Looking into more filters and curious for some of your favorites you've owned/used, some you consider the most underrated, the most unique, best value, etc. etc. Any all recommendations welcome.

I just got the Erica Polivoks VCF II and can’t believe how great it is. It’s a fairly straightforward filter, but I’ve had so much fun with it already. With filters, the old adage “use your ears” really applies, and the Polivoks sounds perfect to my ears. It sits somewhere between an acidic Roland-ish sound and the MS20. It doesn’t have a crazy feature set or anything (like the QPAS, Dipole, Morgasmatron, or Filter 8), just a great sound and can be found for $200 or less.
The Doepfer SEM and Morgasmatron (or Dual Borg) are still on my shopping list, but I’m pretty happy with what I have for a while.

EDITED Aug 11th 2021, 14:23

I suppose the best value filter I have is the Erica Synths Black Dual VCF - thanks to @GarfieldModular for recommending it :)
It's got all the filters type outputs available at once which is something I wanted on at least one of my filters, the feature set is more than enough for the synthesist in me to have fun and most importantly, it sounds just right when pushing resonance right below the self-oscillation point, lovely. It may be discontinued now but prices on Reverb make it a great value, around 250-300 euros.

For the very particular sound and an amazingly plethoric feature set, one could look at the IME Bionic Lester MK3. Sounds crazy and then some, it's got presets, different link modes, you name it. The price may be high, but it's worth it IMO.

Finally, I should mention XAOC's Belgrad, plenty of filter types, and combinations thereof (it's a dual filter). Again, it sounds great and each filter type sounds different enough to offer a lot of sonic variety to the operator. Sounds great as a voice too !

Hi Eexee, Farkas and Toodee,

Eexee: Other than the already mentioned filters by Farkas and Toodee, the Doepfer A-124 Wasp filter is one I love, it can go quite bananas without becoming irritating like a TouellSkouarn filter that mainly just screams. So if you are looking for a screaming filter go for a TouellSkouarn filter, they have a few, the Kala Goañv isn't actually that bad and kind of okay-ish.

Patching Panda, the Vibrazum comes to mind, still discovering that one myself, not sure what to think of it but good enough to consider it. If you like more something smooth then I can recommend the Instruō - Tràigh filter, pretty decent and not rough at all, rather the opposite more like to smoothen your sound or to give it just that extra touch. A bit like the Polivok filter that Farkas mentioned I guess.

If you look more for a Roland style of filter then go shopping at Frequency Central, the State 700 Mk 2 filter for example. Not an exact 100% filter as such however if you are interested in a resonator then the Mutable Instruments - Rings is actually a quite fun "filter" (resonator is a better description) and is recommendable.

Naturally Doepfer has about a half thousand of filters or something like that, not going to name them all here however one or two that might be a bit special and to be considered are the A-108 is a transistor Moog ladder filter with 6, 12, 24 and 48 dB/octave steep slopes that can provide you interesting options. The other less obvious one is the A-128 fixed bank filter. I use that one sometimes to get rid of certain irritating sounds in my music that I can't get rid of in another way (or too lazy too figure out what's causing the irritation). It doesn't do wonders but it can make irritating sounds more smooth or less harsh and of course it can be used for many other purposes as well.

Hopefully this gives you some ideas. Good luck with the search for another nice filter :-) As Toodee mentioned, I indeed can seriously recommend the Erica Synths - Black Dual VCF, it's a great filter with some really nice features and possibilities, check out my demo here:
https://www.modulargrid.net/e/forum/posts/index/8963

Mutable Instruments - Rings can be heard here:
https://www.modulargrid.net/e/forum/posts/index/9279

And the Make Noise QPAS here (and later on in that demo again the ES - Black Dual VCF):
https://www.modulargrid.net/e/forum/posts/index/9003

Last but not least if you are into quadrophonic music or just playing chords, then I can recommend Doepfer A-105-4, here is a demo of it:
https://www.modulargrid.net/e/forum/posts/index/9397

Farkas: Interesting description of the Erica Synths' Polivok filter but I do think I can agree here with you how you described it. For myself I still need to more understand this filter, it seems I can't get the max out of it, or perhaps I put my expectations too high and want to get more out of it than it's possible ;-)

Toodee: He, he, yes that Black Dual VCF is still a fantastic filter, thanks for recommending it :-) I still love this filter a lot, together with my Doepfer A-124 Wasp filter and Doepfer A-106 SEM filter the best ones I have!

