What you are about to read is the result of the perfect storm of aging, dementia, an over active imagination (still going strong), and way too much time on my hands. Oh yeah, comic books and monster movies.
Disclaimer: This post is only for GOF eyes only. By reading this you agree to never reveal the contents to the CIA, NSA, FBI or Interpol or any mental health facility. Destroy your device after reading.
Background: When I moved to the Philippines six years ago I brought with me most of the contents of my electronic junk box(es). As a certified IDIOT savant with electronics I hoped to have a few more "brainstorms" arise from the fog of my mind. Here is one that actually worked. (I have about a50/50 success rate). Among the stuff I brought here was a bunch of spare tubes, an octal relay DIN rail socket, a large box of discrete components, and a bunch of pedals of varying usefulness, collected over the years.
The build: I wanted another tube preamp for bass recording. I had some 6SL7 and 6SN7 tubes and that weird octal socket with screw terminals. I built a clone of the V1 circuit of an Ampeg B15 sans tone circuit. I really wanted some kind of tone control. I have a stereo 2 band parametric that I built like 30 years ago, but I couldn't chop it up....sentimental value, etc. I some how remembered that I had tucked away an Elecrto Harmonix Knockout pedal which is this weird filter based EQ (?) that I never found a use for. The controls are Bass, Dry, and Treble. The tone controls vary the volume of the high and low FILTERED signal and of course the dry is the bypassed original signal. I put this in front of the tube pre. I also added a negative feedback loop to the pre to act as an a gain control. The toggle switch is a range control for the gain pot as a 1meg pot was too sensitive. There is also an output volume control.
How does it work? I like it! With just the dry signal it can be clean tube goodness all the way to sweet overdrive by playing with the gain and output controls. Adding varying amounts of the filtered signal can go from fat or twangy to balls out nasty tubey distortion.
Components from my junk box: I needed to supply three voltages; 9V for the pedal, 6V for the tube filament, and some kind of B+ in the range of 275V to 300V. I had a few SMPS style wallwart adapters so I used the guts of 1 each for the low voltages. T wanted the SMPS style to save weight and to allow 220V operation as all my transformer style were leftover USA 120V. The B+ is from a 220V/12V stepdown to 12V/220V step up pair of transformers. I had the rest of the discrete components for the B+ supply in my junk box.
The cosmetics: I must have been having a flashback that day. The case is a defunct hard drive case. The tube cage is part of an old soldering iron holder. The "High Voltage" bridge is a spare handle that got shipped with a Weber grill I bought recently. The Blue Ball is from a burnt out LED light bulb. As I found the parts it just escalated. I bought one item. The LED'S.
Together it will be perfect for my GODZILLA diorama, if I ever make one.
The name BluBallz: My best friend of 45 years, Bob, a GOF keyboard player, owns the name. All I could come up with was "Tower of Stank" or "Grease Gunn".
Final thoughts: Of course it is too fragile to play out with it, however it has a happy place in my home studio (which I am remodeling and upgrading as I type this).
I will proudly display this as I know I am the first on my block to have one and will certainly be the envy of my neighborhood!
I hope this coming year will bring even better news.
