Peter Pritchard

Today's New York Times carries a brief obituary notice of the passing of audio innovator, Peter Pritchard, on August 23 in Austin, Texas at the age of 83. Peter founded Audio Dynamics Corporation in New Milford, CT in the early 1960's. His original ADC-1 ("Tip mass: 0.6 mg. Compliance. 20x10–6cm/dyne, all directions. Playing weight: 1 gram or less in top quality arms") was a breakthrough product. Indeed, all ADC pickups were notable for their extremely high compliance and low tracking forces and he pursued this approach through a series of successful designs including the well-known ADC-10, ADC-25 and XLM cartridges. They were all based on his "induced magnet" principle, which derived from the older GE variable-reluctance cartridges that had been game-changers for affordable magnetic phono pick-ups in the 1950s.

GE's patent, filed May 2, 1960, acknowledges Peter Ernest Pritchard as the inventor (see above). Since most tonearms of the time had too high a mass for the ADC-1, Pritchard designed and produced the ADC-40 arm to accommodate his cartridges, which allowed them to perform well at tracking forces of 1 gram or less. The ADC-40 had a tapered wooden shaft and anti-skating compensation, then both notable and unusual. Prior to the emergence of moving-coil pickups with their more limited compliance, the ADCs (along with Shure's V-15 line) were pace-setters in phono cartridges.

Pritchard's ADC also introduced a line of interesting loudspeakers based on then-exotic KEF drivers (including the legendary B-1814 rectangular flat-panel woofer) and. later, a very successful speaker line produced locally in New Milford. Pritchard sold ADC in the late 1970s and began producing the successful Sonus line of phono pickups based, again, on the principles on high compliance and induced magnetic design and exemplified by the popular Sonus Blue.

I was an ADC and Sonus fan for many years and thought I had achieved audio Nirvana when I set up the XLM in the ADC-40 on my Empire 208. I also coveted his KEF-based speakers and exchanged a bit of correspondence with Pritchard in the 1960s. I remember his responses as gracious and extremely practical. I am writing this from my house in New Milford and there are reminders of him and ADC to this day, as we often drive down Pickett District Road where ADC was based. We frequently come upon ADC products at the local flea markets and, just recently, I was able to purchase a number of NOS styli for my ADC-25 cartridge. Maybe it is time to re-install it in my SME-III arm for old times sake. Thanks, Peter.

Charles Hansen's picture

A very nice remembrance by Kal. I was too young to be aware of the Peter's earlier accomplishments, but the first of them I knew of was the ADC XLM. Harry Pearson gave it a rave review in a very early issue of The Absolute Sound. He used it as his reference for many years as did all my friends and I. It was very affordable and had a replaceable stylus (as did all cartridges in those days).

When Peter sold ADC and formed Sonus, he only had a few models but they also soon became the de facto reference for just about everybody. This success was not so long lived as the XLM. First came the MicroAcoustics electret capacitor model, and then the final nail in the coffin -- the invasion of Japanese moving coils. I was a bit surprised when the Italian loudspeaker company appropriated the name of Peter's old company, but it's all too easy to forget the distance of thousands of miles, another language, and a couple of decades.

Thanks for the memories, Kal. And thanks for the beautiful music, Mr. Peter Pritchard.

hifitommy's picture

i truly loved the XLM.  the hp mentioned adc25,  which had previously occupied the envied status of his blessing would be a cartridge i would love to have heard, perhaps the forerunner to the XLM design.


the XLMs recommended tracking force of 0.6gr is ludicrous.  it was the result of the 'tracking force wars' of those days in competition with shure.  certainly many records were ruined due to that war by inadequate VTF.

i too had a ma2002e and its linearity reminded me of the sonus carts my friend graduated to from XLMs.  i never owned a sonus but formed an intimate relationship with them in my friends room.  a room that housed IMF monitor IIIs improved, fried monitor IVs, and in those days-GAS thoebe/amzilla.  tonearms were sme and grace 707s. 


the adc 303 speakers were small but excellent.  i once heard, in a karman-ghia, a pair of them driven by a home integrated amp of about 30wpc and it was just glorious.  orchestral hall depth that belied the interior of the sports car the system was shoehorned into.


its a shame that peter was compelled to stop producing the sonus line but it was essentially a descendant of the XLM.  the name sonus wan not stolen by the italian speaker company, peter borrowed the word from the italian language as have many another designer has borrowed names from other languages and myths.

mrradio's picture

Since 1960´s ADC was most trusted phono cartridge for me. From 220 (that Red one!) to the XLM was very reliable. Just last christmas I got brand new (NOS!) Sonus Gold Blue and two Silver Label E models from Sweden. What a lovely items. Thanks Peter for the top phono cartridges !