Can it damage IC if connecting two speaker in parallel in output?

[Prohor]

I have just assembled a "STK 4231 ii" based amplifier unit what is

2 channel 100w stereo audio amplifier. I also have two 8ohm 8 inch speaker and two 4 ohms Speaker. If I connect two 8ohm in two output of my amplifier plays little noise - I think it is because speaker box vibrate much. But if I connect 8 ohm + 4 Ohm speaker ( both 8 inch in size) in parallel, sound plays much better and clear. But I want to know if I play both speaker in parallel, will my amplifier IC be damaged?

I am not expert in electronics but did study as a part and can understand little. If anyone can explain little it will be very helpful.

Thank for valuable time.

 

[duke37]

The recommended load for the STK 4231 is 8Ω but to get the output you need a power supply of +/-51V. Do you have this?

 

[(*steve*)]

8 ohms in parallel with 4 ohms is 2.67 ohms. That's way less than 8 ohms.

If you are operating this at a voltage higher than +/- 17 volts then you risk exceeding the maximum current through the device.

I wonder if your 8 ohm speaker is damaged.

 

[Prohor]

The recommended load for the STK 4231 is 8Ω but to get the output you need a power supply of +/-51V. Do you have this?

Yes, according to data-sheet, supply voltage is DC +/- 51volts.

 

[duke37]

Yes, according to data-sheet, supply voltage is DC +/- 51volts.

That is what I quoted. Measure the voltage that you have in reality and see how it varies as the volume is changed.

 

[Prohor]

8 ohms in parallel with 4 ohms is 2.67 ohms. That's way less than 8 ohms.

If you are operating this at a voltage higher than +/- 17 volts then you risk exceeding the maximum current through the device.

I wonder if your 8 ohm speaker is damaged.

Yes, in parallel ohms will be reduced to 2.6 ohms. I did not run longer in parallel without confirmation, I think it did not damage.

Re: I am sadly announcing that, I have lost one 8Ohoms speaker! you were right!!!, can you tell me why 8Ohms gone instead of 4Ohms speaker??

 

[Prohor]

That is what I quoted. Measure the voltage that you have in reality and see how it varies as the volume is changed.

Ok, I mentioned output voltage of my transformer + bridge rectifier. Sometimes it drops down to 50/49v to 51 to 52. I did not find a output voltage controller to make a fixed 51 volts as 7805 ic does output volts fixed to output 5volts. I found on net something lmxx ic to build a custom one. Is this variation of output voltage of my transformer will damage anything? This transformer is locally build.

 

[(*steve*)]

Your 8 ohm speaker was probably not capable of handling the power from your amplifier.

 

[Audioguru]

The amplifier IC does not need a voltage regulator.
The amplifier is designed for an 8 ohm speaker for each channel. With 2.6 ohms (8 ohms // 4 ohms) or 2 ohms (two 4 ohms in parallel) either the amplifier will be destroyed by the current that is too high or the amplifier will limit the current producing severe distortion.

A speaker needs to have an enclosure designed for its specs to prevent the cone from moving too far causing damage. A sealed enclosure produces maximum cone movement at its resonance frequency (damped by the amplifier) and a ported enclosure at very low frequencies.