Bass Extensions

K.C. Strings C Extensions

Brass Slide C Extension
Brass Slide C
Brass Gated C Extension
Brass Gated C
Wood Gated C Extension - Black
Wood Gated C
Extension - Black

These extensions are truly unique. They are easy to install, easy to adjust and do not mutilate the scroll like other extensions.

Our extensions are made of brass or wood. The wood extensions are hand made and the brass ones are machined out. The wood is a little lighter in weight but the brass is more durable. We originally only made brass extensions and recommend them. Because moving parts always last longer and have less long term adjustment issues when made of brass than wood.

Both brass and wood extensions help conduct the acoustic vibrations onto the scroll. This is due to the extension string going around the scroll and pressing the extension body to the scroll. This helps transfer the vibrations from the extension onto the entire scroll. This results in the scroll becoming a part of the vibrational amplitude of the bass itself. Most will notice a richer, deeper increased volume of sound to their 'E' string after the extension is installed, even with the E gate closed.

The slide extension is ONLY for Jazz players. Having no gates allows the player to improvise playing notes, below the slide, on the extension fingerboard with their fingers.The slide extension also does not work for orchestral playing because of the time it takes to move the slide from the E position to the 'general position' of the lowest note needed. The gated extension is for classical orchestra players that want the gates to be set at 'precise positions' of the lowest notes needed. That way when the E gate is flipped open then the lowest note in the music can already be pre-set with another gate above. The gated extension comes with the 5 gates already shown. (Replacement gates can be purchased separately).

Among the many jazz and classical professionals using our extensions are: Principal bass of Boston Pops, Principal bass of Indianapolis Symphony, and Principal bass New Orleans Symphony.

BXTSCB Brass Slide-C Bass Extension $ 600 Add to Cart
BXTGCB Brass Gated-C Bass Extension $ 600 Add to Cart
BXTGCWB Wood Gated-C Bass Extension - Black $ 750 Add to Cart
BXTIG Replacement individual gate for wood C-Extension $ 55 Add to Cart
BXTIGB Replacement individual gate for brass C-Extension $ 55 Add to Cart

Brass extension with installation: $1,350.

Wood extension with installation: $1,500.


Slide Extension

  • The brass extension with ebony fingerboard has a unique sliding, self-clamping gate.
  • The string glides effortlessly on rollers through the body of the extension and around the scroll.
  • The extension can be easily adjusted to fit on any bass without cutting into the scroll. (See slide C-Extension Installation Instructions)
  • Extension weighs 3 lbs.


The Lever Arm is under spring tension and automatically clamps the attached Lever Foot on top of the string. The unclamping of the string is done manually by pressing the Lever Arm down, using the Thumbpiece below it as support for the hand. With the Lever Arm pressed down, the Gate easily slides along the length of the Gate Runway to any position. Any notes below the clamped Lever Foot are then fingered.


* The top of the scroll needs to be at least 1.5cm below the "neck projection line" (for standard use).
* The Finger board needs to be about 1cm in side thickness

The top of the scroll needs to be at least 1.5 cm below the projected "neck projection line" (for standard use) (shown in the picture above in dotted blue-green). The finger board needs to be about 1 cm in side thickness.

The Wood Shim and extra long Extension Body are cut down to fit individual scrolls. Instructions and all parts for installation come with the extension. A craftsman with hand plane and tool skills can do the work.

K.C. Strings Brass Slide-C Bass Extensions Slide-C Brass Bass Extension

Gated Extension

K.C. Strings Brass Gated Bass Extensions Gated-C Brass Bass Extension
K.C. Strings Wood Gated Bass Extensions - Black Gated-C Wood Bass Extension - Black

Replacement Individual Gate Assembly - Wood

Bass extension Replacement Individual Gate Assembly - wood

Replacement Individual Gate Assembly - Brass

Bass extension Replacement Individual Gate Assembly - brass

What to do if the scroll is at or above the neck projection line:

The Gated C-Extension will still work even if the scroll is at or above the neck projection line and no cutting of the scroll will be needed; When our extension is on a bass with the scroll that is 1.5 cm below the neck projection line then all gates open and close on the string normally. This is done by using only the top two fingers of the left hand (and the thumb underneath the brass extension body). When the scroll is higher then the neck projection line then the C string is very high above the extension fingerboard due to the fact that the extension itself is resting on top of the elevated scroll. So you have to press the "C" string down with the bottom two (pinkie) fingers of the left hand before you can close the first gate with the usual top two fingers.

Once one of the gates is closed with this two step process then the "C" string is pressed down and any other gate can be opened and closed with the usual one step process. This extra first step is so quick that it won't interfere with the playing at all.

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