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Class D Switching Power Amplifiers and Power D/A conversion

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Old 12th February 2008, 05:29 PM   #1
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Default are there any prebuilt 30w-50w modules to be found?

i'm looking to upgrade my bicycle system this summer. last summer i ran a pair of small bookshelf speakers with a sonic impact class T. the system had moderate volume, but i'm looking to add at least a single 50w channel to handle bass duties but can't seem to find any medium power class D modules.

i'm not a kit builder. i'm only looking for prebuilt units and ones that would work with NIMH batteries at that.

many thanks in advance to anyone who can steer me towards an EASY to DIY module that can power a sealed woofer with a bit more authority than the sonic impact. none of my search engine research yielded anything except a manufacturer's "catalogue" of texas insruments modules and one vendor who only sells unbuilt kits. the only other thing i know of is UCD 150w of battery draining overkill amps.

surely the more technical of you know where the modules i'm seeking are hiding.
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Old 12th February 2008, 06:33 PM   #2
dweekie is offline dweekie  United States
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I'm unsure of your budget, but the Winsome Labs Mouse might fit the bill. http://winsome-labs.com/
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Old 12th February 2008, 11:54 PM   #3
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I have a Tripath eval board for sale.....

FS: Tripath EB-TA2022 Ver. 1.7 Eval board

Be aware it takes a dual supply just like the UCD modules do.
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Old 13th February 2008, 12:43 PM   #4
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Check out the discussion on this one:

Sure-Electronics.com class d amps

Not exactly what you were asking for, but might fill the bill for the whole system.

--Buckapound
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Old 13th February 2008, 04:39 PM   #5
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I'd say also look at the Pioneer PRS "Class-FD" series.
"FD" being Fullrange class-D
Watch out because they also make "Class-D" only for subwoofers.
Marketing!

At the same time, to boost bass from small speakers take a look at:
http://www.sonicelectronix.com/item_...+MaxxBass.html
It doesn't actually boost the bass, but instead adds harmonics so you think you hear the bass. Check out the modding potential here:
http://www.wavescaraudio.com/custom.htm
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Old 14th February 2008, 01:58 AM   #6
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thanks for the replies. that mouse unit is DEFINATELY out of my budget range. i wish there was a way to mono bridge sonic impacts. i figured there had to be some sub $100 modules SOMEWHERE.

as to the 20+v units, that would require too many batteries to power as eack NIMH is only 1.5v and i'd be bi-amping so there would be 8 additional AAAs for the sonic impact. i was planning on 8-10 D cells for bass.

the pioneer units would be great if they didn't cut off so low. i was planning on running the subs up to about 1,000Hz to crossover to behringer planar mids & tweeters. the mids can only go as low as 500Hz so i thought 1,000Hz might make it easier on them.

for the subs, i'm considering 4 of those new tymphany LAT250 units in sealed enclosures. i planned on running all 4 off the bass amp at 8 ohms.
http://www.madisound.com/catalog/pro...oducts_id=8288

for any of YOUR interests, just after i posted this thread i did find one place that has RTR 50w stereo modules for about $180

i can't find the site, but next time i come here, i'll give you a URL. i wrote it down, but the paper is at home and i'm at the library.

i'd seen 4 X 50w class D car amp somewhere that i once considered using for 3 of it's channels, but worried that the wasted channel & the higher power drain on the mains might be too much of a strain on 8 or 10 D cells.

would such an amp be doable for, say, 4-5 hour runs on 12 or 15v of D cells using 3 channels? i'm not well versed in circuit math.

if anyone's interested in that unit, i'll try to find the maker for that one too.

in general, it seems that most class D modules are either under or overpowered for my needs.

someone should make 50w modules for those looking for more oomph than all of the 10wpc kits out there.
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Old 14th February 2008, 03:27 PM   #7
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On the underpower issue a more efficient higher sensitivity speaker could help. A 3db higher SPL is the same as doubling the amplifier wattage. Pro sound drivers and the most efficient, but may need a larger box. With a well designed driver/box you save up to 10x power over a typical home type drivers.

Bass also sucks up a lot of power, so psychoacoustic techniques to generate perceived bass can save a lot of power.

I wonder if a tapped horn arrangement would be a good choice for your application?

You can take a higher power class-d and lower the voltage to it to get a lower wattage amp. If it's a car amp with an internal SMPS to raise 12v to some higher rail voltages you would have to dig into the SMPS to figure out how to lower the voltage.

The car amp modules are usually properly packaged and heatsinked already, which is something to think about.

I'd be interested to see whatever you come up with. Sounds like a fun project.
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Old 15th February 2008, 01:12 AM   #8
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right, i'm familiar with the 3dB rule. i'm fairly well read in audio issues, i'm just not a circuit board guy. that's why i wanted to go with 4 LAT 250s, to get 6dB boost by doubling driver numbers twice.

as to horns, no way, i won't settle for anything except acoustic suspension. i don't care if ports are more efficient, i only like the sound of tight damped bass. even better, planars are the very best in bass by my tastes. i like fast, detailed and punchy bass.

THAT'S why i'm looking for more power in the bass region.

in my experience looking at higher efficiency drivers like fostex 8 inchers as well as pro units, they sacrifice bottom octave extension for the higher efficiency. a 15" X 98dB pro driver might only be rated down to 60 or 70 Hz, yet little 6 inch 82dB efficient tang band woofers might have a -3dB rating at 40Hz in a small sealed enclosure.

it's definately an uphill battle to get bass extension out of small enclosures ESPECIALLY if one isn't willing to go ported, but with enough power it can be done. i was surprised at just how much air my little 5 1/4" mission M71 2 ways (the same ones i'm using with my current bike rig) could move in the bass range and without breaking up when driven hard by a 100wpc reciever.

i'm sure those LATs can dig deeper in the bass, are rated higher in efficiency as/is and would be run at +6dB to boot. there would probably be a rolloff penalty though for cramming two into a slightly larger enclosure than one would use.

i love the bass of my missions, fast & tight with the port plug in, but so small and only rated for 86dB, they can't push bass past 15 feet or so and that's only in a quiet area, forget trying to compete with a nightclub exit if the door is open!

i found the URL for those 50wpc modules i mentioned yesterday.
they're called AMP-50 and can be found at http://www.gilderfluke.com/index.php...045fe18a722ddc

they don't give detailed specs and they're a bit pricey at $179, but it's looking like they're the only game in town.
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Old 15th February 2008, 02:48 AM   #9
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Check the distortion specs. This quote on there was pretty scary":

"Typical ‘Linear’ amplifiers have only about 20% efficiency. Fully 80% of the power you put into them goes into the heatsink as waste heat. A fifty Watt linear amplifier only feeds about ten Watts of power into your speakers, and forty Watts into the heatsink, whether or not there is any sound being fed through the amp!"

--Buckapound
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Old 15th February 2008, 06:44 PM   #10
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Quote:
[i]
...
as to horns, no way, i won't settle for anything except acoustic suspension. i don't care if ports are more efficient, i only like the sound of tight damped bass. even better, planars are the very best in bass by my tastes. i like fast, detailed and punchy bass.
...
[/B]
You must have had a bad experience with a poorly designed horn. Horn are very favorable to accurate reproduction of bass.
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