Hi AndresTC,

..........I'm back but with a 2nd posting, not a mail.

I looked at the performance of the NE5532 and there is something I cannot make fit with what the advertisement of the board says.

NE5532 is a double OP-AMP. The board shows 24 ICs, thus 48 OP-AMPs in total. The output short-circuit current of an NE5532 OP-AMP is in-between 10mA and 60mA (quite a span). A typical output short-circuit current is 38mA but short-circuit currents are at zero voltage. However, it leaves an idea about what order of current we can expect from each OP-AMP.

A more relevant information is that with a +/-15V supply voltage and 600 Ohm loading, a total output voltage swing of 26Vpp is likely. 26Vpp is 13Vp. 13Vp in 600 Ohm means a peak current of good 20mAp.

If all 48 OP-AMPs are used for a single mono output, close to 1Ap is obtainable. 1Ap in 8 Ohm gives 4W and a peak voltage of 8V.

Mark is right that the NE5532 can be used up to +/-18V but as the board lacks current capability with normal speaker impedances (up to 8 Ohm), it is little useful to increase the supply voltage.

The advertisement is giving very little performance facts. 2X12W seems unattainable whatever way I look at it. The OP-AMPs can be split up in two groups with 1W in 8 Ohm for each but that is hardly very useful for the size and price of the board.

The advertisement describes in more places the use with a headset. The board has the power potential to drive heavy headphones but similar performance can be made much more compact and at a lower price. Most output power with common loads is in 32 Ohm. But several Watt (around 2x3W) for a 32 Ohm headphone seems excessive to me.

I cannot figure out what is the practical intention with this board. As I cannot tell the realistic use, I cannot advice what power is needed from the power supply. If you buy the board, a +/-15V or +/-12V power supply with 1A or even 0.5A is good for playing around with the board.

My previous calculations were based on that the board could deliver 2x12W in 8 Ohm (at least). As I see it now, it can’t and please forget about my previous estimations.