Simple cab design 1x12... your comments please

[LowGrowl]

Hi there!
I've been doing some homework about DIY cabs for a while. Now that I got a pair of drivers in. It's time to start my first build.

The goal: small powerfull 1x12 and 1x12+6 to move arround easily and combine acording to gig or rehearsal sizes. I play in a rock pop band, so the voicing (as subjective as it could be) should be warm and punchy (or something in between)

So, for the simpler single 12" that I will start with:

Driver: Eminence Deltalite II 2512
Fs = 37 Hz Qms = 3.13 Vas = 147 liters Cms = 0.38 mm/N Mms = 48.69 g Rms = 3.617 kg/s Xmax = 4.9 mm Xmech = 8.5 mm Sd = 519.5 sq.cm P-Vd = 255 cu.cm Qes = 0.44 Re = 5.04 ohms Le = 0.46 mH Z = 8 Ohms BL = 11.3 Tm Pe = 250 watts Qts = 0.386 no = 1.632 % 1-W SPL = 99.9 dB 2.83-V SPL = 96.28 dB

The Box will be front ported with values somewhat close to the ones eminence recomends for a bass cab with this driver

Size H16" W19" D13"
Vb = 1.446 cu.ft Fb = 47.32 Hz QL = 5.859 F3 = 64.42 Hz

Some of the graphs from BassBox Pro:

I did my best to interpret the graphs according to the software help and some other readings and they look fine for my purposes. Of course I'm open to anykind of feedback and suggestions.

Let's get to the specific questions:
Baltic Birch 3/4" ply seems to be the material of choice but is impossible to get in Mexico City. All MDF is out of the question because of weight. All I can get easilly here is pine plywood.
So, what do you guys think? Maybe MDF baffle with pine box?
All pine ply with a lot of internal bracing? what kinds of wood would be better for braces?

Is it worth to make that exercise out of pine plywood anyway?

Any help would be much appreciated.

Ray.

 

[dhsierra1]

did a build like this last year but w/a slightly bigger box and w/o the midrange, this should be fine.

Pine 3/4" is OK, just brace it and be prepared for some weight, alas, but not as bad as MDF.

For bracing, just cut strips from your left over plywood sheet about 1-1/2" (that'd be around 40 mm) wide and you're good to go.

Don't brace at the edges and corners, but every, say, 6 or so inches 150 mm) on the panels. If you can run braces across the sides connecting them as well as the top/bottom that'd be really good.

Take a look at the fEARFUL website/wiki for bracing ideas.

Also check the stickies in the AMPS section for the DIY builds, lots of food for thought, bon apetit

 

[wcriley]

A box that size could be built out of 1/2" ply if properly braced.

I built a fEARful 12/6 out of generic pine ply a couple years ago. Doesn't seem to have any problems, though I did discard a few pieces after I'd cut them because I found voids.

 

[DukeLeJeune]

Your basic design looks good to me. And, that's a real nice woofer.

As long as you get good glue joints and don't have voids in bad places (like where the driver mouinting screws go), you should be in good shape with pine plywood. For minimizing weight, maybe use 1/2" plywood, and then double-thick the front baffle (which really won't be all that much heavier because the cut-outs will reduce its weight).

 

[LowGrowl]

Thank you all for your advice! I'm sure i'll get back with a lot of questions later
ray

 

[b-b-b-bass]

Q.? Is a bass response that is -3db@65Hz, and -10dB@45Hz, desirable?
I mean, ? is it a good curve for bass guitar? What will that sound like?

 

[will33]

+1 on using 1/2" (12mm) birch. The 3/4" ( 18-19mm) is overkill and not needed with half-decent bracing and quality wood. I use a pair of DeltaliteII2512's and a 6 in my regular gigging rig and like it quite a lot, especially when using a mid to carry above 1khz or so. Your charts look good provided you play 4 string and don't use a lot of bass boost. I'd be inclined to go a bit lower tuning (excursion protection) when using a lot of power or increased bass frequencies. I might be playing it a little on the safe side there but I haven't had the drivers crap out even when running things turned way up playing outside.

