Sometimes, a certain combination of sight and sound is impossible to forget. Among the open-baffle speaker systems on exhibit at the New York Audio Show 2022, Treehaus Audiolab’s Phantom of Luxury field coil speakers and associated electronics made a big impression, and I needed to hear more. The brand is manufactured in Southport, Connecticut, but Rich Pinto’s new showroom is 15 miles north along route 95 in Milford, CT.
The focal point in the space are the speakers made from big slabs of salvaged walnut, box elder, elm, and other species of wood with random asymmetrical “live edges” that mirror the natural shape of a tree and break up unwanted sound waves that are reflected off the front baffle. Once Pinto sources interesting pieces of wood, he shapes, sands, and treats the baffles until they’re transformed into Mid-century modern works of art measuring approximately 30 by 50 inches. They are then ready for the equally thoughtful work on the back of the speakers. This is one of the rare cases when the drivers and speaker components are just as interesting to look at as the woodwork.
Each slab is outfitted with a Fostex T900A AlNiCo-magnet super tweeter, strapped on with a piece of leather, and a corresponding high frequency crossover and fine-tuning attenuator. The star of the driver show is the Atelier Rullit “Super Aero” 10-inch field coil driver with whizzer cone. It’s a full-range driver with a frequency response from 80 Hz to 16 kHz with a slow roll-off on either end. Pinto likes a full-range driver because it’s the simplest path from the amp to the music without a crossover in between. Completing the 130 lb. speaker is the Atelier Rullit 15-inch field coil driver, connected to a separate dedicated solid-state amplifier and a DSP (digital signal processor) that serves as an adjustable electronic crossover and also provides low-frequency room correction so there’s no booming or thumping. It’s essentially a subwoofer, but don’t expect the high-excursion drivers used in home theater. The Rullit woofer adds foundation to the very bottom end, which affects room pressure rather than the ear.
Rich Pinto and the Treehaus Audiolab system.
What exactly is a field coil? Field coil drivers use an electromagnet rather than the now-common permanent magnet to create the magnetic field that enables a speaker to operate. While rare these days, field coil drivers were the common design in the 1920s when permanent magnets were too large and expensive to mount onto speakers. Nevertheless, super-efficient field coils worked perfectly with the low-watt directly-heated triode tube amplifiers of the era. Unlike conventional modern magnet drivers, field coils require a separate power supply, so Treehaus includes a tube-rectified power supply unit which feeds pure DC current to the four large wire-wound electromagnets in the Atelier Rullit drivers. The power supply has the added benefit of offering adjustable voltages to fine-tune the sound.
I was not familiar with Atelier Rullit. If there’s a web site, they’re hiding it. Besides an out-of-date Facebook page with a few posts and photographs, there are limited consumer access points to the Nuremburg, Germany company, but DIY enthusiasts can occasionally find a set of full-range drivers online. This is the accompanying sales copy from a current eBay listing:
“I would suggest to compare a ferrite magnet to mere tap water, [and] an AlNiCo [magnet] to the kind of premium mountain water being offered in supermarkets, whereas [a] field coil represents the water you take directly from its origin somewhere in the woods – refreshing and rich in taste. Just close your eyes and try to imagine their undoubtedly different qualities.”
For people who understand Europeans’ appreciation of fine water, this is a subtle yet spot-on analogy. I would agree that there’s something special about these drivers ─ from the delicate textured cone papers with leather surrounds, and the glaze finishes on the field coil “cans” housing the electromagnets, to the tradition from which they hail.
Rear view showing the Phantom of Luxury’s drivers.
I have never seen or heard anything like these drivers in consumer audio because the Rullit workshop rebuilds, restores, and modifies vintage field coil drivers from the nascent days of Germany’s entertainment industry. Klangfilm was the country’s first name in filmmaking, broadcasting, public address systems, and theater equipment. Even having the benefit of my college German, the history is a bit hazy and convoluted, but in short, Klangfilm was founded in 1928 with the backing of Telefunken’s parent companies AEG and Siemens, the European equivalents of General Electric and Western Electric in North America. Siemens eventually absorbed Klangfilm, and by the time home stereo and color television became accessible in the 1960s, monstrous horns, low-watt directly-heated triode tube amps, and field coil dinosaur speakers were relegated to the niche realm of audio hobbyist craft builders. Atelier Rullit incorporates pieces and parts of many of the greatest German drivers from the golden age of 1930s and 1940s.
Although Treehaus Audiolab speakers can be powered by other amplifiers, there is a particular synergy between the Atelier Rullit drivers and the Treehaus Audiolab amplification system built by master craftsman Radu Tarta, based on the designs of Susumu Sakuma (1942 – 2018) of Japan.
