Looking for advice on selecting an amp for 12V supplied portable system

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Ford Prefect

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Joined 2013
#1
Hello, I'm new to the forum and the hobby and have a newb question. I'm building a portable boombox that runs off a 12V SLA. I'm looking for advice on selecting an amp. I have built two before from thrift store speakers using pyle pfa 200 and 300, respectively. Both had problems, the pfa200 had one channel crap out on me shortly after I got it. The 300 has a strange problem with the voltage sensitivity (I'm thinking, still working on it) where it will run off the adapter but not the slightly higher voltage of the SLA.

Anyway, I'm thinking I want to start using these tripath amp boards or maybe someone has some better suggestions.

My question is, what options do I have available. I see these tripath 25wpc ones on ebay for $25 after shipping from china and no name distibuters, are these junk or decent?

When I buy an amp board, how much modification has to be done for a final setup? I've only used out of the box ready amps like the pyle.

Do I need to build an enclosure for the board or just mount it as is.

I'm not really wanting to buy some of the more expensive T-class ready to go amps. I've got more time than money so no learning curve is too steep if it makes for a better and cheaper solution. Thanks, this forum is great and full of so much information, hard to get a grip on it. -Ford
 
#3
The Lepai 2020+ is <$20 from Amazon shipping included if you order above $25 (get some RCA to 3.5 mm cables). Save yourself hassle from buying from China or ebay. For a boombox, you probably don't need to mod it other than boost the power supply capacitor. The other mods are trickier and are for going after higher end nuanced sound which you probably won't discern in a boombox running Pyle's. The Lepai comes with an enclosure and works great with 12v SLA batts. Note that the Tripath chip claims 25w but in reality, if you want to run at low distortion levels, it is 6watts at 8 ohms and 12watts at 4 ohms to stay below 0.1%THD. At full ratung of 25 watts it will be in the noticeable 10%THD range. You should check out the thread by Saturnus on the 'Boominator' to get more ideas and tips on boombox construction with Lepai and SLA's. Good luck.
 
#4
#5
gychang said:
any new update on your impression of different amps?
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Nope, I wrote that this morning... I haven't recieved the MKII yet... But If you want My opinión between the others... The one I like the most Its the lepai, but only after modding... Changed the oamps, the output inductors with coils, and the output caps for vima... Beside I also changed the power input cap, for a bigger one... But, If I had to choose without mods, with no doubt I will choose the YJ one, must say that the YJ sound is clear and with a nice image, but I like the sound of the lepai with the tone control with the LM4562 oamps... I think Its more a matter of taste...

Once I recieve the MKII I Will let you know my opinion, I might also mod this changing the inductors for coils as I did in the lepai...
 
#10
Ford Prefect said:
Portability is the criteria. I have some 8ohm, 8" thriftstore fullrange speakers, and just not sure if 25wpc is enough. It might be, I'm just new to this and don't have a grip on it yet.
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To get 50W into 8 ohm you need 30V supply voltage absolute minimum. Not easy to get on batteries.

Btw, the Tripath amp you have now does not give 25W into 8 ohm on a single 12V SLA. It gives 8W (yes, eight).
 
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#12
I think I'll give the Lepai 2020 a try and attempt the replacement of the big capacitor. Can anyone recommend some beginner audio electronics books? This forum is great but many of the threads are a bit hard to digest, being that I have pretty much zero knowledge of the subject. I'd like to get more familiar with it so I can better understand what your talking about. Thanks
 
#13
Ford Prefect said:
I think I'll give the Lepai 2020 a try and attempt the replacement of the big capacitor. Can anyone recommend some beginner audio electronics books? This forum is great but many of the threads are a bit hard to digest, being that I have pretty much zero knowledge of the subject. I'd like to get more familiar with it so I can better understand what your talking about. Thanks
Click to expand...

am in the same boat as u. there are other threads but too much info...
 
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