Why are REDGUM Amplifiers & Audio Equipment so good?
A lot has been written about which sounds better – Vinyl recordings or Compact Disc recordings. The tracking distortion and inherent noise of vinyl players is a permanent and, they think, unacceptable feature. Still, they happen to agree that an excellent vinyl system has an impact that a lot of C.D. systems seem to lack. During the last 30 years they have repaired and serviced over 17,000 HiFi systems and have observed countless exotic (and more mundane) amplifiers working hard (and easy) into complex and simple loads. During this time, the complex interaction and wave-forms saw permanently changed their thinking on what is or is not a good amplifier.
In the last few years, REDGUM has spent much time studying how vinyl players’ bass impact – mainly through exotic valve amplifiers – is a function of the RIAA equalisation curve and the inherent limitations of the output stages of the amplifier. The frequencies they were interested in were all below 50Hz – with particular emphasis on those below 20Hz!
Anyone who has been to a live orchestral performance knows that there is an impact that is felt rather than heard, and just winding up the volume on your HiFi does not create that effect. They finally decided to practice all this information accumulated over the years, with particular emphasis on detail and clarity but not compromising impact in the bass. This was the impetus that led to the REDGUM amplifier.
REDGUM’s overall feeling was to process the sound as little as possible and, to this end, they did some hard thinking about digital recordings. There are some exciting criteria not previously used (to their knowledge). The loudest possible passage recorded on any C.D. is when all 14 bits are “on”, resulting in the maximum registered number 15384. No compact disc can produce a higher recorded level. Thus, the Compact Disc output is predictable. This information was used to consider how much gain/amplification was required to drive any amplifier to its maximum output.
So the next question was whether REDGUM should use valves or transistors. Both have limitations. Valves are inherently noisy and deteriorate from the first moment of use; transistors are quieter but cannot tolerate abusive overloads and are prone to self destruct! They thought that ideal would be a solid-state valve – a MOSFET (Metal-Oxide doped Silicon Field Effect Transistor).
REDGUM worked extensively on High Power MOSFET amplifiers as sole “Official Warranty Service” for several brands of these amplifiers during the 1970s and 1980s, and REDGUM decided to re-evaluate these devices as they have also improved over the years.
Like many designers before them, they eventually settled on the basic circuit from the manufacturer’s handbook on MOSFET amplifier design, but incorporating much faster and ‘stronger’ MOSFETS than the original specification. The circuit incorporates many local and overseas “Go-Fast Modifications”, that are often offered as after-sale upgrades by specialist HiFi shops.
REDGUM quality criteria
The final criteria decided upon to create a REDGUM amplifier were:
- The highest possible peak current and rise time – at the output terminals
- Minimum’ processing’ of music to reach realistic sound pressure levels
- Shortest circuit paths practical
- Long-life without quality deterioration
- No annoying ‘blown fuse’ syndrome – it must always work
- Realistic pricing
REDGUM construction techniques
- Dramatic changes in output impedances were achieved using the latest MOSFETs, ultra-low resistance wiring in speaker line and power supply lines, silver soldering (pre-RoHS), and peak current enhancements as close as possible to the final output devices.
- A high-gain power amplifier without preampfification was used – just sufficient gain to drive the amplifier into clipping on the loudest transients recordable on CD if the volume control is fully advanced.
- A compact input control board with all controls as close as possible was used with extensions to traditional operating positions.
- All connection points are gold-plated to resist tarnishing forever; all resistors are 1% tolerance metal film, all on-board capacitors rated at 105 degrees Centigrade and the entire amplifier is soldered with Silver Solder (pre-RoHS). Manual volume controls are made of conductive plastic, not carbon deposit, and have a suggested life of 25,000 operations; input switching is by a silver-plated switch with a typical life 10,000 operations. This is a useable lifetime, probably over 20 years!
- REDGUM amplifiers are inherently stable into capacitive and inductive loads, and no current limiting is employed. Suppose the amplifier is driven into a short-circuit or unusually low impedances. In that case, a thermal output will shut down the power supply, which will then be restored once the amplifier’s internal temperature has fallen to an acceptable level.
- Not using insane bunches of components where one unit will do, and using underrated transformers as a method of ultimate current limiting produces a REDGUM.
What has always made a REDGUM different?
- The stereo-imaging and detail are stunning, the follow-through hiss of a cymbal crash is incredibly realistic as is the bass impact of a bass drum in a brass band.
- Playing dance music really makes you feel like dancing!
- The detail and separation of a full orchestra allow you access to the separate instruments, even hear the pages of music turned during performances!
- Choral work becomes understandable again!
- Brass has that crisp bite – without being splashy.
- Organ works – feel the foot pedals go all the way down!
- The lack of noise in this amplifier gives the impression of a dramatically increased dynamic range.
- The tight control of the REDGUM amplifier will make your collection come alive.
- So experience the incomparable with a REDGUM amplifier.
- All REDGUM amplifiers have ultra-high current output stages
- All REDGUM amplifiers use gold input and output connections
- All REDGUM amplifiers use purpose-designed aluminium heat sinks for more significant cooling
- All REDGUM Amplifolia amplifiers use solid one-piece Red Gum wood front panels
- All REDGUM Amplifolia amplifiers are Australian designed & constructed
- All REDGUM Amplifolia amplifiers are hand-built, and burn-in tested
- All REDGUM amplifiers have a 7-year warranty