Lap-pedal-steel
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The idea of making an electric pedal steel came up during constructing (or even designing) the acoustic one. As can be seen, the acoustic working required several compromises, what are needless to take on, unless we’d use it on a cliff, separated from the world (or a festival, which allows only the use of acoustic instruments). However it was sure since the beginning, that the goal is an instrument, usable even lap-held . Hence it should work by bowdens. It would be good, however, if it should be an E9th steel guitar, as much full-configured, as possible.
I designed a well-shaped body of maple-wood. Complete mechanics including changer should be mounted in a routed mortise on it’s bottom. And a simplified one of chipboard. Let the necessary changes to find out, before I’ll fall on the expensive maple-wood by the router. It can be seen according to it, (and usual dimensions of available maple boards),
that far less space is available for mechanics, as in case of an ordinary pedal-steel. Hence the most simple mechanics should’ve designed, using even weakest parts.
According to this, pull-release system had chosen. Each parts had tested on a “board-model”, what contained one string with machine-head, changer-finger, and the adequate part of mechanics. Beside choice of best alternatives for several parts, 2 mm welding rods, instead of M3 thread bolts, have chosen for pulling rods. Proper pull-springs for lowering knee-levers, and their tension-adjusting mechanics had also researched. Spring itself is a Stratocaster tremolo spring, as it properly matches to M6 thread bolt. (Right knee-lever had finally made with smaller spring, as there was not enough space, but it pulls only one string.)
Smaller height of mechanics causes that changer can fit only two pull rods per string, instead of three. This intrigued only in case of high E string, which should be changed 3 ways. (-1/2, +1/2, +1, or: Eb, F, F#). (Solution) Complete mechanics together with changer, and knee-levers, had monted on a framework, made of Aluminium.
This is an almost complete E9th instrument. Almost, hence – similarly to acoustic version - there are 8 strings instead of 10. However, according to standard E9th, 3 pedals and 4 knee-levers are applied, from which, only 2 right knee-levers cannot used lap-held mode.
| ped A | ped B | ped C | lkL | lkR | RkL | RkR | |
|---|---|---|---|---|---|---|---|
| F# (0,13) | G | ||||||
| G# (0,11) | A | ||||||
| E (0,14) | F# | F | Eb | ||||
| H (0,17) | C# | C# | |||||
| G# (0,20) | A | ||||||
| F# (0,26w) | G | ||||||
| E (0,30w) | F | Eb | |||||
| D (0,34w) | C# |
Bring up an eight-string pickup also proved to be difficult. I was about to build a brand new one, as AlNiCo magnet rods to be ordered, were found on WEB, but coil wire of suitable gauge wasn’t. Therefore, a Bulgarian guitar pickup had adapted. It was easily to dismount, turns of it’s coil were tightly clamped by cord, and were wrapped by nylon tape, but the coil was poorly mounted, wasn’t filled by wax, or resin.
A special iron core had been created. It’s edges reach over the coil to fit first and eighth strings, while intermediate ones have adjustable screws. Finally a case have made for all this. It consist of two Alu profiles, the upper one of them, (which would not be covered by the body) had been polished bright.
While three-pedal set was under construction, two-pedal set for acoustic version could be used. Some conclusions however could be drown of it. First cleared up, that 2:1 ratio of pedal is suitable. It produces 20-25 mm peal shift. Comparing to Norbi’s instruments, it’s significantly more then pedal shift of WBS (which is 12-15 mm), pretty much the same as of Haynes. (Norbi says the last to be more comfortable). Different strain of two G# strings however made some problem. These are thinnest and thickest plain strings of set. (On the acoustic version wounded low G# string was used, but here a solid one, according to D’Addario PS490 set, which would be used after test operation.) 
Although mechanics had been designed so, that effective lever-arm can be adjusted by rotation of cranks, very small amount of strain of low G# string could only be achieved by “pushing back” of fine-tuning screws of pull rods. Thus low G# begined to rise only at the very end of pedal travel, when high one had almost totally reached pitch of A. It also meant, that low G# got out of tune, if pedal had even slightly risen from its bottom position during playing. Thus adjustable springs are designed for new pedals, by which pedal could be pushed through it’s bottom position without risk of deforming of parts. This way 2-3 mm headroom appears between effective end-position of pedal and crank-pull-rod system.