All: Enjoy the pleasure of playing around with filters and kind regards, Garfield.

Farkas: Interesting description of the Erica Synths' Polivok filter but I do think I can agree here with you how you described it. For myself I still need to more understand this filter, it seems I can't get the max out of it, or perhaps I put my expectations too high and want to get more out of it than it's possible ;-)
-- GarfieldModular

The Polivoks just fit in perfectly with the sound I was working on this week. My AJH was too "warm" sounding, Ripples was a bit too clean, the Gristleizer was too aggressive, and QPAS was too... well, it was too QPAS. Haha.
The Polivoks fit right in the middle of all of them. I love that weird sort of overdriven resonance right on the edge. I'm sure it won't be the right tool for everything, but I have really enjoyed experimenting with it over the past few days.
And yes, the Doepfer SEM seems to be among the best of the best.
Enjoy your day!

Thanks for the recommendations so far. I may need to watch some videos about different filter types to get a sense of what I'm looking for more. I mean obviously I understand LP/HP/BP etc., but when it gets into what the filter is modeled after or circuit types -- all that stuff is over my head.

I always feel like Erica Synths modules won't be worth their price, somehow, but I had their noise generator and I thought the LPF built into that was pretty fantastic -- I only sold it off because that filter had no CV control of any kind.

I generally like the filter on my Moog DFAM and Moog Werkstatt quite well ... nice and rich and acid-y to my ears.

I had a Doepfer multimode filter and found it oddly underwhelming at the time. Never used the Wasp, but have been tempted a few times.

I currently have an SH-VCF by Radical Frequencies. It's listed on Reverb. I like it pretty well, actually, and it seems sorta hard to come by ... the character of the different slope outputs are interesting and the 6db output has a pleasing grainy saturation ... but it's too deep for my skiff and I'm out of room in my main case, and I want to get money towards something with more modes.

I had a Zlob Modular multimode filter, but just didn't dig it that much. Good value for the space it took up, nothing really wrong with it, but I feel like whatever my filter(s) is/are, I should really enjoy using.

Curious about the Doepfer SEM. I'm probably interested in the more dynamic and acid-y type filters, something you can really push as an interesting soundsource, and -- importantly, I'm realizing -- something that has some kind of gain compensation for the volume loss typical of filters.

My budget for new modules isn't what it was, so any recommendations for the $100-300-ish range are of extra value to me, though long term, I'm willing to invest more for a filter that I really love and has a lot of functionality.

EDITED Aug 12th 2021, 18:32

I don’t believe the Doepfer SEM is capable of self oscillation if that is important to you. It’s a very classic sound. Very late-70s/early-80s vibe. Definitely on my shortlist.

in the middle of your range:

Intellijel Polaris (On my radar)
Mutable Ripples (On my radar, one or the other not both to me)

both solid filters

On the lower price end
Doepher Wasp is on my list (likely before the polaris), there are plenty of others, LPG can be added here as well if that is your jam
Make Noise LxD (I am always finding a use for this)

On the upper end
XAOC Belgrad (In my case currently)
Instruo I-o47 (In my case currently)
SSF Dipole (soon to arrive)

Intellijel Polaris (On my radar)

-- mog00

Based on what @eexee has mentioned, Polaris probably would be a really good/versatile filter to look into. Good suggestion.

I was looking for a Steppy but found Analogue Haven has Polaris in stock ( DO NOT FOLLOW LINK IF YOU CAN'T RESIST IN STOCK FILTERS)

My fave? Tiptop's Forbidden Planet, but that's because I owned an actual Steiner-Parker Synthacon for a number of years and came to LOVE that yowling, cutting filter. Nothing exactly like that weird topology for generating leads that literally RIP their way through your mix!

Has anyone used Patching Pandas filters? I enjoyed the demos for Vibrazum and Moon Phase, so those have made my "maybe" list. I've noted a few of the recommendations here, and there's a few more Doepfers I have to look up demos for, too -- they have a wider variety than I realized!

Sort of curious about Blue Lantern's as well ... people warned me off BL on another thread a bit, but a few of them look interesting and on the budget-friendly side, but they seem a little harder to find good demos for. Anyone used the Hermippe, Millipede, Lunar, Cydonia, or any other BLs VCFs?

