Bass for my soldier

[tb46]

Hi ODougbo,

Post #59: "...are you saying not to build a bigger box to lower the bass - to increase the SP/output?"

The original question was in the direction of a dual driver enclosure, so any volume you save looking at a single driver enclosure, you'll save twice. A dual driver 18" enclosure will be large anyway. But, especially if it has to be portable, every little bit helps. Isn't it amazing how heavy even 1 additional cft of air is?

Otherwise, this discussion was more about the tuning frequency, and the resulting excursion/power handling.

Regards,

 

[Nathenry]

Hi,

If you restrict the bass output of a PA cabinet it will generally handle
more power and go louder in the bass range it covers. As said you
need a high pass filter. Some high output high power handling bass
PA cabinets are very surprisingly restricted in real bass response.

e.g. This 1 x 18" :

Allegedly does 136dB, but
"Frequency Range loud (-10 dB) 50Hz -142 Hz".
"Frequency Range deep (-10 dB) 45Hz -138 Hz".

-10dB at 50Hz and 45Hz is no great shakes by anybodies standards.

rgds, sreten.

Ok now I get the full pic.

 

[tb46]

Hi Nathenry,

You are welcome. Let me point out, that in the factory drawing - SUB18 - no allowance has been made for internal enclosure reinforcements. That may well be because most people who build something like this have enough experience to add little things like corner cleats, panel braces, and side-to-side bracing. So you and you friends may want to keep that in mind when you build the box.

With your limited time frame in mind, don't worry too much which box to build. You'll be building a good loudspeaker with very nice drivers. I'll bet he'll like 'em. Just build the boxes nice and solid.

Regards,

 

[Nathenry]

Oliver
Would it make any difference if the box is build 22w x 24h x 28d so other box could stack on top of it.

 

[ODougbo]

You'll really want to use this...not hard to find, but not easy either.

3/4" x 60" x 60"

Maybe call around to local (small) cabinet shops.

e.g. BALTIC BIRCH PLYWOOD, RUSSIAN, FINLAND, CRAFT PLYWOODS

 

[Etocynned]

Any hardware store with plywood in its name will carry it. The big chains wont.

 

[ODougbo]

This is where we go in this neck of the woods:

A & M Supply Corporation

 

[tb46]

Hi Nathenry,

Post #64: "...the box is build 22w x 24h x 28d..."

Yes, that would get you back to the basic layout of SUB18, with slightly different dimensions:

Regards,

 

[Nathenry]

I see there is a lot to think about when design a speaker box.

 

[ODougbo]

If you want to stack, these may work for you.

Amazon.com: Dayton Audio PC123-16 Plastic Stacking Corner 16 Pcs.: Electronics

 

[Nathenry]

Thanks people for all the links and info

 

[tb46]

Hi Nathenry,

It's kind of like the Dilbert cartoon: "It only looks easy." 🙂 Here is another option:

Regards,

 

[Nathenry]

Hi Nathenry,

It's kind of like the Dilbert cartoon: "It only looks easy." 🙂 Here is another option:

Regards,

Lol. I like the look. Does it give the same response as the one you post earlier.

 

[tb46]

Hi Nathenry,

Yes, it should be the same. There are a number of ways to arrive at the same total port cross-sectional area, and they basically give you the same end result, or something very similar. If the area is a little off you can make up for that in the length. E.g.: 2 ea. 6"Dia. = 364.8cm^2 and 4 ea. 4"Dia. = 324.3cm^2, you will need a shorter duct with the smaller cross-sectional area. That's where the simulation programs come in so handy. You do want to stay away from port shapes that look to extreme, e.g.: very flat slot ports, or multiple internal bends (1 or 2 is fine).

Regards,

 

[Nathenry]

I reallly like that look.

 

[ODougbo]

Oh yeah! That looks great - wish I needed one now.

 

[norman bates]

-10db at 50hz ?

yuck.

 

[sreten]

-10db at 50hz ?

yuck.

Hi,

All about specs. Response is almost irrelevant. For PA you can always EQ
it. What you need to know is the maximum SPL profile of the cabinet.

Instead of the 2 x18's per side suggested in this thread, if you went for
4x18's per side but still low tuned but only say 100L per driver, so the
bass response is restricted, with enough power and EQ you end up with
a set-up that is simply better, SPL wise, for any response. However this
thread is simply refusing to discuss the assumptions its making, YMMV.

As I said miles earlier in the thread bass response is about driver maximum
SPL at any frequency and having enough juice to achieve that SPL. Within
the SPL limits you can actively EQ the bass to any response you want.

rgds, sreten.

 

[Etocynned]

Spl being a direct expression bounded on the upper end by power compression and driver displacement?

 

[Nathenry]

Hi,

The drivers recommended box is 200L tuned to 34Hz.

To hit maximum SPL in the bass you must use a subsonic filter, as
all vented boxes quickly overload below the port tuning frequency,
not so critical at modest domestic volumes but a killer outdoors.

To go deeper (but not as loud) you could tune lower, say 26Hz
and use a peaking high pass filter, 2nd order q=1.5 set to 26Hz
as a combined bass boost and subsonic filter, flat to 30Hz.
This can be build into the feedback loop of the power amplifier.

Power handling for 34Hz is around 600W at 50Hz, higher either
side, around 450W at 40Hz for the lower tuning. Power handling
for the higher tuning drops like a stone at 30Hz. lower tuning 23Hz.

Max SPL is around 123dB in the bass for the higher tuning, around
119dB for the lower tuning, both hit 127dB 100Hz to 200Hz, 1kW.

All numbers are for one driver into half space.

With 3/4 ply add extensive bracing or ribbing or both.

rgds, sreten.

Sreten
Can you post a spl response chart for the higher tunning speaker.