AJH Synth Gemini 2412 Dual Vintage State Variable Filter Review

video upload by Molten Music Technology

"Two lovely 12dB SEM-style filters baked into a configurable dual or cascade architecture with interesting modulation and a ridiculous resonance feedback option. Here's my full review and what I like about it."

Radiophonic Modular Performance

video upload by Starsky Carr

"Sometimes we talk too much... so this is a live performance using 'only' the AJH Synth RadioPhonic*, with Erica Synths *Bullfrog Drums*, the *Bullfrog mixer*, all sequenced by the *OXI ONE Mk2

No talking, I promise!! just the track, the sound of the hardware and an on-screen explanation of whats going on.

All synth sounds come from the RadioPhonic, with Bullfrog Drums providing the percussion. The effects are from the Bullfrog Mixer - simply a lovely sounding reverb and a delay.

The setup:
• AJH Synth RadioPhonic — all synth sounds
• Erica Synths Bullfrog Drums — drums and percussion
• Bullfrog mixer — mixing
• OXI ONE — sequencing"

Moog Micromoog & Modular w/ AJH/MiniMod, Hermod+ analog synth jam

video upload by DreamsOfWires

"Testing my faulty Micromoog with some helpful modules from AJH Synth: My poor old Moog isn't scaling/tracking correctly, so the V-Scale module is being used to modify the 1V/Oct output of the sequencer to produce the correct notes. Video guide to how this was achieved: • Correcting Vintage Synths with V-SCALE - T... [below]

Normally the Micromoog follows a 0.95V/Oct voltage to pitch scale, but mine can no longer even be calibrated to this with it's internal trimmers, so until it can be serviced (probably with some new components), the V-Scale at least makes it useable with external controllers and sequencers.

Sequenced by the Squarp Hermod+, the synth's faulty tracking is then corrected using AJH Synth's V-Scale module, gates coverted by the AMSynths AM997 Gate to S-Trig converter.

Micromoog filter modulated by AJH Tap Tempo VC-LFO, random gate skip by AJH CHance Delay.

Drone is 3 AJH MiniMod VCOs into Matrix VCF.

Mixed in the Cosmotronic Cosmix Pro, reverb from FX Aid, delay from 2HP DLY, final mix recorded on the Disting Mk4."

Video guide to how it was achieved:

Correcting Vintage Synths with V-SCALE - Tackling Tracking & Tuning Problems #ajhsynth

video upload by AJH Synth Official

"Using V-SCALE to compensate for the tuning/tracking problems on one of my Vintage Synthesizers, this time a Moog Micromoog from the late 70's. Also, showing how PRECISION VOLTAGES can also be helpful, and bringing the TAP TEMPO VC-LFO, CHANCE DELAY, and the MATRIX VCF into a short performance demo - FULL performance video by ‪@DreamsOfWires‬ can be found here: • Moog Micromoog & Modular w/ AJH/MiniMod, H... [above]

V-SCALE at its simplest will function as a highly accurate buffered multiple, but four of its five outputs are adjustable by way of multi-turn trimmers. These allow for very gradual adjustments to outgoing CV signals, so that they can be made viable for synths or VCOs that are not scaling properly.

Here I'm adjusting/modifying a 1V/Oct signal from a sequencer so that it controls my old Micromoog correctly, but it could also be used with incoming signals other than 1V/Oct, or even to correct am incoming signal which itself isn't scaling correctly or as desired. Each trimmer has an adjustment range of +/- 5%.

My Micromoog's tracking is so far off that it cannot even be corrected using the internal trimmers on the synth, so I'm using the Keyboard Output (KBD) as the CV input, instead. of the intended OSC input. This method bypasses the keyboard, so the keyboard voltage isn't added to incoming control voltages, and so doesn't interfere with it. The only drawback is that the root key will have to be changed to match the notes on a keyboard. That's where the PRECISION VOLTAGES comes in - it can accurately offset an incoming control voltage by semitones and octaves, either up or down."