A few others I'm vaguely eyeing are the Tiptop Z2040, Electro-Acoustic Research Model 41, Studio Electronics 8106, and Intellijel Morgasmatron. It's going to be difficult to choose just one for the immediate future. Fun, but difficult.

I was too was aiming to get Tiptop's Forbidden Planet filter but then I spotted the Omsonic limited run of their (FLF) Funky Ladder Filter which is like the Steiner Parker filter but with extra control, its a very nice sounding filter and very usable. You can mult your signal and feed all inputs then tweak the levels for each HP/BP/LP, you could do this with a simple attenuator and the Forbidden Planet filter too.
https://omsonic.co.uk/product/omsonic-funky-ladder-filter-le-8hp-edition-fire-sale/

The other thing which I think should be a personal toolbox item is the Rebach VCF-AB, its very affordable and if you like the occasional dirty 303-style acid line then this ticks the box cos it will squeal like a distorted 303 because of its internal feedback path.
https://rebach.eu/catch-series/

I'm very tempted by a Stereo Ripples filter and a Patching Panda Moonphase.

Kinda tempted by the ADDAC604 as its double the same filter that they made for their ADDAC105 4-Voice Cluster, which I found more useful than the 4-voice cluster with the ability to feed it external signals, it was simple and workhorse-like, kind of set-and-forget or just throw a little modulation at it for a background element. So with the ADDAC604 being able to be used as a Dual Mono or Stereo filter its quite a good price to keep the Stereo path from other modules, it won't be too crazy but it will be very usable.
https://www.addacsystem.com/en/products/modules/addac600-series/addac604

EDITED Aug 15th 2021, 08:56

Interesting about the ADDAC filter, that's another company that seems like they have really useful and nicely made modules that I don't see a lot of chit-chat about, really. I was briefly considering their Stinggy Filter, but sort of put that low on the considerations list ... I forget why, maybe not enough CV options or maybe something about the demo that left me a bit meh. But I had their Sum & Difference mixer for a few weeks and it was pretty cool, really solidly made and interesting -- but again, very little CV control over anything as I recall.

Still something about ADDAC appeals to me, though, but they tend to be a little pricey for me at the moment. I did actually recently order their 4-Voice Cluster and their expression pedal adapter, but I don't have them yet. Curious how that will go. The 4-Voice Cluster doesn't seem hugely popular, and I could see from the demo how it could be a bit one-note as a sound source, but there's something about the character of its sound that really appealed to me and feel I'd like to work with, and the price was right at the time I ordered.

ADDAC's got some really wild modules, though...and not just these. They've got a T-network filter pair just for pinging, for old-school beatbox sounds. And the Marble Physics "LFO" is utterly bonkers. Plus, if you need a case that a small family could live in, they were pretty much first with the 197 hp (1 meter) widths.

Yeah, I'd REALLY love to get my hands on the Marble Physics module in particular. Their big Clock Source module also makes me salivate. I went through their website the other day and bookmarked about a dozen units that I'd really, really like to at least try, and maybe own long-term. But... yeah... they are also expensive, and I am poor. Or poor relative to the expense of this hobby at least.

My favorite because its the one I have :) I got it to pair with my Void Modular Gravitational Waves dual VCO but I'm finding I like what it dose with my Arturia Minibrute 2 and Hydrasynth as well...very nice...but I don't have nearly the experience with the variety of those who have posted previously

https://www.modulargrid.net/e/void-modular-sirius-veil

While I haven't been able to pick up any other ADDAC filters yet, I did get an ADDAC105 4-Voice Cluster which has an onboard filter, and I love the sound on that one. It's not super-crazy or anything, but just very nice, clean, sharp, and smooth. Love the ADDACs I've been able to use thus far, but I do wish they had more/better CV input options on their lower cost modules.

EDITED Aug 21st 2021, 03:05

Rossum filters are great. I have lineaus and evolution. Morgasmatron is also badass. Lineaus and Morgasmatron have changed my mind about what a filter can be; if I push them I get totally new unexpected signal. Filter as unique topology waveshaper in that case. Very west coast mentality. Evolution on the other hand is a beautiful ladder filter, expensive for a ladder but totally covers what I want from a ladder filter. Those are my three favorite Euro rack format filters so far. If I wanted to add any more filters I would check out the Joranalogue filter or some of the ones mentioned above.

Yeah, the Morgasmatron at the very least is definitely one I'd like to own at some point.

