DNM Electronics

	Pre Amplifiers
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DNM 3D	3D Preamplifier Details The new DNM 3D Preamplifier (Primus model) NB : Click on almost any photo here to see a much larger version in a new window. The DNM 3D is an ultra-high fidelity pre-amplifier that can select and control up to seven signal sources, including CD high level sources and line level sources like radio and tape. True to DNM tradition the 3D can be fitted with high performance moving coil or moving magnet amplifiers for vinyl disc replay - the 3D RIAA amplifiers are the best yet from DNM. In addition the 3D is also a high quality headphone amplifier. The DNM 3D Six Preamplifier with two pairs of MC boards The form and materials used in the construction of any amplifier affect its sound as much as its circuit diagram. Amplifiers have many connecting tracks interweaving across the circuit boards and these interact magnetically with each other and with the electronic components. This signal-generated magnetic haze, generated by the signal, interacts with the amplifier in a complex way destroying sound fidelity and metal casework further modifies the magnetic fields to produce dynamic compression. Back view : the DNM 3D Six Preamplifier with two pairs of MC boards All aspects of the DNM 3D are targeted to improve sound quality. The design aim for DNM amplifiers has always been to achieve the best sound quality possible, so features that do not support this aim are not included in DNM products. At this time remote control is not possible, there are no micro-processors, no software, nothing that is not linked with optimising sound quality. Just fabulous sound! Underneath the DNM 3D Six Preamplifier - showing the new power supply distribution pcb, a four layer design.

Design highlights listed below are all new and unique to the DNM 3D - and they all contribute to improved sound quality.

1. Three dimensional design to control magnetic effects and exploit the use of printed circuit boards turning their use to advantage in the design.

Underneath the DNM 3D Primus/Twin Preamplifier
- showing the new power supply distribution pcb.

2. Anti-reflection circuits prevent high frequency signal reflections from damaging sound quality. This effect is known from DNM research on high frequency feedback. It is linked to the harshness of sound on digital sources because they stimulate high frequency reflections. Anti-reflection networks are integrated into the 3D's printed circuit design so all switched and open connections are terminated. The pre-amplifier, as a hub component, is the ideal place to do this because it accepts connections from all system sources.

Top view : the DNM 3D Six Preamplifier with two pairs of MC boards

3. A world first, a 'spaced pair' signal pathway inside an audio amplifier! This is designed into the 3D pre-amplifier so that at a fixed spacing (like the DNM cable) giving an ideal magnetic interaction. inside an audio amplifier! This is designed into the 3D pre-amplifier so that the signal runs through the pre-amplifier at a fixed spacing (as in the DNM cable) giving an ideal magnetic interaction. It is achieved by folding the circuit boards to create a three-dimensional construction that defines the electrical impedance. The result is better circuit performance, improved resolution and higher sound quality.

Top view of the new DNM 3D Preamplifier with one set of MC boards

4. The 3D motherboard connection pattern is set by a power supply distribution board. This defines the pre-amplifier's wiring and can be changed to adapt it for single or multiple power supplies, optimising the pre-amplifier for each type of power supply.

5. New three-dimensional plug-in circuits with precision high frequency feedback correction ensure the highest sound quality and neutrality.

Tonal rendition on the 3D is more accurate than any previous DNM amplifier - enthusiasts will find new delights in their music collection whether CD or vinyl.

DNM 3D Six Preamplifier - transparent case
(Owner's photo)

DNM 3D preamplifiers are optionally available with clear cases at the same price; this option displays the unique internal construction particularly well.

DNM 3D Six Power Supply - transparent case
(Owner's photo)

The DNM exclusive non-metal materials technology used throughout the DNM 3D ensures zero interaction between the signal and the casework - a design principle that is still unique to DNM. It ensures unrivalled dynamic performance.

DNM 3D volume controls and input attenuation

Other new and useful DNM 3D features

Switchable mono capability (left) - really useful to improve sound fidelity on early 'messed up' stereo recordings.
The 3D headphone output (right) is driven directly from the line output amplifiers giving much higher performance than any power amplifier. The design allows channel levels to be separately adjusted. As you would expect from DNM, its performance exceeds that of the best dedicated headphone amplifiers.
Three levels of 3D performance/price are available with Primus, Twin and Six power supplies