Obligatory pic for reference. Mine are in about 2.27 cu.ft. tuned about 45hz. Like I say, maybe more than I need for 4 string but so far, really nice sound and no issues. I could re-do these a little more compact, little closer to yours and still get what I need, just "overdoing" it a bit, as I usually do.

The whole stack isn't much taller than a bass and is super easy to move around. Again, could shrink it a little bit and really not lose anything of substance.

 

[Joe Louvar]

Way fun - as you build your 112 and 12/6 cabinets please post pics here. Thanks.

 

[will33]

Q.? Is a bass response that is -3db@65Hz, and -10dB@45Hz, desirable?
I mean, ? is it a good curve for bass guitar? What will that sound like?

Those numbers are good for a 4 string unless you want really deep lows, which usually inferfere with kickdrums and PA's anyway. What most of us hear as 40hz is really 80hz anyway. Even pro level live concerts with big subs have little if any content below 40-50hz. The place you might get into trouble with that high of tuning is using a low B string, with a dose of bass boost, going for super deep sounds. Usually when people do that going for ultra deep, what they really want to hear is the 1st harmonic, an octave above that. Here is a thread/graphs, etc. that shows what's really up with our bass strings/sound.

http://www.talkbass.com/forum/f15/bass-frequency-waterfall-plots-what-they-mean-rigs-510749/

As you can see, you do need to think about unloading below the tuning frequency, but it's not as bad as people think. Although, I do like that extra depth available down there, even if I don't use it all the time. Your bass knob has a great effect over what's going on down there. Remember a 3db boost is the equivelent of doubling power with no eq boost. I just like the "margin of error" and the deep sound, even if I don't use it all that much.

 

[rpsands]

If you're going to cross over to a mid and use two cabs I'd think hard about the S2012.

 

[BogeyBass]

I think the price range and power handling is roughly the same for both speakers. Between the DeltaliteII and the S2012

The cost for the S2012 should be lower its a smaller magnet and a stamp steel frame compared to the larger magnet and cast frame of the Deltalite. but after the whole neo thing it seems they are priced the same.

The thermal rating is much better for the Deltalite, Im only guessing because it has a better vented voicecoil and the nice aluminum cooling fins.
The Qms and max excursion for the S2012 is higher. I have never heard the speaker but might assume at max power it might be a little smoother than the deltalite for fullrange bass guitar. Both speakers perform similar but I think Eminence states the intended use well. The S2012 is more Mechanically suited for Bass Guitar and they Deltalite is more Thermally suited for Live sound PA use.

Blah blah blah... the point
I think it sounds like you already bought a pair of the Deltalites.
And I think in a loud Rock band your going to end up using the pair. So instead of trying to drink more power handling out of the system by making such small boxes. I would go for more Bass response by making larger boxes.
And shaving away power handling wont be so much of a big deal
because as a pair your should be just fine.

Also your dimensions of H16" W19" D13" seems ok for the goal of the design volume.
But in reality if your going to set back the front baffle for a grill
the box is simply not deep enough.
And the 19" width is not super friendly for the correct sized port volume needed.
I dont know what size head you use. But even if I was using a small micro head. I would still want one of the dimensions to match a standard rack with a case. So it should be closer to 21". For a 19" rack which is closer to 20 to 21" with extra 1/2" to 3/4" on both sides with a case.
and with a wider cabinet the height needs to be much taller too. So it does not look goofy by itself. And when 2 are stacked it will be closer to the Golden Ratio. Or 1.618 ratio which is a well known ratio to be aesthetically pleasing.

