AVT 1634 Preamplifier & NE530 Kit: Eliminate Noise in 6W Speakers, Filters & Compatibility

Hello
Recently I have assembled a preamplifier from the AVT 1634 site. As an amplifier I used the ne530 kit with a 2x4W mini acoustic amplifier.
I have connected two 6W speakers to it, can it even work? Coming to the problem, the noise is heard through the speakers, not louder than the music being played, but it is a distraction when listening to it. This can be somehow compensated by a filter or maybe too strong speakers?

Thank you for all your help.

A jack cable from the preamplifier store is connected to the preamplifier, I used ordinary multi-core copper cables with a diameter of probably 0.75mm

Christophorus wrote:

The cables should also be shielded between the preamplifier and the power amplifier. Only ordinary cables can be used for the speakers.

You think this should help?

plm2052 wrote:

I have connected two 6W speakers to it, can it even work?

And why not? provided that the impedance of the speakers is not less than that allowed for the amplifier.

plm2052 wrote:

you can hear noises in the speakers, they are not louder than the music played, but they are disturbing when listening to it.

Noise "szszszsz" or something else you call noise?
What do you supply the system with?
To begin with, you need to find out where the noise comes from - disconnect the preamplifier and short-circuit the input of the amplifier - the noise is still there?

plm2052 wrote:

Christophorus wrote:

The cables should also be shielded between the preamplifier and the power amplifier. Only ordinary cables can be used for the speakers.

You think this should help?

Lack of shielding is most often manifested by hum in the network, but if there is excitation at over-acoustic frequencies, noise may also be a symptom.

Show pictures of the structure.

jdubowski wrote:

And why not? provided that the impedance of the speakers is not less than that allowed for the amplifier.

The only thing I read in the manual is that the minimum load for stereo is 4? and I connected 2x8?.

jdubowski wrote:

Noise "shhhhh" or something else do you call noise?

Yes.

jdubowski wrote:

What do you power the system with?

The voltage of 12V from a power supply with a capacity of 1A.

jdubowski wrote:

Show pictures of the structure

plm2052 wrote:

The only thing I read in the manual is that the minimum load for stereo is 4? and I connected 2x8?.

So OK.

plm2052 wrote:

The voltage of 12V from a power supply with a capacity of 1A.

Pulse? Conventional?
As for the photo - place the tiles apart and see what happens.
In addition, the question - this plate with a heat sink is some kind of stabilizer? Why are electrolytes so small?
Why do you need 5V? What voltage do you supply the final amplifier with (it cannot be higher than 11V) and does the power supply have sufficient current capacity?

jdubowski wrote:

Pulse? Conventional?

Pulse.

jdubowski wrote:

As for the photo - place the tiles apart and see what happens.

I tried at a distance of 15 cm from myself, no results.

jdubowski wrote:

In addition, the question - this plate with a heat sink is some kind of stabilizer? Why are electrolytes so small?
Why do you need 5V? What voltage do you supply the final amplifier with (it cannot be higher than 11V) and does the power supply have sufficient current capacity?

It looks like this: Voltage from the power supply 12v --- Stabilizers 12 and 5V (12 for the preamplifier, 5 for the power amplifier).
Another question is whether the old speakers can be the cause of the problem?

plm2052 wrote:

jdubowski wrote:
Pulse? Conventional?

Pulse.

Then you have the answer why it hums. There are keying pulses on the power supply, or (or rather, if the inverter operates at a supraacoustic frequency) harmonics of this frequency.
Another possibility is "catching noise" through the air. This can be checked by removing or (i) shielding the power supply.

plm2052 wrote:

It looks like this: Voltage from the power supply 12v --- Stabilizers 12 and 5V (12 for the preamplifier, 5 for the power amplifier).

This is a poorly constructed circuit - the final amplifier allows power supply up to 11V and this voltage must be provided to it, otherwise you heat up the heat sink unnecessarily.
And as I wrote - the capacitors at the output of the power amplifier power supply are too small.

jdubowski wrote:

the terminal amplifier allows power supply up to 11V

How do you propose / what to power it with?

jdubowski wrote:

And as I wrote - the capacitors at the output of the power amplifier power supply are too small.

Too low capacitance, voltage?

jdubowski wrote:

Another possibility is "catching noise" through the air. This can be checked by removing and / or shielding the power supply.

So what do i have to do? Could this system be powered with a 105W halogen transformer for 12V voltage, of course, after rectification?

The 12V transformer gives a peak voltage of about 19V, after rectification on the capacitor without load it will be 18V, with a load of 2A (this amplifier will probably consume much less) it will probably drop to 15V. Maybe such a transformer + rectifier bridge + 10,000 uF capacitor + 10V stabilizer?

plm2052 wrote:

How do you propose / what to power it?

A transformer with an idle voltage of no more than 8V, a rectifier bridge and a capacitor with a capacity of several thousand microF. As a rule, we do not use stabilizers to supply power amplifiers.

plm2052 wrote:

Too low capacitance, voltage?

You did not write what they are, so you ask a strange question, after the photos I can see that the dimensions are small, the voltage selection is not a "rocket sience" so count that you did not give 5V electrolytes there.
My concerns have reached too little capacity.

plm2052 wrote:

So what can I do?

Start with the spelling dictionary ...
Seriously - it's best to avoid switching power supplies that do not have shielding. In fact, we should not use switched-mode power supplies at all for audio systems, here we can make an exception due to the class D end amplifier.
Another solution - placing the amplifiers in shielding housings (metal, connected to the ground), of course, will not exclude the interference that gets to the circuit "on the wire").

plm2052 wrote:

Could this system be powered with a 105W halogen transformer for 12V voltage, of course, after rectification?

