set at? And what is it's slope?
When the T48 is 20" above the floor, how far is the mouth away from the nearest wall?

In order to calculate if your T48 is performing as well as it can:
If you do more measurements, do them at 24 feet.
Each doubling of distance from 1 yard gives a loss of 6dB in sub output.
1,2,4,8, so, if your T48 is running as it should, at 8 yards your output is -18dB compared to 1 yard.
This also helps you calculate maximum SPL.

There is some anomolies in your results, hence the questions.

And, bass below 100Hz is omni directional. So a wavy floor should make no difference. What you're hearing probably is room nodes and modes in play...

_________________
Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


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