Wyred 4 Sound STP-SE User Manual
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WYRED 4 SOUND ST Preamp v2.2
4235 Traffic Way
Atascadero, CA 93422
PH: 805-466-9973
FAX: 805-462-8962
©2013 WYRED 4 SOUND
All rights reserved.
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There are so many particulars that make the STP superior to other preamps. The best possible preamp
would be one that didn’t exist! We have created the closest anyone has ever come to that while still offering a fully
functional preamp. For the cleanest sound, what goes in should come out, nothing less, nothing more. For this
we’ve made our preamp passive and active at the same time. To keep the signal path clean as possible, the line
stage is automatically switched in when needed, and left out when not. This offers the quietest operation for any
level up to unity gain. Noise in the passive mode is <6uV, and <18uV in the active mode which is still incredibly
good. And yes, this product is fully balanced input to output.
When we say passive, we mean as in no gain. We all know that all passive preamps have many issues
regarding input and output impedances. These issues are massive because of the lack of drive current the preamp
is able to produce. The result is a loose, floppy bottom end, and a constricted, dry top end. To solve this, we
inserted our Ultra-transparent discrete buffer stages to address this issue, which proved to give us remarkable
results.
Like any audio electronic product, everything starts with a power supply. This is the first stage that gives
the STP unbelievably clean power. With a 25A Schottky bridge rectifier connected through 164,560+uF of
capacitance in our proprietary TRR (Triple-Ripple-Reduction) power supply circuit, the STP preamp has more
capacitance than some amplifiers! By the time power reserves supply the audio chain with power, there is no hint
of noise left to buzz through your speakers. Of course we left 2 stages of filtering up to nothing but the best; the
Nichicon Bi-polar MUSE audio grade capacitors do a fantastic job!
Our proprietary fully balanced dual FET unity gain buffers supply the meat behind the curtains. While
being sonically transparent, our buffers keep the input and output impedance right where we want them and don’t
allow for deviations like so many other passive preamps. Hand selected, matched and adjusted, each pair ensures
minimal DC offset, and maximum linearity.
Every preamp has to have a volume control. This is also a HUGE part in why our unit differs. The easy
route (practically everyone else takes) consists of putting audio in and out of a volume control chip. While being
cost effective and easy to design, the audio is left at the mercy the chip. The best possible electrical connection
that can be made and released on command is made by a switch. The best sounding switch is one that has the
least resistance and can maintain at all frequencies, for this we chose to use relays. While much more expensive,
slower and noisier when switching, they are far more sonically superior to any switcher chip on the market today.
The second part of our volume control is the resistors. That’s right, relays and resistors are the only
components interacting with the audio signal. Like all our other products, we use Dale rn55d copper leaded
precision resistors. Supplying exceedingly accurate channel to channel level matching (+/- 0.05db) and isolation
(>106db), our discrete volume control is the most transparent and spaciously sounding attenuator we’ve heard. A
maximum attenuation of 128db will quiet the loudest of sources, and as little as 0.5db steps allow for the finest
control.