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Finished up a project this morning

My son, Jacob, and I have been building a subwoofer to compliment the small pair of speakers we built for his room two years ago.  I had an extra SD215A-88 sitting on the shelf and I bought one of those 2.1 plate amps on clearance from PE.  Very pleased with how they turned out looking and sounding.  Tons of bass from a single 8" and 50 watt amp.

tajanesjhollanderJeff_FRon_Ehifiside4thtryNicholas_23dynamoTurn2S7910and 3 others.


  • Gorgeous, drool-worthy from his all-important buds, and I'm sure that he will get "the bug". Slam dunk!
    Don, Donno, or "Hey you" all work for me, But never "Mr Johnson"
  • I bet that is a killer setup!

    Makes me wonder why the market is not flooded with a wide variety of 2.1, 5.1, 7.1 etc plate amps. 
    I have a signature.
  • jr@mac said:

    Makes me wonder why the market is not flooded with a wide variety of 2.1, 5.1, 7.1 etc plate amps. 
    Yeah - throw in an HDMI connection with a decoding chip and you could have half decent home theater from your favorite streaming device.

    Craig - those are really cool. I love the color. Reminds me of Turbosound blue.  I'm sure he'll treasure them. I know our oldest won't part with the horribly flawed, but surprisingly decent sounding speakers we built together when he was little.
  • This was a great project for us.  He couldn't wait for me to get home from work so we could do the next step.  Obviously I cut all the MDF on the table saw and flush trimmed the edges with the router.  But he did almost everything else, from gluing/clamping, drilling holes with the drill press, to actually cutting out the speaker through hole and amp cutout with the sabre saw.  Are the cuts perfect?  No, but they are good enough and HE did them.  He really caught on how to roll paint (ruined a shirt lol).
  • If anyone is interested the sub enclosure is 24 liters net with a 2.5" dia x 9" long port.  I would have liked to made the enclosure bigger to take full advantage of the SD215A-88, but this was built to fit in a particular spot in his room.  Sim'd F3 is 36ish.  It is sitting in a corner in his 10 x 12 foot room.  Quite impressive bass really!  Don't let 22W x2 and 50W x 1 fool you....  we're going to have to lay down some SPL rules lol!
  • Great bass boogers, those SD215A-88 are!
  • Nice project.  I have to get to work on a box for the pair you sold me. 
  • FWIW I used the Dayton plate amp bone stock.  I plan to try Ed Perkin's mods/upgrades in the future.  I bought two of these amps.  I just took a picture of the preamp/filter pcb so that Ed can circle and label the SMD components that need to be replaced.  As stock the amp isn't dead quiet buy it's not total crap.  With the inputs shorted to ground there is barely any sound coming from the left and right speakers (you have to put your ear right up to them to hear any hiss).  There is however some low level hiss and noise if you listen closely to the .1 sub.  But I doubt that if you use this at a computer work station with the sub down on the floor you could even hear that.
  • Looks great, cool project!
  • edited November 2019
    Here ya go Ed.

  • Holy glue Batman! Hope it’s less corrosive than the old glue they used in the 80s stuff. Is the discoloration of the glue heat related?
  • Brand new unit so not heat related.  I think they used all that glue to seal around the pots and make the plate amp air tight.
  • Public Service Announcement

    The kids were listening to some Christmas music this morning at a moderate volume and then they came and got me.  "Something is wrong with Jacob's stereo Dad".  Oh boy, the plate amp has already died.  There is some bass music going to the sub but the left and right channels are nothing but a "tick, tick, tick" sound at about 1 Hz.  Hopefully PE will replace it with one that lasts longer that a couple of hours.  Nothing worse than see the bright happy light in your kids' eyes go so dark so quickly.

    Buyer beware :(  
  • That stinks! Hopefully it's just an issue with that one unit you got and not something wonky with the design.
  • First world problem.  Your kids will be fine.  
    Nice build you did with your child, as all of your builds. 
  • Got the picture Craig and I'll update it in a day or two.  Sorry to hear about the amp going belly up
  • I think it went into some sort of thermal shutdown.  A few hours later I tried it again and it worked fine.
  • Here’s the updated MCA2250E PCB picture showing the modifications I made.  It’s the upper left hand corner of Craig’s posted picture.   My before and after measurements are in the "PE DOTD" thread HERE.

    The modifications are:

     Purple ellipse:  Remove resistor (300K) and leave empty.

     Yellow rectangle: Remove resistor (150K) and replace with 75K.

     Green rectangle: Remove resistor (18K) and replace with 47K.

     Blue rectangle: Remove resistor (15K) and replace with 36K.

     Red Rectangles:  Remove the five 100 nF capacitors and replace with same valued X8R capacitors.  I replaced these caps to reduce distortion after I noticed a large (> 25X) distortion increase across the C118 cap (the one located below the IC).  X8R caps are automotive grade (i.e. high temp rating) X7R caps and I figured they were the best I could do in the same footprint.  Ten of these caps cost $2.30 so the price was right.

     The link to my Digikey BOM is: LINK. I bought ten of each item since the price and my SMD soldering skills are both very low.   Let me know if you have any questions.



  • Thanks Ed!
  • Cool project - I like the blue!
  • I cut up a heat sink I saved from some piece of equipment and bolted it onto the back of the plate amp with a little heat sink compound right where it was running the hottest.  We had it playing for a few hours yesterday and it never shut down.  Problem solved!

  • I was thinking of mounting external hear sinks on some high watt zistors since they were heating up...

    but then i got lazy...  :/
  • Nice hack, Craig. I ordered one of these amps this weekend due to the $5 off code and the $49 shipping threshold. I see this week it is 10% off, so it would be another $1.50 cheaper. 
    I have a signature.
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