On my recent visit to the UK, I was spent a weekend with my sister and brother in law in Kingsland Herefordshire, just north of Leominster deep in the heart of the
Malvern Hills.
I had with me my goddaughter Madeline, who was due to start at Oxford University for the fall semester on the Monday. We had a wonderful weekend and explored the ruins of
Wigmore castle. This was the seat of tremendous power in medieval England. It was the castle of the Mortimers, one of the most powerful families that patrolled the
Marches along the English Welsh border.
We spent the afternoon in
Ludlow. We spent time at Ludlow castle and other attractions.
On the way over from Wigmore we were passed by a number of vintage motor cycles on a point to point rally. In the square at Ludlow we found them available for view in the lunch hour.
One bike was of particular interest to me. It was a Scott. My father and my uncle John were great Scott enthusiasts. These bikes from the 20 and thirties had a top speed of just over 90 mph. My uncle raced them for the Scott team in the
Isle of Man TT and raced them with success.
These bikes were twin 500 cc two strokes and water cooled. My father tells me their success was in the design of the crankshaft, main bearings and crankcase. These all had a small profile and generated a very large crankcase compression, such that the engines were effectively super charged.
On Monday on the way to Oxford I had arranged a visit with Billy Woodman founder and CEO of the
Audio Transducer Company (ATC), at their factory in a rural setting deep in the heart of the scenic Cotswolds between Stroud and Cirencester in Gloucestershire, UK.
So Madeline and I headed out south through the Malverns and into the
Cotswolds. Unfortunately you just never know when or where you will run into heavy traffic in the UK, and we encountered a long tail back coming off the M5 to the A419 at Stone house on our way to Stroud. Unfortunately this made for a shorter visit with Billy Woodman and Bob Polley, as I had to get Madeline to Lady Margaret Hall Oxford by early afternoon.
When I say Stroud, ACT was well wide of Stroud at in the country and when I was close I had to ask for directions three times. Fortunately I ran into a delivery driver who knew exactly where they were.
ATC is a small company and everything is made in England. They make all their drivers there. The magnets and chassis come from a foundry. There large cabinets are made on site, the smaller domestic cabinets contracted out to a local shop. All there electronics boards and fabrication are done on site, including their high powered amps and active crossovers.
This company is one of a dying breed and put in mind of many happy visits to Quad in Huntingdon when Peter Walker was the owner and still at the helm. Just like Quad in those days morale among all employees was high. This was not just their jobs, but their passion. There was also a heavy veneer of British eccentricity.
There was a flock of chickens out back if there design offices supplying the employees with eggs as a perk of employment. There was also a large vegetable patch to keep them supplied with vegetables in season. Out front was a twenties FIAT open sports vehicle under restoration.
ATC founded in 1974, by Billy Woodman is primarily a transducer company. They supply a wide range of passive and active monitors to studios around the globe, as well as a line of domestic speakers. Currently most of their business is the design, building and installation of large high powered custom speaker systems, primarily in the USA. I saw a center speaker under construction that will weigh over two tons. This is part of a large system under construction for an auditorium at Stanford University, California.
Billy Woodman started out in business to design the finest midrange driver. Since then ATC have produced the finest midrange, a high powered 3” mid range dome. They also make a four inch dome, but it is the 3” dome that has made their reputation. They also make a complete line of tweeters, bass, and mid bass units to exacting standards.
The ATC dome midrange units can handle the range from around 400 Hz to 3 kHz without crossover. They can handle the whole speech discrimination band without crossover in that range. As well as smooth frequency response, on and off axis, with low distortion, they handle high powers maintain low distortion and freedom from excessive thermal compression and burn out. The secret of their low extension for such a small driver is that it is a low Q driver and can be driven down below resonance.
The units are assembled with great care. The magnets a built at a foundry, but energized at ATC. The voice coil wire is flattened before winding. After winding, adhesives to exacting specifications are applied and the voice coil “cooked”. The fabric dome is bonded to the coil on a balsa ring.
The secret of the high power is that the voice coil is placed in the gap under very close tolerance such that the voice coil gap is only a few thousands of an inch. This requires extreme precision manufacture. The purpose of this close tolerance is to allow the voice coil to radiate heat to the pole pieces and magnet structure with the minimum of air insulation. No Ferrofluid is used. The coil is also placed deep within the gap, (underslung) to ensure the utmost linearity. All ATC drivers are assembled under the same plan, and accounts for the very high power handling capacity of all ATC drivers.
ATC also design and build active crossovers and power amplifiers for their systems. They seem to be solvent and thriving breaking all the rules of manufacturing in the global age.
I auditioned a pair of the
EL 150 SLP speakers in passive configuration.
They were superb, with a smooth deep sound stage. Dynamics of course were huge without strain. Billy Woodman and I are in agreement that large amp powers are required for realistic reproduction. He tells me that in most domestic systems the amps are in almost permanent recovery from overload trying to reproduce concert hall dynamics. His drivers just never sound strained or overloaded.
Billy Woodman does not like high Q resonances anywhere. These speakers are ported but intentionally over damped so bass was perhaps a shade on the light side. The bass was the only area where I thought my speakers bested those, otherwise allowing for a totally different environment it was about a wash.
After the demo I had a very interesting guided tour from Bob Polley. He showed me every detail of their driver assembly, and it is rigorous from start to finish. I asked Bob how many drivers they get returned or come in for repair considering the tight tolerances under which these drivers are made. He said it is a very rare event they have a driver ever come in for repair.
I though it unfair to take photographs of the manufacturing facilities. I would not want to divulge any trade secrets.
I would recommend members look thoroughly through the web site and especially
this page. I would particularly recommend that you download the Design and Development of High Powered Loudspeakers parts 1,2 and 3. Also have a good look at their client list and pictures of their
installations.
Unfortunately due to the recession the domestic business is becoming a small and smaller part of their sales. Billy Woodman is uncompromising and refuses to cheapen any drivers or designs. Everything from ATC has to be the best they can make it, not the best for the price.
We have had a thread: - “Who makes the best speakers.” ATC are a strong contender and when it comes to loudspeaker drivers, in my view it is no contest.
On my next trip to the UK I will try and arrange a visit to PMC. Unfortunately, although over there for a month I had quite a tight schedule.
U of M Student, Madeline at Oxford.