As I often seem to do, I went on Reverb the other day with the complete intention of getting a sequencer and a VCF, and ended up buying up something completely different. I somehow came away with a Xaoc Kamieniec Phase Rotator, Nonlinearcircuits Multi-Band Distortion, and Instruo Lubadh, none of which I'd remotely intended to buy.

While not exactly a filter, I'm hoping the Phase Rotator scratches a similar kind of itch for the time being, it seemed really interesting to me, price wasn't bad, they're hard to find right now, and I like the couple little Xaoc utility modules I have pretty well. The Multi-Band Distortion I just jumped on bc it seemed a good price, I don't see them often, and I love anything that allows me some control over EQ -- if it's distortion oriented, all the better. And the Lubadh, I have no idea really ... seemed a good price for one considering it was being sold with the expander, I've wanted one since I first started modular, and I'd just watched a demo of one that got me all juiced up.

As a kind of tangential question to this thread, I wonder what people consider their favorite "budget" VCFs to be, VCFs for under $200 that hit above their pricepoint in your opinion.

EDITED Aug 30th 2021, 20:20

As a kind of tangential question to this thread, I wonder what people consider their favorite "budget" VCFs to be, VCFs for under $200 that hit above their pricepoint in your opinion.
-- eexee

I'd say any of the Doepfer filters. I've had so many of them in my shopping cart, but haven't bought any of them yet. They all seem great and I just can't decide. The SEM and Wasp filters get a lot of praise, and the A-106-1 Xtreme filter looks great too.

I have Xaoc Kamieniec Phase Rotator, it sounds similar to the various Phaser VSTs I have, but of course is in eurorack. With rate and depth up, IMO it sounds rather similar to other phasers. With rate to minimum, I hear it as giving a static boost to whatever frequency you've set on the big dial, plus that kind of rubbery acid-y sound phasers make. I like that type of setting for a "quick acid" treatment to any sound I would want to apply. I like the unit, but in retrospect, consider it a bit expensive for what it is.

Wasp filter is one I will likely get at some point (if I wasn't already well stocked on filters). It gets so much praise and is a good deal.

I really love my Rossum Morpheus filter a lot! Also the IME Harvestman Bionic Lester MK2 and Erica Synths Dual VCF are superb filters. The Richter Dual Borg filter kicks modular butt as well. I am a sucker for cool filters! Saving up for the Intellijel Morgasmatron and other filters.

I'm going to mention (because they haven't been already) the one filter I started with (Bastl Ikarie, dual stereo), and the one I just ordered (WMD C4rbn, multimode mono with wavefolding).

Anyone used Arcaico Warhorse? Never heard of Arcaico before, someone on Modwiggler turned me onto them. Took a gander at their website, their modules look pretty badass. Warhorse is sold out at the moment, but I bookmarked their site.

Still waiting on my Phase Rotator. Disappointed to hear it's expensive for what it does, but then, looking through Xaoc's modules, I suspect they're all a little bit like that. Not dinging Xaoc, they're just one of those brands that tends to be on the pricey side. I got a good enough deal that if it doesn't take, it should be relatively easy to pawn off without much of a loss, if any. I still don't know quite why I grabbed it -- I don't even typically like phaser effects all that much -- but, I dunno ... the demo made it seem cool and at the time I felt like I'd find a good use for it.

In the non-filter arena I did get my Instruo Lubadh and NLC Multi-Band Distortion. The Lubdah I've barely touched yet, it's going to take a bit for me to sit down and deep dive on it. The NLC is already back up on Reverb ... it's just not what I assumed it would be (a distortion unit). That's what I get for impulse buying. It's actually pretty cool for what it is, certainly not exactly like anything else I've owned ... basically a ring modulator meets a quad VCA meets an EQ/band separator, with some noise/feedback generation and saturation built in. I don't mind having an extra ringmod, and while the EQ control isn't as specific or robust as I'd hoped, it could be a very useful module for things like controlling problem frequencies, saturating and adding color/sizzle, as a random noise source, and being able to CV trigger the gain of each band region independently is sort of cool, too, allowing you to create rhythms "within" a signal, if that makes sense. It also has both summed audio out and individual audio outs per band region, so ... while I'm relisting it (bc it eats up a chunk of space and wasn't what I was actually after when I bought it) I've come to find it useful enough that if it doesn't sell, I'm happy enough to keep it. I suspect there are some potential ways to use it that I haven't thought of yet that could make it uniquely valuable. I guess we'll see.

