Class D Audio Amplifiers

[akilleuz]

Hi,

1. Ok so i will mount it with metal screws in all the mounting holes!
2. Mica insolation between chip and heatsink
3. I will isolate the heatsink from the metal chasis in my HTPC
4. i will seperate the two modules be cutting the heatsink into to pieces.

I hope thats the correct assumptions

[Kjeldsen]

I'm no expert in groundloop issues, so maybe others or cristi can answer the best way of mounting two boards in a PC environment.

[Cristi]

Originally Posted by akilleuz

Hi,

1. Ok so i will mount it with metal screws in all the mounting holes!
2. Mica insolation between chip and heatsink
3. I will isolate the heatsink from the metal chasis in my HTPC
4. i will seperate the two modules be cutting the heatsink into to pieces.

I hope thats the correct assumptions

the reason why i recommend to use all the screws is that the GND copper pour has a star connection on the rectifier bridge hole.
at 4. the measure is effective only if the modules are using separate supply or at least separate windings on the mains transformer, to not have a common GND on the supply path, just at the input connectors.

[akilleuz]

Originally Posted by Cristi

the reason why i recommend to use all the screws is that the GND copper pour has a star connection on the rectifier bridge hole.
at 4. the measure is effective only if the modules are using separate supply or at least separate windings on the mains transformer, to not have a common GND on the supply path, just at the input connectors.

Here is how i would like to connect the supply:



I have mounted the modules with only metalscrews in all holes, but i have done it on the same heatsink as shown "Heatsink one", but is it nescesarry to cut the heatsink into two pieces as shown on "Heatsink two", due to the way i connect the trafo's?

[Cristi]

Please upload the picture here, i cannot see the picture in the link posted.
i'm not very sure what you mean by using 2 heatsinks, maybe the picture explain this, but i recommend to use just a single heatsink on which the amplifier board is installed, making the whole assembly very compact and with good thermal conductivity.

[akilleuz]

Originally Posted by Cristi

Please upload the picture here, i cannot see the picture in the link posted.
i'm not very sure what you mean by using 2 heatsinks, maybe the picture explain this, but i recommend to use just a single heatsink on which the amplifier board is installed, making the whole assembly very compact and with good thermal conductivity.

.



I think the picture will explain what i mean. (i have to modules)

[Cristi]

Now i understand what you mean. each amplfier board to have it's own heatsink. you should do this way if you have 2 heatsinks, and when install them try to isolate them from the case gnd, so that the gnd will be start connected at the input only.
i see that the transformers are 1x22V ???? can you rewind them to have 2x19V AC and to use a transformer for each module ? this will avoid other kind of problems related to the power supply.

[akilleuz]

Originally Posted by Cristi

Now i understand what you mean. each amplfier board to have it's own heatsink. you should do this way if you have 2 heatsinks, and when install them try to isolate them from the case gnd, so that the gnd will be start connected at the input only.
i see that the transformers are 1x22V ???? can you rewind them to have 2x19V AC and to use a transformer for each module ? this will avoid other kind of problems related to the power supply.

Okay i have one big heat sink and two smaller ones, i will just install them on seperate heatsinks and isolate the gnd, no problem at all.

I have just for now installed one module, and it plays very well so far. But when i turn the module on there are some "STRANGE NOISE" on the output, dosnt sound good in the speakers. Do you have any idea on this problem?

Sorry i think i was to fast: I will try to add a cap between mute and GND, first... Thank you for the great help so far, good job!!

[niss_man]

Hi Christi

I am interested in buying the DA-1 class d amp but cannot find many specifications. What is the THD of this amp with a 4ohm and 8ohm load? I was after a low thd amp that can drive a pair of 4ohm speakers.

[Cristi]

Originally Posted by akilleuz

Okay i have one big heat sink and two smaller ones, i will just install them on seperate heatsinks and isolate the gnd, no problem at all.

I have just for now installed one module, and it plays very well so far. But when i turn the module on there are some "STRANGE NOISE" on the output, dosnt sound good in the speakers. Do you have any idea on this problem?

Sorry i think i was to fast: I will try to add a cap between mute and GND, first... Thank you for the great help so far, good job!!

Try to add a 47-100uF capacitor between the Mode pin and GND. while this capacitor will charge slowly, the amplifier will toggle between Off, Mute and Play and eliminate the noise.
on the new version of the TDA89xx amplifier i already integrate the capacitor on the board, to avoid complications and headdache.