Al Johnson píše v Pá 21. 01. 2011 v 10:34 +0000: > On Friday 21 January 2011, Hrabosh wrote: > > Hi guys, > > > > yesterday I opened my freerunner to check whether mine FR is affected by > > R3004 issue [1]. > > > > It was, I put a piece of wire there instead of those two caps and volume > > got better! > > > > I have also connected sine wave from generator to the WD8753 mic input > > and cheched it on the WD8753's output with the oscilloscope. It seemes > > that the audio codec chip gets into trouble (distortion, oscillations) > > if the overall audio path has higher gain than 1. I'm going to write > > more about this soon, with the scope pictures included (taken by my > > camera, I don't have DSO at home :-/ ) > > That would be interesting to see, but your summary seems wrong or perhaps > oversimplified. Distortion is inevitable if you overload an amp, and > oscillation isn't unusual immediately after overload. It isn't a function of > the overall path gain though. The wolfson has a chain of amps and volume > controls, and it only needs overload at one of them to introduce distortion. > Stick the gain too high on the first stage (mic input) and the distortion > won't go away no matter how far you turn down the gain on later stages. This > has been a long standing problem with the default volume settings.
Yes, it is oversimplified. It is obvious that you can't fix distortion by lowering the gain of next-in-chain amplifier. You are just controlling the volume of already distorted signal. I put that picture from my scope with a short description to my web page, here: http://hnet.endofinternet.net/elektro/Freerunner/ALSA/sound_setting.html I was very surprised how LOW I had to set the audio controls to get rid of distortion: Mic2: 0 Sidetone: 1 Strange ... > > > But ... when I was dismounting the phone, I dammaged the bluetooth > > module. The module itself may be OK, but the flex cable is torn off. > > > > Don't you have any idea where can I buy some spare? > > I've not seen anyone list them as a spare for sale, but any of the > distributors might have them available. Nicholas from Golden Delicious answered my desperate E-mail :-) > _______________________________________________ > Openmoko community mailing list > community@lists.openmoko.org > http://lists.openmoko.org/mailman/listinfo/community > _______________________________________________ Openmoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community