TubeOhm SMR4P-multi Eurorack filter


Apologies if this has already been mentioned, but this caught my eye:

I’m a great fan of André’s transistor ladder and Steiner-Parker filters for the Shruthi, as well as the Shruthi SMR4 filter. I’ll be ordering and building one of these.

I’d also encourage André to do a eurorack version of his Steiner-Parker design for the Shruthi, which uniquely tamed the out-of-control resonance characteristics of this design, without losing its character.


Hey! Originally i just wanted to open a thread with my impression for the filter… but since your post has already the perfect name i just will add my impressions here.

May i already say: If you think about buying it: Buy it! It is worth every cent and for all its features it is quite cheap i think.

To the building:
I was the “beta-tester” of the very detailed building instructions, Andre made.
The instructions are very very detailed and every step is explained.
But anyway: the building is sophisticated and definitly only something for someone who is well experienced in soldering!

The sound:
At first i didnt understood the symbol on the frontplate. The razorblade.
But after listening to it, the icon makes sense. The sound is very clear and original. It is a good filter to get rid of frequencies without changing the original charakter. …well if you want it that way.
The resonance first let me think i made a mistake while building, but sometimes it is indeed a feature and not a bug.
The resonance is at its “peak” about at 2/3 of the position, the last third is going into boost.
And what an boost that is.
In “usual” circumstances i went at most to half of the possible resonance.
What i really love is the FM! It strongly depends on what signal you put in the filter… But with that feature you can give a bit charakter to your sound.
And of course: 15 Filter types!! What comes in really handy: you can change the types over cv!
With some signals there is a pop noise when changing on other signals you can change wildly without no problems. Definitly a damn nice feature to just plug some lfo or other random signal in and see what happens.
Also a nice thing which at first i underestimated:
The build in vca: Very nice and clean sound, closing completly.

The quality of the module is very decent and the look is also very nice.

I have to admit it is only the 4th filter module i own/used. But it definitly is my favorite “tool” in my rack so far! And for that price it is a bargain!

And yes… it is a bit of an “advertisment”. :wink:
But i am really happy with that filter and i definitly want to support Tubeohm to help him creating more nice modules in future! :slight_smile:


I noticed this appearing on Thonk the other day.

Thanks for the review, @derkollo. I’m interested to know what makes the build challenging.



It is not challenging in terms of “tricky parts”, but just because there are a lot of parts to solder and the module is made of 3 pcbs. So troubleshooting can be tricky. :wink:


Hi Benne - next - and some other things also …


Mmm… Tempting! Im a sucker for filters and this sure has some unique features…


Excellent! I look forward to the SP filter! I’ll order an SMR4P filter today (from Thonk, I need some other things from them).


Lovely filter!

Couldn’t resist changing the LED colours a little :slight_smile:
For the LP and HP filters at least green indicates gentle filtering, and redder colours signify increasingly stronger filtering.

The orange LED needs a 1k resistor (R6), the red one a 220R one (R5), to get matching luminosities.


Looks like a pretty well featured filter! Much more advanced than many filters that you can get for eurorack, and it being SMR4-based makes it even cooler. Too bad I’m out of DIY for a white…


When you say you’re “out of DIY”, do you mean you’re not designing panels for DIY projects any more, either?



No just that I don’t have any time for DIY atm, or better, when it comes to having to choose I’ll chose making some music over DIY, since my time is a bit limited as of lately.
But I still make panels for DIY projects, recently did a new run of Neron panels for Magpie for example and I’m always open to helping people who develop kits.