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Old 24th January 2011, 06:12 AM   #791
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Quote:
Originally Posted by ThokN View Post
Hello again.

Do you have any detailed plans on a subwoofer for you Boominator?

I've searched the thread, but only found old entries. What do you think of an external Horn Subwoofer to go with the Boominator? Do you know of any pros and cons?
Getting efficient deep bass down to 40 is nearly impossible without a horn, and horns will weight so much.

Isn't the clear point of compromise going to be cutting efficiency in order to save weight?

I think these are the best option:
http://www.tb-speaker.com/detail/1208_03/w8-1363sb.htm

I have one in my car. Check out the reviews on parts express for reassurance that quality control is reasonable.

These weight about 5 lbs each and are 88 db at around 70-80 Hz. Two of them together will break 90 db. They work in ultra-small enclosures around 10 liters, which doesn't matter except that it keeps weight down.

From 35-100 Hz, in BassBoxPro simulations they hold their own with all the subwoofers I've tried, pound for pound. In fact, I can't find anything that will be as loud and deep at this weight and in an enclosure as small.

With 35 watts, the should produce about 104 db freefield with a 35 Hz tuning for sound quality.

If you play with the port tuning and move it upwards, you can get many db more. In BassBoxPro, if you set the tuning in a 10 liter box to 80 Hz, the efficiency skyrockets to 116 db at 80 Hz!! I can hardly believe this result, and I imagine the bass will be "one note." But, it is loud.

I'm curious if anybody else has took a stab at real bass in a portable speaker this size.
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Old 24th January 2011, 07:04 AM   #792
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Originally Posted by bluewhale View Post
If you play with the port tuning and move it upwards, you can get many db more. In BassBoxPro, if you set the tuning in a 10 liter box to 80 Hz, the efficiency skyrockets to 116 db at 80 Hz!! I can hardly believe this result, and I imagine the bass will be "one note." But, it is loud.
That's because you're doing something wrong ;-)

A 84 dB/w/m sensitive driver will never produce anything close to 116 dB unless feed by more than 1600W RMS which sort of defeats portability.
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Old 24th January 2011, 02:31 PM   #793
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Default help!?

Hey dude...

This project is JUST the inspiration I need.

I cant seem to find the suncell batteries tho?
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Old 24th January 2011, 02:47 PM   #794
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ThokN, it was so nice to visit your camp (Fri Ost). I also saw the other one at Roskilde. The blue one in the pics I didn't see. Always very nice to see that people are enjoying their home built stuff. I'll stop by for more beer at this years Roskilde

The current sub I use is just a large flight case that I use for all the camping equipment, tents etc, it's about 320 liters internally and I've mounted 2 15" cheapo pro woofers (not car crap) in the bottom. It's driven by a class D amp (not tripath) running on 24V. Works pretty well, was cheap, and I didn't need to build anything else since I already had the flight case (it was a surplus one of a series I built for Martin Group).
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Old 24th January 2011, 02:48 PM   #795
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I cant seem to find the suncell batteries tho?
Suncell batteries?
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Old 24th January 2011, 02:49 PM   #796
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Originally Posted by Saturnus View Post
Suncell batteries?
Didnt the author build this on based on suncell energy or am I lost in space?
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Old 24th January 2011, 03:10 PM   #797
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Originally Posted by vANGiEEE View Post
Didnt the author build this on based on suncell energy or am I lost in space?
I am the author and designer. Do you mean solar cells? If so, those that I used in the original version is not produced anymore, they were surplus from a production run for miniature space satellites, and were quite pricey.

However, a standard 15W amorphous solar panel with the casing stripped away fit perfectly on top with 4mm to give on each side.

Here's an example of where you can buy it but they're available all over the world in both plastic and alu casing, but since you don't need the casing just take whatever offer is cheapest and easiest for you to get hold of: http://www.frys.com/product/4980041

Last edited by Saturnus; 24th January 2011 at 03:13 PM.
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Old 24th January 2011, 03:54 PM   #798
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Originally Posted by Saturnus View Post
That's because you're doing something wrong ;-)

A 84 dB/w/m sensitive driver will never produce anything close to 116 dB unless feed by more than 1600W RMS which sort of defeats portability.
You have to keep in mind that 84 dB/w/m is the average across a wide band, and this driver is around 88-89 db/w/m where the kick beat in music lies (where the boominator has no boom). That is your first mistake. Then recall that ports can add some bass boost.
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Old 24th January 2011, 04:03 PM   #799
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Originally Posted by bluewhale View Post
You have to keep in mind that 84 dB/w/m is the average across a wide band, and this driver is around 88-89 db/w/m where the kick beat in music lies (where the boominator has no boom). That is your first mistake. Then recall that ports can add some bass boost.
The kick is in the midbass between 100 and 150 Hz, precisely where the Boominator is designed to have the most "Boom".

And no, it doesn't make the slightest difference if the sensitivity had been 88 dB/w/m in the desired range. You looking at the chart wrong, the chart is at 2W, or 2.82V into 4 ohm, so 84-85 dB/w/m is the correct sensitivity of that driver. A port, no matter how it's tuned will not add 30 dB to the sensitivity. I doubt it's even possible in a several hundred meters long horn.
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Old 28th January 2011, 07:16 AM   #800
zubzer0 is offline zubzer0  Denmark
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Hi Saturnus

I have been reading a lot about your (and others) boominator build and I'm currently working on a smaller version myself. I just can't figure out how you use the magnet-to-magnet configuration of the speakers.

Is it called bipole, dipole or isobaric??
And does your "push-pull" work at all when you are using a ventet enclosure?
Would this work with a fulltone speaker as well?
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