The Boominator - another stab at the ultimate party machine - Page 37 - diyAudio
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Class D Switching Power Amplifiers and Power D/A conversion

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Old 10th June 2009, 02:44 PM   #361
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Neat party machine.

Reminds me of the PODZUMA on partsexpress without the solar cells.

PODZUMA
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Old 10th June 2009, 03:00 PM   #362
Havoc08 is offline Havoc08  Denmark
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Quote:
Originally posted by merlin2069er
Neat party machine.

Reminds me of the PODZUMA on partsexpress without the solar cells.

PODZUMA
Why is there 2 woofers per channel? Doesn't that produce a nominal load of 2.6-2.7 ohm with the xover he uses?
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Old 10th June 2009, 03:17 PM   #363
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Quote:
Originally posted by Havoc08


Why is there 2 woofers per channel? Doesn't that produce a nominal load of 2.6-2.7 ohm with the xover he uses?

It looks like he's getting about a 4ohm load with 2x8ohm DAYTON PA130-8 5" speakers in parallel.
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Old 10th June 2009, 03:51 PM   #364
Havoc08 is offline Havoc08  Denmark
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Doesn't the woofers present (8*8)/8+8= 4ohm and the tweeter 4ohm resistor + 4ohm speaker = 8ohm making the whole circuit (8*4)/8+4 = 2,66ohm ?
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Old 16th June 2009, 10:12 PM   #365
Rewind is offline Rewind  Sweden
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I am going to build one myself with a 10 dollar tripath 25W amp. 50 hours on a standard battery? That's a lot of Combichrist!

Almost this one, without the box:
http://cgi.ebay.com/Excellent-2-1-CH...3A1%7C294%3A50

I am thinking about a mono bass 12" driver on one channel and another channel with a 90's low-fi panasonic 3-way speaker with 10", 4", 2" drivers. Power is from a normal sized 12V battery.

I really don't care about hifi, not even about stereophonics. I guess we can't play 60's beatles with guitars on one channel and drums on the other. As if we would want to on the best synth festival in Scandinavia - The Arvika Festival! Fy fan!
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Old 16th June 2009, 11:35 PM   #366
col is offline col  Australia
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Hi Rewind,

Those 3 channel amps are class A/B, they don't use the Tripath TA2020 chip and they are not class D so they will be less than 30-50% efficient. The Class-D are up to 90% efficient. There is some more details of the chips they use in this description:


http://cgi.ebay.com.au/New-Lepai-LP-...rkparms=65%3A1|66%3A2|39%3A1|240%3A1318|301%3A0|293%3A1|294%3A50


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Old 17th June 2009, 09:08 AM   #367
Rewind is offline Rewind  Sweden
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That's good to know, because I almost ordered one of those instead. I actually have the two channel tripath version TDA2030. I do need a basschannel så I will only use one channel for a 12" driver.

I wonder how loud a 12" bass driver with 91dB/W on a 25W tripath will get. And is the 50 hour batterylife on a 550mAh battery correct?
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Old 18th June 2009, 02:00 PM   #368
sune is offline sune  Denmark
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Quote:
Originally posted by Havoc08
Also make sure you run 4ohm and not 8ohm. That roughly doubles youre output wattage.
Does running 4 ohm require that I have 4 drivers, or how do I make them run that? I got two 8 ohm HP-10W and two piezoes connected to an AMP6-Basic.
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Old 23rd June 2009, 02:07 PM   #369
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Hey guys, I see my pet project is still making a stir.

I'm sorry I haven't been around to answer many questions lately. But in the next couple of days I'll back check and answer a few of those I can answer.

Firstly regarding the resistors on the piezos, they don't have to be the value I used unless you use the exact piezo use. The value can be calculated as the capacitance of the piezo and the resistor form a high pass filter, that should have a corner frequency of about 3.5-4KHz. High quality piezo like the ones I used generally but not always have much higher capacitance than low cost piezo so the resistor is of much higher value. I recommend NOT using wirewound resistors at all, these have much too high serial inductance, and in series with a piezo that forms a low pass filter. Even Dale's super expensive "non-inductive" wirewound power resistors have too high series inductance. Use 3W carbon or metal film resistor instead, or several low wattage resistors in parallel.
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Old 23rd June 2009, 02:21 PM   #370
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Secondly, the concept behind the Boominator depends 2 things mainly. The bipolar design which means a lot of leveling over the frequency band comes is completely automatic since there no baffle step to consider. And then a little trick I discovered after having built several test cabinets. If you calculate a standard optimal bass reflex cabinet for whatever driver you use with the optimal Q=0.7 tuning, and you then divide Vb with PI, and multiply Fb with the squareroot of 2, you end up with the optimum tuning for outdoor use Q=1.2, and you get rid of all those bass frequencies you can't play loud enough to be audible outdoors anyways, and at the same time the rise towards the cut-off frequency equalizes the bass to a more or less flat level when used outdoors.
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