Designer Talk: Allan hall of Ajh Synth

AJH Synth are one of the stand out brands from 2015, their range of Minimod Eurorack modules gracefully encapsulate the sonic qualities of the iconic Moog Model D. Allan Hall the companies owner and product developer talks a little about himself, what inspired him to replicate such a legendary synthesizer and his inspiration.

KMR Audio; So tell us about yourself Allan, what got you into synthesizers? What was your first synth?

Allan: I’ve always loved electronics and music in equal measure since my early teens, I was lucky enough to get an electric guitar for my twelfth Birthday,  and a few years later started performing  Zeppelin, Deep Purple and Free covers with a few bands in youth clubs around my home town of Durham in NE England – however, when I first heard “Phaedra” by Tangerine Dream in the mid ’70’s it blew me away and I just had to find out how they made such other worldly sounds – after this my focus changed towards the electronic music of Tangerine Dream, JM Jarre, Vangelis and Kraftwerk.

Allan Hall AJH SynthCool as ice, Allan playing something “prog” no doubt.

I had already built a couple of DIY guitar effects pedals and was gaining confidence with a soldering iron, so after a few years of saving up my pocket money along with the wages from my Saturday job I bought a Powertran Transcendent 2000 monosynth kit. It took me more than six months to build, but to my amazement it worked perfectly when I first powered it up!

KMR Audio: Why Model D in eurorack?

Allan: I’ve loved the huge sound of the Minimoog Model D since first owning one in the late 70’s, to me it is the Stradivarius of analogue monosynths. I developed and built the AJH Synth MiniMod system so that I could re-create all of the sounds and eccentricities of the early Vintage Model D, but with many added features and Eurorack modular compatibility.

Initially I built one for my own Eurorack system with hand etched pcb’s and through hole components, however a few friends loved the sound of it and asked if I could build one for them too, so I set about re-designing it and decided to put it into production.

KMR Audio: Inspired by any other manufacturers?

Allan: I am in awe of the synth pioneers from the 60’s, Don Buchla, Dr Bob Moog, David Cockerell, Alan R. Pearlman to name a few. Analogue synthesiser circuitry is now well understood and documented and we have vastly better access to electronic components and design information than was available in the 1960’s when their ground-breaking designs were first introduced – a lot of their work bordered on genius.

I’ve also been involved in Synth DIY for many years and the amazing work of Jurgen Haible was an inspiration to me, he generously gave lots of useful help and advice, he is hugely missed by the whole SDIY community.

KMR Audio: What was the hardest circuit / part to replicate?

Allan: Without doubt the VCO, it is the very early fully discrete version with a single PFET buffer that I decided to go for in the production modules – my initial prototypes used the later (and easier to build) CA3046 based design but I decided to go for the very early VCO as it sounded just a little sweeter to me.

It took quite a lot of work, many prototypes and some computer based SPICE analysis to get that right.


KMR Audio: Any other classics you’d like to replicate?

Allan: Yes, there are quite a few classics that I love and think would work really well in Eurorack, we plan to have another in production later this year. I’ll be able to give more information on this when it’s ready for beta testing.

Our next releases will probably be individual modules rather than fully synthesisers in Eurorack, but they will still have a very Vintage analogue bias

KMR Audio: How’s your EMS re-build & restoration going?

Allan: It’s going pretty well, almost finished but things keeps getting in the way so it’s on the back burner at the moment 🙂 It’s a 1970’s EMS Synthi AKS that I’m restoring, it is in pretty nice cosmetic condition as it has been virtually untouched since new, so it is completely unmodded and original.

EMS Synthi AWe’re super jelly of Allan’s latest acquisition….

I owned a Synthi A about 15 years ago and really regret selling it a few years later – this one is a keeper!  One of the faults that it is showing is in the sequencer, it uses Static Shift Register IC’s that have been obsolete for years and are unobtainable. They run very hot in normal use and it’s amazing that they managed to struggle along for 40 years or so before dying! For my repair I’ve designed and built a small pcb using some readily available SMT dual 64 bit shift registers that is a drop in replacement.

Once I’ve got it all tested I’ll release the design and possibly manufacture a batch of pcb’s so that other Synthi AKS with the same problem can be easily repaired and saved!

Here at KMR Audio we advertise the complete AJH range and can provide expert advice and support, for more information on the AJH range click online, visit us in store or call us today.

By Tom Lewis