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C'mon... 34-Cent Stereo Amp 2x3W? 29-Cent Battery Savior? — Parallax Forums

C'mon... 34-Cent Stereo Amp 2x3W? 29-Cent Battery Savior?

ercoerco Posts: 20,256
in General Discussion
Can these be for real? Five pcs for $1.69: http://www.ebay.com/itm/201574969988
I have a pile of 386 amps but I gotta try these out, that price seems cheaper than free. Small board.

Another noteworthy tiny board (practically microscopic at about 1/8" x 5/8"), is this 29-cent (OK, ten pcs for $2.89) Li-Ion battery protection chip, which claims to do it all. Overcharge protection, over-discharge protection, short circuit protection, overcurrent protection. I just got these in, will test soon. http://www.ebay.com/itm/162025038275
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Comments

  • mindrobotsmindrobots Posts: 6,506
    Ok, I'm amped!!

    How can you not?? 2.5v to 5.5v operating range - cool!
  • Ron CzapalaRon Czapala Posts: 2,418
    erco wrote: »
    Can these be for real? Five pcs for $1.69: http://www.ebay.com/itm/201574969988
    I have a pile of 386 amps but I gotta try these out, that price seems cheaper than free. Small board.

    Good deal it seems - Adafruit sells the mono version (PAM8302) for $3.95 each https://www.adafruit.com/products/2130
  • User NameUser Name Posts: 1,451
    Great find! Can't wait to test them myself. Got some old PC speakers sans amplifier that I could never bear to throw away.
  • TorTor Posts: 2,010
    edited 2016-06-30 15:55
    Hm.. too expensive. So I went for the 5 for $1.54 deal instead. AddEdit: Link: http://www.ebay.com/itm/262493411717
    Update: Argh, what a waste.. should have gone for the 5 for $1.40 deal: http://www.ebay.com/itm/161995184749
    (or ten for $2.80 in a separate deal)

    -Tor
  • GordonMcCombGordonMcComb Posts: 3,366
    erco wrote: »
    Can these be for real? Five pcs for $1.69: http://www.ebay.com/itm/201574969988
    I have a pile of 386 amps but I gotta try these out,

    Surely you're the only person still using the LM386. This is 2016, my friend -- you know, the 21st century!

    (Sorry for calling you Surely.)



  • David BetzDavid Betz Posts: 14,516
    I know we're not talking about high-end stereo equipment here but how do class D amplifiers compare with the more traditional analog amplifiers as far as noise and distortion? Do purists ever go with class D or is it reserved primarily for low-fidelity applications?
  • rosco_pcrosco_pc Posts: 464
    As with everything people either love it or hate it. However lookup the NAS D 3020, a high end class D amp :)
  • kwinnkwinn Posts: 8,697
    David Betz wrote: »
    I know we're not talking about high-end stereo equipment here but how do class D amplifiers compare with the more traditional analog amplifiers as far as noise and distortion? Do purists ever go with class D or is it reserved primarily for low-fidelity applications?
    rosco_pc wrote: »
    As with everything people either love it or hate it. However lookup the NAS D 3020, a high end class D amp :)

    Noise and THD are generally worse for class D amplifiers than for analog ones, but the NAS D 3020 specs are pretty impressive. They are at a level where 99.99% or more of audio listeners would not be able to tell the difference between the NAS and a top of the line analog amplifier.
  • ercoerco Posts: 20,256
    GordonMcComb wrote: »
    Surely you're the only person still using the LM386. This is 2016, my friend -- you know, the 21st century!

    C'mon, if it's a cute little module under a buck, you know I'm on it like stink on a monkey! http://www.ebay.com/itm/200-Times-LM386-Audio-Amplifier-Module-Input-10K-Adjustable-Resistance-5V-12V-/301953923632

    12D79287178B9A369761D62303CECCCECE0374CD133353CE33C8C7F15323F513.JPG
  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2016-08-17 16:42
    Well. I got my ten Class D, 3 watt amplifier boards from eBay - Thanks erco!

