TA2024 Evaluation Board Mods

ta2024 evaluation board unmodifiedAleš Mravlak  is another hobbyist who has discovered the joys of the Tripath TA2024 Class T amplifier IC.  In his case he started off with a Chinese made module supplied to him by Arjen Helder.  This module uses the Tripath evaluation board schematic and as Aleš shows here, there are plenty of potential modifications you can do to this board to get the most from it. 

 

The first picture shows stock evaluation board for TA2024.   

 

First thing that I did on this Tripath TA2024 amplifier board was to remove the two input filter caps.  The caps have a value of 100pF. These two caps are for filtering high frequency noise from the signal path to the Tripath TA2024 integrated chip (I.C.), This is done on the Tripath amplifier module to remove noise generated by interference.  Ideally this low pass filter (LPF) would filter out noise outside the audio frequencies, however some of the frequencies in the audio spectrum are being filtered in this design.

 

The low pass filter capacitors on the Tripath TA2024 module
The filter capacitors are mounted upon the underside of the Tripath TA2024 amplifier module, you can see them here in the second image marked by two red arrows.  (editors note, on the Sure Tripath TA2024 modules this Low Pass Filter is included as well.  This article details their removal)

 

Then I removed 6 pole connector, on the far end of the PCB where you can hook up the 12-16 volt power supply and cables to the speaker terminals.

 

In the complete amplifier wires will be directly soldered onto these pins, soldering cables offers a better connection than screw terminals.  You may wish to leave the terminals in place at least when testing you modifications to the Tripath TA2024 based circuit board.

 

{include_content_item 45}removing the solder from the TA2024 boards screw terminalsI used de-soldering wick for this job, alternately you could use a solder pump to remove the bulk of the solder from the board mount terminals.  Make sure that you have removed all the solder so that you won't damage the traces and through hole connections between the top and the bottom of the printed circuit board.  Printed circuit boards require little force to damage the traces so be thorough here removing the solder.

 

Before starting the next stage of modifications on the Tripath TA2024 evaluation board I removed all the bigger elements on the board( coils, capacitors, input holder).  I did this to make other modifications easier to manage.  These through hole components were removed in a similar fashion to the screw terminals. 

 

Identifying the components of the Tripath TA2024 eval board
The next picture shows all the elements that will be replaced with higher grade components. The green arrows mark the 100nF caps, with marking on the board C26, C16, C7, C6.

 

The red arrows indicate also two 100nF caps, these form part of the output filter for the Tripath TA2024.  The output filter is an essential part of a Tripath TA2024 amplifier design, it is a low pass filter which removes the switching frequency which is an inevitable by-product of Class D amplifiers.  

 

I removed these two caps and later I soldered them directly on the speaker terminals.  I recommend that you invest here here in some high quality capacitors, because I find it  improved the sound of the Tripath TA2024 amplifier module.

 

Blues circles indicate 470nF caps (C12, C13, C22, C25, C27, C28).  These I removed and replaced with fairly ordinary, polyester caps.  These are specified to have a 10% tolerance on their capacitance.  However using a capacitance meter, I matched the capacitance of the components.

 

Resistors in yellow circles could potentially be replaced with more highly specified components.   I didn't do that, but they will improve the sound, they have a value 22k ohms.  If you do decide to replace these resistors, look for resistors with as low a tolerance as possible.  This is expressed in their specifications as a percentage.  1% tolerance resistors are readily available, though even more closely matched can be found.  Alternately use a multimeter to hand match resistors with lower tolerances.

 

adding solder to the traces of the TA2024 amplifier module
Looking very closely at the Tripath TA2024 evaluation circuit board, you can see how thin the copper traces are to the TA2024 Integrated circuit.  Because the copper lines near the chip are so thin, I decided to cover them with a bit of solder. This should lower the DC resistance of the copper traces simulating thicker traces. 

 

To do this, you first have to scratch off the green protective solder mask layer that covers the copper trace . I used carefully used a knife to scrape this solder mask layer and it takes some patience.  If you are attempting this modification please don't rush because you could potentially damage the copper trace.

 
In the closeup picture of the tripath TA2024 IC you can see solder applied to the copper and the through hole pads that will attach the capacitors to the printed circuit board.


attaching a polyester capacitor to the Tripath TA2024 board
Below you can see where i attached the replacement polyester capacitor to the pads marked C28.  You may notice a bit of extra solder, that makes connection to the negative line of speaker, make sure that you'll do the same. I bridged it with a short wire hare copper wire. You could also use the bent leg of the capacitor itself to make this wire bridge.

 

Capacitor C28 fitted with polester caps on the TA2024 board
Here is the completed board with most of the replacement caps soldered in place.  in this picture the power supply capacitor is still to be attached.

 

The polarity marked on the Tripath TA2024 amplifier module
In the right hand picture I have marked the positive holes and negative holes of the capacitor mounting point.

 

The legs of the capacitor are soldered on the bottom side of the Printed Circuit Board. Almost all of the traces on the under side of the printed circuit board are dedicated to the power lines and grounds Input and power supply Ground's are separated. between the power line and the power ground I've soldered a  2200uF 25V cap to act as a reservoir capacitor, This reservoir capacitor was not soldered to the circuit board traces, instead it is connected via a bit of wire.

 

This capacitor also prevents the pop up sound when you turn your amplifier on.

 

The input caps which block DC are 2,2uF 250V polyester.  For the input capacitors I recommend that you use a  2,2uF cap. This value gives I think the best sound quality sound.  (editor's note.  The reason that different capacitor values affect the sound on Tripath TA2024 amplifier designs is that they in conjunction with the input resistors form a high pass filter.  You can calculate the -3db cut off point of his high pass filter using my online calculator)

 

The TA2024 amplifier mounted in an aluminium case
The best sounding caps for this little amplifier  that I have tried in this position are Audyn Cap KP Sn 2,2uF 160V +-2%.  I settled on this capacitor after testing a few in this TA2024 amplifier module.

 

 

Here are some images of the finished amp. You can see the big capacitor for the power line which is connected to the board with wires. Beside this capacitor you can also see the output filter capacitors (100nF). 

 

Actual size of this amplifier module is smaller than a CD. 

The complete Tripath TA2024 amplifier in its case.

If you have enjoyed this article and have further questions from the author you can contact Ales here.

 

Arjen Helder may still have some of these amplifier modules for sale.  You can visit his ebay store here if you would like to buy one. 

 

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