Combining different widths of cabs

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jemo1234567890
Posts: 7
Joined: Wed Jun 19, 2019 2:51 am
Location: Germany

Combining different widths of cabs

#1 Post by jemo1234567890 » Thu Jul 11, 2019 2:19 am

Hello all,

my plan is to build two T39 or T48 (24 inch version) for my living room.
In the future I would like to build a few more for outdoor applications. These should be wider (around 30 inches) for higher output.
Is it possible to combine these two widths and let them play together in a stack?

I thought that the horn delay should be the same. Only the cab volume is different.

Thank you very much for your answers.

Best regards
Joshua

Grant Bunter
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Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
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Re: Combining different widths of cabs

#2 Post by Grant Bunter » Thu Jul 11, 2019 5:23 am

Combining different widths is no problem.
There are different maximum widths based on driver size choice for each of the cabs you mention, so check that out in the plans...
Built:
DR 250: x 2 (melded array) with March 2012 plans. 2 more under way with CD horn
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

jemo1234567890
Posts: 7
Joined: Wed Jun 19, 2019 2:51 am
Location: Germany

Re: Combining different widths of cabs

#3 Post by jemo1234567890 » Thu Jul 11, 2019 7:46 am

Thank you very much Grant for your answer.
So I was right that cab width has no effect of the horn delay so I could combine different widths of the same cab.

is there a law how much more SPL I get with every step wider?
Some withs I saw in the SPL-Charts.

The maximum widths and the steps for wider cabs I saw in the plans.

Thanks

Grant Bunter
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Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
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Re: Combining different widths of cabs

#4 Post by Grant Bunter » Thu Jul 11, 2019 3:10 pm

jemo1234567890 wrote:
Thu Jul 11, 2019 7:46 am
Thank you very much Grant for your answer.
So I was right that cab width has no effect of the horn delay so I could combine different widths of the same cab.
Correct. However, choose one cab, or the other. You cannot combine a T39 and a T48.

is there a law how much more SPL I get with every step wider?
Some withs I saw in the SPL-Charts.

I don't think so. There is a point of diminishing returns though. Once that point is reached, it makes no sense wasting ply to build a wider cab, for no benefit. Not only in terms of output, but also pack space.
To give you an example, in the SPL charts for the T39, you will see 30 inches being noted on some charts.
Yet, your T39 plans will tell you the maximum width using a single 12 inch driver is 28 inches.
That's because Bill came to the conclusion there was no additional output in a 30 inch wide cab vs a 28 inch wide cab.

The maximum widths and the steps for wider cabs I saw in the plans.

Great. By the way, part of your plan purchase is a sketchup file. You can select metric measurements instead of inches and that should make it easier for you to work out...

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

SethRocksYou
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Location: Sacramento, California, USA
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Re: Combining different widths of cabs

#5 Post by SethRocksYou » Thu Jul 11, 2019 5:12 pm

Grant Bunter wrote:
Thu Jul 11, 2019 3:10 pm


That's because Bill came to the conclusion there was no additional output in a 30 inch wide cab vs a 28 inch wide cab.

If it's important enough, you might double check that with Bill. I clearly recall him stating that he changed the plans due to 28" being able to fit through doorways... which leaves it up to assumption what the difference in overall sensitivity and response there is between the two widths. I, for one, would love to see a chart with both 28" & 30" to judge for myself if it's worth having to turn the cabs sideways to fit through doorways or not.

Grant Bunter
Posts: 6070
Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
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Re: Combining different widths of cabs

#6 Post by Grant Bunter » Fri Jul 12, 2019 4:45 am

SethRocksYou wrote:
Thu Jul 11, 2019 5:12 pm
Grant Bunter wrote:
Thu Jul 11, 2019 3:10 pm


That's because Bill came to the conclusion there was no additional output in a 30 inch wide cab vs a 28 inch wide cab.

If it's important enough, you might double check that with Bill. I clearly recall him stating that he changed the plans due to 28" being able to fit through doorways... which leaves it up to assumption what the difference in overall sensitivity and response there is between the two widths. I, for one, would love to see a chart with both 28" & 30" to judge for myself if it's worth having to turn the cabs sideways to fit through doorways or not.
Hmmm, you're probably right, but you've already got to the crux of it when you can turn the cab sideways and be pretty much guaranteed to fit through any doorway, regardless of width.

Sometimes it comes down to other things as well.
IIRC, my 2 x 28" wide cabs were just less than 4 sheets of 8 x 4 ply.
That extra couple of inches certainly puts 30" wide cabs into 5 sheets per pair.

Ripping 8 x 4's (2440 x 1220 mm for the OP) right down the middle gives panels 23 15/16" wide again IIRC, for nearly 25" wide cabs.
That to me is probably an optimal width in terms of ply, ease of movement, pack space...
Built:
DR 250: x 2 (melded array) with March 2012 plans. 2 more under way with CD horn
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

jemo1234567890
Posts: 7
Joined: Wed Jun 19, 2019 2:51 am
Location: Germany

Re: Combining different widths of cabs

#7 Post by jemo1234567890 » Fri Jul 12, 2019 7:00 am

SethRocksYou wrote:
Thu Jul 11, 2019 5:12 pm
Grant Bunter wrote:
Thu Jul 11, 2019 3:10 pm


That's because Bill came to the conclusion there was no additional output in a 30 inch wide cab vs a 28 inch wide cab.

If it's important enough, you might double check that with Bill. I clearly recall him stating that he changed the plans due to 28" being able to fit through doorways... which leaves it up to assumption what the difference in overall sensitivity and response there is between the two widths. I, for one, would love to see a chart with both 28" & 30" to judge for myself if it's worth having to turn the cabs sideways to fit through doorways or not.

This would be very interesting yes.
But the equations of Grant are a good reason for a smaller width, too.

Do you know if a width of 25 inches are possible? So if your cab would be 25 inches wide, your panels would be 24. If I follow the plans I do not come to a width of 25 inches if the steps would be 1,5 inches (complete cab width).
What a luck that our panels in Germany has a size of 250 cm x 125 cm (98,4 inches x 49,2 inches)

Bruce Weldy
Posts: 6644
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: Combining different widths of cabs

#8 Post by Bruce Weldy » Fri Jul 12, 2019 7:37 am

jemo1234567890 wrote:
Fri Jul 12, 2019 7:00 am

Do you know if a width of 25 inches are possible? So if your cab would be 25 inches wide, your panels would be 24.
I have 4 of 'em that wide, so yeah.....it's possible.

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

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