[LAU] Neve filters for Linux?

Ken Restivo ken at restivo.org
Sat Mar 27 14:47:04 EDT 2010

On Sat, Mar 27, 2010 at 05:15:18PM +0100, fons at kokkinizita.net wrote:
> On Sat, Mar 27, 2010 at 02:45:18PM +0000, Folderol wrote:
> > What! Are you telling me that going round the edge of a CD with a felt
> > tip pen *doesn't* improve the 'clarity'? :D
> Depends on the price of the felt tip pen.
> Regarding the 'feel' of filters, I've put up some examples
> on <http://www.kokkinizita.net/linuxaudio/paramfilt.html>.
> These are three examples of a parametric filter set to
> 1 kHz, fixed 'bandwidth' and gain between -15 and +15 dB
> in steps of 5 dB. The curves for +15 dB are identical for
> all three.
> If you compare Type 1 and Type 2, it's easy to see that
> the two would 'feel' quite different if you turn the gain
> knob. Most filters you'll see in practice will be somewhere
> in between these two. For example my Ladspa filter plugin
> is such a compromise, visually somewhat closer to 1 than
> to 2.
> Type 3 looks quite odd, but it is in a sense the most
> 'natural' of all three: it corresponds to a variable amount
> of a *fixed* bandwidth (i.e. independent of gain) 2nd order
> resonance being added or subtracted. Again this 'feels'
> different. 
> Now the DSP code used to produce these curves is identical
> for all. It has three internal parameters, c1, c2, g, and
> the only difference between the three forms is in the way
> that the three 'user' paramters Frequency, Bandwidth and
> Gain are mapped to the internal ones. Given a certain curve
> (i.e. values for c1, c2, g) all three can produce it.
> So this is in fact three time the *same* filter, just
> 'presented' differently.

None of this really addresses the difference in *sound* of these supposedly-"magical" filters.

But Google turned this up, which I found interesting:

Has anyone tried emulating these Neve filters in software using LADSPA?

Anyone want to? (um, hi Fons!)


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