Headphone amps and a front bay of a computer.

Is it possible to modify a headphone amp (either a MINT or Cmoy) to fit into a front bus bay of a computer and be powered by the main PSU? I'm not to sure about the amount of line noise that the amp makes along the main lines, and I lack the technical skills to actually find out. I was also wondering if it is even safe to run these within a case.

P.S
Is there any company out there that already has such a product...?

I suppose it is doable, but you can't use an amp which uses virtual ground to get two sided voltage out of a single supply (example: -6V - VGND - +6V from GND - +12V). And that is because the signal ground needs to be at the same potential with the virtual ground, but will not work because signal ground of the sound card is at the computer's ground to which all the +12V, +5V etc. voltages are referred. Also computer PSUs are noisier than what is ideal for audio although it could be taken care of with some filtering and using an op-amp with high Power Supply Rejection Ratio.

Now that I started thinking I remember that ATX PSUs have -12V line too. One could use that and the +12V line to get the needed dual supply.

breez said:

I suppose it is doable, but you can't use an amp which uses virtual ground to get two sided voltage out of a single supply (example: -6V - VGND - +6V from GND - +12V). And that is because the signal ground needs to be at the same potential with the virtual ground, but will not work because signal ground of the sound card is at the computer's ground to which all the +12V, +5V etc. voltages are referred. Also computer PSUs are noisier than what is ideal for audio although it could be taken care of with some filtering and using an op-amp with high Power Supply Rejection Ratio.

Now that I started thinking I remember that ATX PSUs have -12V line too. One could use that and the +12V line to get the needed dual supply.

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It should work fine To get the vgrnd, just use a rail splitter. All you need is a +12v and a ground.

As far as the noise goes, I'd imagine it would probably be ok, but I'd add a filter in a anyway. I would think some caps would do fine.

The noise from the PSU would be my biggest fear. I would be much happier using even a 9v battery or using some serious power filtering to clean the power up.

I would be worried about the noise from the PSU, but that can be taken care of through some good filtering, but it might be easier to use a seperate power supply just for the amp. The dual power supply can be created several ways, I suggest checking out Tangent's page for Virtual Grounds. You will want a good metal case for the amp, to shield it from all of the EMI in the case. Why are you looking at using the Cmoy or Mint amp for this project, something like a Pimeta would better and there would be no problems with size. Also, there is no great way to hook the amp into the soundcard, you are either planning to have a wire running out the back of the case, or plugging it into the pins for front panel audio, both solutions are less than ideal, and you will need well shielded cables to prevent excess noise. I know the idea of an internal headphone amp is attractive, I have been tempted to do it myself at times, but the extra noise, both from the PSU and EMI in the case, make an external solution seem much better. What headphones and soundcard are you going to be using this with? If you do end up building this or any amp, make sure you post pictures of it.

Cyrix_2k said:

It should work fine To get the vgrnd, just use a rail splitter. All you need is a +12v and a ground.

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Yes, the virtual ground can be created with a rail splitter, but the problem is the computer's sound card's output which has it's ground lead at the computer's ground. Now the computer's ground is 6 volts below the virtual ground (ie. -6V to the amp is 0V/GND to the computer). The audio/signal ground from sound card needs to be at the virtual ground <-> conflict arises because -6V and VGND would be shorted.

breez said:

Yes, the virtual ground can be created with a rail splitter, but the problem is the computer's sound card's output which has it's ground lead at the computer's ground. Now the computer's ground is 6 volts below the virtual ground (ie. -6V to the amp is 0V/GND to the computer). The audio/signal ground from sound card needs to be at the virtual ground <-> conflict arises because -6V and VGND would be shorted.

Click to expand...

no problem with insulated jacks...

I don't know if it was ever built and it is much more complex than what you are looking at, but check out this thread on Headfi.

Cyrix_2k said:

no problem with insulated jacks...

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I mean that the audio signal swings in reference to the computer's ground, ie. the computer ground is inseparable from the output.