[sdiy] Linear VCF control

Harald sdiy at haraldswerk.de
Fri Nov 9 21:17:42 CET 2018


If you scroll down you can download the docs (PDF)
https://www.haraldswerk.de/NGF_E/NGF_E_24dB_LP_HP/NGF_E_24dB_LP_HP.html#Anker03

Am 09.11.18 um 19:48 schrieb Ove Ridé:
> Unfortunately, the schematic is a bit hard to read because of the low
> image resolution.
> On Fri, 9 Nov 2018 at 19:00, Harald <sdiy at haraldswerk.de> wrote:
>>
>> It is quite easy to add linear control to a OTA based VCF. I have done
>> on most of my DIY filters. Example here:
>> https://www.haraldswerk.de/NGF_E/NGF_E_24dB_LP_HP/NGF_E_24dB_LP_HP.html
>>
>> Am 09.11.18 um 18:01 schrieb Tom Bugs:
>>> I think a few have cropped up recently in Euro (but I can't think of names)
>>> If the VCF is based around an OTA then it is often fairly easy to add linear to
>>> the usual sort of matched-pair exponential converter - not sure how that'd help
>>> with temperature compensation though.
>>> Somehow I don't think I ever actually tried it though.
>>>
>>>
>>> On 09/11/2018 16:53, Mattias Rickardsson wrote:
>>>> Hi all,
>>>>
>>>> following the recent discussions about temperature compensation of
>>>> exponentially VCFs, one could imagine that the easiest way of avoiding the
>>>> temperature dependence would be to control the filter linearly (Hz/V) instead
>>>> of exponentially. I can't remember seeing it done in a VCF, though. Even if
>>>> there are VCOs with linear control in currently produced synths - the latest
>>>> example might be the Moog One if I'm correctly informed.
>>>>
>>>> A quick search in the SDIY archives returned some hits in an interesting old
>>>> thread called "Filter frequency cutoff with linear response?" from 2012, where
>>>> Olivier Gillet, Florian Anwander and Tom Wiltshire pointed out that the
>>>> CEM3394 has linear filter FM from the onboard VCO's triangle wave via an
>>>> onboard modulation VCA. The datasheet of the CEM3394 describes it some more. I
>>>> remember liking the filter FM in the Akai AX-60, and this was it. It still
>>>> relies on exponential VCF in the regular filter CV input though.
>>>>
>>>> PAiA Fatman was mentioned as having linear control of both VCO and VCF. Any
>>>> other pure Hz/V filters out there? Or do people consider it a genuinly bad
>>>> idea (except for the lack of V/oct CV input and the need of increased CV
>>>> resolution/precision in the lower frequency range)? The bonus possibilities of
>>>> linear FM might make it worthwhile. :-)
>>>>
>>>> /mr
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Synth-diy mailing list
>>>> Synth-diy at synth-diy.org
>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>
>>> --
>>> BugBrand LTD
>>> UK company No. 07199808
>>> VAT No. GB 988 2629 57
>>> 1 Ninetree Hill
>>> BRISTOL BS1 3SB
>>> United Kingdom
>>> www.bugbrand.co.uk
>>>
>>>
>>> <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient>
>>>        Virus-free. www.avg.com
>>> <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient>
>>>
>>>
>>> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
>>>
>>>
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> 
> 



More information about the Synth-diy mailing list