So I dont know if your going to use Eminence's 4" recommended
round ports or a Slot or Shelf type port.
Either way the 21" width will make it easier to place the ports closely and symmetrical to the driver.
And if you do use a Shelf port. I would use 2 of them. Not a Single. This allows the ports to still be symmetrical and close to the driver.
I prefer round ports, but one of the better Single 12" cab designs I have seen with shelf ports. Is the [Invalid or Expired Link Removed].
Very close to how I would do it. In fact you could pretty much copy the design and get a very nice cabinet.
Its wider and deeper like I recommended and keeps the ports close to the driver.
So 21W x 18H x 16.5D is close to 3.5 cubic feet
Minus the driver and 2 port volumes and Baffle setback. The actual volume should be close to 2.9/2.7 which is Eminence large recommended volume.
Losing some power handling, but gains more bass response
and makes the box much deeper for winning the war against
standing waves created by large low frequency sound waves.
Even if you still stay with a smaller volume I would still make it deeper than 13" for that reason.

 

[LowGrowl]

+1 on using 1/2" (12mm) ....

Obligatory pic for reference. Mine are in about 2.27 cu.ft. tuned about 45hz. Like I say, maybe more than I need for 4 string but so far, really nice sound and no issues. I could re-do these a little more compact, little closer to yours and still get what I need, just "overdoing" it a bit, as I usually do.

Right! will33 that is exactly what I have in mind. Thanks for sharing!

 

[LowGrowl]

Your basic design looks good to me. And, that's a real nice woofer.

As long as you get good glue joints and don't have voids in bad places (like where the driver mouinting screws go), you should be in good shape with pine plywood. For minimizing weight, maybe use 1/2" plywood, and then double-thick the front baffle (which really won't be all that much heavier because the cut-outs will reduce its weight).

Words of an expert... Thankyou very much! I'll go with the 1/2"

I think the price range and power handling is roughly the same for both speakers. Between the DeltaliteII and the S2012

The cost for the S2012 should be lower its a smaller magnet and a stamp steel frame compared to the larger magnet and cast frame of the Deltalite. but after the whole neo thing it seems they are priced the same.

The thermal rating is much better for the Deltalite, Im only guessing because it has a better vented voicecoil and the nice aluminum cooling fins.
The Qms and max excursion for the S2012 is higher. I have never heard the speaker but might assume at max power it might be a little smoother than the deltalite for fullrange bass guitar. Both speakers perform similar but I think Eminence states the intended use well. The S2012 is more Mechanically suited for Bass Guitar and they Deltalite is more Thermally suited for Live sound PA use.

Blah blah blah... the point
I think it sounds like you already bought a pair of the Deltalites.
And I think in a loud Rock band your going to end up using the pair. So instead of trying to drink more power handling out of the system by making such small boxes. I would go for more Bass response by making larger boxes.
And shaving away power handling wont be so much of a big deal
because as a pair your should be just fine.

Also your dimensions of H16" W19" D13" seems ok for the goal of the design volume.
But in reality if your going to set back the front baffle for a grill
the box is simply not deep enough.
And the 19" width is not super friendly for the correct sized port volume needed.
I dont know what size head you use. But even if I was using a small micro head. I would still want one of the dimensions to match a standard rack with a case. So it should be closer to 21". For a 19" rack which is closer to 20 to 21" with extra 1/2" to 3/4" on both sides with a case.
and with a wider cabinet the height needs to be much taller too. So it does not look goofy by itself. And when 2 are stacked it will be closer to the Golden Ratio. Or 1.618 ratio which is a well known ratio to be aesthetically pleasing.

So I dont know if your going to use Eminence's 4" recommended
round ports or a Slot or Shelf type port.
Either way the 21" width will make it easier to place the ports closely and symmetrical to the driver.
And if you do use a Shelf port. I would use 2 of them. Not a Single. This allows the ports to still be symmetrical and close to the driver.
I prefer round ports, but one of the better Single 12" cab designs I have seen with shelf ports. Is the [Invalid or Expired Link Removed].
Very close to how I would do it. In fact you could pretty much copy the design and get a very nice cabinet.
Its wider and deeper like I recommended and keeps the ports close to the driver.
So 21W x 18H x 16.5D is close to 3.5 cubic feet
Minus the driver and 2 port volumes and Baffle setback. The actual volume should be close to 2.9/2.7 which is Eminence large recommended volume.
Losing some power handling, but gains more bass response
and makes the box much deeper for winning the war against
standing waves created by large low frequency sound waves.
Even if you still stay with a smaller volume I would still make it deeper than 13" for that reason.

