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Acoustic Pedal Steel

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Last update: 31-08-2013
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Historyc antecendent

To tell the truth, I've felt some perverse affection for pedal-steel guitars since my childhood. I would've never descended to even get one, considering it's price and dimensions. I imagined as it was standing in the corner day by day, and I were play it two times a year. Or as I would tote it gig to gig, to play just two songs on it. I was even thinking about to tune a guitar to E9, but finally I hung up about it, because the essence is in the pedals. My attention turned to the acoustic instruments. But in 2012, I met NIKODÉM Norbi, who plays his self-made pedal-steel. Norbi even built a lap-held version, on which levers are used instead of pedals for altering the tones. This method is uncomfortable, and it offers much less options as pedals do. That moment I decided to build a pedal-lap-steel guitar, what would work by bike Bowden cables. And it should be acoustic! Norbi also experimented with acoustic steel guitar, but nothing could heard of it among two guitars and double bass.


Resonator

The task is given. First, I have to increase the sound volume of the acoustic guitar. There are several kinds of resonators that do this job with acceptable results. A plenty of them can be found on the Net: some build factory-made resonators in anything. (Sink, basin, etc.) Others build home-made resonators (dog's plate, cake-box etc.) in given instruments. Or even cake-box in a sink. Came on handy, that a guitar body was laying in ny basement. It had a nice rectangle-shaped hole instead of it's bridge, as a friend of mine tried to repair it in a wrong way, about twenty years ago. As he found out, that it should never be a guitar any more, he gave it to me, perhaps I could use it anyway. I placed two Alu resonators over the hole. They were cut of the bottom of beer cans. An Alu bridge stands against them. This way, the vibration of the resonators is amplified by the hole. Even the residual vibration is not wasted, as the resonators stand against the top of the body, which transmits it forward in a regular way.

changer As a result of the acoustic working, the sound of the instrument is much more "percussive" as that of the electric pedal steel. As you can hear it clicking on the Youtube link, it hase a banjo-like taste. It's because of two things. Naturally there is no volume pedal, by wich the player can lengthen the sustain of the electric version. On the other hand, the long sustain of the electric pedal steels is caused just by the almost vibration less, rigid and massive body (containing several metal parts). As you can see, it is just the opposite of the working manner of an acoustic instrument. Finally gave it a pickup, but a special removable one, because it also would be a needless extra mass against vibration, when it would used acoustic.


Changer

changer Secondly, a simplified changer mechanics should've been designed, what could be placed on the bottom of the guitar body, as it was evident, that a normal changer (which also functions as bridge) can not be used. Although the hole, perfectly at the place of the bridge, landed itself for lowering the changer mechanics in it, that massive metal structure should mute the vibration. On one hand, it's inertia should damp it. On the other hand, the complex structure, made of several parts, should decrease the tightness of the acoustic coupling, therefore decrease the transmission of vibration. Thus this two function (changer and bridge) should’ve been separated. So the bridge can be a light, slim component, what transmits the vibration of the string directly to the resonator. According to the original theory, it should be a solid piece of Aluminium. Unfortunately slim strings cut themselves in it, and they even straitened a bit. It was almost ideal in terms of coupling, but it hardened the working of the changer. Therefore I strengthened the edge, contacting the strings, by a steel rod. changer This is made of an M3 thread bolt, so it also prevents the strings’ side movement. On the other hand, it's fact, that it slightly damps the vibration. For the changer's working, the ideal would be, if the strings should move on rollers on the bridge, but it should loosen the mechanical coupling between strings and resonator. And we've got to the Achilles heel of the construction! The long string portion behind the bridge would be disadvantageous even if the strings could move friction-free on the edge of the bridge. Reaching a given string shift on the bridge - what is necessary for a given tone rising - an approximately 25% more shift is needed at the end of the string. And 25% more pedal shift, or 25% more pedal-force, by untouched pedal-shift. But in the real world, the string movement is not friction-free. Therefore tension in the front- and back part of string is not equal: the difference of them is equal to the friction force. If a given tension gain is needed for a given tone rising in the "working" part of the string, a tension, extended by the friction force is needed at he changer. This makes two disadvantages: firstly, E-string - what should be both lowered and raised - returns to a different position after lowering and rising. Secondly, high G# string - especially raised to A - uses about 80% of tensile of steel. Every percent of tension gain increases risk of string-brake dramatically.

Update, 25. 06. 2013.

changer Problem of rollers just did not leave me alone. Finally I built a new bridge, with two rollers at the most troubled strings (e and g#). Unfortunately, it didn't solve the problem of e-string (maybe decreased it, or I just whish so). In the case of g# string, only time will answer, whether or not they'll exist longer without braking. Anyway, it became much cooler, as it is correctly symmetric, and I devoted time for polishing it.


copedent

It was not a question, it should be E9 tuning, as I wanted to play country songs on it, especially the works of Bródy. I just had to figure out, what of 10 strings, 3 pedals, and 4 knee levers should be omitted, and what is necessary for producing those characteristic sounds. All of them can not be achieved due to the small sized changer. After some speculation and experimentation, I decided to build an 8 string instrument with 2 pedals, and 2 knee levers:

ped A ped B lkL lkR
F# (0,12)
G# (0,09) A
E (0,13) F Eb
B (0,17) C#
G# (0,21w) A
F# (0,23w)
E (0,26w)
D (0,30w)

Eight mandolin keys were easily fitted on the head, just the original six holes should've been doweled, and eight new should've been drilled. Two strings (D and high F# ) are mounted on the side of the changer, so they can not be changed. It's seen in the table, that the low E string is not changed. It should've made the changer too complex.


Vicissitudes

Of course, there were some pitfalls. Firstly, the original Bulgarian body was a bit run down. Of course, the soundboard cracked at the sharp edges of the hole, and the head block was not even a tiger. Of course, I hoped to get away without opening the body, so I repaired the crack, gluing pieces of pinewood through the hole. In case of head block, I concluded, that it should stand. I was wrong in both cases. First the crack opened, as I was tuning the strings. I opened the back at bottom part of the body, and glued it correctly. Next time, as I was tuning it again, the head block had separated into two parts, one of which jumped back about 5 mm, together with the neck. Well, the Bulgarian luthier designed it for six nylon strings, it's somehow legal, that tension of eight steel strings breaks it. I repaired the block (opening the top of the body), and put a rod of pinewood through the body, connecting the head- and tail blocks. Even scale-length made some trouble. I found out, that it's impossible, to find a high g# string (riseble to a) for the classic scale-length. (Independently of gauge, tensile of steel is not enough). Scale-length of steel guitars is somehow shorter then classic, so I shortened it. But the place of bridge is given by the hole. The length of neck is also given, I didn't wish to cut, and join it, so changer there was no more choice, then shift nut back one frat. Not an elegant solution, but works. Later turned out, that knee lever doesn't work properly in "lap-steel mode". It is very uncomfortable, and unergonomic. I took a lot of experiments, but I was not satisfied. Finally I gave it up. No knee levers in lap-steel mode, only A and B pedals. However, I bought an X-stand for keyboards, and fixed both guitar and knee lever on it.


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