SCIENCE Hellhawk 50W User manual

1

Intro
Thank you for purchasing a Science Hellhawk 50W guitar amplifier! This manual goes over the
different features of the amplifier, maintenance, tu e, and warranty information as well as
some general tu e amp info.
Front Panel
Input jack: ¼” for your guitar ca le.
Full gain control: Adjusts the overall gain for the Full channel. This channel is voiced to have
more low-end, warmth and an overall darker tone. The Full channel can e lended to taste
with the Focused channel or muted y turning the gain control all the way down.
Focused gain control: Adjusts overall gain for the Focused channel. This channel has a tighter
low-end and an upper-mid range and high frequency emphasis. The Focused channel can e
lended to taste with the Full channel or muted y turning the gain control all the way down.
(Pull) Bright switches: Each gain control has its own respective right switch, which oosts
the upper frequencies in either channel. Pull the kno (s) to activate right oost. (Note: the
effect of this control is diminished the higher the gain controls are set.)
Tre le: Adds tre le frequencies to oth channels when turned clock-wise.
Middle: Adds midrange frequencies to oth channels when turned clock-wise.
Bass: Adds ass frequencies to oth channels when turned clock-wise.
High Cut: Control upper-most frequencies and harmonics. The effect of this control
ecomes increasingly apparent the more the amp ecomes overdriven, smoothing out the
highest harmonics present in distorted tones. The control will not dull clean tones or cut into
the critical mid frequencies.
Loudness: Controls the overall the volume of the amplifier.
On/Off switch: Turns the amplifier on and off.
Stand y/Play switch: With the amplifier ON, Stand y mode mutes the sound allows the
tu es to heat up efore applying high voltage in Play mode. Leave in this mode for 30 seconds
to a 1 minute efore switching into Play mode. Stand y can also e used to mute the amplifier
while leaving the tu es warm short reaks. For long reaks it is est to turn the amplifier
completely off.
To turn off the amplifier, follow the same turn-on procedure in reverse – allowing the amp to
2

idle in Stand y mode for a out 30 seconds efore powering off. While it is perfectly okay to
turn the amp off immediately, idling in stand y efore powering off lets the filter capacitors
inside the amp fully discharge. If turned off immediately, there will still e some sound as the
filter caps continue to discharge.
Rear Panel
120 VAC power input: Plug in the included standard IEC power cord here. For use with 120
VAC (USA) only unless otherwise specified.
WARNING!: Use with grounded power outlet only! Discard power cord immediately if
ground pin is damaged/ roken. The ground connection is for your safety in case of a
fault!
Footswitch jack: Plug included 2- utton footswitch here.
Speaker Jacks and Impedance Selector
Note: Speakers must be rated for at least the full rated clean output power of the
amplifier (50W or 100W depending on model). nder overdrive conditions, the
clean power can be exceeded by tens of watts, therefore it is preferable to use
speakers whose combine power rating exceeds the clean power rating. This topic is
up for debate as some speaker manufacturers rate their speakers with this
knowledge in mind (i.e. four 25W rated speakers may be OK for a 100W amp).
Using one speaker ca inet: With the amp OFF, match the impedance selector with the
speaker ca inet's impedance. Always verify a speaker ca inets impedance efore using with
the amplifier. An impedance mismatch can potentially damage the amplifier.
Using two speaker ca inets: When using with two speaker ca inets, oth must e the same
impedance (i.e. two 8 ohm ca s), and the impedance selector should e set for half each ca 's
impedance. For example:
•When using two 8 ohm ca s: Set the impedance selector should e set to 4 ohms.
•When using two 16 ohm ca s: Set the impedance selector should e set to 8 ohms.
•Using two 4 ohms ca s: This configuration is not supported ecause there is not 2 ohm
tap on the Hellhawk's output transformer.
3

