I'm brand new to CSound, and the learning curve is steep, so I hope
you will bear with me.

My goal is make compositions with the overtone series, and I am trying
to design instruments that would be appropriate for this. (I'd be very
happy to simply find instuments others have designed, but I can't seem
to find what I want. Maybe I don't know where to look?)

I have designed a waveguide instrument based on Hans Mikelson's
waveguide bass (c.f.
http://www.csounds.com/mikelson/index.html#waveguide), which I have
modified to have two delay loops, one at the harmonic frequency and
the other at the fundamental, and I switch from the harmonic to the
fundamental to produce something like playing a harmonic on a guitar
string.

My instrument is attached to this post, and is also online at
http://abstractfactory.org/csound/harmonic1.orc. There is also a
.sco file in the same location to test it.

The main problem I'm having is that, although an individual note
sounds fine, after three or four in succession the fundamental will
come in on each note attack, which is a bit of an annoying distraction
for me and not what I want. I've tried putting a high-pass filter on
the output, but it doesn't seem to ameliorate this problem.

I realize I'm kind of working at cross-purposes here, using a
waveguide at the fundamental frequency and then not wanting that
frequency audible in my final composition, but I don't know how else
to approximate the "harmonic" sound I'm after.

The second thing I should mention is that I didn't exactly understand
how Mikelson's DC blocker worked and I'm not sure if I've modified it
correctly in this instrument.

Any assistance would be greatly appreciated.