Support

If you have a problem or need to report a bug please email : support@dsprobotics.com

There are 3 sections to this support area:

DOWNLOADS: access to product manuals, support files and drivers

HELP & INFORMATION: tutorials and example files for learning or finding pre-made modules for your projects

USER FORUMS: meet with other users and exchange ideas, you can also get help and assistance here

Tilt filter, "blue-ing" filter (cough cough martin?)

DSP related issues, mathematics, processing and techniques

Tilt filter, "blue-ing" filter (cough cough martin?)

Postby guyman » Wed Sep 26, 2018 6:48 pm

Hello all !

I was poking around and managed to get my hands on Martin's noise modules - pink, brown, and white. I noticed they were white noise oscillators, running through corresponding "pinking" and "browning filters" (-3 db, -6 db filters / octave respectively). I was wondering if we could collaborate to bring about "blueing" filters that could make blue noise (+3db) out of white, or white out of pink or brown noise... or perhaps a freely adjustable perfect tilt filter in general. I had reached to Spogg, but the wise man said I should share this idea publicly, and that our great savior Martin would be the gentleman who would more than likely bring insight into the matter. I'm not a coding genius with filters, so hopefully we can all learn and benefit from this creation.
guyman
 
Posts: 63
Joined: Fri Mar 02, 2018 8:27 pm

Re: Tilt filter, "blue-ing" filter (cough cough martin?)

Postby martinvicanek » Wed Sep 26, 2018 11:46 pm

I can offer these . I might do a general purpose tilt filter some time where you can vary the slope within, say, +- 12 dB/octave with a sigle knob...
Attachments
IntegratorDifferentiator.fsm
(42.24 KiB) Downloaded 225 times
User avatar
martinvicanek
 
Posts: 915
Joined: Sat Jun 22, 2013 8:28 pm

Re: Tilt filter, "blue-ing" filter (cough cough martin?)

Postby guyman » Thu Sep 27, 2018 1:31 am

Wow thanks!!

A general tilt filter would be boss... what's the slope on these different curves?
guyman
 
Posts: 63
Joined: Fri Mar 02, 2018 8:27 pm

Re: Tilt filter, "blue-ing" filter (cough cough martin?)

Postby martinvicanek » Thu Sep 27, 2018 8:20 pm

Here ya go - spectral tilt filter. The transfer curve is an approximate power law over the entire audio spectrum, with powers selectable within the range -3/2 to +3/2, or, equivalently, +-9 dB per octave (or +-30 dB per decade). You can stretch the range a bit but those would be extreme settings really.

The filter is a 3pole/3zero IIR , where the poles and zeros are suitably dragged aroud as you turn the knob. Normalization is chosen such that if you feed in pink noise, you get constant output power whatever the tilt.

The device would work in poly or in stream, or packed stream for stereo.

Have fun!

P.s. Uploaded improved version 2:
- extended range -15 dB/octave to +15 dB/octave
- more accurate power law approximation
- improved ultra-low frequency response
- optimized filter
- suppressed denormals
Attachments
TiltFilter2.fsm
Updated and improved
(1.35 MiB) Downloaded 242 times
TiltFilter.fsm
(1.32 MiB) Downloaded 222 times
Last edited by martinvicanek on Sat Sep 29, 2018 7:06 pm, edited 1 time in total.
User avatar
martinvicanek
 
Posts: 915
Joined: Sat Jun 22, 2013 8:28 pm

Re: Tilt filter, "blue-ing" filter (cough cough martin?)

Postby RJHollins » Fri Sep 28, 2018 3:21 am

Very nice !

Thanks Martin V.
RJHollins
 
Posts: 1350
Joined: Thu Mar 08, 2012 7:58 pm

Re: Tilt filter, "blue-ing" filter (cough cough martin?)

Postby adamszabo » Fri Sep 28, 2018 9:56 am

Thats really nice Martin! Is it possible to adjust the frequency of the middle point where the tilt occurs?
adamszabo
 
Posts: 405
Joined: Sun Jul 11, 2010 7:21 am

Re: Tilt filter, "blue-ing" filter (cough cough martin?)

Postby guyman » Fri Sep 28, 2018 2:29 pm

Martin. You are in full beast mode at all times. Thank you !!
guyman
 
Posts: 63
Joined: Fri Mar 02, 2018 8:27 pm

Re: Tilt filter, "blue-ing" filter (cough cough martin?)

Postby guyman » Fri Sep 28, 2018 4:32 pm

You could do that adam, but I believe it would defeat the purpose of the perfect tilt per decade which is consistent across the spectrum... needed to perfectly "pink", "brown", "blue", or "white" a noise profile.. (or signal 8-) )
guyman
 
Posts: 63
Joined: Fri Mar 02, 2018 8:27 pm

Re: Tilt filter, "blue-ing" filter (cough cough martin?)

Postby guyman » Fri Sep 28, 2018 4:38 pm

This is my (failed) attempt at using this exact tilt to create a "simultaneous tilt filter" that would attain the perfect "smile" or "frown" shape to apply to the signal which would "brown/pink" the highs while "blueing/whiting" the lows - and vice versa. I believe phase and other things I'll attribute to my lack of cleverness is defeating this idea before I can get it out the gate....
Attachments
Smile Up, Frown Down.fsm
(10.08 KiB) Downloaded 210 times
guyman
 
Posts: 63
Joined: Fri Mar 02, 2018 8:27 pm

Re: Tilt filter, "blue-ing" filter (cough cough martin?)

Postby guyman » Fri Sep 28, 2018 4:42 pm

Seeing as how we use these 4 noise profiles (white,pink,brown, blue) to tune/test systems and signal chains... creating a multipurpose tool that allows us to manipulate the spectrum consistent to this "perfect" tilt, satisfies the portion of my mind that craves a consistent control/metric at which I like to quickly alter the spectrum. I need to sit down and study filters so I can be more like Martin...
guyman
 
Posts: 63
Joined: Fri Mar 02, 2018 8:27 pm

Next

Return to DSP

Who is online

Users browsing this forum: No registered users and 6 guests