Doepfer A-106-5 12dB SEM Filter Special Edition

Temporarily a special edition of the Doepfer A-106-5 12dB SEM Filter is available. It is equipped with a stylish Oberheim-style cream-coloured anodized front panel and black knobs.

A-106-5 SEM
Filter
Special Edition

Module A-106-5 is a 12dB multimode filter that is based on the filter circuit of the Oberheim SEM
module.

The filter is equipped with a band pass output and a combined low/notch/high pass output. 

For this output a control knob defines the relation between low and high pass signal. 

If both signals appear at the same level (i.e. middle position of the Mix knob) one obtains a notch filter. Otherwise the low or high pass signal predominates. 

The module does not feature self oscillation in contrast to most of the other filters of the A-100 system. 

The module generates a distorted audio signal if the level control is set to about 50% (i.e. center position) or more with A-100 standard signals like VCOs.

Inputs: Audio In, CV1 In without attenuator, CV2 In with Polarizer
Outputs: Bandpass Out, Low/Highpass Mix-Out
Controls: Audio Attenuator, CV2 Polarizer, Frequency, Resonance, LP/HP Mix

You can find my review of the original A-106-5 module HERE, 

and find all additional info/demos/etc on the A-106-5 on PatchPierre.Net via http://patchpierre.blogspot.nl/search/label/A-106-5

Doepfer A-106-5 Filter Demo (August 2012, by PatchPierre)

" Short Doepfer A-106-5 Demo by NetPierre
Starts with a sequenced bassline, generated by my Doepfer MAQ16/3 and Doepfer VCO A-110 (saw wave)
Bandpass Mode first,  LP/HP later
A-118 Random voltages added to VC2 input somewhere in the middle.
Drums provided by an Elektron Machinedrum" 

The module will be available in spring 2016

Source: Doepfer.com

Doepfer A-121 Multimode Filter Re-Design

A-121-2 Re-design

We all knew a re-design of the Doepfer A-121 Multimode Filter has been in the pipeline for a while, due to the unavailability of certain chips inside.

Since the beginning this has always been one of my favourite filters, because of it's sophisticated sound and the VC infut for resonance control. Oh, and the multiple simultanuous outputs...

At Namm 2016 Doepfer will present the A-121-2, the successor of the obsolete module A-121.

The circuitry is totally different from the A-121 which used the obsolete CEM3320 filter circuit. 

Module A-121 is a voltage-controlled multi-mode filter with a cut-off slope of -12 dB / octave.

Four simultaneous outputs are available, each with different characteristics: low-pass, band-pass, high-pass and notch (or band reject). 

The cut-off frequency determines the point at which the respective filter effects appear. 

The frequency can be adjusted manually, or by voltage control (Filter modulation, for instance by an LFO or ADSR). 

Two CV inputs are available, whose control voltages are summed. Resonance (Emphasis or Q ) can be adjusted manually, or by voltage control, right up to self-oscillation, in which case it will behave like a sine wave oscillator.

The sound of the new module A-121-2 is identical to filter of the Dark Energy II but has been expanded by the voltage controlled resonance feature (like the original A-121).

Read all about the specs of the original A-121 at http://patchpierre.blogspot.nl/2011/03/filters-ii-121-vcf2-multimode-filter.html

The modules will cost Euro 120.00 and will be available around March 2016

Source: Doepfer.com

Doepfer A-106-5 12dB SEM Filter Tutorial Videos by Raul Pena

While I was gone, Raul Pena kept on making new A-100 video tutorials.

Here's the next series (now presented here as a playlist instead of weekly updating a blogpost), showing you all the ins and outs of the A-106-5 SEM Filter.

A-106-5 12dB
SEM Filter

Module A-106-5 is a 12dB multimode filter that is based on the filter circuit of the Oberheim SEM module.

The filter is equipped with a band pass output and a combined low/notch/high pass output.

For this output a control knob defines the relation between low and high pass signal. 

If both signals appear at the same level (i.e. middle position of the Mix knob) one obtains a notch filter. Otherwise the low or high pass signal predominates. 

The module does not feature self oscillation in contrast to most of the other filters of the A-100 system. 

The module generates a distorted audio signal if the level control is set to about 50% (i.e. center position) or more with A-100 standard signals like VCOs.

Inputs:
Audio In, CV1 In without attenuator, CV2 In with Polarizer
Outputs:
Bandpass Out, Low/Highpass Mix-Out
Controls:
Audio Attenuator, CV2 Polarizer, Frequency, Resonance, LP/HP Mix

Click HERE for more A-106-5 on PatchPierre.Net

Doepfer A-106-5 12dB SEM Filter Tutorial (Playlist)

"... Sound and Video by Raul Pena."

