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piątek, 31 stycznia 2020

Allan J Hall- AJH SYNTH Interview '' the thing that I find fascinating about vintage circuity of any kind is that it is imperfect, and the imperfections are what make them sound so great ''


AJHSynth is headed up by Allan "J" Hall, who has been involved with synths, electronics and music for more years than he cares to remember! He started by building a guitar fuzz box at the tender age of 12 and an interest in synthesisers and electronic music soon followed, fuelled by an unhealthy overexposure to early Tangerine Dream, Pink Floyd, Vangelis and Kitaro. For the last 15 years he has been building and modding synth systems both for himself and other electronic musicians, as well as spending some time as a semi-pro musician playing keyboards in several rock and tribute bands.

Allan spent five years as a service technician repairing and modifying Moog, Arp, Korg, Roland and other analogue synthesisers along with some Pro Audio design work, previous to this he spent two years designing and building "boutique" valve (tube) guitar amplifiers.

AJH Synth has been growing for many years and offers many great modules witch use artists like Colin Benders or Hans Zimmer.

I had the pleasure to talk with Allan about how his company was created, what drives him, his inspirations and how created many of his modules.



Hello Allan, can you say something about AJH Synth first?

what motivated you to start making eurorack modules?

I spent many years servicing vintage synthesisers and also building and using large 5U format modules, but I noticed that with the 5U modular systems a lot of panel space seemed to be wasted and I wanted more function in a smaller form factor. However, when I started buying Eurorack modules I was frustrated that I could not achieve the wonderful rich vintage sounds that I was familiar with, so I started to design my own modules, initially based around the very early Minimoog Model D circuitry.

When was the first module he released?

The first commercially released AJHSynth modules were launched in 2014

You develop the amazing Minimod series, this is an ideal replica of MInimoog, was it something you missed in eurorack that you thought you would give people the exact Minimoog sound in the modules?

Exactly, but not just the MiniMoog, there were many other vintage instruments and effects that I was also interested in introducing to Eurorack .



Minimod is a series that has all the elements carefully reproduced as in Minimoog, you can see that the modules are described very well in terms of not only the function but also the history of moog itself, can you tell whether it was difficult to recreate the original sound to translate it into such small electronics?

Yes, it took a lot of development - around 18 months of work and I built many prototypes before I was happy that I had achieved my original goal. The toughest part is not the small size but the fact that some of the original parts are no longer manufactured, so I had to find parts that accurately replicated the original sound. Things like pcb layout and choice of passive components can be very important to the sound too – simply “cloning” the original circuitry in a smaller form factor with SMT components will not replicate the vintage sound correctly.



Each Minmod module is basically a different story, but they are not only a replica of Minimoog but also have additional features, you wanted to give something more to get unique sounds and more strongly sounding classic Minimoog model D?

The vintage Minimoog is a superb sounding instrument, however the largest limitation with it is that it has fixed patching and is effectively a closed system, which limits the range of sounds available. The Eurorack format allows an open architecture, and the AJHSynth MiniMod modules are designed to maximise their versatility and allow external control from external sequencers, keyboards and other Eurorack modules– this hugely expands the possible sounds; we can control gain staging between modules so that individual components can be overdriven, we can have voltage control of many of the parameters such as Filter Frequency and Resonance, oscillator PWM width -this was a fixed setting on the Minimoog but now we have external voltage control. Additional features such as oscillator sync and linear modulation are also possible – and of course if you wish to patch in extra VCO’s, filters etc then this is all very simple.

But you also develop additional modules, whether they are also modules that you want to have in your system.?

The whole AJHSynth range consists of modules that I wanted to have in my own system and could not find in the Eurorack world, so I set about creating them.




The Sonic XV Eurorack module is a four-pole diode filter with a ladder, containing circuits and the sound of the Musonics Sonic V synthesizer, which has a completely different character than the transistor ladder filters.
can you say something more about this filter?

The filter core was originally designed by Eugene Zumchak as a "work around" of the original patent (held by Dr Bob Moog) for the transistor ladder filter - the diode ladder was considered sufficiently different that it did not infringe the patent at the time.

My understanding is that Zumchak had previously worked as a design engineer for Moog but left after a disagreement and he decided to design his own portable synthesiser, his interpretation of what the Minimoog should have been – which became the Musonics Sonic V.  Because of the friction between himself and Moog he felt it would not be a good idea to copy the transistor ladder filter as that could have resulted in legal action being taken against him, so he re-designed the ladder filter using diodes instead of transistors. The diode ladder filter has quite a different character to it's transistor ladder parent, largely because the individual filter poles are not fully buffered as they are in the transistor ladder variant. This pioneering design was also taken up by EMS for the VCS3 and Synthi A filter, and of course later by Roland in the TB303.

The filter core of the Sonic XV very closely replicates that of the Musonics Sonic V, however I took the opportunity to add Band Pass and 6dB outputs too, which were not part of the original design. And of course it includes a Wavefolder on the inputs, which adds a whole range of extra sound possibilities.





If we are talking about filters then there is one more double Gemini 2412 filter based on SEM.
This makes your filters are very Vintage and do you always want to get classic old analogues in your system?

Yes, the thing that I find fascinating about vintage circuity of any kind is that it is imperfect, and the imperfections are what make them sound so great. A perfect filter can be very boring, it simply filters and processes the sound without adding any distortion. The early VST instruments and virtual analogue synths proved this point, they were a little too perfect and sounded very bland.  Vintage filters add lots distortion to the sound, or “character” as we prefer to call it!



What is the difference between Gemini filter and Ladder filter?