EDITED Sep 3rd 2021, 03:35

Rossum filters are great. I have lineaus and evolution. Morgasmatron is also badass. Lineaus and Morgasmatron have changed

Hell yeah! I love my Rossum Morpheus filter so unique and lots of tone shaping options. Also love IME/Harvestman Bionic Lester so many shaping options. Erica Synths filters are great fun for self oscillation purposes and gritty tones.

Now I'd like to get my hands on the XAOC Devices Belgrad filter as well as Intellijel Morgasmatron and Mannequin Three Sisters.

Filters are loads of fun in eurorack land.

doepfer - all of them - reasonably priced and do what they say on the tin (mostly) and a reasonable amount of voltage control

EDITED Sep 21st 2021, 16:22

I still have the Doepfer SEM filter that came with my A100 Basic system and it sounds good.

I've got the SEM, Wasp and the Moog style ladder filter - plus the LPG - all great value for money!!!

EDITED Sep 21st 2021, 17:29

I´ve got the Wasp and love it for the more gritty things, as it´s a tad bit noisy. Love my AJH Gemini and generally like dual filters compared to patching two single. Totally understand the itch for K/Morgasmatron. Then again, there are things like the Serpent Modular Sirius, which I really like for its character. High on my wishlist are Bionic Lester and RT-451. Last buy was a wmd aperture, but can´t yet say if that is a keeper, as I only did a function test so far (used).

My filter wishlist:

Doepfer Wasp
Xaoc Devices Belgrad
Mannequin Three Sisters
Mutable Instruments Blades

What I have now

Rossum Morpheus Z plane filter
Erica Synths Black Polivoks v2
Erica Synths Dual Filter
Doepfer SEM
IME/Harvestman Bionic Lester
Schlappi Engineering Angle Grinder- can be a filter or oscillator.

I forgot one...and it's definitely a "holy grail" filter: the Rohde & Schwarz UBM. However, this ancient tube-driven bit of WDR Cologne's electronic music history (especially in Stockhausen's hands) is VERY screwy. Tubes, of course, are AUTOMATICALLY screwy, but whatever's going on inside these huge gray boxes (I have two) is NOT simple filtering. Push the input, and you get warm, wooly fuzziness. Run up the regeneration control, and the filter first acts LPF-ish, but then gets into a NASTY, ringy passband configuration with that Q rising as the control is raised.

What does it sound like? OK, it's all over this: along with a few other filters, but the UBM handles the bulk of the load on this work. Frankly, I'd love to see one of the tube-oriented Eurorack companies take on a challenge like this...and it could be lucrative, too, given that there's only a finite number of these still in operation and when one pops up, the feeding frenzy gets INTENSE.

Hi Lugia,

Ah yes, Mr. Stockhausen :-) Still need to get a CD from him, it's still on my wish list. Nice to hear him here at work the Rohde & Schwarz UBM filter! Thank you very much and kind regards, Garfield.

I am mainly in Experimental Music.
I use 4 filters :
- (the gentle) Mutable Instruments Ripples (https://www.modulargrid.net/e/mutable-instruments-ripples);
- (the wild) Pittsburgh Modular Lifeforms Binary Filter (https://www.modulargrid.net/e/pittsburgh-modular-lifeforms-binary-filter);
- (the experimental gentle) NLC BBX291 VCF (https://www.modulargrid.net/e/nonlinearcircuits-bbx291-vcf);
- (the unpredictable wild) NLC Digital Filter Simulator (https://www.modulargrid.net/e/nonlinearcircuits-digital-filter-simulator).
They are used in series and/or in parallel depending of the desired result.

EDITED Oct 1st 2021, 08:28

I can confirm Farkas' description of the Polivoks II. It's a bit dirty and I can't get it to fully close, but it is quite versatile especially for gnarly bass or lead lines.
A hugely underrated filter in my view is the Pole-Zero by WMD SSF with integrated VCA. It's got a nice small footprint and affords a wide range of sounds from smooth to overdriven saturation. I find myself coming back to it in nearly every patch and use it mostly for polyphonic stuff or leads. The integrated VCA is a nice feature as well and it tracks V/Oct quite nicely.

