Modify Trust Mila 2.0 USB speakers / Deadbug QFN

Edited:see ‘update’ below for bonus features!

Recently I got a present for Sinterklaas, a USB audio set. I asked for this as I like watching movies from my laptop, but hate the hassle of cables that surround my previous set. Also, my 3,5 year old son popped the tweeters of the old setup by pushing the nice shiny conus….

So I got the….

Trust Mila 2.0

Trust Mila 2.0 speakers

This system is really easy in use: just use USB for power and the audio jack for the sound. Although I was glad to have a working audio setup again I had a few nuisances with this product:

  • No audio-> lots of noise. The volume control controls input volume, but all the noise on the speaker is apparently coming from the output stage, as it’s VERY noisy.
  • Overall sound quality is flaky. It sounds very thin. I got the impression that better performance might be possible
  • VERY bright blue LED

Other power amp

I opened up the speaker containing the amplifier, and found the PCB shown in the image.

Original Electronics


I couldn’t find the datasheet of the amplifier, and thought little improvement could be made to this circuit. I went looking for a replacement amp. The criteria were:

  • 4.5 to 5.5 V supply voltage
  • More than 1.5W audio power
  • Minimal external parts count
  • Able to drive 4 Ohm
  • Easy to obtain

On the site of maxim I found the MAX9759. It matched my requirements, and I could sample it. Hooray!

Soldering

The MAX9759 is a 16-lead TQFN, which means it has no legs like a DIL or TQFP IC. I took a deep breath, and soldered it ‘deadbug style’:

Dead bug QFN 'right'

Dead bug soldering QFN 'left'

Dead bug soldering QFN 'left'

This took about 2 hours a piece, I used a normal soldering station, and yes, you can debate if it would have been faster to etch my own PCB. I used the circuit as described on page 9 of the datasheet with maximum gain (G1 and G2 both grounded). The result is a major improvement:

  • The speakers sound LOTS better, with less noise. I included a video (shot with a normal still camera) in this post which gives a hint of the difference in sound quality.
  • The amplifier IC’s do not get noticeably warm
  • Removing the original PCB also removes the irritating blue LED

Finally, when everything was working I added a BIG blob of epoxy glue to fix all wires. When mounting all components I shortened the wires to match the size of my laptop.

Ready to fix circuit

Final considerations

USB soundcard

I thought about using a USB soundcard I purchased for $2 at DealExtreme some time ago. That way, I’d only have a USB connection to my speakers. I decided not to do that, as that would mean switching soundcards every time I’d plug in speakers. Also, I can use them to play other sources now.

Quality

How, ON EARTH can it be cheaper / better for Trust to use this crappy amplifier board with lots of components whereas the budgetary price of the Maxim IC is USD 0.75 at 1000 pieces? I know Trust is known for making decisions based on cost, but this is quite baffling for me. Is can’t be that much cheaper to place and purchase so many through hole components. This does not make sense to me….

Demo video

http://vimeo.com/33724857


Update


After using the modified speakers for some weeks I still found the wires too messy. Also, the sound output from my laptop gives a bit of a buzz when my harddisk is busy. Bad design Acer! I had a $2,80 usb soundcard lying around and decided to build that into the speaker housing. Now I’ve got true USB speakers, with power AND sound over USB. They’ve been in use for some weeks, and I’m very happy with the result.

Yes, it's a mess on my desk. Glue gun warming up.

PCB of soundcard visible on the left

11 thoughts on “Modify Trust Mila 2.0 USB speakers / Deadbug QFN

  1. [...] [Victor] likes to watch movies on his laptop, but the tiny speakers in his machine don’t do [John Williams] and other perfectly fine soundtracks justice. To pump up the jams a little bit, [Victor] got a pair of Trust Mila 2.0 speakers for Sinterklaas. Unfortunately, these speakers were terrible – noise everywhere, tinny output and a brighter-than-the-sun blue LED. These problems were fixed once [Victor] replaced the amplifier in both speakers. [...]

  2. [...] [Victor] likes to watch movies on his laptop, but the tiny speakers in his machine don’t do [John Williams] and other perfectly fine soundtracks justice. To pump up the jams a little bit, [Victor] got a pair of Trust Mila 2.0 speakers for Sinterklaas. Unfortunately, these speakers were terrible – noise everywhere, tinny output and a brighter-than-the-sun blue LED. These problems were fixed once [Victor] replaced the amplifier in both speakers. [...]

  3. [...] [Victor] likes to watch movies on his laptop, but the tiny speakers in his machine don’t do [John Williams] and other perfectly fine soundtracks justice. To pump up the jams a little bit, [Victor] got a pair of Trust Mila 2.0 speakers for Sinterklaas. Unfortunately, these speakers were terrible – noise everywhere, tinny output and a brighter-than-the-sun blue LED. These problems were fixed once [Victor] replaced the amplifier in both speakers. [...]

  4. [...] [Victor] likes to watch movies on his laptop, but the tiny speakers in his machine don’t do [John Williams] and other perfectly fine soundtracks justice. To pump up the jams a little bit, [Victor] got a pair of Trust Mila 2.0 speakers for Sinterklaas. Unfortunately, these speakers were terrible – noise everywhere, tinny output and a brighter-than-the-sun blue LED. These problems were fixed once [Victor] replaced the amplifier in both speakers. [...]

  5. Elias says:

    Damn, I wouldn’t have tried to solder that for sure.

    Let me know if you need a milled PCB sometime, I live in Enschede and have some gear in my workshop.

    • admin says:

      Hello Elias (speaking Dutch?),

      That would be a fine offer!. I already have one or two very small designs that would benefit from a milled PCB, let alone that it’s interesting to see a PCB mill. I’ll send you an email to make further appointments.

      With kind regards, and thanks for the offer,
      Victor

  6. [...] [Victor] likes to watch movies on his laptop, but the tiny speakers in his machine don’t do [John Williams] and other perfectly fine soundtracks justice. To pump up the jams a little bit, [Victor] got a pair of Trust Mila 2.0 speakers for Sinterklaas. Unfortunately, these speakers were terrible – noise everywhere, tinny output and a brighter-than-the-sun blue LED. These problems were fixed once [Victor] replaced the amplifier in both speakers. [...]

  7. M4rc3lv says:

    Ik koop nooit rommel van Trust, maar ik moet het misschien toch vaker doen, je kunt er een leuk hobby-projectje mee uitvoeren.

  8. [...] [Victor] likes to watch movies on his laptop, but the tiny speakers in his machine don’t do [John Williams] and other perfectly fine soundtracks justice. To pump up the jams a little bit, [Victor] got a pair of Trust Mila 2.0 speakers for Sinterklaas. Unfortunately, these speakers were terrible – noise everywhere, tinny output and a brighter-than-the-sun blue LED. These problems were fixed once [Victor] replaced the amplifier in both speakers. [...]

  9. midnight says:

    Regarding your comments about Trust products and the costs not making sense… Write your analysis to them and I am sure you can get a nice (side) job assessing their electronics.
    Make a cost case and they basically HAVE to hire you as a consultant :D

    Their products usually are re-branded Chinese products that are probably bought at bulk prices. I think Trust doesn’t look at the internals (judging by the crap you can find inside sometimes).

    Interestingly enough some of their products actually can be very good if your lucky. But it’s always a gamble.

  10. tuyul says:

    you can get big and also best amplifier from cheap original aiwa radio cd , it’s player has separate tunner fm , amplifier audio and separate cd audio panel … it’s fun

    Aiwa CSD-MP100

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