On Thu, September 6, 2012 9:02 am, Charles Henry wrote: > Hi all > > I know this is not the ideal place to ask a question about > Android--but I hope someone here can help confirm my suspicions. > > I wanted to create some circuit tools using the 1/8" stereo output + > line input jack on my android phone (a droid razr). To start with, > I've got a simple signal generator (built with PdDroidParty)--and what > I found is that there is a high-pass filter on the output. It is > mostly unsurprising, but what *kind* of high-pass filter is it? > > If it was just a RC impedance on the output, I could compensate for > that. However, it seems likely that there's a high-pass filter in the > software, or somewhere else. > > When I drive it to clipping with a combination of sine tone and dc > offset, the noise characteristic is weird. The pitch of the distorted > tone goes down, and there's a very steep transition between the > undistorted and distorted tone. The distorted tone is also much > louder. I'm typically testing with a tone at about 1kHz, but I've > been sweeping through a lot of frequencies to see what happens. The > symptom is the same whether it's played through the speaker or a set > of headphones. Are you sure that is not just the normal (ugly) result of digital clipping? You may wish to try a SW limiter in the chain somewhere or something that limits slew towards clipping in software. That is limit the max output to less than 0db so that some sw has a chance to "round the corners" to keep the frequency within 20khz or so. -- Len Ovens www.OvenWerks.net _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
