Resonant Chamber

This is just an amasing video by Animusic project. "Resonant Chamber" features a ton of steampunk strings combined in an amazing music machine.

Contrabass saxophone

The contrabass saxophone is one of the lowest-pitched members of the saxophone family. It is extremely large (twice the length of tubing of the baritone saxophone, with a bore twice as wide, standing 6 feet four inches tall, or 1.9 meters) and heavy (approximately 45 pounds, or 20.4 kilograms), and is pitched in the key of EE♭, one octave below the baritone.

Especially in its lowest register, the instrument produces a massive and somewhat harsh, foghorn-like tone. Because of its extremely low register (like the contrabassoon), it can be difficult for listeners to perceive individual pitches; instead of hearing a clearly defined melody, listeners may instead hear a series of "buzzy" tones with little pitch definition.

Here is a page with some mp3's of the thing.

Tubax contrabass saxophone

Bazantar - Five String Double Bass

The bazantar is a custom made string instrument invented by musician Mark Deutsch, who worked on the design between 1993 and 1997 (US patent 5883318 issued March 16, 1999).

The bazantar is a five string double bass with 29 sympathetic and 4 drone strings and has a melodic range of five octaves. It is designed as a separate housing for sympathetic strings (to deal with the increased string tension) mountable on a double bass or cello, modified to hold drone strings.

Here is a 10 min video by Mark Deutsch himself.