    I wired one up to some 3 ohm speakers and 4.5V battery pack.

    It sounds better than the video - my camera doesn't have the best microphones,

    BTW - The eBay specs for the amp indicate that you need two wires for each speaker - do not try to use a common wire for the negative!

  • ercoerco Posts: 20,256
    Great demo, glad to hear you're pleased with them. As usual, everyone gets theirs before I do!

    Now you have me recalling which songs which 1980's stereo stores blasted to demo their high power stereo's dynamic range and all I come up with is Journey... :) Don't stop believin'!







  • ercoerco Posts: 20,256
    edited 2016-07-16 00:51
    Hoarder's Haiku:

    My amps came today.

    But I have no time to play.

    Hoarding anyway.


    Bonus points for rhyming!
  • John A. ZoidbergJohn A. Zoidberg Posts: 514
    erco wrote: »
    Hoarder's Haiku:

    My amps came today.

    But I have no time to play.

    Hoarding anyway.


    Bonus points for rhyming!

    Damn, now you have to influence me to buy one, will buy these soon! :)

    ... and I hoard them for future use!

    Yeah, I'm in the middle of repairing a musical clock, so this one helps a lot too! :)
  • ercoerco Posts: 20,256
    edited 2016-07-16 14:46
    Irresistible deals only sold in lots of ten, makes us all hoarders.

    Care to Super-Size that?

    Only in America. And China.
  • TorTor Posts: 2,010
    Got mine yesterday, no time to play yet.
  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2016-07-18 15:43
    Picked up some 5x7 speakers at Walmart on sale for half price - $14.44. (This was the online price, but they matched it at the local store).

    http://www.walmart.com/ip/Scosche-5x7-6x8-4-Way-Speaker-Set/46997824

    Supposedly they handle 50 watts RMS - these little amps actually drive them pretty well!

    BTW - The eBay specs for the amp indicate that you need two wires for each speaker - do not try to use a common wire for the negative!

    5x7%20speaker.jpg
    5x7 speaker.jpg
    800 x 525 - 46K
  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2016-07-19 17:55

    Decided to upgrade the speaker enclosure from an old Sparkfun red box (in my video above) to a solid poplar one:

    Looks better and sounds better, of course. Luckily I had a 4 inch hole saw so I didn't have to use a jigsaw for the speaker cutouts...

    speaker%20cabinet.jpg
    speaker cabinet.jpg
    1280 x 960 - 232K
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2016-07-19 19:28
    Ron Czapala wrote: »
    Luckily I had a 4 inch hole saw so I didn't have to use a jigsaw for the speaker cutouts...

    Pshaw. Get a CNC like the rest of us!

    For a really nifty wood-cutting CNC in action, check out Frank Howarth videos on YouTube. His CNC is a more recent acquisition, so fiddle with the later vids. Your drooling can start here:





  • PublisonPublison Posts: 12,366
    edited 2016-07-19 19:54
    GordonMcComb wrote: »
    Ron Czapala wrote: »
    Luckily I had a 4 inch hole saw so I didn't have to use a jigsaw for the speaker cutouts...

    Pshaw. Get a CNC like the rest of us!

    For a really nifty wood-cutting CNC in action, check out Frank Howarth videos on YouTube. His CNC is a more recent acquisition, so fiddle with the later vids. Your drooling can start here:





    Thanks for sharing. NOT! Now I know I can't afford my dream shop. :)

    I have the same Dewalt Radial Arm Saw, circa 1965. Still working as well as my circa 1965 Delta (Rockwell) band saw. Handed down from my grandfather, to my father, to me. I'm sure they will last to give to my son.

    EDIT: I see this was WAYYY OT for this post.