As a fan of Erica Synths modules, I can vouch for how awesome their filters are since having both their black polivoks and dual vcf filters. I love making them self oscillate and screech plus they can be modulated easily. Filters are one part of the variety and joy of modular besides sequencers for me.

There are multiple types of filter circuits. But I want to talk about the format of the filters.

Here are some of the major configurations.

Can the filter self-oscillate? By turning up the resonance does the filter begin to generate its own sign wave? Some do and some don't.

Does the filter bass compensate for higher resonance levels. You'll find with a lot of filters, you lose low end as the resonance goes up. This isn't a good or bad thing. But just the nature of the beast. If you want high resonance with a bass sound. This might come into play.

Outputs. When dealing with a multi-mode filter, how are the outputs structures. Some modules put all the filter types on separate output jacks and all filters are simultaneously available. Others use only one output and the user selects (usually on a switch) which filter feeds the output.

Input (levels). Some filters have input level controls. How hard your signal hits the filter can alter the sound significantly. So an input level control might allow you to adjust things to your taste.

Modulation. This can range from simple CV control over the cut-off point or you can get into modules with multiple controls including the afore mentioned FM control (linear and exponential), 1/V Octave tracking, CV over resonance, and even some exotic controls like ping, mix levels, even control over filter type.

If you want high resonance with a bass sound. This might come into play.

just use 2 filters in parallel - 1 for high resonance and 1 for more bass!

Outputs. When dealing with a multi-mode filter, how are the outputs structures. Some modules put all the filter types on separate output jacks and all filters are simultaneously available. Others use only one output and the user selects (usually on a switch) which filter feeds the output.

and often somewhere in between - see Doepfer Wasp and SEM filters, for example!

Input (levels). Some filters have input level controls. How hard your signal hits the filter can alter the sound significantly. So an input level control might allow you to adjust things to your taste.

always a good thing - but an amplifier module (or a vca that actually amplifies instead of attenuating) in front will also do the job

Modulation. This can range from simple CV control over the cut-off point or you can get into modules with multiple controls including the afore mentioned FM control (linear and exponential), 1/V Octave tracking, CV over resonance, and even some exotic controls like ping, mix levels, even control over filter type.

-- Ronin1973

more modulation is always good!

Moogah Sem - among the barrage of clones going for this, comparing to my old sems, i feel this is the most faithful and best sounding implementation in euro.

Am Synths am8109- silky, bubbly Roland cascaded ota sound, that came with beginning of the new decade (Jup8, Juno 60,,,). this version has original IR3109.

Livewire Frequensteiner (Synthasystem) and Elby CGS735 (Synthacon) - two Steiner filter variants. vintage, almost archaic tone at times. can be liquidy, characterful, edgy, as well as go dark side of the moon, falling apart when you crank the resonance.

Wiard Borg 1 - MS20 Sallen Key realized with vactrols. works as wonderful slow lpg, and when you move into vcf mode and crank the resonance, Id comes out.. perhaps one of the true classics from the early eurorack era

micro Hadron Collider - dual SVF with distortion and industrial deep in its dna. works great with harvestman osc.

EDITED Jul 4th 2023, 10:30

Oh yeah Bionic Lester MK3 is super fun and crazy good. I use it with my Hertz Donut MK3 a lot.

Very interesting discussion and it's giving me several ideas for my next filter!

As a kind of tangential question to this thread, I wonder what people consider their favorite "budget" VCFs to be, VCFs for under $200 that hit above their pricepoint in your opinion.
-- sparrowbred

I have the Feedback Lo-Fusion for around €100 which is very nice for a basic LP. It has a nice warm sound to it, which is what I wanted. I thought I'd save some money getting just an LP, but I miss a HP, of course. Getting the Hi-Fusion as well would still be quite cheap, but it starts eating up HP room. Still, if budget is important, you should check it out.

I'm surprised nobody mentioned [Steve's MS-22[(https://www.modulargrid.net/e/threetom-modular-steve-s-ms-22) yet. I mailed Tom, the creator, and he's obviously extremely dedicated to producing quality with a personal touch. Look it up on YouTube, it sounds great. Just don't add too many orders to the queue, will you? I'm still planning to order one myself in the coming months ;-)

I saw some mention of tube filters above, I've definitely gotten some unique sounds out of the Metasonix RK4. It's hard for me to pick a "favorite" filter, I've got a bunch and I feel like they're like colors to a painter - sometimes you want some red, sometimes blue works better, etc. But the RK4 does stand out to me as far as being unique.

