wood mounting screws.
The only significant negative
change — if you can call it that — is
the need for a three-cond jumper
from the guitar to the pedal board,
but even this is not a big deal since
there are ready-made stereo guitar
cables available. Just Google it.
Aside: Since you have done the
work to decipher the active filter
calculations for your schematic, I
wonder if you would be able to
create a nice Excel-based macro that
would allow one to change RC
values in your schematic and see the
effects on a plotted frequency
response graph.
Admittedly, I have been lazy over
the years and simply played with
values until I heard what I liked. Since
you have done most of the legwork,
it would facilitate knowing how to
tweak the design without explicitly
doing SPICE models.
Finally, on the subject of
shielding, I prefer to use a spray-in
coating rather than copper foil. You
will find the adhesive of the copper
strips will not be permanent and so
the shield itself will fall apart. Too
many interfaces. (Doesn't stick too
well to wood either!)
There’s a good example of such
a spray shielding material at
www.mgchemicals.com/products/
protective-coatings/emi-rfi-shielding/total-ground-carbon-
conductive-coating-838.
Of course, you need to pretty
much put the entire guitar inside a
large plastic bag, carefully create a
void in the area of the control cavity,
and use painter's tape to attach the
bag opening to the edge of the
cavity.
For the plastic cavity cover, there
are primers available for plastic. Use
that first, and then spray the inside of
the cover with the shielding spray.
You will get adequate mating of the
conductive surfaces of the cover to
the cavity if you mask the cavity well.
Thanks for the great article.
Jon
Thanks for sharing your
experiences of some alternatives to
the guitar hotrod project. Having
hung out with musicians my entire
life, I just knew there would be
different wants and needs, so tried to
keep it general for modifications such
as those you propose. The
arrangement I ended up with suits my
purposes perfectly, but there's no
reason to expect it to match everyone
else's needs as well. Long live
customization!
We're all different, but I prefer to
have the batteries within the guitar,
obviating the need for a special cord,
strap, or external pack.
Battery life has never been a
problem, even back some 30 years
ago when I was gigging and
performing daily. I would usually
replace the batteries every December
31st, whether they needed it or not.
One of the guitars that I outfitted for
a neighbor is on the same set of
batteries these three years later.
Opening the rear cavity so
infrequently really isn't much of an
inconvenience.
The conductive paint sounds
interesting, but foil tape has worked
very well for me. Just clean out the
sawdust left by the manufacturer,
swab the cavity with a cotton ball
soaked in rubbing alcohol, and away
you go. In any event, the entire cavity
is filled with foam rubber making it
impossible for the foil to come loose.
I suppose a person could devise
an Excel worksheet for the frequency
calculations (maybe my article,
"Spreadsheets: The Forgotten Analog
Design Tool," which appeared in the
October 2006 issue of Nuts & Volts,
pp. 59-63, will suggest something).
I sure found the SPICE approach
to be fast and easy, however, and the
visual representation of the frequency
response via Bode plots is a definite
plus.
Your suggestions offer a number
of excellent options many readers will
find useful as they personalize the
project to their own needs. Thanks
again for contributing them!
Thomas Henry
November 2014 73