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TOPIC: Mini-dsp 2.1 setup using modified TPA3110 amps.

Mini-dsp 2.1 setup using modified TPA3110 amps. 4 years 5 months ago #19287

  • footbaldd
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I just finished my Mini-dsp stereo and thought I would share. I am using the unbalanced 2x4 mini-dsp to feed a pair of modified Sure TPA3110 amplifiers with one of them setup in mono for the subwoofer. The full range drivers I am using are Tangband W3-881SFJ, and the subwoofer I am using is a Tangband W5-1138SM. I am still playing around with the dsp setup, but it is rather satisfying to say the least.





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Mini-dsp 2.1 setup using modified TPA3110 amps. 4 years 5 months ago #19288

  • Jim the Oldbie
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+1 karma for the cigar box alone! Nice work all around. :-)

-- Jim
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The following user(s) said Thank You: footbaldd

Mini-dsp 2.1 setup using modified TPA3110 amps. 4 years 5 months ago #19306

  • devteam
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Agreeing 100% with Jim here.. That cigar box is is a real nice touch.. :-)
Intrigued by your sub design.. That looks neat. Tell us more!

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Mini-dsp 2.1 setup using modified TPA3110 amps. 4 years 5 months ago #19313

  • footbaldd
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The sub enclosure is the first transmission line box I have made. I don't have my notes right now, but I calculated the quarter wave length using a bit of optimization from my starting point of 45hz. The quarter wavelength is used to determine centerline length, and then cross sectional area was maintained above 14 sqin throughout. I designed it in Sketchup. I built the box out of 1/2" baltic birch. The box was then sealed with polyester resin and coated in bed-liner internally (The idea is to promote laminar flow). I used a moderate amount of stuffing in the line.

I want to get more familiar with the Mini-dsp, and with designing bi-quad filters before I get out my measurement tools, but right now I have the setup running a Butterworth 18db/oct low-pass on the sub at 230 hz, with a Bessel high-pass at 230 hz on channels 3-4. I also had to attenuate the full range speakers by 6 db to get a proper response for right now. Since the output voltage on the mini-dsp is a bit low for the amplifiers, I ordered a pack of surface mount resistors to change the gain bias on the amps in an attempt to recover output. My plan is to setup the sub amplifier with 32db gain, and keep the other amp at 26db gain. Then I should be able to remove the 6 db attenuation from the highs and make up a bit of output.

I have run the sub off of a much larger amp, and it seems that it could easily be driven at twice the rated power. I am building an upgraded version of this one right now with two subwoofers and more power.

I also have much better heatsinks to install after I finish changing the gain. While looking through the ti data set for the amps, I noticed that I might be operating into the thermally limited region of operation, so I am going larger on the heatsinks, but it is important to note that I have not witnessed either amp go into thermal shutdown or get excessively hot. (being more concerned about the amp for the subwoofer)

Here are a few additional pictures:







Heres a quick pic of one of my other current projects. The raspberry pi dragon box. RPi2, PCM5122 DAC, TPA3116 amp. I want to incorporate mini-dsp into the next one.

Last Edit: 4 years 5 months ago by footbaldd.
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