WOW! a lot of things to think about. I'll run some variations with the dimensions and the ports.
I'll take your point of matching the width with a standard 19" rack (to 20-21) and make it 2 or 3 inches deeper to see what I can get.
I've also heard about the golden ratio before. Interesting idea to have that ratio in both cabs together and not in every sigle one.

Thank you all!
Ray

 

[LowGrowl]

I think this is going to end 10 times better than what i could have been done without help... I'm so excited! I wish I could try them in tonight and tomorrow gigs

I guess i have to build them first

 

[rpsands]

I agree with Bogey on going a bit bigger. The Deltalite really wants to breathe!

Also: Do not copy Will's midrange driver position. It is bad Check the fEarful cabs for better options. No offense intended Will!

 

[LowGrowl]

OK! Thank to your suggestions i did some changes:
Box is now 2.5 cu.ft
Fb = 40.88 Hz
QL = 6.892
F3 = 55.37 Hz (almost 10 Hz down the original)

This is the response (Grey is the original design, Orange is the new):

BUT!!!

This two are not so good...
With only 175w I'm exeeding Xmax by Far...

With some extra mud

So, Is this that bad? Suggestions to improve the design?
Thank you all again for your kind comments
Ray

 

[will33]

I agree with Bogey on going a bit bigger. The Deltalite really wants to breathe!

Also: Do not copy Will's midrange driver position. It is bad Check the fEarful cabs for better options. No offense intended Will!

Ya, I know.. One of my tradeoffs to make the cabs amp width so they all buckle together and roll.

OP, proper would be to put the mid centered above the 12, or at least within it's outer edges if it's a little off to the side to make room for a tweeter. Likely not room for that in your boxes unless you make them tall and skinny and let the amp hang over the edges, or use a micro amp. Mine sounds good like it is but can always be improved on. I use both cabs about 95% of the time anyway so am considering re-doing it all in one box with all the drivers vertical and more ports on both sides of the woofers for a more even air pressure on the cones when cranking it up for outside gigs. I only have one little gig where I use a single cab, although being abke to break the stack down into small pieces helps sometimes with getting everything packed in the car when I bring PA stuff to gigs.

 

[will33]

OK! Thank to your suggestions i did some changes:
Box is now 2.5 cu.ft
Fb = 40.88 Hz
QL = 6.892
F3 = 55.37 Hz (almost 10 Hz down the original)

This is the response (Grey is the original design, Orange is the new):

BUT!!!

This two are not so good...
With only 175w I'm exeeding Xmax by Far...

With some extra mud

So, Is this that bad? Suggestions to improve the design?
Thank you all again for your kind comments
Ray

One tradeoff for using a bigger box for more bass extension is you reach xmax sooner. It's your judgement call to make. Try modeling them in an even 2 cu.ft. per and see what you think. I'm leaning that way for re-doing mine, seems to be a decent middle ground, for my preferences anyway, your needs/wants may be entirely different. For how mine sound, I don't really need the extra 1/4 of a cubic foot for anything.

 

[LowGrowl]

.....And I think in a loud Rock band your going to end up using the pair. So instead of trying to drink more power handling out of the system by making such small boxes. I would go for more Bass response by making larger boxes.
And shaving away power handling wont be so much of a big deal
because as a pair your should be just fine. ...

Now I understand that!
feeling stupid jaja Well, I'ts a tradeoff

 

[will33]

FWIW, putting them vertical move any comb filtering/interference around the crossover frequency to vertical plane which gives the purest, clearest sound spread wide throughout the room. It's usually best to move any glitches or narrow dispersion to the vertical axis. Audiences, and big stages can be quite wide but the difference in ear level between a short person sitting and a tall person standing is still maybe 4ft. at the most, no matter how far off to the side of the sound source they might be.