Unless you’re a DIY tube amp builder or a student of the Japanese magazine MJ Audio Technology, the name Susumu Sakuma might not be familiar. He was not a commercial amp builder but a chef by profession and a tube junkie, who built his unique mono single-ended triode amps, usually in his restaurant Concord, where he purportedly made a single dish, the hamburger steak. Otherwise, Sakuma dedicated his life to submitting articles in MJ magazine, writing poetry and books on amplifier design, conducting demonstrations of his creations, and plumbing the depths of old-fashioned amplifiers. According to Pinto, “[Sakuma’s] transformer coupling between DHTs (directly-heated triodes) is similar to very early Western Electric designs, where they used transformers rather than capacitors between the amplification stages.”
These are the origin stories behind Treehaus Audiolab’s striking designs, built on a foundation of Japanese Finemet audio transformers, Coleman filament regulators, and Cardas connectors. With Pinto building the heavy wooden chassis and Tarta assembling the electronics, their components and materials achieve a level of visual appeal that will seduce any audiophile. Beside its practical function, the amplifier is absolute eye candy. As for the design, Rich Pinto puts it most succinctly: “The 6.5-watt amplifier employs directly-heated triode (DHT) driver tubes, [using] VT-25As, interstage-coupled via transformer to a pair of 300B Western Electric tubes (also DHTs). The stereo amplifier is powered by a separate tube-rectified separate power supply to keep the transfer of both mechanical and electronic noise to a minimum.”
The preamplifier is the epitome of minimalist utilitarian design, with a power switch, on/off light, and two heavy knobs for volume and source selection. But, behind the faceplate, Pinto notes:
“The Treehaus preamplifier also features a separate tube-rectified power supply. It accommodates three sources and is equipped with a transformer volume control (TVC) for most efficient attenuation. Utilizing a 4P1L vacuum tube for gain and a pair of Finemet output transformers, the design follows a similar ethos to the 300b amplifier.”
The system is tied together with Iconoclast by Belden cables: OCC 1×4 RCA interconnects, BAV 19106 12 AWG power cables, and SPTPC (Silver-Plated Electrolytic Tough Pitch Copper) speaker wires. Rich has also used Blue Jeans Cable, my go-to wiring for many years. Aesthetically, the entire system is tied together by warm wood hues, corroded industrial aluminum, and pops of textured copper and brass materials to achieve a combination of antique, Mid-century and modern styling that would be at home in a sprawling loft, an organic Frank Lloyd Wright house, an ultra-modern build in the Hollywood Hills, or even a 14 by 14-foot room with 8-foot ceilings like Pinto’s demonstration room where I auditioned the system.
Another view of the drivers. The midrange cone is a work of art unto itself.
We began with Rush’s “The Spirit of Radio” on vinyl, proceeded to Applewood Road, an all-female trio recorded direct to tape, and moved to cuts by Bjork, and the English alt band Black Country, New Road. Because the drivers are free of cabinets, every cut sounded alive and present as sound seemed to emanate from a stage rather than a pair of speakers. Nothing about the system is sappy, tubby, or overly warm – rather it is revelatory of the recorded material. Although the volume the speakers can produce is substantial, these are not heavy metal or floor-rattling hip-hop speakers, but it would be fun to try.
There are some systems that perform their functions as audio wallflowers, but this is not one of them. I’ve seen lots of silver and black electronics which are fine sitting hidden away in racks or corners, but Pinto and Radu’s bespoke creations are worthy of longer speaker wire just so I could have the electronics right next to me in full view.
Treehaus Audiolab also offers their National Treasure speaker with a Rullit “Aero” field coil driver, Rullit ferrite-magnet 15-inch woofer, and Fostex T90A AlNiCo Super Tweeter for $18,000, but that day I listened to the Phantom of Luxury speakers made with walnut slabs sourced from Western Pennsylvania and cost $29,000 per pair. The amplifier is priced similarly to other 300B-based amps at $17,500, and the preamp is $16,000. The total system cost is $62,500 before adding sources and wires.
You can buy an audio system for a few thousand dollars (or even less), but why drink water from the municipal reservoir when you can tap into magical mountain springs of Germany and Japan? Treehaus Audiolab does more than build a stereo system, it reaches back to the earliest days of craftsmanship, design, and sound while incorporating a contemporary sensibility.
I encourage everyone to experience the system for themselves. For those new to tube amplifiers and field coil speakers, don’t get too overwhelmed by unfamiliar terms and components. Just sit back and enjoy. Rich Pinto and Treehaus Audiolab will be exhibiting at AXPONA 2023 in April. If you’re near Milford, CT, you can schedule an appointment in their demonstration room. Be sure to bring your vinyl to play on Rich’s Micro Seiki BL-91 turntable!
Here’s a video of the Treehaus Audiolab system at the last New York Audio Show (video only, no audio):
All images and video courtesy of Tom Methans.
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