Project: keyhead changer on knife-edges

[Georg]

My own halfnote/fullnote stop...

...an improved and downsized variant of the movable stop I have used on my modded Dekley for 20 years. As on that old PSG I will use such stops on raise and lower of E strings, with the "lift halfnote stop out of the way" on the vertical lever between LKL and LKR.

[Georg]

Rudementary sketch of a "gear-shift" for my PSG...

...to change which bellcrank axle a pedal or lever is pulling on.

Using the same "hinge" as for the halftone/fulltone stop, the gray wheel with teeth is operated by right-knee vertical lever (RKV) in 90 degree turns between positions - haven't drawn the turning-mechanism yet.


- When hinge is straight it will push on the guided pull-rod, thus the bellcrank that rod is attached to will turn with that pedal or lever. Turn a bellcrank = make a change. (In the sketch the hinge is never quite straight, but that's just a flaw in my rough GIMP-drawing.)

- When the hinge-arm is lifted by a gear wheel tooth the hinge will no longer be straight, thus can't push with any force on the guided pull-rod for a given bellcrank - the hinge will just "bend up" more. This means no pull = no change.

- The gray "gear wheel" must lift hinge free - not engage it for pull, as the entire mechanism will otherwise be exposed to quite some force if I want to "change gear" while geared pedal/lever is activated. By lifting the hinge free when shifting gear, the present change will simply be de-activated - go back to neutral - and new pedal/lever/change combination be ready once the pedal/lever has been briefly released.


Intend to build the entire "gear shift" as a module, and attach it inside the skeleton above RKL/RKV/RKR since most gear shifts will be for RKL/RKR levers and RKV acts as "gear stick". Have also contemplated using the same gear shift for pedal 1, 4(C) and 5.

My thinking is to keep the "normal" changes on the 5 pedals / 4 levers in one gear position, and switch in some of the less used changes on the "normally less used" pedals/levers if/when I need them.

Although I think I will find it impractical to have more than 4 gear positions to keep track of while playing, only lack of space and sensible changes on a 10 string PSG limit what changes I can switch between via such a gear.

[richard37066]

Georg -

My thinking is to keep the "normal" changes on the 5 pedals / 4 levers in one gear position, and switch in some of the less used changes on the "normally less used" pedals/levers if/when I need them.

This is one of those things where ya slap your forehead and say "Why didn't I think of that!?"

I have but one concern: - If you keep your fertile mind in high hear then you might fast approach "multitasking overload"! However, you could always push some "shift" buttons with your nose! MMMMmmmmmmmm. Gonna have to think on that one.

Richard

[Georg]

Richard,

Regarding "multitasking overload" ... think of my approach as a PSG with potentially 4 different pedal/lever set-ups, with the RKV as switch. I need a form of indicator for where in the rotating [1][2][3][4][1][2]... sequence my PSG is at any one time, to avoid becoming confused while playing. But, with the "gear shift" right in front of me and only covered by a "shell", a mechanical or LED indicator should be easy enough to install.

It is mechanically much easier to add pedals/levers than to have a "gear shift", but I find playing with more than 4 pedals and 4 levers problematic. Reusing the same few pedals/levers makes IMO for a more playable instrument, and I definitely do not want to build a PSG that is technically advanced but hard to play.

Using the present set-up on my modded Dekley as reference (haven't decided whether to rig for my very personal "Twin Tuned Extended E major" or for "regular E9"), all I really need is to switch RKL/RKR to raise/lower the chromatic strings 1 and 2 in patterns more like what are found on most older E9 set-ups.
All other changes that I find "necessary" are already there - without "gearing", so I will have to play around and search for some "totally unnecessary" and/or "impossible" changes to fill a 4 position gear.

