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Over the years I’ve heard a number of Cymer designs in a variety of systems including my own driving all manner of speaker designs at varied price points from budget to exotic. This included electrostatics and ribbons. The constant factors always included superb sound quality and an eerie transistor-like quietness even when mated to very efficient speakers. A few months ago Elson lent me a prototype of a new circuit he’d been working on. This was to eventually become the subject of this review. So impressed was I with this basic prototype that despite its overall lesser parts compared to the final version I ordered a personal set after the loan period.

The SE-35 is unusual in a number of ways. It’s obviously a valve circuit but it may just about be unique. Elson will explain this far better than I but the gist of it has a 12AT7, 12AY7 or 12AU7 drive a 45 which in turn drives a choke (no interstage transformer to avoid reducing dynamic range) and then the large and rather pretty 13E1.*

* Kang Su Park and Gino Colombo of Allnic Audio Labs and Colotube Amplifiers respectively likewise believe in the superiority of choke-loaded DHT drivers – Ed.

By way of background Elson’s early audio education started whilst working in two of the biggest recording studios in Rio de Janeiro. In his first position at Musidisc, Elson was responsible for setup, wiring, maintenance and service of 8-channel Ampex tape recorders, main console/mixers and all other preamps, compressors, equalizers, microphones and channel switchers.

He was also involved in mixing down to copy from master tapes. Later at CBS Studios Elson was contracted to revamp the existing 8-channel tape recorders and convert them to 16 channels. This was a huge undertaking. "We used about 10 kilometers of balanced shielded wire to finish the job. The result was great and everything performed perfectly with no hum or noise."

A move to New York in the late 1960s saw Elson further his career and experience by working in more studios and record pressing facilities. Later and before once again pulling up roots and migrating to Australia, he carried out service work for New York’s largest electronics retailer. Elson has been building valve amps for a very long time. He even tried his hand at solid-state designs based on his own interpretation and modification of renowned Pass Labs circuits. Although finding such efforts quite satisfactory, in the end they did not meet his ultimate goal which he believes only valve-based amplifiers can reach.

As he explains it, "to me solid-state amplifiers lack natural sound. There’s insufficient ambience, lesser harmonic content, less air and depth. The sound can lack richness and body. Solid-state sound is like a PA trying to mime the true sound of an instrument. Now lets get to the real picture. Valve sound has a lot of harmonics, ambience, depth, natural bass, dynamic contrast, extended silky highs and complex midrange harmonics. To really say it all, just ask any musician if they would use a transistor amp for their amplification rig."

Having established that valve designs were the way forward for Cymer, what convinced Elson that among those single-ended triode was the superior alternative? "Single-ended triode amplifiers are less prone to instability and since single-ended can only be class A, the voltage at the anode does not change, therefore the signal/sound never sags and crossover distortion does not exist".

The other special element of today’s monoblocks are its transformers. These are massively over-engineered hand-wound units custom-made for Elson to his strict design specifications. These things are enormous in size and weight and use the best ingredients and geometry. "First you have to make the output transformer large enough to cater to the high current demanded by the valve so there is no core saturation. The air gap must be very critically set or else the bass will be loose and distortion high. In my transformer designs I use the best iron cores imported from Israel and Japan and the best insulating material available. The output transformer of any valve amp is the heart of the matter.

"So we start with high-grade ingredients like Finemet transformer cores from Hitachi Metals in Japan. Those have the best permeability of all audio output transformers for a valve amplifier. The OPT must be big enough to handle the high current required by class A bias, avoid saturation in the low frequencies and remain low distortion. The insulating materials in the coil windings must be of the best quality possible like Mylar, polyester and Nomex for high voltages between layers. Now the big crunch. The air gap required for a single-ended output transformer is most critical because it needs to be adjusted to give both very good LF response and low end distortion. To achieve this you have to adjust the air gap in circuit to observe the low waveform on the oscilloscope and truly minimize losses at proper power output. To achieve very good HF response means interleaving primary and secondary such that winding coupling is maintained to minimize ringing and overall instability. The magnetic wires used in our transformers are oxygen-free copper from NEC in Japan. They have excellent insulation and are very malleable so the transformer winding is very neat and compact when terminated.

"My design philosophy is to build amplifiers that have very extended response at either end. As explained, when I design an amp I start with a very high-quality output transformer of my own design and then improve its performance with the very best components/materials. A simple design is the key to better performance. The less complicated the circuit, the better the sound will be."