HEL JFET PREAMP MKII
After countless hours over the course of several years and literally dozens of prototypes, the HEL FET has evolved into the HEL JFET MKII.
THIS IS THE PREAMP I HAD ENVISIONED
My initial prototypes with JFETs proved unsuccessful as production of through-hole J201 or other high quality JFETs for use in high gain circuits has ceased. (And the fakes out there are just awful!) so I went with MOSFETs for what has become the “MKI MOSFET” version.
These weren’t bad but they were a compromise.
My move into hybrid SMD / through-hole design opened up the possibility of using the current production SMD J201 JFETs.
I can’t even begin to describe how happy I am about this revelation.
IMPROVEMENTS:
•From switching to J201 JFET
✔️Astronomically better tone and gain structure over MOSFETs
✔️Better clarity and articulation
✔️Run other gain pedals in front of it for even more brutality.
•Due to the new PCB layout and added diode gating
✔️No oscillation.
✔️Minimal hum or hiss.
✔️Feedback only happens on high settings or when boosted
✔️Gain knob also functions as a "gate threshold"
•"Soft touch" momentary switching
✔️Instant switching
✔️No mechanical switch failure
✔️Easy on the feet for home use
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WHAT IS THE HEL JFET PREAMP?
The HEL FET is a discrete component, J201 JFET high gain preamp inspired by the handwired, high voltage, high gain HEL tube preamp.
The tube version is tight, articulate, throaty and saturated but with a brutality and tone stack design that is totally unique to BLACKHAWK.
The HEL tone stack was designed by BLACKHAWK over the course of years of R&D.
While it was originally influenced by the DR103, it has been so heavily modified and provides such an extreme range of sounds, unless you’ve tried one, you've never heard anything like it before.
By using FETs instead of tubes, the more brutal aspects that can be described as extreme, ugly, gnarly etc. are even more pronounced and the saturation makes it amazing for other styles of playing as well.
The HEL FET is excellent for:
•DEATH METAL
•BLACK METAL
•DOOM
•SLUDGE
•PUNK
•GOTH
•SHOEGAZE
•DRONE
•EXPERIMENTAL/NOISE
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WHAT IS DIFFERENT ABOUT THE MJOLNIR JFET PREAMP:
The MJOLNIR is based on the British voiced MJOLNIR 100 amplifier which is versatile while remaining “in the pocket” and classic so to speak. Warm, full, articulate throaty and brutal, all at once.
The MJOLNIR FET is excellent for:
•DEATH METAL
•BLACK METAL
•DOOM
•PUNK
•HEAVY ROCK
•PSYCHE
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HOW TO USE THE HEL JFET PREAMP:
🚨THE HEL PREAMP IS HIGH GAIN ONLY!!!🚨
•The HEL is designed to be placed in front of any CLEAN single channel amp for huge low end and clarity, effectively making that amp a two channel amp.
It is important that the amp be clean (this means CLEAN, not edge-of-breakup) If the amp it’s being run into has breakup/gain, the tone stack becomes less effective into those additional gain stages.
It is also important to check that your amp does not have a bright cap or has a switch to turn the bright cap off.
(The “brightness” is actually an absence of low end as the gain control is turned down and will chop off all low end of the HEL.)
•The HEL PREAMP is also designed to be used into an FX loop or power amplifier.
When used into a power amp it is darker than into the front end of an amp but that may be what you are looking for.
In my opinion, tube amp power sections (plugging in the FX loop return) and rackmount tube power amps will give the best tone as they also have a pleasing power tube breakup.
However solid state power amps do the job and can sound excellent as well as they have the highest headroom which is killer for those who use a lot of time based effects.
•The HEL PREAMP was not designed to be clean nor was it intended to be plugged into computer interfaces.
(Plugging into interfaces may be possible, I just haven’t tested it enough to suggest or recommend that)
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CONTROLS AND SWITCHES
Using the unique BLACKHAWK designed HEL tone stack, an astounding range of tones are possible.
V = Volume
F = Frequency (this shifts the entire tone stack spectrum and intensity)
🔱= Gain
T = Treble
M = Midrange
B = Bass
•Right toggle = bass shift
•Left toggle = treble shift
•Right Footswitch = BYPASS
•Left Footswitch = BOOST
USER ACCESS TRIM POTS:
•Presence pot inside rolls off high end (good for “pedal use” into an amp) or turn it all the way up when you use it into a power amp
• clipping (additional MOSFET clipping. Be aware when adjusting, this affects the tone stack as well)
•boost (sets the amount of the boost)
•depth (sets the “tightness” of the boost. Tighter settings also increase gain)
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POWER REQUIREMENTS:
‼️POWER WITH 9V ONLY‼️
FET PREAMPS include a built-in voltage doubling charge pump.
All BLACKHAWK pedals and preamps are true bypass and standard “one spot style” 9v, Negative tip, 2.1mm barrel.
CURRENT DRAW 200ma to 300ma
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ADDITIONAL IMPORTANT INFORMATION:
❌ PLEASE DO NOT TOUCH THE BIAS TRIM POTS ❌
(unless you have a multimeter to rebias with) they are essentially 9v but because each JFET has its own unique character, this is best set when building and not meant to be user adjusted.
Videos are available on Instagram @blackhawkamps
Please allow 1-2 weeks build time as every BLACKHAWK pedal is made by hand for YOU.