Footswitch
The first utton on the footswitch toggles etween the Full and Focused gain controls. When
the LED is illuminated the Focused channel is on.
The second utton lends oth the Full and Focused channels together when the LED is
illuminated. When the Blend is switched off, the amp will go ack to the channel of the first
utton.
Tip: The first button can be switched while in Blend mode, allowing the user to switch back to
either channel.
Bias adjustments
Left ias adjustment: Controls the ias of the left output tu e, V5 (See tu e chart on pg. 10).
The setting is locked in place y the outer locking nut. To make an adjustment, slightly loosen
the outer locking nut.
Right ias adjustment: Controls the ias of the right output tu e, V4 (See tu e chart on pg.
10). The setting is locked in place y the outer locking nut. To make an adjustment, slightly
loosen the outer locking nut.
Test jacks: For use with standard multimeter pro es.
Black common pro e jack: Plug in common meter pro e here.
Left red pro e jack: Plug in pro e to monitor left output tu e's ias voltage.
Right pro e jack: Plug in meter pro e to monitor right output tu e's ias voltage.
Bias procedure (50-watt version)
WARNING!: Maladjustment of the ias controls can lead to output tu e failure. The ias
adjustments are not fool-proof, and output tu es can e under- iased ecause a
reasona le ias range needs to e given to account for different output tu e samples. If
under- iased for a sustained period output tu es will likely fail. Science Amplification is
not responsi le for output tu e failure due to mal-adjustment of ias controls.
Please familiarize yourself with the ias procedure efore making ias adjustments. If
you at all feel uncomforta le making adjustments, take the amp to a qualified technician.
We do, however, encourage you to ias yourself ecause it is completely safe. It is also
easy once you get the hang of it, and can save you quite a it of cash!
Note: A electronic volt meter (digital preferred) with a millivolt setting is needed to make ias
4

readings/adjustments. A digital multimeter can e found cheaply at any hardware store. Here's
the cheapest we've found on the we , which is totally sufficient for the jo :
http://www.har orfreight.com/7-function-digital-multimeter-90899.html
With a speaker ca inet plugged in,turn on the amp, let it warm up for a out 30 seconds, then
take off Stand y into Play mode (The volume can e all the way down for the test). Let the
amp run for a minute or two.
Next, set the multimeter to DC millivolts (mV).
Insert the lack test pro e into the lack jack on the rear panel, and the red pro e into either
red jack. The left jack measures the ias of the left output tu e (V5), and the right jack
measures the ias of the right output tu e (V4).
For the correct ias range you should read etween:
•6L6: 37mV to 43mV
•EL34: 31mV to 36mV
•KT88: 31mV to 36mV
Anything lower settings will not harm the tu es, ut anything higher than:
•41mV and up per tu e for EL34s
•50mV and up for 6L6s
•41mV and up for KT88
will lead to shortened output tu e life or imminent failure.
Remove the red pro e, and insert it into the other jack to check the reading. Ideally it should
e the same as the first reading, ut a couple millivolts difference is no ig deal.
Here are some situations where you may need to check the ias:
•The amp sounds thin, or a normal in any way.
•The amp is quieter than normal.
•The amp hums more than normal.
•The ias controls are accidentally maladjusted.
If a reading is elow the safe range y more than 10-15mV, then it's likely a tu e has failed on
that side and needs to e replaced. This will also cause the other side to e higher than
normal.
5