Check out Raul's latest survey at http://www.surveymonkey.com/s/K3Z9PVF

Other places to find Raul's World of Synths on the Web:

raulsworldofsynths on YouTube

raulsworldofsynths on Vimeo

raulsworldofsynths on SoundCloud

raulsworldofsynths at iTunes

raulsworldofsynths at CDBABY

Dave Smith Instruments DSM01 Curtis Filter

Known for their great in-depth reviews, SonicState/Soniclab has published another long video demonstrating Dave Smith Instruments' latest product, the Dave Smith Modular DSM01 Curtis Filter, that was released earlier this year.

Dave Smith Modular
DSM01

" The module takes its name from the original filter chip designed by the late Doug Curtis and provides both a switchable 2/4-pole low-pass filter and a VCA.

The Curtis filter is an integral part of the sound of many synthesizers created by Dave Smith, including the classic Sequential Circuits Prophet-5 and Pro-One, and more recent instruments such as the Evolver, Mopho, Prophet ?08, and Prophet 12.

The “Curtis sound,” which is often described as saturated, brash, and powerful, was fundamental to not only Smith’s synthesizers, but also to such highly-regarded instruments as the Oberheim Xpander, Rhodes Chroma and Polaris, PPG Wave, Korg MonoPoly, Waldorf Wave, Elka Synthex, and many others.

“We wanted to make the classic Curtis filter sound, which I’ve always found very versatile and expressive, readily available to modular users,” said Smith. 

“Adding the DSM01 to a modular system is an easy way to give it the sonic edge that people typically associate with a vintage Sequential synth. 

But it’s also a big part of the sound of my current synths such as the Prophet 12.”

The module is a standard 8HP wide, Eurorack-format device with interconnections made using 3.5 mm phone jacks. 

A set of inputs and parameters allows voltage control of filter frequency and resonance. 

Filter slope is selectable between -12 dB and -24 dB. 

The module also provides its own VCA and features two separate outputs for the filter—one pre-VCA and the other, post-VCA. 

A unique feature of the filter is a Boost function that introduces harmonic distortion into the signal for more aggressive coloration."

Video: DSM01 Eurorack Curtis Filter - Dave Smith Instruments
" The first module from Dave Smith is the classic Curtis Filter. In 8HP it also has a VCA to further expand the features available in such a small module."

Find out more at http://www.sonicstate.com/news/2014/10/06/sonic-lab-dsm01-curtis-filter-eurorack-module

Video uploaded by sonicstate 

Twitter: Sonicnick

Doepfer A101-1 Vactrol Multitype Filter Review by SoloStuff

SoloStuff created a nice review video about the Doepfer A-101-1 Vactrol Multitype Filter and uploaded it to YouTube...

Video: Doepfer A101-1 Vactrol Multitype Filter Review

" I wanted to do this for a while. The thing about the A101-1 is that it can be aggressive and easy. Vactrols are known for their non-distorting response, combined with the Steiner design kinda gives a more tamable beast.
Also, Vactrols behavior is not always precisely predictable because of tolerances in each. Doepfer says:

"mechanical and electrical tolerances cause that each vactrol will behave a bit different (e.g. because of the differences in alignement and distance between LED and LDR, different brightness of the LEDs at the same current)"
This effectively means that A101-1 modules can sound slightly different than each other no matter what calibration is done.."

Uploaded by SoloStuff

Random Video: Doepfer A-100 Modular System w Legacy Filter Demo by LesIndes

Electronic Music Analog Synthesizer shop Les Indes from Berlin uploaded this long (almost 13 minutes) demo to YouTube.
The video mainly shows off the A-111 VCO and the (discontinued) Doepfer A-121 Multimode Filter...

Video: DOEPFER A-100 Modular System w Legacy Filter

" Featuring: High End VCO A-111 (running out of production), Multimode Filter A-121 (discontinued)"

Uploaded by LESINDES

On Facebook: https://www.facebook.com/les.indes.3

Modular Wild Presents PROFILE - Tiptop Audio Z2040 LP VCF

Another new episode of Modular Wild Presents by Raul Pena.
This time all about the TipTop Audio Z2040 4-Pole Voltage Controlled Filter

Enjoy!

Video 1: Modular Wild Presents PROFILE-Tiptop Audio Z2040 LP VCF

" A brief description of the basic features of the TipTop Audio Z2040. Sound and Video by Raul Pena."

