are there any prebuilt 30w-50w modules to be found?

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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.
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.

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.
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.
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

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.
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!"


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.

You must have had a bad experience with a poorly designed horn. Horn are very favorable to accurate reproduction of bass.
all i remember is way back in the 80s when i listened to horn loaded klipsh heresays (la scalas?), i hated their sound, probably mostly due to the horn mids & tweeters. the FIRST real hi-fi sound that i heard was a friend's pair of $120 infinity acoustic suspension minimonotors on a B&O turntable through a 45wpc denon reciever.

that's when i realized all of the speakers in shops were overpriced, gimicky and bogus. aside from the amazing image those little 4.5" two ways threw with their grey styrofoam tweeters, i was stunned by how much tighter and clearer the bass was compared to bloated and sluggish ported and large woofer floor standers. back then, the only full range speakers i liked were bostons with 8" woofers. that's when they still made acoustic suspension before selling out to "duh... me want louder" idiots who want more volume in showrooms.

from that day on, i became hardcore acoustic suspension & the smaller the better. to me, ports & horns are gimicky & take away from pure sound. i've heard plenty of horn drivers in nightclubs and to me, they suck rotten eggs. the sound is sluggish and boomy. maybe part of it is 12-15" woofers & ports, but i just hate that blurred sound. betwen nightclubs & klipsh demos, i just associate horns with distortion the same way i do ports.

you can argue that quality varies between designs, but the bottom line for me is that good designs are less distorted than others while i've never heard acoustic suspension sound bad outside of department store no-fi junk.

acoustic suspension has that quick snap i like without any of those unforgivable resonances designed to increase efficiency. the only way i'd veer away from acoustic suspension is or planars which are even quicker.

i'm all for quality over quantity, but want as much quantity as i can get without sacrificing speed and detail. as far as i'm concerned, there are only two speaker makers left... NHT & magnepan.

i thought the literature for those AMP-50s sounded suspect too. i know A/B amplifiers are closer to 50% efficient and only class A gets down to 20% or lower. still, i need more power than 10-15 watts and don't seem to have ANY options other than battery draining class A/B. i like the sound of class D anyways. it, too, is quick and detailed. i love my panasonic reciever and hated my NAD.

there's a total market niche out there waiting to be exploited. everty day i see more and more street party bikes. someone should make realistic modules for those or high end DIY boom boxes.
The fact of the matter is that if you want more than 10-15 watts you either need relatively low impedance or a DC-DC converter to obtain higher voltages. You can't change Ohms law here, it is was it is.

I think your best bet would be to get a kit from There's pretty much a kit to cover any need. I know you want a completed module, but you're going to have to compromise somewhere. I'm sure if you ask nicely you could persuade someone into assembling one for you.
I have 8 channel 41Hz Amp5 with (1000Vac) 2 500Vac trafo, no case yet. I'm selling it for $480 just to cover my expenses. This is 60W @8 ohms and 100W@4.
The board has built in supply, all you need is transformer.
I can sell (2 channel) 1 board for $90.00.
If you are interested, Please PM me.

yes, 41Hz i think is the place that had a kit that was close to what i needed, but after reading a review for the charlize (or one of the other 10 watters) online, i was totally put off building a class D module because the builder started talking about something like impedence mismatches & needing a voltmeter etc. to fix it. THAT'S getting over my head. if i set my mind to it, i could build a speaker crossover from schematics, but solid state is different eg. you can't do resistors backwards.

as the "ohm's law" thing, 50w is DEFINATELY doable with 1.5 batteries. JVC's kaboom box has 50w for the subs PLUS something like 4wpc for the mains and that's a class A/B unit. i would have thought that class D would be even easier on batteries.

now, i'm just starting to think that the best thing would be to just quit trying to get 50w on my bike and build a 12v car battery trailer. i could easily do 4 x 8 inchers for subs with no cabinet volume issues and run as many watts as i want to. it's a bigger undertaking, but it has a few other upsides:
no more bike tipping with the slightest lean
i could use a car deck & changer with a remote on my handlebars
i could build a better looking cabinet without fear of dings & scratches
i could add SFX lighting

thanks a bunch for all of your input. so there really aren't any quality RTR 50w class D modules like i though there would be. oh well.

just for kicks though, i think i'll try a $30 40wpc car amp and see if it works with 15v in the short term. if it does, i'll get a pair of 93dB pyle outdoor speakers too.
budget minded said:
i'm looking to upgrade my bicycle system this summer.

Bicycle system?!?! Nobody in all those posts called him on this? Has my reading comprehension completely gone or are you using a small set of bookshelf speakers on your bicycle?!

Could I interest you in a set of these:

I know you said you only want completed modules, but if you get desperate enough, you can get a variety of power levels from the kits at 41Hz.

budget minded said: can't do resistors backwards....


budget minded said:
JVC's kaboom box has 50w for the subs PLUS something like 4wpc for the mains and that's a class A/B unit. i would have thought that class D would be even easier on batteries.

I had a kaboom box about 8 years ago when they first came out. I can tell you with certainty is was nowhere near 50w RMS. When it ran on the batteries it had even less output power due to an automatic power reduction to lengthen the battery life. Strangely you could bypass the power saver mode by just plugging the AC cord into the back of the unit but leave it unplugged from the wall.
yes... bicycle system! here's my V1.0

you've never seen a street party bike? some of them are sick with megawatts. check out some of them i posted in this old DIYaudio thread

recently, i've seen a realy twisted setup that has a ton of speakers all over. i found it on a search engine, but don't have the URL. the owner claimed it cost $4,000, but it looked like alot of cheap gear.

as to my upgrade plans for the bike at my website, i've found what i need by accident. for a minute i was resigned to mounting motorcycle batteries above my crank & using car amps, but i just found two nice class D amps that aren't killowatters

Alpine PDX-2.150

Blaupunkt THA275 PnP

that blaupunkt is PERFECT and as small as it is, i could mount it inside my frame over a 12 motorcycle battery instead of a more power hungry A/B unit.

BTW i'm also planning on getting lighter pyle outdoor 2 ways with 6 1/2" woofers that's rated at 93dB.

stay tuned. i'll update my website when i get v 2.0 built and 3.0 will be a tricked out 12v trailer with lighting effects etc., but that's probably next year
i've found the bike i was talking about again, here it is

and here's ANOTHER example

and another by a SERIOUS DIY customizer

and another from the "soul bike" "fossil fool" crowd who sell off the shelf pre-made gear

people who own gass guzzling pollution machines aren't the only ones who like taking their music on the go. it's amazing just how surprised people are to hear of, or see, bikes pumping tunes. it's not THAT radical an idea like, say, putting a swamp boat propeller on the back of a bike. now THAT'S radical.
not that i need it now, i found a 2X20w class D amp that can be bridged to 40w mono at ramsey electronics when thumbing through nuts & volts magazine.

if anyone needs a 40w class D monoblock, they can be found here...

right now i'm building a 560w bike trailer system with power acoustik plasmasphere amps, my NHT super zeroes as mains and a goldwood 10" acostic suspension sub but i thought i'd stop by and share my knowledge of the ramsey modules for anyone else looking for efficient & portable amps.
Looks like it uses the MAX9708 "Filterless Class-D".

The two stereo outputs are already in a BTL configuration; they can only be paralleled, not bridged, for use with ~4 ohm loads.

Running this board off of a 12v battery won't net you any more power than a sonic impact or equivalent, plus there are no output filters so I'm sure the radiated EMI is lovely. :smash:
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