Light glows brighter when bass kicks in on amplifier.

[I really don’t know]

My GE “Vintage Style” led light bulb glows noticeably brighter when bass kicks in on amplifier, connected to 4 1-15 watt speakers in parallel. The amplifier has 120 watt max output power, with a 100 volt output, a 70 volt output, and a 4-16 ohm output (4-16 ohms is the one being used).You cannot switch off any of the outputs. The speaker system is drawing around max 4 amps FROM THE 4-16 OHM OUTPUT ON THE AMPLIFIER. The light is connected to the bottom outlet on the receptacle, and the amplifier on the outlet on the receptacle (not that it matters). Is this something I should be concerned about or not? Feel free to ask me for more information.

 

[pirate]

It's all about the bass...

 

[Lucien Nunes]

The fact that the light gets brighter suggests that the voltage at the outlet is increasing when the amplifier load increases, but normally you would expect it to decrease due to voltage drop in the wiring. You haven't mentioned any other electrical interactions between appliances in the house, so I am assuming there is nothing wrong with the main supply to the panel and the odd behaviour is limited to the amp and LED light.

I see a couple of possible scenarios:

Is the lamp connected to a dimmable or smart controllable fixture? Regardless of whether you use the dimming functionality, a pairing of dimmer and LED that are not 100% suited to each other can cause subtle variations in the line voltage to disrupt the operation of the LED in peculiar ways, and could be responsible for it getting brighter when the voltage falls or pulses.

Another possibility is that the duplex receptacle is on a 120/240V multi-wire branch circuit, with the two receptacles connected to opposite hot legs. This might be the case if the circuit is fed from a 2-pole breaker. In this case, when a heavy load is placed on one leg, that voltage goes down but the other one goes up by half the amount, due the voltage drop in the common neutral. E.g. suppose there is exactly 240V at the panel and the neutral is exactly in the middle dividing it into 120+120V. If the amplifier load causes 4V drop in total, 2V will be in its hot and 2V in the neutral, so the amplifier gets 116V. But the other receptacle has no drop in its hot and 2V in the opposite direction in the neutral, so it gets 122V, increasing the lamp brightness.

It would have to be an annoyingly sensitive driver circuit inside the LED to change brightness with tiny modulations of the voltage though. Alternatively, the neutral in that circuit might have a high-resistance connection, causing the two sides of the circuit to interact more than they should.

What happens to the light if you unplug the amplifier and operate a high load appliance from that outlet e.g. a hairdryer? If you have a power strip or twofer handy, what happens if you operate the amplifier and light from the same outlet on the duplex?

 

[I really don’t know]

The fact that the light gets brighter suggests that the voltage at the outlet is increasing when the amplifier load increases, but normally you would expect it to decrease due to voltage drop in the wiring. You haven't mentioned any other electrical interactions between appliances in the house, so I am assuming there is nothing wrong with the main supply to the panel and the odd behaviour is limited to the amp and LED light.

I see a couple of possible scenarios:

Is the lamp connected to a dimmable or smart controllable fixture? Regardless of whether you use the dimming functionality, a pairing of dimmer and LED that are not 100% suited to each other can cause subtle variations in the line voltage to disrupt the operation of the LED in peculiar ways, and could be responsible for it getting brighter when the voltage falls or pulses.

Another possibility is that the duplex receptacle is on a 120/240V multi-wire branch circuit, with the two receptacles connected to opposite hot legs. This might be the case if the circuit is fed from a 2-pole breaker. In this case, when a heavy load is placed on one leg, that voltage goes down but the other one goes up by half the amount, due the voltage drop in the common neutral. E.g. suppose there is exactly 240V at the panel and the neutral is exactly in the middle dividing it into 120+120V. If the amplifier load causes 4V drop in total, 2V will be in its hot and 2V in the neutral, so the amplifier gets 116V. But the other receptacle has no drop in its hot and 2V in the opposite direction in the neutral, so it gets 122V, increasing the lamp brightness.

It would have to be an annoyingly sensitive driver circuit inside the LED to change brightness with tiny modulations of the voltage though. Alternatively, the neutral in that circuit might have a high-resistance connection, causing the two sides of the circuit to interact more than they should.

What happens to the light if you unplug the amplifier and operate a high load appliance from that outlet e.g. a hairdryer? If you have a power strip or twofer handy, what happens if you operate the amplifier and light from the same outlet on the duplex?

Hi, thank you for your response. The lamp is not connected to a dimmer. I tried plugging in a hairdryer in place of the amp. When I switch the heating element to low, the light very subtlety gets brighter. When I switch the heat to high, the lamp noticeably gets brighter. I tried plugging the amplifier and lamp to a power strip connected to the receptacle. The light does the same exact thing (gets brighter when bass kicks in).

 

[I really don’t know]

I have hooked a digital multimeter to the power strip. The voltage goes down by a couple volts when the hair dryer is turned on. Same with the amp running a constant low frequency signal, but not as much voltage drop. I swear the light is getting brighter. Could the bulb be affecting the voltage it is getting somehow? I took a video, and it gets brighter in the video. My friends agree it is getting brighter too. So I know I am not going crazy lol.

Edit: Sorry to waste your time, but it is the light bulb. I hooked up a different bulb, which is the same brand name, but even more vintage like, and it gets dim instead of bright.

 

[Lucien Nunes]

Thanks for posting the update, not wasting time at all, it's interesting. So there is some strangemess in the current regulator / power conversion circuit inside that original lamp that is causing the brightness to increase with reducing voltage. I wonder whether all that model are the same or whther it's just one odd bulb.