Does anyone know if different firmwares set the audio output to different levels?
Thanks.
Yes, this was confirmed by phatnosie, each firmware has a setting that controls the output voltage of the DAC to keep from clipping the input of the head unit.
Is it possible to change the setting? I believe, in some cases, that my VW Phatbox's output is overdriving the input to my OEM VW MFD Navigation HU... I'd like to increase the attenutation , if possible...?
as I understand it, no that isn't something we can currently mess with. I believe it is set in the firmware that gets loaded onto the 8051 controller that we have no access to in so far.
Is there another firmware out there that natively has higher attenuation, that I might try...?
if you were to try that, it would break the ability to use the phatbox with your head unit. the "firmware" governs the communication between the phatbox and the head unit. i believe that is where the settings for the DAC are stored so changing firmware means a different protocol. I think you are pretty much boned.
according to posts on the old phatnoise forum (not available anymore) they specifically tuned the output levels to NOT allow clipping of input of the HU or output from the phatbox for each type of HU supported.
Yes - changing firmware will probably just stop everything working. If you have any electronics knowlege, you could try either breaking into the cable or opening up the Phatbox and putting a simple attenuator network in the audio path.
Something like this...
(http://www.wizard-widgets.co.uk/volvo/attenuator.jpg)
This will lower the signal level significantly (reducing signal voltage by around 70%) - you will need to experiment to see if you need more or less attenuation in your case.
Good luck,
Les.
You could do that in the cable so you don't have to open up the box also...