I think Ripples v2 (and Blades) is of the most under-rated filters. I prefer the sound of V2 over V1 for both inputs. It's just incredibly flexible and has nice variety of sound with different kinds of modulation. I feel the same about QPAS when especially when used with audio rate modulation. Moonphase is great, just not a fan of the popping when switching between filter types (possibly handled later in the chain).

I've slept on Belgrad despite being a heavy XAOC user. I like the sounds that Mathsmathsmaths gets with it; he mentioned about the importance of gain staging. Belgrad is top of my list to pickup as soon as I master Fumana, haha see you in 2030.

I traded a Zlob VCF with a friend who is fn loving it for techno stuff with NE voices.

EDITED Apr 3rd 2022, 21:19

@adaris Been very curious about the tube modules. The Karltron Tube looks nice and the Saevitum seems to be the tube version of Ripples.

https://www.modulargrid.net/e/karltron-tube
https://www.modulargrid.net/e/abyss-devices-saevitum

Filters -- don't get me started ;-). Had a Doepfer A-121 first and still have it. Does it all without much coloring.
Polaris - very versatile and a good and only one in a small rack. Selling mine was kinda dumb.

Most fav'd ones... Hard to say. Recently I use Blades a lot, for its versatility and dual use as a VCO. As far as character, I love my Doepfer Wasp and Bastl Cinnamon. Also, Steve's MS-22. Font is a good and versatile one.

On a more neutral perspective, Ripples is great. Toying with the idea of having a stereo version in my sum. Joranalogue Filter 8 is clean and precise and a 8-phase oscillator, too.

As for specialties, the Klangbau Köln Twin Peak Resonator is great, almost an instrument in itself. King of pings!
And last but not least, the mighty Serge Resonant Equalizer. Not a filter but a fixed filter bank - and a very opinionated one at that! Squelchy squealy feedback goodness, as those distorting filter bands interact which each other. Can it get any better?

Still interested to get my hands on a Three Sisters, North Coast Coiler and Leap Frog, as well as Moon Phase and Linnaeus (not so much the Morpheus). Keep hearing great things about IMÁGENES and Inertia as well as Neutron Flux (which seems to be deeep).

Right, filters. Don't get me started.
BTW, who needs oscillators when you can have filters that oscillate?
I should build a rack devoid of oscs.

@adaris Been very curious about the tube modules. The Karltron Tube looks nice and the Saevitum seems to be the tube version of Ripples.

https://www.modulargrid.net/e/karltron-tube
https://www.modulargrid.net/e/abyss-devices-saevitum
-- t4mber

I have Saevitum, it's awesome, I don't really think of it as a filter though, it's more of a distortion/VCA with a filter section.

EDITED Apr 4th 2022, 11:34

I don’t believe the Doepfer SEM is capable of self oscillation if that is important to you. It’s a very classic sound. Very late-70s/early-80s vibe. Definitely on my shortlist.
-- farkas

Possibly related to this post, I just found out this weekend that the Doepfer Extreme Filter A-106-1 indeed is capable of self oscilation, and to my surprise to an audible and absolutely usable level. Im not sure I remember the patch correctly, but it definitely involved no audio oj the inputs (obviously) and the use of the send/return jacks (I think I just amplified the module's natural send output and routed back without creating an obvious loop.
Im sorry I dont remember and this is my first post in this forum, so if anyone ever finds this useful and/or you want to know the exact patch, let me know..

OK I'll give you my two cents on this.

If you count filter banks into this then two honorable mentions are the Res EQ (wait for v2, it will have CV control) and Monotropa (mine has a mod for tone control inside the feedback path, a "baxandall tilt EQ"). Those two are absolutely nuts. Especially the Res EQ is very non-linear and sounds gnarlier than anything else. You move only one band and the whole sound changes. Turning up a low band can make the sound brighter and vice-versa. It's completly crazy, you need to try it. Both are absolutely mental for feedback patching. If you decide for a Monotropa please buy it from RTFM on modular grid. He will build you one for a very fair price with the tone control mod that I mentioned. It's AWESOME!

The best dual/stereo filter for pinging, oscillations and FM is the Blades right now in my opinion. You have CV over the filter mode, routing and resonance. Especially resonance CV is a feature I absolutely love, every filter should have it.