The Sounds We Forget To Hear

video upload by Starsky Carr

"The joy of sound, before it becomes music. A wind chime looping in the woods at Superbooth, La Monte Young's Composition 1960 No. 7 in a Liverpool theatre, and one thick, warm tone from the AJH Synth RadioPhonic that I couldn't stop playing.. 🎧 Put this on headphones or big speakers - the bass is lovely.

Why do we remember a melody but not a sound? Why is Superstition not Superstition without the clav, or In the Air Tonight without those drums? And when did we stop just listening?

Which single sound gives YOU a physical reaction? Tell me in the comments - I read every one, and I'm collecting favourites.

🎛 GEAR IN THIS VIDEO
AJH Synth RadioPhonic: https://ajhsynth.com/
AJH Synth MiniMod (mentioned)
Ian Boddy helped design the Chance Delay on the RadioPhonic

🔗 MORE FROM ME
Presets, sample packs and Decent Sampler libraries: https://starskycarr.com"

GEMINI 2412 Dual SEM VCF Sequencer Tweaking #eurorack

video upload by AJH Synth Official

"Some 70's-inspired tweaking with the GEMINI 2412, SAMPLE & Hold, and a Sequencer.
Video & Performance by ‪@DreamsOfWires‬
The Gemini is based on the classic Oberheim SEM filter, but with expansive flexibility, including a unifying CV and Audio mixer section between the two multi-mode VCFs. There is a shared output for both filters in 'Dual' mode as used here, but also separate shared outputs for each VCF, through which filter mode can be selected, and individual outputs for LP, BP and HP filters on each.
Also, a jumper on the back alters the behaviour of both filters individually - standard SEM resonance range, or extended high resonance setting that'll allow the filter to self-oscillate. 1V/Oct inputs are present for both filters, so each can even be used as a simple sine wave oscillator over a few octaves.

AJH Synth Eurorack modules used:
Vintage Transistor Core VCO
Gemini 2412 Dual State Variable Filters
Discrete Cascaded VCA
Dual LFO + VCA
SAMPLE HOLD + SLEW
RING SM (Moog CP3 mixer/sub bass generator/ring modulator)
DH-ADSR (looping envelope generator)

Other gear:
‪@vermonagear‬ DSR-3 Stereo Spring Reverb
‪@solidstatelogic‬ BigSix Mixer & Audio Interface
Eurorack Case by @Casa_Modular_ (Instagram, Reverb, Etsy)
Case Power by ‪@konstantlab2976‬

#modularsynth #synth"

Stupidly useful, simple & small // Low Fat VCF from AJH Synth

video upload by DivKid

"Here's a fun one and something stupidly simple, really easy to use, small, affordable but way more useful than you might think. It's the Low Fat VCF from AJH Synth, which is a 2HP non resonant (it's supppppeeeer smooth) high pass filter.

I think my favourite thing is using it to pair with low pass filters and to make a variable width band pass filter. It's also nice as a simple "clean up the mix" tool, as a pseudo spectral sidechain, multiband ducking style device or just for performance sweeping low end out of things."

"The Low Fat filter packs a switchable 6dB and 12dB slope High Pass Voltage controlled Filter into a miniscule 2HP of rack space, with a very low power consumption of less than 12mA per rail.

Sometimes there is just too much bottom end in a patch and it swamps everything else, by feeding it through the Low Fat Filter we can remove some of this bottom end to balance things up.

It also makes a great companion to the MiniMod Transistor Ladder Filter and can be placed before or after this in a patch to create a Band Pass filter with a variable passband and a choice of a softly rolling 6dB slope or a stronger 12 dB slope.

It's a great way to populate one of those frustrating gaps in your eurorack modular case with something that is deceptively usefuI.

In Depth

The LOW FAT is a new 2hp Eurorack module by AJH Synth, it's a High Pass filter, with frequency control by either manual pot, and/or external CV with attenuator. It's intended to compliment other filters, particularly low pass VCF modules, in practical tasks such as removing excessive low frequencies, for example when the bass is swamping a mix. It can be switched between 6dB (1 pole) response and 12dB (2 pole) response.

