Electronic Audio Experiments Longsword V4 User manual

Longsword V4 Technical Manual
Introduction
Thank you for your purchase of the Electronic Audio Experiments Longsword!
This manual is an in-depth guide for properly using and enjoying your pedal.
But first, a little bit on the origins of the Longsword: I conceived this circuit to be a general-
purpose distortion with character – in other words, you can coax a wide variety of tones out of it
while never compromising its sonic signature. There are many distortion pedals I love, but this
one was designed to meet specific needs I had which, as it turns out, are not as unique as I
thought (and probably why you bought this pedal). When playing distorted guitar in a band
setting, my preferred style is to set a single channel amplifier on the verge of breakup and push
it a bit harder with a mix of pure clean gain and some saturation inherent to whatever pedal(s)
I’m using. The Longsword with its EQ, adjustable clipping settings, and high output volume on
tap is well suited to this purpose – but also manu others.
At its core, the Longsword is an op-amp drive with diode shunt clipping. An integrated circuit
called an operational amplifier (aka op-amp) increases the signal amplitude (loudness), and a
pair of diodes limits the peaks. Cutting the peaks off of a signal generates a bevy of extra
harmonics, producing the distorted tones we all know and love. This circuit block is found in
hundreds of pedals (including the Distortion+, Rat, OCD, even the venerable Klon Centaur/KTR)
and is, in itself, not special.
The Longsword is made special because of the way the clipping amplifier is nested in a series
of other amplifiers and filters. Many op-amp-centric overdrive pedals sound good with one
particular kind of guitar or amp, or they have only one sound that they do well. Oftentimes, ones
that sound good on their own can drop out of the mix in a band setting. By taking advantage of
the Longsword’s dynamic range and powerful equalization, the player may easily defeat these
shortcomings.
-John Snyder, EAE

Operation
Only use a standard reliable 9-volt center-negative DC power supply with this pedal! (e.g.
OneSpot, Voodoo Labs, Pedaltrain, etc.) Also, the Longsword does not operate on batteries.
The Longsword contains a charge pump which converts a 9V supply to 18 volts internally for
extra headroom.
A distortion circuit with more than the standard volume/tone/gain arrangement can take some
work to dial in, so here’s my recommended algorithm for dialing in the Longsword for the first
time.
1. Begin with your amplifier set to its optimal clean tone.
2. Then, set all of the EQ controls on the Longsword to noon, set the drive and level at
minimum, ensure the boost is is off, and set all toggle switches up.
3. Turn on the pedal and slowly increase the drive and level until they are to your liking.
You’ll notice that the drive control introduces a natural high-end rolloff as it is increased,
reducing harsh upper harmonics. You’ll also notice lots of volume on tap!
Next, it’s time to adjust the tone controls. With everything at noon, the Longsword has a
mostly flat response for guitar frequencies. The Longsword controls are like a studio EQ - the
bands are largely non-interacting, and small changes can have a drastic effect. Thus it is
recommended to adjust the equalizer gradually, with small boosts and cuts away from noon.
The low and high controls form a James-Baxandall arrangement, which are shelving filters that
cut frequencies below or above a certain crossover point. The mid control is a single band
boost/cut with a selectable center frequency using the FREQ toggle switch. Up on the toggle
corresponds to 1Khz (hi mid), and down corresponds to 300Hz (low mid).
Some notes on the EQ:
●The James-Baxandall stack is not just a bass and treble arrangement. If you boost both
the low and high, you can get an effective mid-scoop, and conversely you can cut both
to get an effective mid boost. Certain settings may reduce the volume output but there is
more than enough output on tap to compensate.
●The Longsword has a great deal of low end available, but a tighter tone can be achieved
by cutting the bass, particularly when combined with an already dirty amp
●Don’t be afraid to scoop the low midrange (set the FREQ switch up), as it may be a
source of muddy tone with some guitars, especially on the neck pickup!
●Extreme settings may be of interest, for example:
○Maximum bass and high gain will result in extra clipping of the later circuit
stages, producing a more fuzzy tone
○High midrange settings coupled with high gain, particularly on the center position
of the clip switch, will result in extra clipping at that particular frequency band
○High treble settings will result in a “clangy” sound with lots of pick attack

The DIODE toggle switch will affect the dynamic response of the pedal, with settings as
follows:
●Switch up is medium compression via LEDs, which have high headroom but a smooth
transition into clipping. Gets fairly aggressive at higher gain settings.
●Switch center removes diode compression altogether, which lets the natural clipping of
the op-amps shine through. This mode is recommended if you want high dynamic range
or are using the pedal as a clean boost/EQ into an already dirty amp.
●Switch down is high compression, using a symmetrical arrangement of silicon diodes.
The overall volume when using this mode may sound quieter compared to the right and
middle positions; this is normal. Just turn the level knob up!
Finally, the Boost Footswitch corresponds to the Longsword’s Boost knob, which sets its gain.
A clean gain boost from 0dB to about 20dB is applied to the front end of the circuit. In addition
the boost circuit has a moderate low cut, which is perfect for tightening up the Longsword at
higher gain settings and providing two distinct tones.
In conclusion…
The Longsword is a very versatile distortion / overdrive pedal with a plethora of options on hand
and we hope it helps you dial in the exact tone you’re looking for, regardless if you’re playing
indie rock or doom metal. Thanks again!
Changelog
Version 4 (Fall 2018)
•Boost knob moved outside
•Rearranged graphics
•Relay bypass w/ soft switching
Version 3 (Fall 2017)
●Charge pump for 18V of headroom from a
9V supply
●Boost channel added
●All new clipping modes
●New artwork
Version 2.1 (November 2016)
●Updated PCB layout
●Eliminated range toggle
●Removed most electrolytic capacitors from
the signal path
Version 2 (Fall 2015)
●New PCB layout (Rev 1)
●Added gain switching
●Added clipping selector
●Added range toggle
●Now capable of running from 9V to 18V
Version 1 (Summer 2015)
●Original release
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