Let’s Talk about Upright Bass Extensions

Ted's Talk: Why get a ``C`` Extension for your Upright Bass?

Getting a “C” extension is really a matter of practicality; if the music you wish to play requires notes below the low “E” on your bass, then a “C” extension is the easiest way to achieve those low notes, without making radical changes to the instrument (or re-learning the fingering!)

Picture 1: The bass on the let has a C-extension while the bass on the right does not.
Picture 2: Close up photo of a bass extension in our workshop.
Picture 3: Photo of a bass extension, separate from the upright bass.

I make custom “C” extensions out of hard maple, with a cap (a mini fingerboard) of ebony or dyed Wenge. I don’t use metal extensions because they are usually heavy, which can change the balance and sound of the bass. Also, every bass “scroll” and peg box are different, so I make every extension to order. The extension hugs the contours (see pic #2) of the box and scroll, and is shaped thickest where it needs the most support (see pic #3).

Picture 4: Gates installed on a bass extension.
Picture 5: a bass extension with only the "E" gate installed.

The brass capos or “gates” act as mechanical fingers to select the lowest note you want to play. (see pic #4) The larger “E” gate returns the bass to standard tuning. Some players prefer to finger the notes manually, and choose to install only the “E” gate. (see pic #5)

Picture 6: Importance of a smooth connection between fingerboard and bass extension.

The meeting point of the extension and bass fingerboard ought to be the same as the string height at the nut: if the E string is normally almost resting on the edge of the board, then the extension can meet flush (see pic #6); if the E height at the nut is perhaps 1mm, then the extension overlaps the board by 1mm, and so forth.

Picture 7: creating a bass extension mockup/beta using soft wood.

In crafting an extension, we first create a mock (or beta) extension from soft wood. It is roughly fit in place and string alignment is determined. (see pic #7) We then copy the mock extension in hard woods. A slot is cut in the end, and a string pulley is installed. Depending on the size, shape and antiquity of the bass scroll, different methods of stringing are employed. Most brands of strings are available in C-extension length.

Picture 8: Anzelotti gate attached to the bass extension.

Then the gates are attached. I only use Anzelotti hardware on my extensions. Rob Anzelotti makes his hardware to a very high standard. It’s expense is offset by ease of installation and function. (see pic #8) It doesn’t hurt that they look classy, either!!