JBL 104 BT - How Disabling Startup Sound Melody?

[kirikudr]

I am very concerned about the loud melody when turning on the speakers. The problem is that the volume of the melody does not change when turning the regulator (apparently, the regulator here is digital and analog not connected to the amplifier output circuitry, but goes as a remote control to the speaker microcontroller)

The only time the start-up melody does not play in the speakers is when the mini-jack is plugged into the headphone socket (and the cable does not necessarily have to be connected to the other side of the jack).

As I understand it, there is a push-button contact inside the socket that closes when the jack is plugged in. Otherwise, the speaker would not recognize the empty cable that was plugged in.

Question:

How can I simulate turning on the headphone cable for 6 seconds (the time the start-up melody plays) using circuitry?

I am ready to solder to the elements of the speaker controller's printed circuit board. I have experience in DIY. But I don't know how to create such a temporary connector using resistors, transistors, capacitors... .

Perhaps the start-up melody can be disabled by some combination of pressing a button and turning the speaker control? I couldn't find any information anywhere. I only found a way to disable sleep mode using such manipulations.

I would appreciate any circuit advice, thanks!


You can see how the speaker turns on and the start-up melody sounds here:

 

[staticV3]

Hi @kirikudr! Welcome to ASR.

As I understand it, there is a push-button contact inside the socket that closes when the jack is plugged in. Otherwise, the speaker would not recognize the empty cable that was plugged in.

More likely, there are multiple spring contacts contacting e.g. 3.5mm Sleeve and if they short, the microcontroller knows that a headphone is connected.

Keeps moving parts to a minimum, improving reliability.

Imagine there was a physical push button and it got stuck so the 104 BT permanently thought there was a headphone connected and you could no longer play through the speakers.

Sadly, there is no way to disable that startup sound: https://help.harmanpro.com/Documents/2777/JBL 104-BT startup sound.pdf
(No clue why JBL made a PDF just for that )

So it looks like the only way is to modify the PCB.

Some sort of relay+timer combo that highjacks power from the 104's internals somewhere and shorts the headphone jack for a few seconds.

 

[AnalogSteph]

My regular old 104 sans BT didn't do that. Probably comes from the BT section then, which would make sense as announcements for various functions are pretty standard in that realm.

 

[Schlippwhip68]

I have a pair and learned to live with it annoying as it is at times.

 

[Schlippwhip68]

These are good little speakers. I use them at home for DJing with. They have a good shape for the desktop, like a pair of giant liquorice TicTac. They sound good enough for what I use them for and in regards to value for money the only other speaker that came close was the Presonus Eris 3.5 but the JBL wins in mid range resolution.