By patching a CV signal to the FCV input it can be voltage-controlled and used musically as with any other VCF. When used in conjunction with a LP filter it forms a fully customisable band pass filter, allowing the range of passbands to be cherry-picked. Feeding in a 1V/Oct pitch CV and setting the FCV pot to a suitable level allows it to track an incoming pitch CV, so the amount of High Pass filtering remains constant as the pitch of the incoming VCOs traverse up and down the frequency range. This can be particularly useful in creating percussive sounds, such as snares and hats, but also on sequenced bass lines. Since it is only 2HP it's a great way to occupy one of those frustrating gaps in your eurorack modular case with something that is deceptively useful, and adds another dimension to the classic bass monster that is the Transistor Ladder Filter."

Recreating Pink Flyod's Iconic EMS Synthi AKS Sound | Voltage Labs

video upload by Voltage Labs

"In 1973, Pink Floyd released 'The Dark Side of the Moon', one of the most influential albums of all time. The track 'On the Run' is famous for its use of the Synthi AKS, a classic London-made analog synthesizer by EMS (Electronic Music Studios).

Today I’d like to show you how to recreate the iconic sequence of that track on an EMS Synthi A, then show how to program it on a Moog Mother-32, and finally how to patch it in a Eurorack system."

AJH Synth Radiophonic Synth

video upload by Jarkko Tuohimaa

"Short sequence to test #AJH Synth #Radiophonic Synth at #Superbooth 2026."

Probability-based Transposing with PRECISION VOLTAGES, CHANCE DELAY & a Step Sequencer #eurorack

video upload by AJH Synth Official

"A sequencer patch using PRECISION VOLTAGES and CHANCE DELAY modules for probability-based transposing of steps. Also featuring sound from a single VCO and the SONIC XV filter & wave folder.

Video & Performance by @DreamsOfWires

PATCH BREAKDOWN:
A Doepfer Mini Sequencer is playing a simple 5-step sequence. The clock is from the DUAL LFO + VCA module, which is also triggering an DH-ADSR envelope generator (connected to audio VCA), and the SAMPLE HOLD & SLEW module.

Because the sequencer gates aren't being used to trigger the envelope generator, I can use them elsewhere, and on the Mini Sequencer they can be turned off per step, so instead I am sending these gates to the PRECISION VOLTAGES (Gate A). This means that whenever a gate signal is received, Precision Voltages will activate, shifting the pitch of connected VCOs by the selected amount.

To add variety to this, I am first running the gates through the CHANCE DELAY, with which I can adjust the chance/probability of the gates being passed through to the Precision Voltages, or ignored. This means that the transposed notes will only randomly occur, based on the position of the 'Chance' pot, here at 50%.

Precision Voltages is dual channel (A & B), but I'm using the combined A + B output, so that any semitone or octave changes that I make to channel B will be combined with those on channel A, which is the only channel being switched on or off by the incoming gates. This means I can transpose the whole sequence by the same selected semitone and octave values (here plus or minus 5 semitones) and still have the selected sequencer notes randomly transposing by the same interval.

As for the sound - just a single triangle wave into the SONIC XV Diode Ladder Filter, manually adding the wave folder to create a much more interesting timbre, and with the clocked SAMPLE HOLD & SLEW module randomly modulating the filter frequency, via the DUAL LFO\s built-in VCA, which is slowly modulating the level of the Sample and Hold from strong to nothing.

Mixed on a @solidstatelogic BigSix with @vermonagear DSR-3 Dual/Stereo (real) Spring Reverb. Both cases powered by the Konstant Lab StrongPWR, with small case using a Polyend Anywhere USB PSU, powered by the USB output of the StrongPWR. Clear acrylic Eurorack case by CASA Modular, Japan."

It's Only Noise - Random Percussion with Sample & Hold, No Sequencer...just for fun #eurorack

video upload by AJH Synth Official

"Messing about with noise and random voltages. This patch is just various noise sources through various filters, frequency-modulated by sample & hold, with envelopes controlling amplitude (VCA) or affecting filter frequency. No sequencer was harmed in the making of this video.

The ‪@solidstatelogic‬ BigSix is used to mix all 4 sounds, with the ‪@vermonagear‬ DSR-3 providing stereo spring reverb for the drone and occasional sound.