Other places to find Raul's World of Synths on the Web:

raulsworldofsynths on YouTube

raulsworldofsynths on Vimeo

raulsworldofsynths on SoundCloud

raulsworldofsynths at iTunes

raulsworldofsynths at CDBABY

Doepfer A-106-5 SEM Filter Test by Paul Johnson

Paul Johnson posted this video on YouTube, showing his newly acquired Doepfer A-106-5 SEM filter.
(and the rest of his setup)

Video: Doepfer A-106-5 SEM Filter Test

" Experimental noisy patch including the Doepfer A106-5 SEM filter."

Uploaded by Paul Johnson

On Twitter: https://twitter.com/Electronicaz

SoundCloud: soundcloud.com/electronicaz

Doepfer A-106-5 Demo by Icaro Ferre

This one popped up on Vimeo a few weeks ago.

In a short video Icaro Ferre shows what the A-106-5 12db multimode SEM Filter module can do in multiple modes, and with different resonance settings...

Video: Doepfer A-106-5 Demo by Icaro Ferre
Doepfer A-106-5 Demo from Icaro Ferre on Vimeo.

" Running a sequence through the Doepfer A-106-5 SEM Filter module."

Uploaded by Icaro Ferre

on Twitter: Twitter.com/icaroferre

I have this module too, and I like it a lot.
The only thing i miss in this filter module is an extra CV input to control the resonance, just like the A-121 Multimode Filter or the other Oberheim filter, the A-122 24 dB Lowpass filter VCF3 have.

Doepfer A-124 WASP Filter Simple Sweeps Demo by MylarMelodies

MylarMelodies (formerly known as Cymatic and MusikMesse 2012-picture-provider for PatchPierre.Net) has uploaded a nice video showing off his Doepfer A-124 WASP filter.

It's one of my favorite filters, so it's not really a surprise he likes it too...

Video: Doepfer A-124 Wasp Filter Simple Sweeps Demo.

"Being a video that shows the Doepfer Wasp Filter's character off on some simple square waves. Modular signal is processed with a tiny touch of UAD EMT-140 Plate Reverb to take the edge of its dryness. " 

Check out the rest of his music at mylarmelodies.com and his blog at http://howdoyoumakemusic.tumblr.com

Also check out the easy modifications for A-124 self-oscillation HERE and HERE

Doepfer A-127 VCRF Re-Design

I almost missed this between all Doepfer's other MusikMesse announcements;
As of April 2013 the Voltage Controlled Resonance Filter A-127 is available in an improved version.
Instead of the CA3080 chip (not available anymore) that was used in the original versions, new high-end circuits (SSM2164) are now used.

Doepfer A-127 Triple Voltage Controlled Resonance Filter

"The SSM2164 chip contains four independent voltage controlled amplifiers (VCAs) in a single package. High performance (100 dB dynamic range, 0.02% THD) is provided at a very low cost-per-VCA, resulting in excellent value for cost sensitive gain control applications.
Each VCA offers current input and output for maximum design flexibility, and a ground referenced -33 mV/dB control port."

A-127 + Expander

This is probably the Doepfer filter that i use the most, and the brand new re-design also promises to reduces the noise floor and the distortion clearly, according to Doepfer.
(The noise that i never really noticed before...)

The price of the new A-127 VCRF remains unchanged.

Check out how to make an A-127 expander module HERE.

A-128 Modification by Ernst van der Loo

Dutch Sound Designer, Engineer, Composer & Performer Ernst van der Loo posted a few pictures of his latest DIY-project in the Doepfer A-100 Facebook group.

Tools of the trade and lots of wire

The project involved creating 15 individual outputs for his Doepfer A-128 fixed filter bank.

Module A-128 (Fixed Filter Bank) is a filter bank, made up of 15 parallel band pass filters, all with fixed middle frequencies and bandwidth.

Each band pass filter has its own amplitude control knob, with which that frequency band can be attenuated. 

The bandwidth of each of the filters is approximately half an octave.
The signal at the original output of the A-128 contains a mix of all the filters, depending on the position of each one's amplitude control knob.

Finished project 

Ernst used an 8HP blind panel to create the expansion board for his A-128, drilled 15 holes, mounted the mini-jack-connectors and connected them with the correct terminals/outputs on the A-128 PCB board.
There is even the choice between pre-attenuator terminals (fixed volume) or post-attenuator.
You can find the document that shows how to add these single outputs to the filter bank A-128 in THIS PDF (from Doepfer's DIY page)

Ernst commented on the end-result:
 "Not too happy with the alignment of the mini-jacks yet. Maybe I'll need a new drill exercise..."