[richard37066]

Georg -

I, too, rebel at having to contend with a plethora of levers and pedals hence I'm trying to limit things to 5 pedals and 5 levers. (Six levers, max) As wacky as it may sound, I've even entertained the idea of a pivot - a lazy Susan - for my left foot (heel) such that I don't have to pick it up off of the floor and move it in order to access a pedal. The pedals would be "splayed" in a semicircle. (I know, it's been done many moons ago) I've already mocked it up on the floor and it works for as many as five pedals.

I think that it would be advantageous to you to come up with a way to reverse things at will instead of just having a strict sequence. Worst case: - you're in the #2 position and want to move to the #1 position - a situation which requires 3 moves forward instead of just 1 move backwards. Other scenarios apply as well. Ya wouldn't need a clutch, would ya, in order to get into reverse? How 'bout one VKL for forward and another VKL for reverse? Still leaves you with the desired 4 "playing" levers. Reduces the "dead" time in shifting from 3 moves to only 2 - worst case.

Aren't I just great at muddying things up?

Richard

[Georg]

Aren't I just great at muddying things up?

Yes, and Thank You!
...keep it up

I will use the LKV as "stop mover" to get LKL/LKR from halftone to fulltone change for E strings, so that one is occupied.

B0b touched on an existing solution a couple of years ago, that used sideways tipping of the Volume Pedal to engage extra set-ups. Will work, but such a solution pretty much incorporates the VP in the set-up and I am not sure if that is acceptable on my PSG.

As for floor pedals, as I see it the problem is that we can't activate and rock on/off more than 2 regular pedals. I have contemplated extending the 1st and 5th pedal inwards behind pedal 2, 3 and 4, so I can heel-operate them and operate - rock on/off - 3 pedals at once.


Anyway, here's another rough sketch: the "flip-over helper spring"...

...which - when tuned right - doesn't add any "help" on a non-activated change but will add considerable "help" once the relevant bellcrank axle start turning. "Balancing" is the keyword for smooth action here.

[richard37066]

Georg -

A rather inventive guy by the name of Gene Fields has come up with innovative solutions to several knotty problems. Go here:

http://www.gfimusicalproducts.com/Pages ... Steels.htm

One, in particular, for Al Petty has an array of pedals much like a console organ. Was this in the neighborhood of what you had in mind? I've been eyeing this for a couple of years and wondering what I might do with it. Maybe now?

Richard

[Georg]

Richard,
Yes, Al Petty's GFI show one way to do it. I have looked at that one a few times over the years.

With only 5 pedals my thoughts have circled around something like this...

...but I am not sure if the sideways twist on the angled heel-pedals won't create problems. May have to add support in between the 3 regular pedals.

[Georg]

The main part in my project: the floating neck...


Larger drawing: http://www.gunlaug.no/att/div-2011/psg-var-5.png

In my PSG the neck and its backbone are the only parts that are supposed to affect tone, so I will have to tune them in for the tone, sustain etc. I want. I don't know how many of these I will have to put together to get it right, but with a bit of luck one will do.

It is a large subsonic tuning fork resting on 4 vibration dampeners near the keyhead end, with some profiled steel bracing. The neck itself is supposed to exhibit no dominant resonances in the string-tone frequency range - sound pretty dead if knocked on.

The good thing is that once tuned in it is easy to replicate for identical tone qualities - in case another such PSG is ever built. The potentially bad thing is that a tuned-in neck like the above will only work with keyhead changers, although it will work pretty OK with any keyhead changer system that has all its parts past the keyhead rollers.

[richard37066]

Georg -

As regards the pedal arrangement I can only point you towards your own GFI for stability at the pivoting ends. Search as I might, I've been unable to find an extrusion which even closely approximates Gene's.

Although I endorse the use of heel pedals, I have but one concern and that is the inadvertant pressing of the lever such as to de-tune one or more strings. My not-so-elegant solution would probably be to increase the force required to activate it. As an alternative, one might consider some sort of "detent" arrangement such that an initial force would be required to overcome that resistance followed by a "normal" pedal pressure. The curved configuration certainly affords flexibility in position and motion. Nice.

Richard