  • User NameUser Name Posts: 1,451
    Ron,

    Thanks for the demo! My boards arrived >10 days ago, but I'm ashamed to say I just looked them over and set them on a shelf. 200 WS2812b LEDs arrived about the same time and they got all the attention. After seeing the class D amplifier at work, I realize I've got to give it higher priority.
  • Ron CzapalaRon Czapala Posts: 2,418
    GordonMcComb wrote: »
    Ron Czapala wrote: »
    Luckily I had a 4 inch hole saw so I didn't have to use a jigsaw for the speaker cutouts...

    Pshaw. Get a CNC like the rest of us!

    Way out of my price range - plus I don't have room for it.

    Have to make due with my table saw, drill press, etc.
  • ercoerco Posts: 20,256
    Now THAT'S a beautiful speaker box, Ron. It's the wood that makes it good! Is there a divider wall between the L/R speakers?
  • ercoerco Posts: 20,256
    Ron Czapala wrote: »
    GordonMcComb wrote: »
    Get a CNC like the rest of us!

    Way out of my price range - plus I don't have room for it.

    Have to make due with my table saw, drill press, etc.

    You ain't alone Ron! IOW this SOB is SOL WRT a CNC.

    Have at it, mods! I had my acronym fun.

  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2016-07-19 22:32
    erco wrote: »
    Now THAT'S a beautiful speaker box, Ron. It's the wood that makes it good! Is there a divider wall between the L/R speakers?
    Thanks! I love those "hobby boards" from Home Depot. Their oak boards are nicer, but this little box did not warrant oak ;-)

    I put some Wipe-On polyurethane on it.


    I decided not to bother with with a divider in this cabinet - since the separation is only a few inches.
    You can hear the distinct left/right channels and I won't be pushing big watts thru it.
    The speakers were out of an old CD boombox (I taped them in so I could mark the mounting tab holes with a punch).
    Might swap out the speakers for some better ones although it sounds pretty darn good with the little Class-D amps.


    insides.jpg
    insides.jpg
    800 x 600 - 87K
  • localrogerlocalroger Posts: 3,451
    That's a very clean, pretty build, Ron. Not everything in life has to be CNC!
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2016-07-19 23:37
    Try some batting in that enclosure. In an odd counter-intuitive way, the batting actually increases the apparent space of the enclosure as "seen" by the drivers, and you get a better sound (at least in the midrange, which is what those speakers are built for).

    Though fiberglass is better, you can use white polyfill from Joann's -- costs something like a buck for a sheet, and you'll only need one sheet to try it out. Worth a shot for the non-ported cabinet you've made (without a CNC...).
  • Ron CzapalaRon Czapala Posts: 2,418
    localroger wrote: »
    That's a very clean, pretty build, Ron. Not everything in life has to be CNC!

    Thanks!
    GordonMcComb wrote: »
    Try some batting in that enclosure. In an odd counter-intuitive way, the batting actually increases the apparent space of the enclosure as "seen" by the drivers, and you get a better sound (at least in the midrange, which is what those speakers are built for).

    Though fiberglass is better, you can use white polyfill from Joann's -- costs something like a buck for a sheet, and you'll only need one sheet to try it out. Worth a shot for the non-ported cabinet you've made (without a CNC...).

    I was wondering where you could find batting - thought about ripping open an old pillow.

  • SeairthSeairth Posts: 2,474
    Ron Czapala wrote: »

    I was wondering where you could find batting - thought about ripping open an old pillow.

    Look for a local fabric store. Even some Wal-Marts have batting, if it has a fabric section.
  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2016-07-20 02:24
    Seairth wrote: »
    Ron Czapala wrote: »

    I was wondering where you could find batting - thought about ripping open an old pillow.

    Look for a local fabric store. Even some Wal-Marts have batting, if it has a fabric section.

    Thanks. I have a Jo-Ann's fabric store close and a couple of Walmarts...

  • VIRANDVIRAND Posts: 656
    Has anyone bought any Russian electronics on ebae? I'm leery of them but curious about how it goes because they also have interesting and different stuff.
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