Electronic transformers (converters) are not suitable. A transformer on a toroidal core or EI would be OK, but here again the voltage is not as it should (18V at idle). It would be nice to replace the final amplifier with another one ...

jdubowski wrote:

It would be nice to replace the final amplifier with another one ...

Could you name some reasonably simple power amp that a beginner could make? If it was necessary to buy an 8V transformer, what would the minimum current efficiency be?

plm2052 wrote:

Could you name some reasonably simple power amp that a beginner could make?

What do you think simple means?
How is the output power supposed to be?
What is your speaker resistance?
What voltage do you have available?

It is essential for you to answer these questions.

One of the simplest is TDA2003 (mono, 5 pins, in addition to the power supply and power capacitors, it needs 5 capacitors, 4 resistors and a loudspeaker); similar are TDA2004 and TDA2005 (stereo, 5 capacitors for each channel, 3 resistors and a loudspeaker, slightly different circuit - there is bootstrap, but one less frequency compensation circuit); all of them are designed to work with a voltage of about 14V (18V with signal allowed, 28V without signal), with 4R speakers - maybe this halogen transformer will be just right.

With the 8V ~ transformer, you would have to use a bridge circuit to have a few W of power - maybe TDA2005, or on the TDA2822 (each of them can be bridged for one channel - for stereo there would have to be two circuits; TDA2822 has better efficiency, but the maximum power is about 1W, so it probably falls out). On elenota.pl you will find descriptions of these systems. The transformer should have a power several times greater than the sum of the amplifiers' powers.

plm2052 wrote:

If it was necessary to buy an 8V transformer, what would the minimum current efficiency be?

1.5A, and for 8? speakers there is less (1A). You will have a problem with the preamplifier (you need a separate power supply, because it requires a 12V power supply).

In the bridge circuit, 1.5A is hardly enough for a decent power supply for mono (with a 4? speaker . For 3A stereo.

_jta_ wrote:

In the bridge circuit, 1.5A is hardly enough for a decent power supply for mono (with a 4? speaker . For 3A stereo.

Note that the amplifier is class D ...

jdubowski wrote:

Note that the amplifier is class D ...

Yes, but a friend suggested using a different amplifier.

Freddy wrote:

What do you think simple means?

The point is that, as a beginner, I would be able to do it, I would like it to be stereo.

Freddy wrote:

How is the output power supposed to be?

I have max 2x6W speakers, but the question remains whether the old speakers are not the cause of noise.

Freddy wrote:

What is your speaker resistance?

2x8?

Freddy wrote:

What voltage do you have available?

As I said, a halogen power supply, but it probably won't be a good choice.

Do you prefer to do everything yourself or do you want to buy some ready made from a Chinese?
How do you want to do it yourself, what class should you work in?

plm2052 wrote:

As I said, a halogen power supply, but it probably won't be a good choice.

It will be hard to filter out .

The author of the topic just wants to make a different amplifier - in class D the current is actually a bit smaller, but at full power it is not a big difference.

MAX13301 is very nice, but will the author handle it?

8? speakers, 6W power - this means that the voltage amplitude should be 10V, i.e. either 24V power supply, or a bridge circuit and 14V power supply. Easier without a bridge circuit (because this circuit is 2X more elements), but not on TDA2003 / TDA2004 / TDA2005, but on TDA2006 (mono - you need 2 for stereo), or TDA2007 (stereo), or (a bit more expensive) for 2 TDA2030. The disadvantage of the first two is the limitation of the supply voltage: TDA2006 30V, TDA2007 28V; it is little more than the necessary 24V, and it is difficult to ensure a small range of voltage changes, especially + -8% for TDA2007; The TDA2030 can be supplied with voltage up to 36V, and 23V is enough to give 6W on the 8? speaker. You can also consider using the TDA2006 / TDA2007 with stabilization of the 24V supply voltage.

There is a lot of it.
The author must start, however, by changing the power supply because those to halogens sow mercilessly and it is very difficult to filter it.

Hmm ... isn't it sometimes the case that the author of the topic connected a 12V stabilizer to the 12V power supply and powered the preamplifier from there? A typical 12V stabilizer needs 15V to work properly, and at a lower voltage it lets noise ... into the preamplifier so that it is amplified later, so maybe it's no wonder that it has noise?

_jta_ wrote:

Hmm ... isn't it sometimes the case that the author of the topic connected a 12V stabilizer to the 12V power supply and powered the preamplifier from there?

It is possible too.
Once I insisted and tried to use such a halogen electronic power supply, but the cost of building effective filters for it exceeded its value significantly .
Such a power supply usually looks like below.

The author of the thread did not write down what is happening in the listening session, how the preamplifier and the input of the final amplifier will be shorted to ground from the 530 kit.
And to confirm whether the power supply generates noise on the power supply line, a capacity of at least 4700uF on the output amplifier board, disconnect the suspect power supply (then a boost - without inputting the audio signal to the input - it should work for a few seconds with the "clean" energy accumulated in this large capacitor ) and if, despite disconnecting the power supply, the noise continues, there is a suspicion that the amplifier on the KA2206 has too much gain and is hum by itself - a known unpleasant phenomenon in many amplifiers (also in portable battery-powered equipment) with an unnecessarily too high gain set. Then you have to increase the feedback resistors. What are your resistances on pins 6 and 9 of the indicated KA2206 chip?

I wonder where the manufacturer of this kit took the power of 2x4W - the manufacturer KA2206 gives 2x2.3W on a 2x4? load (with 9V power supply and 10% distortion).
And I do not know how to understand the supply voltage in the characteristics (and not as permissible): typical 9V, maximum 11V. Does it mean that typically above 9V the protection is triggered and the amplifier stops working? And at what voltage does this protection definitely not activate yet?