PSOne LCD speaker change

[ken_cinder]

I've replaced the 8ohm 1w speakers on my PSOne LCD with 4ohm 10w speakers, as the originals couldn't handle full volume from the LCD, they sounded distorted.

The new speakers sound excellent, but when there is heavy bass or very loud output, it causes interference on screen.

Should I be putting some 4ohm resistors inline? If so, only on positive? Only on negative? Or on both?

[kendrick]

I don't know anything about the amp circuit in your particular LCD screen. However, my instinct is to suspect that your new speakers have wickedly strong magnets which would be a more likely source of interference. It might also be simple vibration that shakes the screen and produces the video noise you see. If you can pull apart the whole screen to its components, I would do some testing to see if the distance between the speakers and the LCD itself have any bearing on the video output problems you describe.

-KKC

[blackevilweredragon]

In an audio circuit, a general rule is, if the speaker has lower impedance, use a resistor on the negative side of the speaker.

If the speaker is higher impedance, the speakers will work, but not be as loud.  Amplifier damage from higher impedance speakers is unknown, but I recommend a resistor in parrelel to lower the impedance to what the amp was designed for...

[viletim]

Magnetic fields don't bother LCDs. It sounds as if you are overloading the audio system to the point where it's starving the rest of the display of power. Use some active speakers instead?

[ken_cinder]

The speakers are driven off the amp on the LCD's board itself, and it can't be a power issue. I'm using an adapter that has variable voltages and a polarity switch. Feeding it more power doesn't solve the problem, and I have a custom LED backlight in it (Broke the original) that stays strong no matter what is going on.

I'm actually feeding the panel 7.5v over the required 7v to compensate for any extra draw incurred by my backlight, which is wired for 5v directly off some points on the PCB. I'm pretty sure the LED draw is actually only like 1v for the whole strip.

Can't be caused by the magnetic field, as the original speakers were 0.5" from the screen, and the new ones are nearl 8" away. Even though they are considerably larger.

I'm going to try 4ohm resistors on the negative terminal of each speaker, as they are half the resistance of the originals, and I figured this was the problem and just didn't know for sure what I should attemtp to correct it. (Thanks blackevilweredragon)

Edit - I have to pick up some 4ohm resistors, turns out I don't have any left. Confirmed that it cannot possible be magnetic field, because unamped from one of my Jamma boards there is no interference.