They are very different indeed, the Gemini is based on two identical filters based around the Oberheim SEM core – these are state variable filters, which means that Low pass, High Pass and Band Pass outputs are all available simultaneously – of course they are a two pole rather than four pole design, therefore in the case of the low pass filtering it has a 12dB per octave rather than 24dB slope. The Gemini allows two filters to be cascaded together to create a 4 pole topology. However the resonance of the SEM filter are very different from the Ladder filter because of difference in phase cancellation between the two designs – with a ladder filter the output level usually drops as resonance is added – this is because we are feeding some of the filter output back into the input, and the waveforms are fairly close to being completely out of phase, so they tend to cancel one another out, which results in a lower output level. With the SVF design of the SEM filter the opposite is true, when the output is fed back to the input it is mutually in phase, so it is added rather than subtracted and the overall output level therefore tends to increase as resonance is added. The phase differences of each filter contribute considerably to their respective resonant sound signatures.











You also did effects like The V-Shape is two modules in one, a wave twister and a distortion / wavefolding module or A beautiful sounding and versatile next generation analogue phaser Next Phase.


these are the next modules that should be found in most eurorack systems?

The V-Shape is unusual in that it isn’t based on a vintage design, it allows a sawtooth waveform to be skewed across to a triangle and then a ramp wave, so that we can add PWM style modulation to sawtooth waveforms – this wasn’t possible on any of the vintage synthesisers and is fairly unique to AJHSynth.

The NextPhase is very much a vintage based design – it is a 12 stage phaser built around the core of the EH SmallStone phaser, which is probably the nicest sounding phaser ever built. However our design allows the individual stages to be tapped and positive or negative feedback can be added from a completely different stage – this allows a huge range of phaser sounds to be re-created, and it can be mono in, stereo out. And it is perfectly adapted to modular systems as we can voltage control the important elements of it.

Also, the effects are important, you have here the Finalizer R-EQ Reverb, EQ and Maximiser module, is it also a module that gives Vintage sound and increases the final sound level?
can you say something about this module?

Again this was a module that I designed for myself as I needed a nice sounding EQ and maximiser and couldn’t find anything that was convincing enough. Obviously it is designed to go at the end of the chain so that you can fine tune the sound of your rig, and add some nice stereo reverb to the sound too.



What can you say about the new series you announced for SB 19?
these modules seem straight out of space, for example your new Lunar Module.
can you tell a little about him?

The Lunar Module and Entropic Doom modules were launched at Superbooth 19 but have only just gone into production. The Entropic Doom is what we call a “Noisillator”, as it generates tuned and resonant noise. However it will also allow external audio and sync signals to be added to the noise loop. It also has an unusual XOR Ring Modulator and XOR VCA sub modules built into it too, so a huge range of noise and ring modulated effects are possible.

The Lunar Module was something that I designed as a tribute to the Apollo moon landings, it generates authentic Quindar tones and has bandwidth limitation, distortion and noise circuits so that it can make a voice sound like it is being transmitted from Houston control to space, or from the capsule back to earth. Just a bit of fun really – however it can also be used in a modular system as a distortion, noise and fixed bandpass processor.



Precision Voltages is also a module that seems to be a 'must have' in the system?
seems like the perfect tuning in eurorack was quite difficult or is that why you did it?

I designed the Precision Voltages modules some years ago just for our own use – we needed a very accurate voltage source to calibrate and tune our VCO’s after manufacture, and a few friends thought that it would be a very useful module to have in their systems too – so we re-designed it as a Eurorack module. It allows the generation and addition of very accurate voltages – pretty essential if you wish to keep everything in tune!

What do you recommend for beginners who want to have really good sound in the first system? do you recommend any AJH kit for start?

For anyone buying their first modular system I always would recommend that they buy everything (or as much as possible) from one manufacturer, because it can then be guaranteed that they will all work together well. There is not really a “Eurorack standard” as such, different manufacturers have different ideas on signal and modulation levels, signal bias etc which can make interfacing modules from different manufacturers a little tricky. Experienced Eurorack users are generally aware of this and know how to use utility modules to interface between various modules, but for a beginner mixing and matching modules can cause problems that they do not fully understand. The main reason to buy an AJHSynth modular system would be for the sound it can create, it is the nearest that it is possible to get to vintage synths in Eurorack, and this is why many professional musicians choose to use AJHSynth modules. Music producers understand that the source sound is paramount, we have a signal chain and the resulting sound will only be as good as the weakest link in the chain so every part of the audio signal chain should be given careful consideration, post processing afterwards can never add back quality and character that is missing or lost.



You also have quite a long history in repairing old synthesizers. are you still repairing classical synthesizers or are you currently only eurorack modules?

Unfortunately I no longer have time to do any synth repairs and servicing, AJHSynth takes up all of my time now. I do miss working on vintage synths, however I still have a bit of a collection of vintage synths that I have built up over the years.

How do you see the future of eurorack, do you think it is developing in the right direction?

Eurorack is going in many different directions right now, so almost everyone should be able to find something useful in Eurorack for their particular musical journey.


You can see a big increase in new companies, but you think what makes AJH Synth different?

We concentrate on the audio signal chain, in making the very best sounding modules available without regard to cost – so if you desire something that has a wonderful rich vintage sound without the unreliability and servicing issues of old equipment and desire the open architecture of the Eurorack format then you really should consider AJHSynth first.


More info about AJH Synth modules and more demos here : https://ajhsynth.com




See also last Interview with Rene Ubachs from Rebach ''Here a conscious choice was made for a minimal design but maximum sound''


Some demo with AJH Synth modules :












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