Effectrode Mercury Space Charge Fuzz User manual

Specifications
• Input impedance:Greater than 1M
• Outputimpedance: Less than 40K
• Controls: Fuzz and Volume
• Features: ‘Hot’/‘cold’ bias switch
• Thermionic!: Based ona N.O.S.space-grade
mil-spec subminiature triode vacuum tube
• True bypass: With ‘anti-pop’ or ‘thump’ foot-
switching circuitry
• Power requirements: 12VDC@ 600mA-
Centre positive 2.1mm barrel connector
• Dimensions: Width 4.75"; Depth 3.75"
• Weight: 12oz (onEarth); 4½oz (Mercury)
• Construction:Solid die-castaluminum box
• Finish: Mustard powder coat
Serial #
COPYRIGHT©2021EFFECTRODETHERMIONIC
12 Broughton Crescent, Barlaston,
Staffs,England. ST129DB
www.effectrode.com
TF-3A

Introduction
The MERCURY™ fuzzpushesvacuum tubes
beyondtheirnormal operational limits to generate
larger-than-life,devastatinglyrich,liquid fuzztones.
The fuzzcircuitry is built on ahandselected vintage
space-gradetube and amatrix of NOSgermanium
point-contact crystal diodes–there’s alotof glassin
this pedal! At lower fuzz settingsthe MERCURY
cleans up toproduce natural (real!) tube dirt and
overdrive.Asthe‘Fuzz’ knob isrolled upthepedal
addsever-increasing amountsofharmonic
saturation andsoaring sustain,stretching notes
towardsinfinityuntil,at fullthrottle,the guitar signal
is crushed into fuzzed-out oblivion.
Silver solder and top-notchaudiophile grade
components are utilisedthroughouttheconstruction
of this pedal.Instrumentation grademetal-film
resistors arespecified for theirlow noise and
stability,polyester coupling capacitorsfor theirability
to resolvefine signal detail.Ground-plane
construction ensures lowest possible noise and hum.
Thankyoufor supporting Effectrode–we really
could notdowhat wedo without yoursupport. We
wish youmanyyears of musical enjoymentfrom this
limited edition hand-built, all-tube fuzz pedal.
Phil Taylor – Designer
Tubes
The MERCURY fuzzaudio signal
path isbased on a Sylvania N.O.S.
‘6948’ high-m double triode.
Theseminiscule tubeswere
originally developedby Sylvania
Electric for guided nuclear missiles.
Theymeet stringent military Mil-E-1
specificationsfor reliability and
long service life under conditionsof
severe shock, vibration,high
altitude,andhigh temperatureand
radiation levels–conditions that
would destroytypical electronic
components. Sylvania subminiature tubes represent
the absolutepinnacleof thermionictechnology; they
are unquestionably the finest tubes manufactured by
any company,ever.

Within afew years germanium/galena'cat-whiskers'
were being used by amateurradio enthusiastsand
in early commercial radios. The development of
radar systems during WWIIthen ledto ademand for
amore reliable highfrequency,low-noise
detector/mixer–the ‘diode’.
Millions of crystal diodesweremanufactured in the
1940s for military radar use. Sylvania pioneeredthe
useof germanium for diodes,with the introduction in
1946of the 1N34–the world’s first commercial
germanium crystal diode.
Controls
Fuzz knob controls the signal level from thetube gain
stagesfeedingthecrystal diodeclippingcircuitry.This
is alogarithmic control with awide range goingfrom a
balanced,rich overdrive toendlessly sustaining,
obliteratedfuzztones. Thevacuumtubecircuitry
within the MERCURY makesthispedal exceptionally
expressiveand super touchsensitive.Setting the
‘Fuzz’ knobalittle higher thanyoumight normally use
ensuresit’s possible totake advantage ofpedal’s
dynamicresponse.Rolling back the volume of your
guitar and pickinglighter willproducearangeof full-
bodied,smooth,bluesydrive tones,however youcan
stilldig in to pushthe MERCURY into heavier
distortion sounds.
Volume knob isusedto match the relative volume
levels of the MERCURY fuzzwhen in bypassor
engaged.When the effect is engaged the output level
canbeincreased provideadditional boost to push the
input of a tubeamp for further drive and distortion.
Bias toggle switch alters the biasingofthe
MERCURY’s second tubegain section:thisaffects
the sensitivity,feel andcharacter ofthefuzz.Inthe
‘up’ position thetube isbiased inits linear region
creatingsymmetrical clipping distortion.Inthe‘middle’
position it is ‘cold’ biased whichresults in
asymmetrical clipping of thetophalf of thewave.And
in the ‘down’ positionthetubeis ‘hot’ biased creating
asymmetrical clipping of thebottomhalf of the wave.

Further,when biased for symmetrical clipping the
MERCURY is operating at maximumgain generating
maximum distortionandsmooth,sustaining fuzz
tones. Conversely,‘hot’ and ‘cold’ biased
asymmetrical clipping resultsin slightly reduced gain
and a rougher, grittier distortion.
Footswitch allowsselection betweeneffectified
(fuzzed) and non-effectified (dry) signal.Silenttrue
bypass switchingensures there are no‘pops’ or
‘thump’ whenengaging the effect and that there is
absolutelynolossof tone fromyourguitar to your
amp whentheeffect is disengaged.Additionally,the
tube signal path in this pedalis built to demanding
audiophile specificationto ensurehi-fidelity and signal
integrity atalltimes–thebenefit beingthatyourguitar
tone alwaysremainspure and intact.
TheoryofOperation
The MERCURY operateson precisely the same
principlesastheoriginal ‘Astrotone’ fuzzbox.The
Astrotonefuzzwas madein New YorkCity by
Universal Amplifier Corp backin 1966-1968 and
utilised what were,atthetime,the verylatest
innovationsin solid-state technology.Silicon
transistors boosted the guitar signal to highlevels so
that passive shunt silicon diodescould ‘clip’ the top
and bottom of thewaveform creatingacoarse,
gnarly, rough-sounding distortion, a.k.a.fuzz.
Insteadof transistorsoperatingfrom a9VPP3
battery,the MERCURY employs vacuum tubes
running at real amp plate voltagesof 300Vto boost
the guitar signal.Thesignal level is amplified to
massivelevels–far greater than in the Astrotone–
beforehitting the clipping diodes. Infact thesignal
voltage swingis so great that amatrix of series
germanium diodesneedto beused tohandle the
high voltages. Theresult is acolossal fuzzsound
with beautifully complexand richharmonic
overtones and devastatingly smooth, liquid sustain.
Historyofthe Crystal Diode
The first crystal diodeswere developedin the early
1900s.Wirelessreceivers (radios)utilised athin wire
in mechanical contact against the faceacrystal.The
wire had tobemanually adjusted tofind the 'hot-spot'
on thecrystal for best radio wave detection.This
device allowed current to passin one direction only,
and so rectified the receivedcarrier signal to providea
DC voltage that could drive headphones.