Maybe he should have saved himself the trouble, because if desired Doepfer can carry out this modification in the factory  (price for blind plate 8HP + 15 sockets + about one hour working time) for about Euro 100 altogether.

Pictures used with kind permission by
 http://www.ernstvanderloo.com

Doepfer A-106-1 Xtreme Filter Tutorials by Raul Pena

Raul Pena is back with a new video tutorial series, this time all about the A-106-1 Xtreme Filter.

Here are the first two, of four... 

Video 1: Doepfer A106-1 Xtreme Filter Basics

" A brief description of the features and functions of the Doepfer A106-1 Xtreme filter.
This filter is similar to the filter in the Korg MS20 but has its own unique character. Sound and Video by Raul Pena."

Video 2: Doepfer A1061 Xtreme Lowpass/Highpass Filter Audio Demonstration

"A look at an audio demonstration of the basic features of the Doepfer A106-1 Xtreme Lowpass/Highpass Filter. Sound and Video by Raul Pena."

Video 3: Doepfer A106-1 Xtreme Lowpass/Highpass Filter Modulation and Resonance Part One

" Audio Demonstration of Modulation and using the resonance insert of the Doepfer A106-1 Xtreme Lowpass/Highpass Filter. Sound and Video by Raul Pena."

Video 4:
Doepfer A106 Xtreme Lowpass/Highpass Filter Modulation and Resonance Part Two

" Part Two of an Audio Demonstration of Modulation and using the resonance insert of the Doepfer A106-1 Xtreme Lowpass/Highpass Filter. Sound and Video by Raul Pena."

Check out Raul's latest survey at http://www.surveymonkey.com/s/K3Z9PVF
Other places to find Raul's World of Synths on the Web
raulsworldofsynths on YouTube
raulsworldofsynths on Vimeo
raulsworldofsynths on SoundCloud
raulsworldofsynths at iTunes
raulsworldofsynths at CDBABY

Filters VIII: Doepfer A-106-5 SEM Filter

Yay... finally a new filter-module :-)
Last week i treated myself with an A-106-5 SEM Filter.
The A-106-5 is a 12dB multimode filter that is based on the filter circuit of the Oberheim SEM module (Synthesizer Expander Module), Oberheim's first official analog synthesizer that was produced from 1974 to 1979.

On the outside it looks quite like the A-124 Wasp filter, but sound-wise they are very different.
The filter is equipped with a band pass output and a combined low/notch/high pass output.
For this output a control knob defines the relation between low and high pass signal.
If both signals appear at the same level (i.e. middle position of the Mix knob) one obtains a notch filter. Otherwise the low or high pass signal predominates.
The module sadly does not feature self oscillation in contrast to most of the other filters of the A-100 system.

I had heard some good things about it, and it really sounds incredible.
I do have a slight preference for 12dB filters (like the A-121 Multimode Filter and the WASP filter - two of my favorites), and this one is another great sounding filter module.

The sound is hard to describe but i can say this one sounds fat enough for me (not very thin like most reviews say), and is already in my favorite filter-list.
It does not sound like any of the other filters that i own...
The only thing i miss in this filter module is an CV input to control the resonance, just like the A-121 Multimode Filter or the other Oberheim filter, the A-122 24 dB Lowpass filter VCF3 have.

Video: Doepfer A-106-5 Filter demo

" Short Doepfer A-106-5 Demo by NetPierre
Starts with a sequenced bassline, generated by my Doepfer MAQ16/3 and Doepfer VCO A-110 (saw wave)
Bandpass Mode first,  LP/HP later
A-118 Random voltages added to VC2 input somewhere in the middle.
Drums provided by an Elektron Machinedrum
More info on the A-100 and related stuff at http://PatchPierre.blogspot.com "

Also check out http://blog.andreaskrebs.de/2010/05/08/doepfer-a-106-5-sem-filter-example/ for sound examples and find more A-106-5 on YouTube

Filters VII: A-106-1 Xtreme Lowpass/Highpass Filter

The Doepfer A-106-1 Xtreme Filter was built as a kind of Korg MS20 filter clone.
The famous original MS20 included two filters: a 12 dB lowpass and a 6dB high pass filter connected in series both with a very special design.
On the A-106 product page Doepfer writes: " The A-106-1 is definitely not the right choice for "moogish" and "civilized" sounds but for extreme, exceptional and experimental sounds - this is why we call the module "X-Filter"... "

Doepfer found a way to use the same circuit simultaneously as lowpass and highpass for 2 different audio signals (a bit similar to the A-101-1 Steiner Vactrol filter that has even different audio inputs available, but with the special MS20 circuit).
For this two separate audio inputs for lowpass(LP) and highpass (HP) with separate level controls are available.
The sockets are normalled, so the signal applied to the LP input is available for the HP input too provided that no plug is inserted into the HP input socket.

