Fuchs Audio Technology ODS-30 Operation Manual page 4

1
Introduction to Fuchs Audio Technology Amplifiers
What makes our products unique?
The recent proliferation of "Boutique" amplifiers, allow guitarists to recognized
what audiophiles have known for years, properly designed tube circuits can offer the
finest musicality, detail, and sensitivity to playing subtleties of any type amplifier.
Anyone who's enjoyed the sweet, responsive character of a well-built tube amplifier
realizes you can't model or computer simulate the "organic" qualities, no matter how
hard you try. It's like enjoying fresh food or food that's been frozen. Something gets
lost in the translation.
We feel our designs go a few steps beyond those of other manufacturers!
In addition to refining our circuit designs and operating points with computer
"Spice" modeling, we also spend countless hours tuning our circuits through careful
parts selection and refining the internal layout of our products. Details like single-
point star grounding of all internal circuits, premium audiophile grade power and
output transformers, high speed switching diode power supplies, regulated and
buffered DC power supplies for both filaments and high voltage sources, are key
elements to producing an amp that has truly unique sonic advantages. All completed
amps are compared to reference samples on both test equipment by live players
before they may be shipped.
Our attention to the power supply and grounding result in an amp with extremely
high gain capability, but with a super low noise floor. This reduction in noise and
increases in overall circuit clarity makes the selection of components an even more
critical element to achieving good tone. While we use many time honored component
brands and features like "Orange Drop" Capacitors and/or carbon/metal film
resistors, we also use Audiophile grade "Wonder Caps" and unique circuit
refinements in many parts of our amplifiers as well.
It's a well-known fact that chassis materials can change the tone of the circuits
built into them. We use an aircraft grade T-6 aluminum chassis, which is 1/6" thick,
bent at it's edges for strength, and when the front and rear panels are attached,
forms a strong yet lightweight chassis. Aluminum also provides an excellent heat
sink for excess tube, transformer, or regulator heat. Although we install fans in all
models, our amps would dissipate plenty of heat even without a fan. The front and
rear panels are attached to the chassis pan with pem-nuts, a 1/8 thick assembly
formed at both the front and rear of the chassis for rigidity.
A combination of modern and traditional wiring methods
Internal construction in all models is based around a central circuit board, which
supports most of the power supply and the amplifiers FX loop, driver and bias
circuitry. The balance of the amp is hand wired, with particular attention paid to the
preamp section and low-level circuits. All tube sockets are chassis mounted for
strength and ease of replacement, in the unlikely event a socket fails. This also
keeps tube heat away from the other internal components in the amps.
Our amplifier power supply starts with a high voltage supply, which is rectified
using high-speed switching diodes, combining the sonic attributes of a tube rectifier,
with the efficiency of solid-state diodes. These produce greater voltages, a more rigid
supply that doesn't 'bend' under the stress of loud playing, and they also produce
zero heat. This DC supply is highly filtered, using over 200 ufd of power supply
filtering, contributing to an amplifier that has a strong voice yet remains loud & clear
up to it's limits.
Our output stage(s) feature separate bias for each power tube. Although we use
premium "matched set" tubes as standard equipment, by individually setting bias,
we can obtain maximum power before clipping, extending tube life with better tone.
Our power amp driver circuit uses an AC balance trim control, which adjusts the
signal balance to the power stage, keeping it linear, producing a clean, strong tone.
When driven to clipping, overloading is ultra- smooth, compressing in a sweet way,
not at all aggressive or harsh.
ODSm 3/2005