Filter Board Opinions

I know some of you guys have built a few variants of the filter boards available here and was wondering what your thoughts were in comparison.

I really enjoy the sound and performance of my Shruti-1’s 3379 and was thinking of getting a 3379 board with my next Shruthi-1. Or the SSM2044.

I’m honestly not too thrilled with the SMR-4 filter but that is most likely due to my tune job and subconsciously expecting it to act like the 3379. I’ve been running the Shruthi’s audio-out into the Shruti’s audio-in to help with this until I re-tune, replace, or mod-up the SMR-4. It helps a lot. :slight_smile:

Any opinions from those whom’ve used different filters?

Favorites, opinions, performance quirks, dial setting characteristics, etc…

Favourite: SMR-4 as its very gently and sublte when tuned right. Its not as rough, powery and beefy as the 3379 which i like also. I still had no time to build the SSM Board but at the moment i’d say theres no reason whi i couldn’t do without. But you are right, took me some time (try retuning the filter from scratch after a few hours playing wit the shruthi) to find the sweet spot and its even harder to make 2 filters match. I gave up to tune both exactly the same and now declare this as the polychaining integrated OB-X Magic…

I think my tuning is close, as it is gently and sublte. To me it’s a bit thin and could use a bigger bottom. 8o

There is tuning to be done on all three boards for the Shruthi is there not?

My 3379 worked from the first moment on at the sweet spot so i did not touch the trimmers… sometimes even i have a bit of luck :wink:

I find this whole obsession about tuning quite puzzling. At the exception of the fixed DC offset compensation, all the filter settings are just range controls - they do not introduce anything different in the way the filter operates, they just shift what a cutoff / resonance value of n means in terms of hertz / gain. What I mean here is that there’s no change obtainable by tuning that cannot be obtained by dialing in a different value of cutoff or resonance on the filter page.

Maybe I’m a skeptic on this topic, but I can’t help smelling some kind of placebo effect here. I wouldn’t go as far as adding a trimmer which has no audible effect in my next design, but this is very tempting :slight_smile:

Hey Olivier, if you like to add one just do so, please mark it "useless trimmer " on the silkscreening, ISO9001 like where everything has to be labelled clearly :wink: See here:

Well if that’s the case then what I meant to say is I prefer the 3379(Shruti) over the SMR-4. I’d just heard a lot in the way of tuning problems that I was trying to curb the whole “maybe you need to re-tune it” comment possibilities.

Personally i find that the idea is to turn the knob as much or as little as you want to ^^
In the end you’ll have a very hard time finding two shruthi’s sounding the same, which is kinda the charm of it all :slight_smile:
Welcome to the analog world - where even gravity has a magical effect on the sound (kinda like fairydust in Apple products) D:

Its the capacitor fairy that brings good sound…

I’ve only tried 2 boards so far… The SMR-4 and the SSM2044.
The SMR-4 board is very good in my opinion. But I was curious how different the SSM2044 filter would be, so I built one up more out of curiosity than anything else. The SSM is quite nice… But im pretty sure I prefer the SMR-4 board.
With the SSM, there is a level drop when cranking up the resonance that personally im not so keen on. Plus it really seemed to change the sound of the stock patches a lot, to the point many of them sounded quite wrong to my ears. I don’t especially use presets so much, but they do always form a good starting point for tweaking. So I like it to sound good from the start.

For now, the SMR-4 board is staying in my Shruthi. Maybe i’ll build up another digital board so I can give the SSM a home. Or just sell it… Or perhaps swap it for some other filter board of the future?!

Re tuning: It’s not as important as it is on your average analogue synth, granted. But it’s still fairly important on a hybrid Shruthi… If the resonance is wrong, then you could get oscillation all over the place. On the SSM board, I found the gate trimmer also made a big difference (for the worse) when set incorrectly. It seemed to do strange things to the envelope.
Filter tuning width to me is quite important too. If thats wrong, then using a lot of self oscillation sounds awful…

I have to take back that comment about not being too thrilled with the SMR-4.

I love it more everyday.

The CEM 3379 is fantastic. I probably could have left all the trimmers alone as well. Not that I did…
I didn’t install the optional no-click cap at first because I didn’t ever notice the click on my previous Shrutis. I did notice it quite a bit on this Shruthi so I installed the cap and that set it just right.

Can’t say anything about the SSM filter unfortunately.

Digi/fx and IR3109 on the way.