Video & performance by ‪@DreamsOfWires‬

Patch Breakdown:

Drone: This is just pink noise going into the FIXED FILTER BANK 914, but with an LFO from the DUAL RVG modulating the mix between the left and right bands of the Filter Bank, creating that slow, breathing effect. The AJH SYNTH 914 has built-in, voltage-controllable mixing/cross-fading functionality, which wasn't present in the original Moog 914 on which it is closely based.

Percussion 1: White noise going to the SONIC XV Diode Ladder Filter, using its band pass output. One channel of the DUAL RVG is sending random voltages to the Sonic's Filter Frequency/Cutoff, whilst a DH-ADSR envelope generator controls its audio level in the TRIPLE CROSS (being used as a triple VCA).

Percussion 2: This starts with noise generated by the LUNAR MODULE - this has 2 noise sources with different character and tone control, and built-in distortion. Its output goes to the MATRIX VCF, which has 16 different filter modes, which I cycle through manually during the video. See out User Guide video for more information: • NEW MODULE! MATRIX VCF User Guide - Vintag...

Occasional Sound: Here I'm using the SAMPLE & HOLD module to randomly trigger the MULTI BURST ENVELOPS module. The Colour control on the Sample & Hold determines the range of random voltages generated. It is a combination of Low Pass and High Pass filter over the onboard noise that is used to derive the voltages, so turning it anti-clockwise from the centre acts as a low pass filter, reducing voltages produced to be in the lower range, whereas turning it clockwise of the centre position acts as a high pass filter, meaning voltages in the higher range. Since it is generating lower voltages here, it is only occasionally producing enough of a voltage change to trigger the Multi Burst Envelopes. If I raise the Colour control it will trigger more often.
The Multi Burst Envelopes produces a chosen number of bursts of the selected envelope shape. The built-in LFO controls the speed of the bursts, as does the Clock input, but both can be used together or independently. I'm using it to control the frequency of the ENTROPIC DOOM's low pass filter, to generate an occasional burst of filtered noise."

RING SM Sounds - A Ring Modulator/Sub-bass Generator & CP-3 Mixer for #eurorack

video upload by AJH Synth Official

"Playing around with the RING SM from AJH Synth. This is a hugely useful module, combining a 3-way all-analogue Ring Modulator, a -1 and -2 octave sub-bass generator, and 5-channel Moog CP-3 based mixer.
This is a real ring mod, as opposed to the more common, simpler and cheaper circuits found in many synths, such as the Odyssey, which often used CMOS chips to mimic the same behaviour. The authentic vintage circuit recreated in the RING SM is based on the Ring Mod of the EMS Synthi/VCS3, and has a hugely thick, rich tone.
The Sub Bass generator derives shaped square waves at 1 or 2 octaves below the pitch on an incoming VCO. This shaped squares are slightly curved at the edges, almost a cross between a square and a sine wave, which produces a much better balance of harmonic content and warmth/fatness than the common, purely square or sine sub basses found on most synths and modules, resulting in thicker yet more musical sub-octaves. Additionally, the 'Double' feature can generate an octave above the incoming triangle or sine wave.
The CP-3 mixers saturates as you'd expect from this classic vintage design, with soft clipping, and a boosted gain level on input channel 5."

MATRIX VCF & Voltage Control - Creating presets with fixed voltages

video upload by AJH Synth Official

"Here I'm using Pressure Points to select different sounds/settings on the Matrix VCF - this filter has full CV control of all functions, including the selection of all 16 different filter types (Mode). Because the Matrix has such a huge range of filter sounds, it is very useful to be able to recall them instantly using a fixed-voltage controller or sequencer.
I'm also feeding it 2 VCOs and noise initially, but later replacing the raw sawtooth waves with the same saw processed by the WAVE SWARM - this is a sawtooth animator, creating 12 additional faux saws from 1 or 2 incoming oscillators to create a fat 'super saw' effect.

Video & Performance by @DreamsOfWires

The AJH SYNTH Eurorack modular range consists of high-end modules, all hand-made in the UK, most of which are based on classic, vintage designs, authentically recreating the circuitry of much sought-after analogue instruments and technologies of the past, whilst greatly expanding them, and bringing them to modern Eurorack levels of convenience, limitless flexibility, and reliability.

Official website page: https://ajhsynth.com

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CWEJMAN SM-1 // FM Sounds // Roland TR-6s // No Talking // PART 2

video upload by LESINDES

"Experimenting a bit with the SM-1 module from CWEJMAN with a little helpf from WINTER MODULAR ELOQUENCER and AJH SONIC XV VCF"

A simple Bandpass filter trick you should know.

video upload by Monotrail Tech Talk

"Zappy, croaky, and squeaky resonant filter sounds aren’t for me. But I do like the texture, crunch and air a lot of resonant filters can add to a sound. In this video I show a simple trick combining a band- and low-pass filter, allowing you to detach a high resonant point from low pass filter modulation."

AJH MINIMOD & XAOC Belgrad

Mini Analog Sequencer & Matrix VCF: Changing Filter Type Per Step & More #eurorack

video upload by AJH Synth Official and DreamsOfWires

"Using the new @DoepferMusikelektronikGmbH Mini Analog Sequencer to change filter modes on the Matrix VCF, whilst also providing a melody for the VCOs. Ideally, a separate sequencer would be used for each purpose, but just for fun I wanted to see what I could creating using the same sequencer CV to create both a melody, and change filter type on the Matrix. This is made much more viable using the CV MIX module, to adjust the range of CV to cover the modes I wanted to use - predominantly those at the bottom, including 4-pole low pass, band pass, all pass, and the combined 3-pole all pass & 1-pole low pass mode.

Stereo Panning per step also features towards the end (headphones recommended), using the Triple Cross module to pan the mono sequence between 2 outputs, which is sent to a stereo input on the Cosmic Pro. The Tap Tempo VC-LFO is providing sample & hold-style random stepped voltages, which go to the Triple Cross module, modulating the amount of stereo panning between left and right on each sequencer step. I didn't increase the panning amount to maximum, because the result was just too extreme for my delicate ears! It's a great effect though."

SONIC XV 'FM Drone' - Diode Ladder Filter/Wave Folder Vs Audio-rate modulation (1 VCO) #eurorack

video upload by AJH Synth Official

"A simple FM drone using the SONIC XV Diode Ladder Wave multimode filter & wave folder from AJH SYNTH: https://ajhsynth.com/Sonic_XV.html

Video & Performance by @DreamsOfWires

The AJH SYNTH Eurorack modular range consists of high-end modules, all hand-made in the UK, most of which are based on classic, vintage designs, authentically recreating the circuitry of much sought-after analogue instruments and technologies of the past, whilst greatly expanding them, and bringing them to modern Eurorack levels of convenience, limitless flexibility, and reliability.

Official website page: https://ajhsynth.com

Check out the AJH Synth playlists for module 'User Guides', and 'Patch of The Week' videos, which will be either performances or 'how to' guides, detailing functions/methods, and a range of sounds, some familiar, some less so, containing a patch sheet at the end to show you how to construct it for yourself."

MUTING MIXER & VCA Jam w/ V-SHAPE wave shaper/folder #eurorack by AJH Synth

video upload by AJH Synth Official

"The V-Shape is a wave-folder/wave-shaping module, and also features a distortion circuit, with full CV control - it can make a single VCO sound a lot more interesting. The Gemini also features here, using both of its 2 VCFs and shared CV control to filter the same input signal separately.

Video & Performance by @DreamsOfWires

The AJH SYNTH Eurorack modular range consists of high-end modules, all hand-made in the UK, most of which are based on classic, vintage designs, authentically recreating the circuitry of much sought-after analogue instruments and technologies of the past, whilst greatly expanding them, and bringing them to modern Eurorack levels of convenience, limitless flexibility, and reliability.
Official website page: https://ajhsynth.com

Check out the AJH Synth playlists for module 'User Guides', and 'Patch of The Week' videos, which will be either performances or 'how to' guides, detailing functions/methods, and a range of sounds, some familiar, some less so, containing a patch sheet at the end to show you how to construct it for yourself."

