Zero experience! Wanting to learn with Sidechain EQ - reasonable?

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Hello - this is my first post here. First off - I know next to nothing about audio electronics, DIY, mods or repairs but have wanted to for years so I joined here to see if I can get a start. I have loads of experience in audio processing but experience with processing & production does not equal knowledge of the electronics - in that regard I'm lucky if I can solder two wires together on the 1st try.

I'd like to design and build a relatively-easy something I'll actually use, not just a test project. At the moment I'm looking for a sidechain EQ for compression control. Without knowing the complexity of designing such a thing I've come up with this concept - it would cover almost any sidechaining need I may encounter:

HP 20-350, 18db/oct slope
Peak 20-20k / -12db/+12db / Variable Q (1.0-8.0)
Shelf 20-20k / Fixed Q 1.0 / -12db/+12db
1/4" In + Out (TS / TRS?) for interfacing with pro level gear / SC
(I assume this would be an active design to keep it simplest, but unsure.)

Now, I have no idea how complex this would be, especially with the crossover frequencies and the parametric band - from what I've found a HP is quite simple, but no idea about the complexities when it's integrated into such a design. Can anyone comment / point me to a place to start or fill in the blanks (and they're mostly blanks) about what this would involve?

Thanks!
 
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First question. Are you sure these slopes are what you want? If not and you have a linux laptop then give the calf studio tools a run as they allow you to test out the filters you want digitally and be sure you are choosing the right ones.

I would also pop over to Pro Audio Design Forum - Pro Audio Design Forum and have a look at some of the designs there. They are a friendly bunch and lots of schematics posted for exactly what you want to do.

Looking at your requirements a variable Q peaking filter that can do the entire audio band could get tricky as you are switching a lot of components. 3 Bands would make more sense here. But nothing impossible, although I would make it modular so you can add as required.
 
First question. Are you sure these slopes are what you want? If not and you have a linux laptop then give the calf studio tools a run as they allow you to test out the filters you want digitally and be sure you are choosing the right ones.

I would also pop over to Pro Audio Design Forum - Pro Audio Design Forum and have a look at some of the designs there. They are a friendly bunch and lots of schematics posted for exactly what you want to do.

Looking at your requirements a variable Q peaking filter that can do the entire audio band could get tricky as you are switching a lot of components. 3 Bands would make more sense here. But nothing impossible, although I would make it modular so you can add as required.
The applications for side-chaining in the way I'd be using it should be well covered by those filters. I didn't spend a ton of time coming up with them - 15 minutes with a digital parametric EQ and knowing the dozen or so ways I use sidechaining - of course if people are already building dedicated multi-band sidechain filters there certainly may be better, time-tested designs and I'd want to take a look at those to see if there's more sense in an existing design (and its filters) rather than reinventing, especially considering my newbie-ness!

I do have a linux VM available, but is there anything more calf studio would provide over using an EQ (Acon Digital's EQ) as I did? I had a look at all the slopes and interactions and they add up for my usage.

On the 20-20 variable - are you saying this would be better split into 3rds (of the total 10 octaves) and incorporating 2 additional pots (+ Q for each & gain for each)? - it's stuff like this (why the full range would be possibly problematic) where I don't know a thing, though I chose that thinking that the design would be much easier and liked the idea of only 3 pots for frequency selection..

Thanks for the input - I will check out any / all DIY pro-audio forums I can find - I'll pay a visit to the one you mentioned. :)
 
One way to cover 1000:1 frequency ratio is to use 10:1 potentiometer range and 3 switched capacitances - one circuit, but switched. Very large ratios of resistance are a problem as large resistances introduce noise, and small resistances are hard to drive from the previous stage.


30:1 potiometer range and two switched capacitances is also feasible.
 
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