[sdiy] my first schematic - please critique

[Scott Gravenhorst]

"Ray Wilson" <raywilson at comcast.net> wrote:
>The only thing I see is that you will be applying 4.5 volts DC to the 
>outputs. You may want to add some output caps. Depending on what you are 
>driving (low impedance around 1 to 10K or so 100 uF, high impedance > 10K 
>maybe 20uF). You will still get a thump when you turn it on but it will 
>settle down after that.
>
>Nice looking schematic. Especially for a first go at it.

Yes, nice work.  I would add that the resistors R5, R6, R7 and R8 provide a constant
path for .9 mA to flow just for biasing the + inputs on the opamps.  I'm not familiar
with the OpAmp you chose, but I'll bet it will take more than 9 volts across it's power
terminals.  Consider using two 9volt batteries in series (18volts across the OpAmp
power terminals), the connection between the batteries becomes your ground and then you
can just connect your + inputs to ground.  This eliminates the 4 resistors and the
current that is consumed by them.  

>----- Original Message ----- 
>From: <eat-it at new.rr.com>
>To: <synth-diy at dropmix.xs4all.nl>
>Sent: Wednesday, December 27, 2006 5:33 PM
>Subject: [sdiy] my first schematic - please critique
>
>
>> hello all,
>>
>> with some help i've designed my first schematic and i'm looking for
>> critiques on what could be done better.  please keep in mind that
>> simplicity is key and i just want it to work right.  this is designed to
>> accept two stereo inputs, mix the two allowing crossfade, and amplify
>> the output.  please let me know what you think.
>>
>> http://www.sub-version.net/images/crossfading_headphone_amp.gif
>>
>> drew
>>
>> 
>


-- ScottG

---------------------------------------------------------
-- Scott Gravenhorst
-- Xilinx Spartan-3E Based Music Synthesizers
-- FatMan: home1.gte.net/res0658s/fatman/
-- NonFatMan: home1.gte.net/res0658s/electronics/