Yeah the tones are pretty annoying, I'll have to play around with the modules I have (shelved the project for now!) to see if I can get rid of them altogether. The problem really is that these modules cannot have their firmware changed, so if the firmware doesn't allow the boot up/down tones to be changed/disabled, then there isn't much one can do, aside from some clever "delayed unmuting" using an external headphone amp.
As for volume changing tones, I believe those are fixed, after all, if you change the volume, the user has no idea of what value the volume is at, so it must play a tone at that volume. When connected to your phone, the user has feedback - the screen shows a bar and sometimes a volume value.
What are you using to connect to your PC? I have a cheapo "CSR 4.0" dongle, that may behave differently. Another option is - set the volume to something you are comfortable with, and use an external headphone amp with a volume control - either passive or active. For my DIY headphones, I have the bluetooth volume set at half max, with a headphone amp (gain 2) and a passive, 400ohm dual pot for volume. That way I don't have to touch the volume controls on the bluetooth module itself.
I think you misunderstood me a bit. Whenever I talk about changing volume/muting whatever, I mean by that manipulating the vol only on device like smartphone or computer. Not by knob on amplifier, nor by pressing a vol up/down buttons on the BT reciever board. Also, it looks like those beeps can be heard, only if A2DP streaming is currently active, I mean, when I just connect my PC to the receiever (yes, via bluetooth,) and start changing/turning volume up/down muting, no beeps, but as soon, as I start playing some music/video/anything with sound, and change volume during the playback, then I hear the beeps mixing with the sound. The reason why is this so much annoying for me, maybe more than you, might be the way I am changing the volume on pc. I have programmable mouse, and while I hold the button on the side, turning mouse wheel causes no scrolling, but volume changing. One step=2% of vol up/down. And pressing the whell toogles mute. So when I want to turn vol up by 20%, so I hold the button on the side, start "scrolling" and at that moment, I am in a beeping hell for a few seconds...
I know that It has to be possible, to disable this bullshit, even though maybe it is really hardcoded in the TROM (TROM=True ROM not like these "ROMs" wich are actually RW), I had the same chip before, which did not make these beeping sounds, but I have shorted on it someting accidentaly, so... :/ yeah... I bought a new one, which does beeps.
So, if you did not figured it out yet, and it appears to be TROM, so no flashing, even there is some "BlueFlash" tool, do you think, that the "ROM" (I mean "OS") could be stored on the P24C128 IC? It is "I
2C-Compatible Serial E
2PROM" ? Do you think if I would swap these it could behave like the old one I shorted?