The output tu es will also age unequally (much like car tires), so some may adjustment may
e needed through out the tu es' life to keep them in alance. Although it's not necessary to
keep the tu es perfectly alanced, it will keep the amp putting out maximum power with the
least amount of hum.
If adjustment is necessary, first loosen the outer lock-nuts on the ias adjustments. Make
move the control with a flat-head screwdriver (a guitar pick works well too), while monitoring
the num er on the multimeter. You may have to adjust oth controls ack and forth until they
are alanced ecause they are somewhat interactive.
Tu e life and trou leshooting
Output tu es (V4 and V5 – See tu e chart on pg. 10) generally produce a good strong sound
for 6 months to a year when played regularly, then they may ecome dull sounding, and/or
the amplifier may egin to loose some power. Output tu es may last much longer depending
on how hard the amp is played. Sometimes they die gently, sometimes a ruptly causing a fuse
to low, which in turn protects the amplifier from further damage. Output tu es may also
ecome microphonic like preamp tu es.
It's sometimes possi le to see which power tu e(s) is damaged. If necessary, remove the
output tu es to inspect them (Remove power cord, allow tu es to cool, then gra y the
plastic ase, and gently pulling up in a circular motion). Here are things to look for:
•Shiny silver area on top of tu e turns white.
•Burned spot on the large gray structure inside the tu e.
Sometimes a output tu e or preamp tu e will ecome “microphonic” when something
ecomes physically loose inside the tu e's glass envelope. In turn, this noise then gets
amplified through the speaker. The noise can e anything from static, a high-pitched ringing,
or intermittent sputtering noises. This is usually exacer ated y vi ration from the speaker
ca inet. If you think a tu e may e microphonic, try isolating the amplifier from the speaker
ca inet.
Tip: If you think you have a microphonic tube, you can very gently tap on each tube with a pencil's
eraser to see if the sound becomes worse or changes. All tubes will amplify the sound a little,
especially preamp tubes. But for example, if you hear an intermittent ringing sound and tap each
tube to find V1 is causing the ringing to start and stop, you can be sure it's the problematic tube!
In general preamp tu es (V1, V2, and V3 see tu e chart on pg. 10) can last many years, and
usually ecome microphonic efore wearing out or failing.
Changing preamp tu es
6

V1, V2, and V3 (see tu e chart on pg. 10)
To remove tu es, gently pull upward using a very slight circular motion if necessary. When re-
inserting a preamp tu e, mind the pin/socket orientation as they are “keyed” to insure proper
installation.
Changing output tu es
V4, V5 (see tu e chart on pg. 10)
CAUTION!: Tu es can ecome extremely hot during normal operation. Make sure the
amplifier is OFF, and always allow tu es to cool efore handling to prevent urns.
In general, it's est to change oth output tu es at once (V4, V5 – See tu e chart on pg. 10),
and prefera le to uy a "matched pair" from a reputa le dealer. However, ecause of the dual-
ias system, it is possi le to replace only one output tu e, then alancing the ias level with
the existing output tu e.
Tip: Buy “burned-in” tubes when possible for maximum stability and minimal bias drift.
To change tu es, remove the old tu es and set oth ias controls all the way down (counter-
clockwise). Insert the new tu es minding the “key” on the ottom of the tu e, and slowly
ring up oth ias controls until they are equal and in the safe ias range.
If tu es are not pre-“ urned-in,” check the ias after playing to see if it has drifted from the
initial setting. Full urn-in may take up to 24 hours depending on the tu e set. This is why
urned in tu es are preferred.
Different tu e types and ias ranges (50-watt version)
The Hellhawk 50W can use oth EL34, 6L6, and KT88 output tu es. Below are the correct ias
ranges for all types:
•6L6: 37mV to 43mV
•EL34: 31mV to 36mV
•KT88: 31mV to 36mV
Anything lower settings will not harm the tu es, ut anything higher than:
•41mV and up per tu e for EL34s
7

•50mV and up for 6L6s
•41mV and up for KT88
will lead to shortened output tu e life or imminent failure.
Fuses
WARNING: Only check/change fuses with amplifier unplugged from the
wall socket!
Fuses are user-replacea le, and if a fuse needs replacement, always replace with the correct
"T" type and rating. The "T" stands for "Time delay" also known as "Slow Blow." Also e sure to
use the correct amperage rating (Ex. 1A = 1 Amp). These fuses are the 3AG type and are
commonly availa le. The correct fuse values are located on the ack panel of the amplifier.
If a fuse lows, it's a good thing! Fuses are put in place for safety and to protect the most
expensive parts of the amplifier. Fuses can low for various reasons, however the most
common is a output tu e failure. To check if a fuse is lown, push and twist counter-clockwise
to remove the fuse holder and see if the small wire inside the glass is roken. There may also
e a urnt area the inside of the glass.
If you replace a fuse, and it lows again, there is likely a more serious pro lem. Please contact
us efore changing the fuse again at [e-mail] so we can further assist you with
the trou le-shooting.
Safety
•Always use a 3-prong ca le into a grounded outlet. This makes sure the amplifier is
always grounded and safe in the rare occurrence the chassis should ecome "live"
(electrified).
•Tu es ecome very hot during normal operation. Allow them to cool efore handling
to prevent urns.
•Never change tu es with the amplifier ON.
•Always make sure the amp's vents are open, allowing heat to escape and air to flow
freely.
•Keep the amp away from moisture, and never put any everages on top of the amplifier,
no matter how convenient it may seem!
8