The level control of the HP input is realized as a polarized input. This means that the signal can be added with the same polarity (+ range) or opposite polarity (- range) compared to the LP input.
This feature enables notch (+) and bandpass (-) filter functions too.

A lot of audio-examples can be found HERE
and on Andreas Krebs' blog

As you will hear in the demo's this is a very nice sounding filter with a distinctive sound.
It can sound very squelchy and dirty, and still also quite smooth...
If you are looking for a do-it-all filter, this might be the one you are looking for.
It is not my favorite filter, but i still rate it at 7/10...

Video:
Hans Richter - Rhythmus 23 - Figur 10 - KABELTON
http://www.youtube.com/watch?v=vNW6XXvJ74A

" ...just a test for something bigger... but i like it though.the sound was made with benjolin (rob hordijk and joker nies) and doepfer a-106-1."

Uploaded by Kabelton

Modifying the A-124 Wasp Filter a Little More

I don't know why i didn't come up with this idea earlier, but here is a short follow-up to my earlier self-oscillation modification post for the A-124 WASP filter ( original post can be found HERE )

The (mini-) modification consists of adding a switch to toggle between self-oscillation on/off modes.
To do this i had to use an extra 4 HP wide blank panel because there isn't enough space left on the A-124's front-panel to add a switch.
This is not my first 'expansion module',
i  made one earlier for my A-127 Triple Resonance Filter

I did this modification in less than an hour; i carefully drilled a 6 mm. hole in a new 4HP blank panel, desoldered one side of the resistor that i added earlier and connected that one to the new switch.
Another piece of wire connects the other side of the switch back to the original position of where the resistor was connected.

I am very happy with the result, i can now manually switch, turn the resonance-knob up to self-oscillation and simply switch back to the original mode again...

Thanks to Tony Steventon from Synovatron for the project review

Filters VI: A-122 24 dB Low Pass Filter VCF3

Module A-122 (VCF 3) is a voltage-controlled low-pass filter, which's circuitry uses a Curtis Electromusic chip (CEM3320), and sounds very similar to the classic Oberheim filter that was used in the OB8, OBX-a and Xpander synthesizers.
(and also in the Sequential Circuits Prophet 5 and Roland SH-101)

Because of its different circuitry and controls, the A-122 has a considerably smooth but thin sound, different like the A-120 'Moog-like' filter and other Doepfer filters.
Also the way the resonance behaves is quite different.

Luckily this module does have Voltage Controlled resonance that cannot only be controlled manually, but by voltages as well, right up to self-oscillation.
In this case, the filter behaves like a sine wave oscillator.
In this oscillation mode, you can simply use the FCV1 input to contol the pitch because it also works on the 1V/ octave rule, like regular VCOs.

I love the sound of it, you can use it to make fat and smooth basses up to the squelchier TB-303 style sounds.
A very nice filter, but not on top of my favorite filters list.
PatchPierre rating: 7/10

Check out the short (and not too in-depth) demo that i shot earlier today:
Video: Doepfer A-122 VCF3 Demo

" Short Doepfer A-122 Demo by NetPierre
Starts with a sequenced bassline, generated by my Doepfer MAQ16/3 and Doepfer VCO A-110 (saw wave)
Slow LFO sinewave A-147 into QCV input - ADSR into VC2 input
Drums provided by an Elektron Machinedrum "

As the special circuit CEM3320 used in this module is no longer available the module was discontinued.
Doepfer recommends the A-106-6 XP VCF, that is based on the filter circuit of the Oberheim Xpander, as a replacement module.

Doepfer A118 Filtering with A120 VCF Low Pass Filter

More Video from Raul Pena (of http://raulsworldofsynths.com/)
This time almost 45 minutes long tutorials on using the A-118 Noise/ Random Voltage Generator in combination with the A-120 Moog Style Low Pass Filter... creating some interesting wind-effects...

