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View Full Version : Audio Shield line out - quick question



unicornpower
04-16-2016, 05:45 PM
With the Teensy Audio Shield, should the volume of the signal from the mounted headphone socket be the same as the line out solder holes? I'm finding the solder holes (sorry I don't know the correct term :) ) to be slightly quieter. I'm only dealing with mono in and mono out, so the right channel of the headphone out should be silent. Thanks in advance, apologies if this is answered somewhere else, I couldn't find it..

PaulStoffregen
04-17-2016, 02:06 AM
Unless you set the volume just right, they'll be different levels.

The sgtl5000.volume() function only changes the headphone amplifier. The line-level outputs stay the same.

However, you can configure the line level output with sgtl5000.lineOutLevel(). See the documentation in the design tool's right-side panel for details: (scroll down to "Signal Levels")

http://www.pjrc.com/teensy/gui/?info=AudioControlSGTL5000

unicornpower
04-17-2016, 11:12 AM
Ah, hadn't noticed that part of the documentation before. Thanks very much!

B.Jacquot
04-20-2016, 07:37 PM
It's also worth mentioning a trick I've used:

The headphone volume control has fairly fine granularity, while the line out amplitude is constrained to a somewhat small set of stepped values.

If you want fine grained control over both, throw a multiply block in front of your output, and use it as a volume control.