•Only change fuses with the amp unplugged from the wall!
•There are potentially lethal voltages present inside the amplifier. Do not open the
amplifier chassis unless authorized and are a qualified technician.
Limited Lifetime Warranty
Science Amplifiers are warranted to e free from defects in workmanship for the lifetime of
the original owner. Electronic components such as capacitors, resistors, transformers, jacks,
and potentiometers are warranted for 5 years (not including tu es, see elow). Any part
determined defective y Science Amplification within the 5 year period shall e repaired or
replaced y Science Amplification without charge for parts and la or provided the unit is
returned and transportation costs prepaid. Science Amplification will pay return shipping
costs to the original owner. Any unauthorized repair, modification, or tampering voids this
warranty.
The warranty excludes:
•Normal wear and tear: worn out tu es, jacks, cosmetic damage, etc.
•Misuse and a use: operating the amp without a speaker connected (although the amp
has some uilt-in protection against this), operating the amp into the wrong speaker
load, improper tu e installation, using the wrong value fuses, maladjustment of ias
controls, etc.
•Accidental damage: Dropping the amp, spilling liquid inside, etc.
•Acts of "God”: Natural disasters and other non-preventa le/foreseea le events that
damage the amplifier.
•Tu es, unless within manufacture's warranty period of 90 days (replacements offered
at manufacturer's discretion).
•Any damage caused y authorized or unauthorized repair or modification that is not
performed y Science Amplification.
Speakers carry Eminence's 7-year manufacturer's warranty. The terms can e found here:
http://www.parts-express.com/docs/warranty/eminence-manufacturer-warranty.pdf
If you think you have a speaker pro lem, please contact us first.
For warranty service, please email [e-mail] for return authorization. Amplifiers
9

must e sent ack in the original packaging or equivalent packaging. The cost of return
shipping to Science Amplification is to e paid y the owner. Science Amplification is not
responsi le for damage caused in return shipping. Science Amplification will pay for the
return shipping after the warranty work is completed.
In general, we will e a le to fix your amp for free, and help with tu e changes, etc. if needed.
We will also e happy to modify the amp in any way possi le until the amp is perfect for you.
Non-warranty repair is also availa le – please inquire for shop rates. Don't hesitate to contact
us!
Care and Maintenance
If plexiglass panels need cleaning, use only a soft clean, and dry 100% cotton cloth to wipe off
smudges with just a little pressure to avoid scratching. If needed dampen the cloth with a little
water, or use Novus rand plastic polish. Avoid harsh alcohol- ased cleaning products as they
may cause the acrylic to “ loom.” Also avoid the u iquitous “microfi er” cloths, which can
leave lint and/or tiny scratches the plexiglass in some cases since they vary so greatly in
quality.
Periodically check the 4 mounting screws on the ottom to make sure they are tight. These
screws secure the chassis to the head ca inet, and also insure contact to the aluminum RF
shielding plate inside the ca inet.
If possi le, move the amplifier when the tu es have had the chance to cool down for a couple
minutes. Because the tu es get very hot, the elements inside ecome more vulnera le to
physical damage until the tu es have cooled. In general, try to move the amp off stage last.
Tu e Chart
Birds-eye view of the Hellhawk's tu e layout. Only replace tu es with specified types listed
elow:
10