Back in the 80's, after seeing the film "The Hunger" with David Bowie, I became moderately obsessed with Bach's cello suites. I obtained about a dozen recordings of different cellists performing them. Later on I started transposing them to my primary instrument, the four stringed electric bass. Trying to duplicate the range of an instrument tuned in fifths on an instrument tuned in fourths is a challenge on its own. Try to do it on the fret distances of a 34" scale bass and you're gonna have a bad time.
Here are some of the issues I encountered, and how I was able to resolve them with the help of the D'Addario string catalog.
Step 1: Tension
Truss-rods and Intonation
In order to achieve a uniform playability and uniform tone on an electric bass (or any stringed instrument, really), the strings must be approximately uniformly tensioned. As the strings are tuned, they exert more tension on the neck, bending it into a concave shape. If the fretted neck remained concave, some fretted notes would sound louder since they would be closer to the pickup, some would sound softer because they are further away, some would buzz because they hit the frets, and the intonation (the relationship of the fretted note to its correct subdivision of the string) would be inconsistent. To prevent these issues, a truss rod in the neck is tensioned to pull the neck in the opposite direction. When the truss rod is properly adjusted to match the tension of the strings, the string height and intonation are at their optimal. Note, it is impossible to get perfect intonation on any fretted neck, but you can get close enough. Some fretted notes will always sound out of tune, that's life in the digital world.
The pitch of a string is related to its tension and it's mass by this equation:
T = (W x (2 x L x F) ^ 2) / 386.4
T = tension (lbf)
W = unit weight (lbm per linear inch)
L = length (inches)
F = Frequency (cycles per second)
The units of Tension are in pounds-force, which is foot-pounds per second squared.
In the case of wire-wound electric bass strings, mass translates to diameter (an length), which is represented as gauge in inches. So a 105 is a 0.105" wide string. Bass strings are typically selected in sets that have approximately the same tension per string, between 38 (.100 E) and 46 (.110 E) pounds of tension. A fatter string requires higher tension to achieve the bottom E, whereas a thinner string requires a lower tension to achieve the same pitch.
The remaining three strings in the set are selected to match that tension, with some slight variations (+/- 8 lbs).
If you try to just de-tune your 105 gauge E to sound like a low C, it won't have enough tension to vibrate and it will flop pathetically against the pickup cores. Trying to tune the G up to a D will break in a few hours. And your neck will be a mess.
Go Home, Bass, You're Drunk
What to do? If you've ever played a chapman stick (which I strongly recommend: you'll either love it or be humbled into oblivion) you'll notice that somehow they manage to have 5 or 6 bass strings tuned in fifths. How did they pull it off?
Fortunately you can either have custom strings wound for the weight, pitch, tension. Or you can pop on over to the wonderful folks at D'Addario, who offer a suprisingly wide array of bass strings in various tensions. I suspect this is due to crazy 6 string bassists, but it helped me pick my strings. Which I am getting to!
Step 2: Picking Your Strings
In order to decide if I could even pull this off on a 34" scale, I first had to make a spreadsheet of all of the pitches and then map out where both a cello and electric bass fall. Here's a read-only version you can look at my read-only Google Sheet to see how approached the problem.
Next I looked up what typical tensions were for 110, 105 and 100 gauge E strings. I found that my ear and fingers prefer the lower tension of the 100 gauge sets, which are around 38.4 lpf.
I didn't think I would find a match so I made two columns: one for a standard violincello, and one for a "mock" cello shifted down an octave into the bass range.
Looking at this string tension guide from D'Addario I started scanning for all of the strings that could play a C2 (or just "C" in their terms). I found that there were several choices, which made me happy, so I picked the XLB065, which comes in at around 40 lbf, close enough to my favorite 38.4. But now you have to find other strings to fill out G2-D3-A3 (G-d-a). This took some work and I had to compromise a little. I could have shifted the C2 up or down, but after a few iterations I landed on the string set in column G (plus the higher a-string was getting frightfully small).
The high "a" is a mere 0.018" and isn't even wound. It's basically a guitar string.
Step 3: Intonation? Who Needs Intonation?!
The nut has to go. There's no way you can put a 0.018" string in a 0.045" groove. Nut files are expensive, but guess what, you don't need them. You can go to Home Depot and buy a thin enough file to get the job done, and a new graphite nut is about $10 on Amazon. Assuming your nut isn't glued in, you can just tap it out with a mallet and a punch. There are plenty of YouTubevideos on this.
Yeah, bass bridges really cannot handle thin strings. I got a lot of buzz on my SMG bridge, I ended up using little bits of electrical tape to cut back on the noise. This surprisingly didn't impact the brightness. The problem is the intonation. For some reason the higher bridges were bottoming out as I tried to dial them back. I didn't expect this, but the intonation isn't THAT bad. Periodically you can hear it when you change keys with a oddly placed Bach accidental, but that's life. I plan to go fretless soon.
Since I picked string tensions in the ballpark of what my bass is set up for, I did not notice an appreciable twist or bow in the neck. This was the only part I didn't have to mess with, thankfully.
Step 4: Picking Is Not Bowing
The biggest problem with this conversion is the utter lack of expression. A bow can do so much more than pizzicato, which is essentially the majority of electric bass. The Ebow doesn't resonate quickly enough. In order to compensate for the lack of sustain with a bow, I cranked up the Hall Reverb effect on my rack to 11. That really solved the problem. I tried a compressor to take away some of the attack, but the breathing was too noticeable. I would like to try an analog synth envelope shaper to see if I can dial back the attack.
Step 5: Ta-da!
I hadn't played the prelude in over 15 years, so learning the new fingering in 5ths didn't take long. It was amazing how much more sense the notes make when played with the proper tuning. The brilliant coincidence of the notes and the positioning & fingering seemed very suddenly not a coincidence. What struck me most was the challenge of phrasing. There is essentially zero phrasing in modern electric rock bass. Zero. Lock in with the drummer, keep your volume consistent, and if you do get an opening, the venue typically can't handle too much expression in volume. But try to play Bach cello music with that approach and it just feels... icky. As you can see by this video I'm wrestling with pitch and tempo: I still haven't decided how I want to feel the piece, simply because I don't have a lifetime of experience playing music this way.
I encourage any bass player to try this, it is truly an eye-opener.