DNM Start	The 'Start' preamplifiers are sourced from the previous DNM Series 3 and Series 3A products. Both preamplifiers use the basic Primus power supply, with the 3A Start benefiting from slit foil capacitors. The main control units are also based on the Primus model from the earlier series. Each unit is subjected to a complete overhaul and fitted with new switchgear and volume control pots. All circuit board tolerances are checked and corrected where necessary. Each unit is then soak tested for 24 hours prior to listening tests.
DNM Primus 3c	The DNM Primus preampifier is based on the same chassis as the more expensive models. The materials technology advantages are therefore fully expressed in the Primus making it extraordinary value for money. The boards are fitted with more cost-effective components. Despite its lower price, the Primus is still 100% DNM. The Primus power supply features a smaller non-acrylic plastic case with a single pair of regulators being supplied by a pair of 1,100µF slit foil reservoir capacitors. Even with the basic power supply, the DNM 3C Primus package gives outstanding sonic results.
DNM 3C Twin	Our intermediate-priced preamplifier is the DNM 3C Twin. This unit uses more expensive components than the base model. The result is a much closer tolerance set-up procedure for the plug-in boards. The external power supply uses a full-size acrylic case to match the control unit visually. This houses a larger transformer featuring electrostatic shielding and a low noise core. A pair of 10,000µF slit foil reservoir capacitors feed a matched pair of regulators, giving a considerable performance improvement over the base model.
DNM 3C Six	The DNM 3C Six is simply the best we make. Features additional to those in the DNM 3C Twin include the extensive use of tight tolerance resistors and decoupling capacitors in the control unit. The full-size acrylic power supply case houses a carefully selected screened low noise transformer. A pair of DNM 10,000µF slit foil reservoir capacitors feeds three pairs of matched regulators which allow individual power supply drive to each amplification stage in the DNM 3C Six control unit, effectively giving 24 separate on-board power supply stages. The DNM 3C preamplifier uses advanced technology in truly imaginative and lateral ways to bring the listener closer than ever before to the live sound. Such attention to detail in our amplifier designs results in a preamplifier which is refreshingly different, one which can sound delicate and at the same time convey the weight and gravitas of the performance. The DNM 3C Six will continually surprise listeners with its expansive dynamics and expressive resolution.
	Amplifiers
DNM PA3	The 40 watt PA3 unregulated stereo power amplifier incorporates DNMs own slit foil capacitors. Mains power is supplied via a separate Primus-sized power supply box, which contains the mains transformer, fuses and switches, keeping sonically deleterious AC mains effects away from the sound-signal circuitry. This power amplifier uses an all-new three-dimensional circuit design which is considerably more advanced than that of the majority of power amplifiers these still cling to the traditional two-dimensional etched copper on a flat printed circuit board. 3-D DesignThe DNM three-dimensional design is identified by the symbol - this represents the "impossible" triangle which is an optical illusion used to show how vision is deceived by a trick of perspective. Three dimensional construction allows the amplifier to run power supply tracks vertically through the structure of the amplifier, obviating the need for an extensive wiring loom. It also allows for much more precise circuit layout and gives improved control of magnetic effects. The resulting shorter circuit tracks help to improve high frequency performance and thereby reduce the sonic signature of the design. Each level of the circuit board is designed to work in its optimal setting. For example, the central level of the amplifier houses all the sensitive reference circuits which are placed near the grounding to minimise interference. State-of-the-art surface mount devices are used to define all the time-critical settings. By contrast, the top layer houses the power distribution board which feeds all the amplifier circuits. This board places the metal-bodied decoupling capacitors well away from magnetic fields in other circuits. The PA3 amplifier is a high performance, high resolution design with the typical strengths of all DNM amplifiers, but its comparatively high power rating allows its use with a wide variety of good quality loudspeaker systems in domestic settings.
DNM PA3 S	Considered by many in the audio industry to be the finest solid- state power amplifier ever made, the regulated PA3 S stereo power amplifier is the first design in the world to use the revolutionary new T-Network capacitor designed by DNM's Denis Morecroft. The PA3 S uses a form of AC regulation and a unique DC regulator system which feeds ultra-smooth, ripple free power to the amplifier circuits. It also utilises three-dimensional board layout to minimise magnetic interference in the circuits. A considerable amount of research and development time was spent in ensuring that the full potential was gained from the use of DC regulated power supplies. Application Notes The PA3 S, with its lower power rating of 23 watts per channel, is intended for use with more efficient loudspeakers (90dB/Watt with 4-8 Ohm load) in a domestic environment. In such a system, it can deliver unsurpassed levels of resolution, scale and power in the music. The PA3 S achieves a sense of power and scale through sheer resolution and timing accuracy. Quiet Quality Finally, an aspect of sonic performance rarely discussed but so critical to many customers, is that of high quality sound at low listening levels. Such levels require limited power but often sound 'flat' and unsatisfying to the ear. As the DNM PA3 S primarily relies on resolution to create the sense of scale and power, listening enjoyment is retained whatever your chosen replay level.
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