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Old 24th February 2010, 02:06 PM   #491
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yup! $116.51 in shipping only (4 panels, UPS WorldWide Expedited), giving a total of $196.51.

Ok, a Swedish dealer would be great! Thanks
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Old 26th February 2010, 07:33 AM   #492
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Default damping

Oh, I was meaning to ask you another thing:

Do you use any damping material inside the speaker enclosures? Sure, it might make it less loud but theoretically it would improve the frequency response by attenuating the box resonance peaks (and thereby improving the percieved sound quality).

But on the other hand, since the enclosures are so small, the resonances would be in the slightly higher frequency range (~500-700Hz), perhaps making them less noticeable?

Whats your opinion?
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Old 26th February 2010, 11:48 AM   #493
dododoo is offline dododoo  United Kingdom
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Default sketchup file?

hi guys,
have been slowly digesting this thread for a number(!) of nights, trying to absorb enough info to be semi confident in giving the design a go myself. although there seems like there is a lot to learn and a lot that i could easily mess up!

there has been mention of a sketchup file for the box design, someone offered to host it i think, but i haven't seen reference to a file anywhere, anyone know where it can be found?

cheers simon
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Old 27th February 2010, 05:06 PM   #494
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Default No battery

Hi.
I would like to build something like The Boominator, but i will run on
xternal power. Would you stil use the same setup?
I don't care if it will be more ekspensive.
The boombox is for use in a sportshall and outdoor.
Thank you for any help.
ps. is MDF ok for the box?
Bjoern
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Old 27th February 2010, 06:11 PM   #495
dododoo is offline dododoo  United Kingdom
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hi, another question! i've just read in another thread saturnus saying the position of the boominator relative to the ground will make a diference to the sound quality. On this post saturnus says..

"For the Boominator I use a Q of 1.207 which gives a 3db boost at twice the Fb. This is what I have found sounds the best for outdoor environments provided the speaker is placed directly on the ground."

"Lifting it off the ground on a stand or cart will require an even higher box Q depending on height off the ground and tuning frequency."

I was planning to put it on a bike at about 75cm above the ground, will this make an appreciable difference?

(Hope not - i can't see where to change Qb in WinISD anyway to even begin to take account of it..... :-) )
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Old 27th February 2010, 07:49 PM   #496
gfiandy is offline gfiandy  United Kingdom
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Hi, The Q of the box will incease as you make the box smaller. So if you are going to use it on a bike you may want to rework with a smaller box as this will probably be more convinient as well.

Regards,
Andrew
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Old 27th February 2010, 08:07 PM   #497
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dododoo:
I've built a slightly modified version of Saturnus original design with some extra spacing around the sides of the box enabling me to easily attach a protective grille. Picture here. (not 100% accurate though...)
However, I used 8 pcs. of 12mm 7ply plywood with the following dimensions:
2 end caps: 30x30cm
2 fronts: 27,6 x 87,9cm
2 top/bot. : 30 x 87,9cm
2 inner pcs. 22,1 x 27,6cm

Middle compartment is 10,1cm wide (on battery width =) ). End caps has the bass reflex port of which is 3,6cm deep (3 sheets of plywood), 12cm wide and 3cm tall, rounded at the ends. Hope this helps!

Regarding the Q-value, this is a general factor describing how resonant a system is, easily put. Ideally, the perfect speaker should have a flat frequency response for the perfect sound. However, some humans like bass =), so in order to enhance bass response we can introduce some resonance by create a bass reflex port. And by tuning this port to a certain frequency we "boost" the sensitivity here: higher Q = more boost and narrower frequency band.

As Saturnus write is in the post, the room we're in shapes the sound in the lower frequencies to a large extent by introducing resonances, enhancing bass response at certain frequencies. By playing in the free field, you remove the walls that are creating these resonancies, thus leaving you with a less "bassy" sound. The only reflecting surface you have outdoors is the ground, and by lifting your speaker above ground you slowly remove this surface aswell, thus requiring even higher Q-value to compensate.

This is how I see it, correct me if I'm wrong, I'd appreciate it =)
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Old 27th February 2010, 09:58 PM   #498
dododoo is offline dododoo  United Kingdom
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thanks for the quick replies - pardon my questions if they seem daft...

i'm planning to put the boominator i make on the back of one of these bikes so i've got a bit more room than average, but weight is definately an issue for the long touring holidays i have planned w/ all the extra camping gear (and the hills).

About Q - does that mean that Q is just a description of how peaky your box design is ? where it peaks still being dependent on the type of driver and the tuning of the box?

My 'problem' is i'd really rather not have to cycle up hills w/ around 14kg of bass drivers on my bike and would rather spend more money on lighter drivers, ( The weight of four 10" neos ( 6kg ) looks like they'll shave off about 8kgs, which is definately worth trying for !

But this then means having to understand how to optimise the box for different thiele small paramters, which i'm having problems getting my head around. WinISD help file made no mention of Qb that i could see! and i'm not entirely sure what the ideal frequency to aim the peak of the db gain curve at is, or for that matter how high to make it ( 3db above 0db? )

So if my legs can't deal w/ the weight of the hp10w's, what frequency should i be aiming to get the peak at?

Or can anyone suggest some other drivers that cost more but weigh less and react similarly to the HP10Ws ?

Jimtegel - thanks for the pic and the measurements, that's made it a lot clearer for me... From your measurements it seems like the internal volume of each of your chambers is around 46 litres minus the drivers, and trying to workout the volume of the hp10w drivers imagining them as a truncated cone ( is that the way to do it? ) i get you internal box volume to be about 46 - ( 2* 4.4 lt ) = 37.2 litres. is that about right?

Just trying to see if i understand enough, i've learnt the hard way doing woodwork that you should always 'measure twice cut once' and in this case I'm finding i've got to first learn how to use the ruler and what it is that i'm actually supposed to be measuring!....
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Old 27th February 2010, 10:34 PM   #499
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From this thread I read out that the boominator enclosure volume was supposed to be about 2 x 23L, I did not compensate for the driver volumes... maybe that was a mistake

If you need a lighter system, maybe you should use smaller/lighter drivers? I've built some stuff with these drivers once: Visaton BG17. They are light (6.5", around 700g) fairly sensitive (93dB) and very cheap! I've searched pretty much everywhere for low weight/high sensitivity drivers but there's really nothing like the HP-10W:s.

Another way to save weight is to choose the right plywood. From what I know, the lightest is from coniferous tree (not sure if thats the right english translation ), such as spruce.


As Saturnus has mentioned, it's a waste of energy playing anything under 100Hz in the open field, so putting your -3dB point around this frequency should be a good starting point. Also you might wan't to create a peak in the bass register, like this. Try it in WinISD, and you should probably get a pretty decent sounding box (of course sound "quality" is also dependent on the frequency response of the driver)

About the Q again: I was just trying to describe my comprehension about Q-factor, (which might be wrong). But yeah, it's pretty much about how "peaky" or resonant your system is, and yes: it depends much on the T/S parameters on the driver and box tuning.
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Old 28th February 2010, 04:55 PM   #500
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Are there enyone who could shere some mesurements on the boominator?
I like to start building the box asap.
Bjoern
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