Video 1 : Doepfer A118 Filtering with A120 VCF Low Pass Filter
http://www.youtube.com/watch?v=vin9o4GpJs8

" Part One Discussing the features of the Doepfer A188 Noise and Random Voltage Source module. Followed by a Demonstration of Filtering white and Colored Noise with the Doepfer A120 VCF Low Pass Filter. Sound and Video by Raul Pena. "

Video 2 : Doepfer A118 Filtering with A120 VCF Low Pass Filter Part Two
http://www.youtube.com/watch?v=9ZxRsxPLuI4

"Part Two Ongoing Demonstration of Filtering white and Colored Noise from the A118 Noise module with the Doepfer A120 VCF Low Pass Filter. Modulation Capabilities also explored with A147 VC LFO and A145 LFO. Sound and Video by Raul Pena."

Read more on the A-118 HERE
Read more on the A-120 HERE

Filters V : A-120 24 dB/Oct Low Pass Moog Style Filter VCF1

Perhaps the best known low-pass filter in analogue synthesis was developed by Dr Robert (Bob) Moog in the late sixties.

It was used in the modular Moog synthesisers of that decade, but it got really popular in 1970 with the introduction of the Minimoog.

Moog's 4-pole filter is built with a co-called "transistor ladder" design with a cut-off slope of -24 dB/octave. That’s what gives it its classic, legendary Moog sound.
 Resonance is adjustable all the way up to self-oscillation - in which case the filter behaves like a sine wave oscillator.

The Doepfer A-120 is a very nice Moog emulator, but still most reviews say it doesn't sound 'Moogy' enough.
( i sadly don't have a real Moog to compare and verify that )
Moog's original circuit was flawed because it exhibited a small amount of distortion. Many engineers would have tried to correct this but Moog didn't.
He probably found that the sound was musically pleasing and he was probably right...
Maybe this module just sounds a bit 'too clean'.
It does still have a warm character, and it sounds very impressive in my opinion.
( and definitely unlike any of my other filters ).

Whenever i hear the name Moog i mainly think of great (Minimoog) synth-lead solo's or hand-played fat basslines, but you can also use this filter for wobbly dub-step basslines, sequenced loops and other (housey) basslines.

An interesting and more in-depth study on the Analysis of the Moog Transistor Ladder and Derivative Filters can be found in this PDF by dr. Timothy E. Stinchcombe.

Video : Doepfer A-120 (Moog) Low Pass Filter Demo by NetPierre

" Doepfer A-120 (Moog) Low Pass Filter Demo by NetPierre
created for my blog at http://PatchPierre.blogspot.com
A simple sawtooth wave from my A-110 into Audio in.
An envelope generator signal is sent into CV2, and some noise from the A-118 is fed into CV3.
Drums are provided by an Elektron Machinedrum "

Filters IV : A-103 18 dB Low Pass TB-303 Filter VCF6

The A-103 18 dB Low Pass filter (VCF6) is Doepfer's own 'TB-303 filter clone' ;
It uses a so-called transistor ladder with a slope of 18 dB/Octave as frequency controlling element.

It is very similar to the transistor ladder of the A-120 24dB Moog type Low Pass filter, but the ladder of the A-103 is a modification of the original Moog ladder and identical to the ladder used in the Roland TB-303.

The in -and outputs are very basic; Three CV inputs are available, and the sum of the voltages from these affects the filter cut-off.
And an audio in- and output are also available, with one level knob.

That is the same layout as the A-102 and the A120 so sadly there is no CV control over the resonance. 

Luckily the resonance cán be adjusted with a knob, all the way up to self-oscillation.

And how does it sound?

I've always loved the sound of a real Roland TB-303 and the sound of it's filter.

This one sounds very nice too, it has that nice warmth in the lows, and the typical sharp edge when resonating, but don't expect that you can re-create a whole TB-303 with just this single module.

Some of the TB-303's other features, like the glide, accent and envelope modulation are missing here, and they (partly) give the legendary acid machine it's very original character.With some creative patching you should get very close to re-creating that original Acid sound...

I got pretty close by using my MAQ 16/3 for the sequence, and the A-160/A-161 Clock Divider/Sequencer combo for additional 'accents'. (You can add an LFO, or Noise for more random accents to experiment with / ,an  A-142 VC Decay/Gate envelope is also a useful addition with CV modulation to CV2 of the A-103 to create basslines like that* )
Overall this filter module can be a nice addition to your Eurorack. (7/10)

Video: Doepfer A-100 does TB303


* thanks to Jakob Paulussen  (@Jakobsweb) for that last tip and the kind permission to embed his video here. More info on the video after the break: