Frequently Asked Questions

Here is a list of some of the more common questions that we have been asked about the MiniMod synthesiser modules.

Yes, all of the modules are 100% analogue, no virtual analogue or digital modelling here!

Yes, it works on the same signal levels and system voltages. It has a Eurorack compatible power bus connector and front panel sizes and hole spacings are also compatible.

Yes, the Moog Mother 32 is Eurorack compatible and so MiniMod modules will work with it. However, there is a known issue when using the Mother 32 KB Output with external VCO's - including the MiniMod VCO. Because of the relatively high output impedance (1 Kilo ohm) of the M32 KB output a suitable active buffered multi must be used to correct the impedance missmatch so that tracking problems are not experienced - if connected directly without an active buffer the external VCO will go flat at the rate of 1% per octave, or 2% per octave if two VCO's are attached, assuming that the VCO's have an industry standard 100K input impedance, so with two VCO's attached they would be 120 cents (more than a note) flat over five octaves. The input impedance of the MiniMod VCO is 100K so this applies.

Also, please note that not every active buffered multi will be effective, to obtain correct tracking it is very important that the active buffer has a very high input impedance (ideally 1 Megaohm or higher) and also a very low output impedance (ideally 10 ohms or less). Our V-Scale multi is very effective in this role and it was specifically designed for this purpose. Active multi's from other manufacturers may also work, but only if they meet the above design criteria.

For best performance we would strongly recommend a linear (rather than DC/DC switched mode) Eurorack power supply. Hinton Instruments and Doepfer power supplies have been proved to work very well, however there are other linear and some switched mode power supplies that are equally suitable. Some (but not all) of the currently available DC/DC converter based Eurorack power supplies can inject quite large levels of switching ripple and noise (up to 200mV!) onto the power rails, this may cause audio problems and instability with analogue modules such as ours which use low internal signal levels.

It is also good practice not to mix digital and analogue modules on the same power buss bar.

It is currently available in Eurorack format only, and we do not have any plans to realease it in other Modular or stand alone formats.

Moog S trigger is not supported on the Eurorack synthesiser format as it uses the more common voltage rather than switch based trigger system.

However, an S-Trigger facility can be added at a fairly low cost on the MiniMod and/or other Eurorack modules by using a third party S-Trig to Voltage Trigger adapter.

The main advantage of building the MiniMod into Eurorack format is that it opens up a previously closed system to experimentation, with interesting and sometimes unexpected sonic results.

The MiniMod VCO in particular can produce some quite extreme sounds when using sync or cross modulation, check out some of the video's in the Sounds and Video's section; particularly "VCO Sharktooth Modulation" and "VCO Sync Weirdness"

Unfortunately when Doepfer created the Eurorack format they decided to use unshrouded connectors on the distribution bus and modules, so it is entirely possible to connect the power header the wrong way around and in the process destroy a module by applying a reversed voltage to it.

We have built protection circuits into the positive and negative rails on all MiniMod modules. It does not use a fuse or a crowbar circuit that can overload the power supply,it is a safe solution that simply prevents the flow of current in the wrong direction and it ensures that no damage is caused either to the module or any other part of the Eurorack system.

Do still be careful to connect it up correctly though, the stripe on the ribbon cable denotes -12v and the cable should be connected so that the stripe lines up with the -12v markers on both the module and the power bussbar connectors.

The VCO can be used as an LFO, there is a Lo setting on the octave switch for this and it acts in exactly the same fashion as the Model D VCO 3, except that it does not have the reverse ramp waveform which VCO 3 featured instead of Sharktooth. There wasn't space on the panel to add this feature, but if required this can be easily obtained by passing the sawtooth wave through an inverter. At low frequencies is actually a VC-LFO rather than a simple LFO, as the frequency can be varied by adding a control voltage to 1v/oct or exp CV inputs, and a negative voltage is acceptable. So, if you had lets say 1Hz with 1v applied to the V/oct input, then patching -1v to the 1v/oct input will drop the frequency to 0.25Hz, -2v will take it down to 0.125Hz and so on. It will go pretty low, with -5v to the 1V/Oct input it runs at around 0.02Hz, or one cycle every 50 seconds.

No, they are all handbuilt by ourselves in the UK. We do not use assembly robots or farm out assembly to other companies, instead we paintakingly hand assemble, test and calibrate each module ourselves from high quality components to ensure the very best sonic performance, quality control and customer satisfaction.

The vast majority of components on the MiniMod circuit boards are small SMD devices, which are much more compact than their older through hole equivalents. We only use through hole components when an SMD equivalent is not available or would change and/or compromise the sound.This allows all of the circuitry to be fitted into the much smaller Eurorack module format, this would not be possible with vintage through hole components.

For the transistors themselves we commonly use paired transistor devices to save space, these contain two transistors within a small six pin or eight pin package. These transistors use EXACTLY the same silicon die as their much larger through hole equivalents. In through hole transistors the actual die inside is very small, as can be seen from the illustration below. Most of the transistor package is either empty space or filler resins which have no effect on the electrical characteristics of the transistors themselves.

In addition to +12v, -12v and +5v rails the Eurorack power supply bus has extra connectors to distribute CV and gate signals. If you attach a compatible Midi/CV converter to this bus then (usually by default) it will output it's 1 V/oct and gate signals to this bus, which can then be accessed by other modules as they are distributed in the same way as the +12v, -12v and +5v supplies.

For this to work correctly it is necessary that both the Midi/CV converter and distribution bus adhere to the Doepfer Eurorack standards. All of the AJH Synth MiniMod modules follow this standard, the VCO's accept CV over the bus, the Dual Contour and Glide+Noise get their gate from the bus by default, however connecting patch leads to the the front panel CV and Gate inputs defeats the bus signals and connects the input signal from the patch lead to the module instead.

For customers requiring a suitable Midi/CV Converter we strongly recommend the Kenton Modular Solo, it has the essential low note priority mode (in addition to last note and high note priorities), variable retrigger times, a very accurate low drift 16 bit D/A converter and a host of other useful features.