# power source??

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#### FauxFrench

A Spanish power source evidently .

I believe I see a +15V. The other is probably -15V, thus +/-15V.

12W+12W equals 24W and a safe estimation for the power supply is 50W. My proposal is +/-15V 1Amp and good power rail decoupling. 6-8 Ohm speakers.

Buena suerte!

#### Mark Tillotson

NE5532's can run as high as +/-18V, gives more power

#### FauxFrench

Hi Andres,
Sorry, I made a mistake. I meant +/-15V 2A, not 1A. But, there is more to it.

Let's assume you use the most heavy load of 6 Ohm. We assume the NE5534s can do an output swing of 12V. That means, the maximum current in one speaker is 2Apeak. That is a peak value, not effective value. Worst-case the two amplifier channels may be in phase at full (clipping) power. 2Apeak for each channel means 4Apeak for the two channels (worst-case).

Big electrolytic capacitors have the ability to buffer (average) the dynamic current-needs to the load such that only the average current needs to be supplied to the electrolytic capacitors.
This is the case for unregulated power supplies with large rail capacitors. Then, 2A average from the transformer will do with margins.
If you have a voltage regulator before the amplifier, such as you show in a first example, the large electrolytic capacitors are connected before the voltage regulators and little energy storage is found at the output of the regulators. In such case, the voltage regulators need to be able to supply the full peak-current without invoking the current limiters. The total peak current we found to be 4A. I do not know this regulator board or the regulator ICs but I doubt they can do 4A before current limit.

I will return in a following mail because my dog insists on a walk..........

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#### FauxFrench

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.

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#### AndresTC

then the 5534 4w + 4w of how many w will be hehe..

In any case it is to attack a beyma tpl150 and beyma 6mcf200 both are very sensitive of 100 db.

then this more this It is more than enough

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Transformador de PCB, 2 x 15V ac, 2 salidas , Montaje en PCB, Potencia 30VA | RS Components

#### FauxFrench

the 5534 4w + 4w
Just below 2x1W in 32 Ohm. Only 8 OP-AMPS per channel. Better for a headphone.

#### AndresTC

I was thinking of replacing op amp 5532 with lm4562 ... I have enough to replace them all would it be possible?

#### FauxFrench

Seems fine as well.

#### AndresTC

perfect for a while I wanted to use those operational amplifiers and didn't know what

#### AndresTC

Did you mean the source that happened in the previous post or the change of opamps? hehe

#### FauxFrench

Both. LM4562 can generally replace NE5532. LM4562 only accepts +/-17V as supply. Use IC sockets when you remove the NE5532 (I now see that they are already in IC sockets). Removing all the NE5532 is quite a job. With LM4562, the total idle current should be around 250mA so the voltage regulators may be warm.

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#### FauxFrench

Just to make sure that I understand you well: when you replaced the NE5532 with LM4562 in the electronic cross-overs you show, you got significant distortion?
LM4562 generally has wider operational limits than the NE5532 and personally my replacements never failed.

#### AndresTC

that's right .. more distortion and noise and quite significant

#### FauxFrench

Andres, would you have an oscilloscope? There is a possibility that the LM4562s perform some self-oscillation. Noise and distortion are certainly not characteristics of the LM4562. Please also check the supply voltages.

#### AndresTC

no I don't have unfortunately ... the fact is that with the 5532 it works perfect is strange..maybe they are false 5532 and the circuit is indicated for them I don't know