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The Loopbone
Audio Path
In order to route the guitar signal to various loops
without changing the volume, increasing the load
on the pickup, or adding noise, it must be buffered
with introduction of a pre-amplifier into the signal
path. To ensure the very cleanest and most natural
sounding tone, there must be no signal degrading
chips or op-amps in the audio circuit. As such,
the Loopbone employs Radial's highly acclaimed 100%
discreet Class-A circuit, which as serious audiophiles
know, is the only choice.
The engineers at Radial weren't quite done yet –
they went one step further and equipped the Loopbone
with Drag™ control, Radial's innovative load
correction circuit that allows the guitarist to
properly match the load on his pickup, so that it
replicates the tone when connecting directly to
his amp. Simply brilliant!
The Ins & Outs of the Loopbone
The Loopbone is a unity gain device. This means
that what you put in - you will get out. This of
course completely gets tossed out the window based
on the type of effect device you place in the effects
loops. For example, some effect pedals tend to rob
signal for no apparent reason. (Tuners can be particularly
bad – this is why the Loopbone has a separate
tuner out.) Other pedals are so noisy, you wonder
how they ever got past the research & development
stage. But love’em or hate’em, these
effects can be loads of fun and using them can often
lead to some great creative tones that can spur
on new ideas and make your music more interesting.
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Front panel Loop-1 and Loop-2 send receive
jacks |
To deal
with these ‘problem children’, the
Loopbone has two separate effects loops. This
allows each loop to contain several different
effects in a chain that can be inserted into the
signal path as needed. You could for instance
have five pedals in the chain, turn three on and
two off to set-up a searing solo tone while playing
a clean rhythm, and when the moment comes, simply
engage the loop for that moment of bliss! With
two separate loops, you can set up two completely
different effect chains. You could for instance
designate one for soloing and the other for wild
effects. In fact you could even turn both loops
on at the same time if you wanted to combine devices
and have the two worlds collide!
In
order to make loop switching work quietly and
un-obtrusively, the Loopbone employs optical switching
technology. In switching, opto-couplers have the
distinct advantage over relays in that they do
not create a pop or click caused by arcing as
the relay contacts get close together before finally
touching. The opto-couplers we use in our circuits
are actually micro-controller actuated to ramp-up
and ramp-down for completely silent switching.
On the downside, photocells are much more expensive
thus limiting their use to only high-end gear.
Augmenting your tone with VariBoost™
Loopbone’s VariBoost power booster
is true to one of the cardinal rules of great
sound... it employs a true Class-A circuit to
boost the signal. One cannot overstate the advantages
of Class-A. Although less efficient than the 'easy-school'
push-pull circuit designs, a Class-A circuit is
without doubt the most natural sounding and transparent.
They also require more physical space and more
power, which is why a 15V supply is necessary
instead of the typical 9VDC or battery supply
used by most other manufacturers to power their
cheaper and invariably bad sounding booster circuits.
Class-A circuits employ a single buffering device
to amplify the gain, thus eliminating zero-cross
distortion; a nasty by-product of the usual op-amp
style AB designs. By eliminating zero-cross distortion
and increasing the headroom with more power and
larger, discreet components, we enjoy lower phase
distortion and significantly less intermodulation
distortion. This yields a more natural tone, which
has the distinct effect of allowing natural harmonics
to flow, augmenting the tone of the amp –
not fighting it with odd-harmonics.
The Power of Slingshot™
– the un-MIDI solution
For the past 20 years, MIDI has been
the standard control interface for keyboard players.
MIDI works exceptionally well in the world of
synthesizers, keyboards, and drum machines etc.
whereby digital commands are used to turn notes
on and off.
The guitarist has never quite adopted this technology
as it is the relationship between
the guitar body's resonance, the pickups, amplifier
and speakers that magically combine to create
the tone. Guitar strings vibrate
in a magnetic field causing electron flow. There
is no on/off switch. It is all analogue, it is
imperfect, it spits and sputters – it is
alive.
But the allure of MIDI is certainly valid. Stomping
on a single footswitch and having multiple devices
spring into action is fascinating. This led us
to develop Slingshot™, a remote control
system that follows the traditional method of
channel and reverb switching found on most amplifiers
whereby a simple contact closure is all that is
required to make a device change status. Slingshot
employs standard, everyday ¼” guitar
cables to interface between various pieces of
gear.
Besides the Loopbone, we have equipped other Radial
Tonebone pedals with Slingshot switching as well:
the Cabbone speaker
cabinet switcher and the Headbone
VT, Headbone
SS and Headbone
TS amp head switchers. Each pedal’s
Slingshot implementation has been optimized for
simplicity and practicality. For instance the
Loopbone, as a master controller, is equipped
with an assignable Slingshot output to control
various devices. The Headbone on the other hand,
is equipped with a Slingshot input designed to
receive status change signals. Cabbone is slightly
different again – it features both Slingshot
input and thru-put. For more information about
Slingshot remote switching, view the Slingshot
'smartsheet' pdf
Loopbone is equipped with three Slingshot control
slide switches to achieve universality with most
devices. The first switch assigns the ¼”
jack to either the ring or tip for amplifiers
that employ TRS style ¼” cables with
their footswitches. The second switch lets you
select either latching or non-latching (momentary)
type switching for amps that employ an electronic
pulse to switch channel or option (eg: reverb
or tremolo) status.
The third
switch makes the Loopbone particularly fun in
that the Slingshot remote control function may
be assigned to any one of the three footswitches.
This could for instance allow you to send a channel
change command to your amp at the same time you
activate one of the FX loops or the boost switch.
Add a Cabbone to your system and you could instantly
switch speaker cabinets and really zero-in on
the tone you are looking for. Best of all, you
can make all of these devices switch at the same
time with a with a single foot action.... and
no tap dancing!
Slingshot
'remote output' assign panel
And
then there was MIDI
Of course for those players that choose
to employ MIDI systems as a means to get as many
tonal variations as possible on stage, there is
good news here too… Most MIDI controllers
are equipped with contact closure style I/O connectors
that can be set to receive a status change command
from the Loopbone or transmit a status change
to the Cabbone or
Headbone.
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