I am using the Kontakt factory library with Upright Bass and it goes as low as a C but is there any instrument that can do a Bb (A#)?
Cheers
How low can a double bass go?
B/C depending on the bass. 5-String/Low B, C with a C extension of the E string. Or manually tune down.
The octobass goes an octave below that , down to C (0) .
That is an octave below the lowest C on a piano .
16.25 Hz . Below the range of human hearing !
It needs two people to play it . One to bow and another to operate the pedals and levers that stop the strings .
that is awesome!
I don’t guess anyone has sampled this instrument?
I could maybe fake it with an acoustic bass tuned down, or use a synth patch but what are my options (other or similar instruments) if any?
“In all its glory!”
Other options ;
Church/Cathedral Organ samples
or
Maybe try the ring modulator plugin in Cubase .
A Bflat and an F a fifth above will produce a tone containing a Bflat an octave below combined with a D a tenth above which could then be filtered out .
Bear in mind this may be going below the range of most monitors !
I’m using avantone but need to program a bass part.
There would be enough harmonics to know what note is being sounded however it must be represented in some way.
I guess with this information in mind, a double-bass of any description won’t cut it; least of all in a live performance (unless there is a corporation involved) 
I will try out the organ idea though, sounds like a reasonable thing to do in the circumstances otherwise I’m gonna have to supe it up with a synth but this is not normally the approach I take, now days at least I use synths (x-station) merely to write, change it to piano, program a bass and acoustic guitar always starting with…
you guessed it: A double bass
Then other basses are created of the more contemporary kind and I normally don’t transpose the upright parts unless the piece calls for it so I might get stuck but the organ sounds like a good idea, at least in the interim.
Thank you everyone you are all 