PC 7.1 audio on motherboard

Modules Audio Hi Fi Projects
1

I am new to audio system building so my question may be simple to answer for you.

I wish to amplify the audio signal coming from my PC’s motherboard.

I have two choices:

  1. From the headphone output jack (Pre amplified)
  2. From the 7.1 speaker outputs (3 only)

My question for option 1 is:
Will I need to use two power amplifiers (VM100) and two transformers (or one with larger VA) for left and right channels?

My questions for option 2 are:
Can I use these non pre-amplified signals for the input to the VM100?
Will I need to use three power amplifiers (VM100) and three transformers (or one with larger VA) for left, right and sub woofer channels?

Any help or circuit diagram would be much appreciated

Thanks in advance for your help

Cheers

2

Some answers:

  1. You need two VM100 but you can use ONE bigger transformer (more VA, same secundary voltage!).
  2. Yes you can! Same modus operandi as in answer 1.
3

The use of one transformer for two VM100 will generate problems, as both units have a rectifier bridge on board. This will generate GND problems. We strongly recommend separate transformers for the amps.

4

I don’t see any problem. All GND references are to the same ground. The GND is the middle tap of the transformer. If the two VM100’s are fed with wiring that is thick enough and from 1 point to the 2 or 3 amplifier modules (star topology) and ofcourse all amplifier modules are built within the same housing (keeps the wiring short and +/- equal length) it makes no difference if each module has his own bridgerectifier or not? Why should that give problems?

5

As you state, a single transformer makes the wiring critical. To avoid problems which are sometimes not easy to solve by the (inexperienced) hobbyist, we recommend floating supplies.