Mechanics had been designed so, that effective lever-arm decreases as the pedal is being pushed down. (see animated diagram!) The same way, pedal force, and changer travel also decreases. Thus grater part of rising occurs at the first part of pedal-travel.
Volume pedal is a very important accessory of pedal steel playing. After I had unsuccessfully tried to get one of acceptable quality for affordable price, I made up my mind for some modification. I have a vintage Farfisa analogue organ. I used it in the Silver String, many years ago. It has an excellent, indestructible opto-electronic volume pedal. A plate with a specially shaped gap moves between a bulb and a photocell.
Of course, it needs a power supply, but it’s not a problem, it even provides a way for build an active circuit for impedance matching, and in addition, for solve another problem: I won’t like to carry a dedicated guitar combo, however my active speaker I use for amplifying my piano, has only microphone, and line inputs. Fortunately, there is a plenty of space on Farfisa pedal, more then enough for this electronics. Of course original structure should not been destructed, as it is a vintage one. I even found holes for the mounting screws. The whole electronics is connected to the Farfisa equipment through its original DIN plug. Fortunately I have the original circuit diagrams, so impedance matching should not be a problem.
Circuit consists of three stages. First stage is an impedance matching buffer, formed by one JFET, in source follower setup. This is a boardless “free-mounted” circuit, its’ parts are simply soldered on the pins of the input jack. Next stage is the original Farfisa photocell (ldr), and two resistors, which are originally mounted inside the organ. Last stage is a Conrad preamp panel , which had been lying in my drawer for years. Power supply is a one from a second-hand shop, rated for 12V DC / 300 mA.
“High” (250 mA) and low-current eras are separated by a 1k resistor. Each stages has independent stabilizers formed by electrolytic capacitors and Zener diodes.
The Conrad panel produced strange noises for some undisclosed reasons. Finally I gave up searching for the reasons, and replaced it by a free-mounted emitter follower circuit. That way, I had to - temporarily - pass up the option of voltage gain, but it still works with the microphone input of my amplifier.
Even PCB is already done. Free-mounted circuit was built only for testing, and to find the correct values for each parts. And this job is done yet. PCB itself was made by freehand drawing.
Finally, this stuff didn’t work properly. At first, considerable power consumption of bulb (250 mA) caused some difficulties, mainly manifested in hum. (A stronger – therefore larger and heavier – power supply could solve this problem, but wouldn’t do anything with the next two.)
Secondly, voltage gain was still missing. Especially, when I played on “big stuff”, where signals of my piano and sound modules are summed by a line mixer. How great it would be, if steel could also join here! And the same time (point three) some EQ would be needed. Of course, of that guitar-combo style “tone-stack” design!
First point was done by replacing the bulb by LED. Of course, constantly kept in mind, that a vintage equipment should not be modified irreversibly. So I constructed a LED-bulb, compatible with the original one. That consists of an 8 mm power LED, and three resistors mounted in the socket. Power consumption has reduced to just 100 mA, while light emission has increased significantly. Especially on the surface of LDR, caused by the 20° emitting angle of LED. This is very important, because the more the energy of light concentrated on the LDR, the greater the damping factor of the pedal in “min” position. (Unfortunately, total muting can not be achieved).
Other two requirements can be satisfied by one excellent circuit, I’ve found on a site named Redcircuits. This emulates the tube preamp of a good-old Fender Blackface combo by JFET transistors. “What a nice warm sound your steel has! Was it so even last time? Or have you just tinkered something on it?” – asked a guitar player colleague, when I first tried the stuff.
The device itself consists of three boards. The first contains the input jacks with the three resistors. The preamp circuit is mounted on the second, while third one contains the output socket, series resistors of power supply, with Zener diode, the connection network for pots, with the small capacitor of “bright” switch, and resistors for LDR, and emitter-follower buffer stage. Power-supply capacitor (two 2200 uF electrolytes in parallel) and voltage regulator for LED (LM317) are mounted on the chassis, and connected to the board by wires. All these parts connected to chassis-mounted star-point ground by separate wires.
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