"Another thing to try is a higher-order butterworth (I assume you are  
using 2nd order)"- Because of emphasis prior to Frequency cut-off?

Emulating 6dB/oct passive or a 20dB/oct active filter?


-Partev



=====================================================================



--- Victor.Lazzarini@nuim.ie wrote:

From: Victor Lazzarini 
To: csound@lists.bath.ac.uk
Subject: [Csnd] Re: Re: Re: calculate amplitude loss in butterbp
Date: Fri, 04 Dec 2009 08:35:36 +0000

Another thing to try is a higher-order butterworth (I assume you are  
using 2nd order).
On 4 Dec 2009, at 08:27, Victor Lazzarini wrote:

> Reading  again, perhaps eqfil will not do what you want. It boots or  
> attenuates a given
> band, but lets other pass unchanged. It looks like you need to  
> remove all but the band.
> On 4 Dec 2009, at 08:16, Victor Lazzarini wrote:
>
>> You can try eqfil.
>>
>> Victor
>>
>> On 3 Dec 2009, at 23:03, Oeyvind Brandtsegg wrote:
>>
>>> Hello,
>>> I'd like to calculate the amplitude loss of a signal when it's run
>>> through a bandpass filter, currently using butterbp.
>>> The rudimentary observations are:
>>> The narrower the bandwidth, the less amplitude the output signal  
>>> will have.
>>> Also, the gain loss is not equal across the frequency range.
>>> Basically, lower frequencies have more gain loss at the same  
>>> bandwidth
>>> than higher frequencies.
>>>
>>> I tried to adjust empirically, but I don't seem to find anything  
>>> that
>>> gives a close to unity gain for all (any) center frequency and
>>> bandwidth combinations.
>>> I could use balance to do it, but since the amplitude variation  
>>> can be
>>> quite large, balance does not work really well either. As balance
>>> needs a short amount of time (ihp) to find rms and do the balancing,
>>> excessive transients are likely to bleed through, and adjusting  
>>> ihp to
>>> a very low value can cause distortion due to rapid gain changes.
>>>
>>> Maybe there's another bandpass filter I could use that has a close  
>>> to
>>> unity gain output regardless of cutoff and bandwidth setting ?
>>>
>>> best
>>> Öeyvind
>>>
>>>
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>>
>>
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>
>
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