TECHVIEWS
R.G. KEEN
Should You Bypass True Bypass – Again?
There aren’t many things worse than step- Over the years, the reliability of electronic
ping out on stage in front of a crowd and gear has improved dramatically, but the
being met with silence from your rig, but reliability of mechanical things like DPDT
there’s a growing risk of that occurring and 3PDT switches has gone down mark-
from an unexpected direction: the reliability edly. Globalization has led to problems with
of stomp switches for true bypass is on materials, accuracy, and new factory start-
the decline. ups. Meanwhile semiconductor manufac-
turing moved to fully automated, intensely-
managed production lines, and the silicon
has improved consistently every year.
Effects makers don’t want to tell you
that, because guitarists have demanded
true bypass switching and they continue
to vote for it with their wallets. Effects
makers may privately admit that stomp
switches are getting worse, but you can’t
blame them for not wanting to give up a
cheap and easy advertising opportunity.
Designing good alternatives to true bypass
requires hard work and technical skill
– throwing in a stomp switch is dead easy.
All those Boss pedals made over the
decades still bypass the first time, every
time. On very rare occasions, the environmentally sealed, contamination-free tactile
switch inside will finally die. A quick 50
cent switch replacement and it’s good
for another few decades. Say what you
will about how the pedals sound, but
the makers got it right when it comes to
switching reliability.
The old-line DPDT stomp switches were
originally designed to switch AC line voltage, not delicate audio signals. Audio sig-
Over the years, the reliability of
electronic gear has improved
You won’t see this come up in pedal ads,
but what sounds vintage and righteous in
the ads may not be perfect.
dramatically, but the reliability
It takes higher-class design work, but a
good buffered bypass circuit can offer
great sound, and just as importantly, it can
offer reliable results. The buffer handles
your carefully handcrafted guitar signal
gently and provides a strong enough
signal to keep your audio clean. A well-designed buffered bypass setup can
reduce or eliminate the static discharge
and signal-interruption pops that metal-contact switches make.
Take, for example, this story from a very
skilled guitar tech: he had set up the stage
rig for the guitarist in a multi-platinum act
for a crowd of 30,000 people at an outdoor
festival. The guitarist was a pro at every
level, seasoned at touring and possessing
a pedalboard of about fifteen handcrafted,
true bypass pedals. The board was cleanly
and professionally wired and powered,
and had fared well over many shows.
Conditions looked good.
of mechanical things like DPDT
and 3PDT switches has gone
down markedly.
nals can be blocked completely by a layer
of surface oxides a few atoms deep; AC
power will hardly notice it’s there.
The moral of the story is not to dump true
bypass or to go to all buffered pedals. The
moral of the story is to think. Be open-minded and be prepared.
Got hard-wired true bypass pedals? There
are better and worse stomp switches – get
some high quality spares ahead of time
when you can, just like you do with tubes.
And don’t forget to give a listen to those
buffered bypass pedals; your ears will
know the truth.
The stage was covered, which was good
due to rain following the first performance,
letting up by the second performance.
When the tech went to check the guitarist’s rig, three of the true bypass pedals on
the board refused to switch at all. This was
from accumulated wear and the humidity
in the air, since no rain had hit the pedalboard. Fortunately, there was just enough
time to rip the pedals out and get them
running before the band came on stage.
Telephone companies found out long ago
that to reliably switch low power audio the
best practice is to use precious metal contacts and protect them from contamination.
Reliability engineering says that things that
are stomped on are prone to mechanical
failures. The simpler a thing is, the fewer
ways it can fail. Putting a DPDT switch
inside is bad enough; putting in yet another switch section for 3PDT is a step in the
wrong direction.
R.G. Keen – Chief Engineer
Visual Sound
visualsound.net
