[sdiy] HP from LP ?

[Quincas Moreira]

I don't think any design, made in smd by chinese robots, will increase the cost of these synths significantly. My guess is they have two separate filters, or a multimode like the 3320.

Sent from my iPhone

> On Jul 31, 2017, at 13:42, Vladimir Pantelic <vladoman at gmail.com> wrote:
> 
> see http://sound.whsites.net/articles/derived-xovers.htm
> 
> even with a higher order lowpass you only get a first order highpass with subtracting.
> 
>> On 31.07.2017 20:10, Michael Zacherl wrote:
>> Hi,
>> I discussed that briefly in one of the last SDIY meetings,
>> did some experiments but never came to a sound conclusion:
>> 
>> Is there a ‘cheap’ way of turning a low pass filter into a high pass?
>> 
>> How’s that possibly approached?
>> Just something like subtracting the LP’s output from its input signal?
>> If so, what about resonance?
>> 
>> My point about doing that cheaply is the (upcoming) release of two synths with Moog ladder filter featuring a switchable high pass mode.
>> To my knowledge, there was no resonating HP filter from Moog so far in any synth.
>> Until now.
>> Since both synths (Moog Mother-32 and Behringer Model D) are on the budget side in terms of money I’d rather expect a simple solution compared to a, say, DSI Pro-2 with two fully featured filters in it.
>> 
>> Any hints?
>> Thanks, Michael.
>> 
>> 
>> --
>> http://mz.klingt.org
>> 
>> 
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