The best bang for buck filters with a character are the Bastl Cinnamon (harsher distortion, square-wavy) and the Doepfer Wasp (bubbly, with a slight fuzz from transistor distortion). They both sound amazing. Feature wise the Cinnamon has more to offer, it has VCA in it as well. Sound wise I would prefer the Wasp. Theres no filter like it. Even the clones don't sound quite like it. The Dual Wasp from Haible did not have the same sound unfortunately. The wasp filter can make these amazing bubbly, wet, water droplet type of sounds. Pairs perfectly with a benjolin and some reverb, love it. Highly recommended. You can get one on the used market for 50€, absolute no-brainer.

Now for my favourite filter category: Slope Generators, the most versatile filters out there. One of them is Inertia by New Systems Instruments. I think it has the most impressive function density I have seen on a filter. It can be used as V/Oct-tracking oscillator, filter, slew, envelope generator, LFO, frequency divider, phase shifter, envelope follower and phase-locked-loop. The thing sounds absolutely crazy. The filter sounds that come out of it sound very "saw like". Like stepped or spiky, razor sharp. Beautiful module, phenomenal sound. Expensive but totally worth it. Very rewarding when experimenting and useful both as utilty, sound source or modulator.

The other slope generator I want to mention is the Quad Slope from CGS. That thing is totally bananas as well. Using the inputs of the envelopes for filtering essentially makes it a quad filter as well. Whats special about it is that the boundaries between what is an LFO, what is a filter, what is an envelope and what is a slew are disappearing. Super fun to crosspatch the envelopes, it makes one "filter" or "envelope" modulate another one for example. You can do that with all four of them. Ranging all the way from sub-audio territory (LFO range, slewing) to audio territory (oscillator, filtering). Super fun to do. I wish it had a "cycle switch" tho. You need to patch the TRIG OUT to the TRIG IN every time to get it to cycle, pretty annoying. Best envelope out there tho.

The only filter that I really want to try still that is also completly crazy and that I will 100% buy at some point is the Sprott from IFM.
Since I have never used it I cannot comment on it but it's a chaotic filter that plays with the "bounds & bounce" theme that Peter Blasser introduced. Maximum GAS for me :)

I'm definitely a fan of the Bastl Cinnamon, in fact I have 3 of them. I saw the Frequensteiner mentioned above as well, I recently got a hold of one of these and have quickly become a fan, in particular of the bandpass and highpass modes. You do have to be careful where you put it in your rack due it's propensity to pick up signals from other modules, but I've got it in a Doepfer mini case with just a couple other filters so as long as I'm not using them at the same time as the Frequensteiner it's not a problem. And yes it can be a little noisy but a noise gate like the one from Ladik or the one in the FX Aid takes care of that easily. You may also be able to handle that by simply putting it in front of a VCA, depending on how you're using it. But anyway it sounds fantastic.

EDITED Aug 6th 2022, 01:13

And yes it can be a little noisy but a noise gate like the one from Ladik or the one in the FX Aid takes care of that easily. You may also be able to handle that by simply putting it in front of a VCA, depending on how you're using it. But anyway it sounds fantastic.
-- adaris

Actually, this is a major symptom of using either the wrong VCA or wrong envelope behavior. When you use linear VCAs and/or linear envelopes, this can happen because our ears aren't linear with respect to "apparent loudness". We hear exponentially as far as volume is concerned, and the Decibel scale reflects that.

The actual fix here isn't a noise gate (sorta-kinda), it would be one of the following:

• Change the VCA after those filters. This needs to be an exponential VCA, or a "multi-topology" one like the Veils VCAs that's been set to exponential response. Or...

• Keep the linear VCA...but send it an exponential envelope.

Now, the reason I said "sorta-kinda" above is because, when you do this correctly, it actually has some dynamics elements in common with a noise gate. The response of these VCAs when properly set is actually VERY close to the sort of thing going on with a noise gate, inasmuch as the noise will fall nearly to or all the way to inaudibility when there's no generated audio thruput.

Rule of thumb: LINEAR is for DC, low rate modulation signals, and basic audio use upstream from the final output stages. EXPONENTIAL is for any audio rate signal, and NOT DC or low rate modulation. Many exponential VCAs aren't DC-coupled, so if you try and pass DC or a low rate mod signal through one, you'll get either nothing or a very attenuated output signal as far as those signals go. Very useful to keep in mind when trying to keep DC out of your monitoring setup!