Melody & Probability - #eurorack Session with all AJH SYNTH Sound & Modulation Modules

video upload by AJH Synth Official

"This session consists of 4 voices, mixed, effected and recorded directly into the modular (see 'Modules used' below). A simple Moog-style bass line using the Transistor Ladder Filter is accompanied my a pitched drone from 2 VCO's going into the Wave Swarm, then Fixed Filter Bank 914.

These are joined by a melodic, sequenced part, created with a single VCO going into the Ring SM for sub-bass/sub-octaves, then the Sonic XV Diode filter. This part is randomised later in the track, and uses the Chance Delay for step probability.

Percussion comes from the Entropic Doom, with random stepped voltages from the Tap Tempo VC-LFO modulating it's built-in low pass filter frequency. The Tap Tempo VC-LFO also acts as a clock multiplier for this part, and later the melodic pattern too.

Video & Performance by @DreamsOfWires

The AJH SYNTH Eurorack modular range consists of high-end modules, all hand-made in the UK, most of which are based on classic, vintage designs, authentically recreating the circuitry of much sought-after analogue instruments and technologies of the past, whilst greatly expanding them, and bringing them to modern Eurorack levels of convenience, limitless flexibility, and reliability.
Official website page: https://ajhsynth.com"

'An Unearthly Choir' on an AJH SYNTH #eurorack Modular Synth System

video upload by AJH Synth Official

"A 3-part/3-voice use of human voice & choir-like sounds performed on a AJH SYNTH RadioPhonic Eurorack modular system. No samples were used, this is purely analogue oscillators, filters, modulation, and a wave form animator one one of the voices.

Whilst the RadioPhonic system was used here, it is of course modular, so these modules can be acquired individually or as part of smaller systems, meaning each part could be achieved using the same modules in your own custom system.

Key MiniMod modules used:
Vintage Transistor Core VCO
Wave Swam
Fixed Filter Bank 914
Transistor Ladder Filter
Sonic XV Diode Ladder Filter

Video by ‪@DreamsOfWires‬"

Live Set Re-recorded - from Superbooth25, feat AJH SYNTH all-analogue modules

video upload by AJH Synth Official

"This is a re-recording of a 20-minute live set by @DreamsOfWires for Superbooth25, and consists of two old tracks from my video back-catalog. It's quite a minimal rig, configured as two all-analogue synth voices - one for melodic patterns, one for pitched drone parts.
The actual performance at the event suffered technical problems as a result of failing cables and a dodgy musician's inability to recover much from it. As a result said musician decided to record a version of it after returning home, demonstrating how it should have sounded.
In my defence, this rig had been on display for 3 days at the AJH Synth booth, demoing modules, being re-patched, fiddled with, then re-patched, etc... but then again, a bad workman always blames their tools :P
I hope this version is more audible.

Modules used:
(AJH SYNTH)
Matrix VCF
Transistor Ladder Filter
Sonic XV Diode Ladder Filter
Vintage Transistor Core VCO x4
Sample Hold & Slew
Contour Generators
Wave Swarm
Ring SM
Muting Mixer
Discrete Cascaded VCA
Glide + Noise MkII
Dual LFO VCA
(Other brands)
Squarp Hermod+ sequencer
XAOC Devices Sarajewo analog delay
ALM Busy Circuits MFX for reverb
Cosmotronic Cosmix
Happy Nerding Isolator
Homemade case powered by Konstant Lab BoardPWR

The AJH SYNTH Eurorack modular range consists of high-end modules, all hand-made in the UK, most of which are based on classic, vintage designs, authentically recreating the circuitry of much sought-after analogue instruments and technologies of the past, whilst greatly expanding them, and bringing them to modern Eurorack levels of convenience, limitless flexibility, and reliability.
Official website page: https://ajhsynth.com

Check out the AJH Synth playlists for module 'User Guides', and 'Patch of The Week' videos, which will be either performances or 'how to' guides, detailing functions/methods, and a range of sounds, some familiar, some less so, containing a patch sheet at the end to show you how to construct it for yourself.