Maybe this will help? Use four biquads, each set to the same frequency, but 
with Q set as indicated by the calculator:

http://www.earlevel.com/main/2016/09/29/cascading-filters/

Nigel

> On Dec 23, 2016, at 8:59 PM, Waverly Edwards <[email protected]> wrote:
> 
> I need to apply an eight-pole Butterworth low-pass and later a high-pass 
> filter.  Are there any built-in mechanisms for this?
> If there are not, would someone mind providing some algorithmic guidance as 
> to how this could  accomplished?  Why?  I am attempting to reproduce an 
> experiment in which an eight-pole Butterworth filter was used -- a high-pass 
> at 300Hz and a low-pass at 3000Hz. If it matters, this is not for iOS.
>  
> Thank you kindly,
>  
>  
> W.
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