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Class D Switching Power Amplifiers and Power D/A conversion

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Old 9th February 2011, 05:59 PM   #51
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Quote:
Originally Posted by Buckapound View Post
Too cool. Did you line that pot with fiber ior foam of some kind to cut down the resonance?
Resonances were not a problem in the end. These steps I took may have been overkill:
1) Used a super heavy commercial aluminum stockpot from cooking.com . The stiffness raises the resonances to very high frequencies.
2) One cross-brace attached with plumbers epoxy
3) Pink insulation

In the end, the cabinet was incredibly dead, rugged, and rigid.

Quote:
Sounds better now, with much better bass. Great product and really easy to use.
I totally agree that the Mini-dsp will produce better bass!! It uses fewer resistors and has more capacity to direct amplifier energy to where it will be used the most effectively.

Protecting the woofer from breaking up when it reaches full excursion is half the battle. Bass-box pro can identify that frequency, and there probably is a free program somewhere that can do that.

A bass boost right before the low frequency cut-off can also flatten out the bass. This is what ported subs typically use (also open baffle and and super-small enclosures need EQ lovin).
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Old 12th February 2011, 11:55 PM   #52
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Quote:
Originally Posted by mr. doom View Post
I have a 9vEQ with low cut @75hz ($50 behringer) but have not noticed a huge increase in run times with a 12v T-amp.
You haven't mentioned the slope of the low cut. The reason why EQ'ing the music files themselves worked is because you can do very steep cuts with digital EQs. If you had the same in hardware, like the miniDSP mentioned by someone else, you would get the same increase in run time without having to edit every MP3.
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Old 13th February 2011, 08:02 AM   #53
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Location: yxc
My design is a bit different, I used four 13 cm full-range drivers from Visaton FR 13 4 Ohm version and did a small line array because I wanted directional sound and they don't need a crossover. I used a cheap car audio amp which I had available (I would prefer any D-class amp). Batteries are lipo (will be changed for a stronger ones, also lipo), box is made from fiberglass and carbon and so everything comes together around 5 kilograms of weight.

Sound is very nice for a simple setup and because it uses four drivers it can play very loud. As mentioned in thread, when used with players that have equalizer I usually set to minimum frequencies below around 60 Hz, it doesn't effect sound much, but it can play louder and longer.

After all I'm satisfied with result, but if I did it again I would use 10 cm drivers instead of 13 cm to get a bit smaller backpack.

And here is a video of backpack in action YouTube - wwwrolanjeeu's Channel

It is easy enough to carry it around for two hours without problems, well that is the longest time I did carry it.
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Old 17th April 2013, 05:16 PM   #54
rjsaenz is offline rjsaenz  United States
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Here is my portable party backpack I have been perfecting this for the last 10yrs. It weighs 12lbs total, backpack, speakers, amp, and battery. Has great sound and gets pretty loud. I ski with it.

Speaker Backpack - YouTube

In the wild Copper Mountain Colorado.
Perfect Spring Day at Copper Mountain April 2013 - YouTube
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