newbie diode/rectification ?s

[dan mcmullen]

hello all,

i had a notion over the weekend of using a diode in-line w/ my synth output
to remove one half (< 0V) of the signal.  basically, i'm wanting to
experiment w/ asymmetrical waveforms.  so, i'm trying to turn:
\   |\   |\   |\   |
_\__|_\__|_\__|_\__|
  \ |  \ |  \ |  \ |
   \|   \|   \|   \|

into:
\   |\   |\   |\   |
_\__|_\__|_\__|_\__|

i was able to get this to happen, but w/ some side effects that i don't
understand:

- the signal magnitude after the diode is initially connected is half that
of the input as expected.  gradually however, over a period of ~15 seconds,
it *attenuates* down to less than 1/8 of the input. 

- diode orientation is significant.  depending on the phase of the signal,
one of the orientations seems to attenuate down to almost nothing.

can anyone enlighten me here?  and, is there a better way to achieve what
i'm trying to accomplish.

thanks very much in advance,
dan

ps- the signal originates from an Oberheim Matrix-12, which has a 4051
demux feeding either a 10k resistor to the individual voice out, or a pair
of TL072s in series to the mix out.  the behaviors appear in both
configurations.
___
dan mcmullen, sf, ca, usa                  don't worry - pay attention
mailto:dog at well.com                                       415.681-0712
pgp fingerprint  =  1C70 8D81 6B94 93A9 F2D8  9609 2122 BF70 8619 EDAF