Topology \ Build QualityT
econ chose Audiophile quality Rubycon
capacitors keeping the signal path clean and costs down. Additionally the Model "55" circuitry is based primarily on a PCB. Vacuum tube Purists (myself included) would eschew printed circuit boards, for point to point wiring wherever feasible as point to point generally produces a clean, accurate sound. This is because a PCB is essentially a semi-conductive medium and while it is ideal for countless applications including digital audio, when it comes to signal integrity shielded copper/silver wire offers many more benefits for Audio. Where Tecon did employ point to point wiring, the wire gauge is more robust then I've seen in similar products costing much more then the Model "55". Tecon designers struck a balance incorporating a PCB and heavy gauge point to point wiring where it was sonically and financially viable. The Model "55" exemplifies one of those rare sum its parts
Insofar as topology is concerned, what often looks superfluous in audiophile circuitry such as wire gauge/material, capacitor type or brand can have a marked affect on sound. If there is a singular vision among High End manufacturers then it is to build a sonically neutral product. One which does not add or subtract from the music, even where certain characteristics may "sound" more soothing. The ultimate goal is to hear music as it originally sounded in the recording environment. This not only requires neutrality it also demands our system be capable of reproducing every minutia of detail. In our desire to hear every nuance in the music at some point we reach an inevitable caveat. As your system reveal's more information this includes just about any weakness in other components. This may include your cables, speakers and/or the recording itself. These types of scenarios are what separates High End Audio from Audio and the Audiophile from layperson. I've provided many examples of Audio extremes in design, in cost and in materials, for our purposes I found example where point to point wiring is used in a "Purist" example of an integrated vacuum tube amp using EL84 tubes. Leben Hi Fi Stereo Company
offers a 2x 15W integrated in their Leben CS300 X
, reviewed by 6moons
, I've provided photos below taken from that review. For more detail check out this high resolution photo of the CS300X
. At a cost of $3295 the Leben is not expensive as far as High End, although its not a single ended triode amp, nor does the Leben CS300X incorporate a USB fed DAC. B
ack to out Model "55", Tecon chose a vacuum tube circuit board which accommodates just about all the main circuitry including input vacuum tube driver section and output devices (vacuum tubes/capacitors?). There is a transformer mounted on the main PCB as well as the 12 Rubycon capacitors. The daughter board at the front of the amplifier serves the Audiophile quality Alps attenuator. As I have indicated in previous articles I prefer stepped attenuators to less expensive potentiometers which use a thin film of carbon and metal scraper for volume adjustment. Potentiometers by virtues of their design alone tend to introduce unwanted noise into the signal. The advantage of stepped attenuators is that they use fixed resistors and contact switches resulting in more accurate control and because each step is isolated they go a long way in preserving signal quality. Not all potentiometers are inferior to stepped attenuators, Alps
makes some high quality potentiometers for Audio. The photo below captures the main PCB and volume potentiometer daughter-board. Thumbnails provide more detail.
In the main photo below we look to the rear of the amplifier, including two mains transformers as well as the input/output connectors. I removed one of the Tecon stickers from a transformer revealing it was intended specifically for the Right channel. Thumbnails below provide close-ups on the internal RCA inputs and left speaker outputs, Main AC circuit board, and USB and left channel speaker connectors. Whether the connector accomodates the input or output, point to board heavy copper wire is used throughout.
Throughout the process of photographing the internal circuits I was unable to locate the Burr Brown PCM2707 DAC daughter board. After tracing the USB input I discovered these circuits were placed up under the transformer cover at the rear of the amplifier. Most designs install a transformer cover to isolate the transformer for noise purposes, to protect the device from the elements (dust) and/or keep out of reach for safety reasons. Whatever lives under the Tecon Model "55" faux
transformer cover, shares that space with the digital to analog converter chip.
Onto listening tests ->