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Audia Flight FL Pre MK3 preamplifier

 

Audia from Italy

Italia

 

 

Haute Fidelite

Mar, 2008

France

"The Audia Flight Pre is a very nice machine that deserves its place in the best reproduction chains proposing a manufacturing quality and performances of very first order. Transparent and musical, its circuits in A Class deliver a very extended bandwidth at both extremes of the audio spectrum, a quality of timbres of a rare elegance with a large and stable soundstage.


Magnificently realized, the Flight Pre is easy to use with its very nice and complete remote control, offers several both balanced and unbalanced input and outputs.


A good and beautiful machine that confirms our thought about this Italian brand, to which we accord without restriction our Best Buy recognition. Rate 19/20"

 

- Antoine Gresland, Haute Fidelite

 

Audia FL Pre MK3

Audia FL Pre MK3 Preamplifier

 

 

FL Pre MK3 stereo preamplifier

 

The new reference quality Audia Flight PRE MK3 is designed for complete neutrality, allowing all the nuances and ambience in the music to shine through.

 

Audia Flight PRE MK3 preamplifier is the perfect interface between source component and the power amplifier. Incorporating the excellent Audia Flight circuit design, highest quality volume control, and cabinet interior layout with isolation between key stages, the Audia Flight PRE MK3 exhibits complete transparency and lowest possible noise.

 

The high current, Class A output stage, separate power supply for each channel and one for the logic control, the high quality input selector and constant impedance volume control, provides an extended frequency response, tonal accuracy and wide soundstage.

 

If so much are the factors that make difficult the design of an amplifier, even more are those affecting the design of a preamplifier.

 

In a HI–END chain, the preamplifier should be transparent as much as possible, to be able to interface every power amplifier, to be as quiet as possible, and so forth…

 

Audia Flight PRE MK3 combines the merits of AUDIA FLIGHT circuit design based on the local feedback and the trans-conductance amplification, the use of a constant impedance attenuator with 0.5 dB steps and a chassis designed to get an a total separation among every stages, still keeping a single cabinet.

 

 

More Technical Details

 

Cabinet

The cabinet plays a fundamental role in the realization of a preamplifier since its structure (and the corresponding placement of the boards) helps to fix the degree on immunity against external noises and of interaction among different internal stages.

 

In a preamplifier, the shielding of audio boards with respect to transformers is also very important, since the stray flux could be “detected” and amplified by sensitive stages.

 

Audia Flight PRE MK3 is a single cabinet unit (the hypothesis of designing a “two chassis” unit has been left out for two main reasons: the problems connected with installation and encumbrance and the question of the alimentation cable that could have reached “worrying” length), however the internal volume is strategically divided to suppress interference, with the horizontal partition placed at half height.

 

In the lower section are placed the three toroidal transformers into a secondary shield metal box and the main supply board, whereas the main audio board is placed in the upper section.

 

A massive sheet of damping material is stuck under the upper cover plate.

 

Since the Audia Flight PRE MK3 is microprocessor controlled, the control board is placed behind the front panel and it is closed in its proper volume in a metallic shell.

 

The cabinet is completely made of aluminium and has been made exclusively by means of Numerical Control (NC) units and laser machines; the front panel is realized starting from an aluminium ingot 25 mm – thick and worked out by means of NC micro millers.

 

 

Supply stage

The main supply stage of the Audia Flight PRE MK3 is placed in the lower part of the cabinet. Here, in fact, there are two toroidal 50VA transformers (one for each channel) and a third 15 VA one to feed the control logic.

 

All transformer are explicitly made for audio applications, that is designed to have the least stray flux but, at the same time, with a great driving ability. The 10.000 Gauss core plate is autoclave resin sealed and dried in oven. The coils are realized with automatic machine-tools assuring the appropriate wire tension.

 

The three toroidal transformers are close into a secondary shield metal box.

 

The high-current supply stages for the audio sections are realized exploiting, in each channel, four “Ultra Fast Recovery” diodes with bypass capacitance to eliminate possible commutation noises of the diodes.

 

There are eight filtering capacitors by 3.300µF 63 V (52.800µF total) with high discharge velocity (low internal impedance) and discrete stages stabilizer , for a stabilized output tension of 50 + 50 V.

 

The third supply stage, the one for the control logic, uses EMI filters and an integrated stabilizer.

 

Moreover, on the amplification board are inserted four more dual discrete stages stabilized supply units per channel, that provide the alimentation of the various section of the amplification board, drastically reducing interference among different stages in the preamplifier.

 

In practice, Audia Flight PRE MK3 is endowed with 18 stabilization circuits just for the audio stages supply, each designed as a discrete stage.

Input selector

 

The input selector allows to choose four unbalanced inputs and two balanced ones by means of sealed relays in inert atmosphere and with golden terminations.

 

Only the selected input is connected to ground.

 

 

Attenuation control (volume)

The Achilles’ heel of many preamplifiers is represented by the volume-control since this usually introduces a variable impedance element as a function of the attenuation value (that is of the position of the potentiometer).

 

The result is that the frequency response, the slew-rate and even the internal impedance couplings among different stages are not fixed but are function of the attenuation value (volume).

 

This is a problem which affects above all the potentiometers; using instead integrated attenuators (I.C. dedicated to volume control or the use of D/A converters) solves the problem of variable impedance, but not that of the frequency response and of the absolute velocity response.

 

For this reason, AUDIA FLIGHT developed a constant impedance attenuator, realized with discrete components (low-noise metallic film resistors), which provides a gain range as high as 127 dB, with constant steps of 0.5 dB.

 

The result obtained probably overcame the wall of standard performance, since Audia Flight PRE MK3 grants an extremely extended frequency response (3Hz / 1MHz –3 dB) and the high value of slew rate (> 250V/µs in all the gain range (-90 / +10 dB).

 

As the volume is micro controlled, all interconnections between the analog stage and digital stage are insulated using hi-speed fotocoupler

 

 

Gain stage

The gain stage of the preamplifier is realized using AUDIA FLIGHT technique, that is using a current-feedback circuitry, entirely A – class biased and realized with discrete components.

 

As sketched in the section about “alimentation” is fed by four stabilized independent stages per each channel: one for the input buffer, one for the input stages for the signal amplification, one for the current mirror and the last for the output stage.

 

The high-current low-noise output stage, made of audio-use transistors, A-class biased, is not closed in the feedback ring.

 

 

Control logic

The heart of this section is based on the use of an 8 bit micro-controller endowed with a 16 Kbyte ROM.


The control of peripherals is given to two PIO devices, to get the control of the 40 characters fluorescent alphanumeric display, of the infrared receiver, of the custom optical encoder, the buttons and the relays.

 

 

Remote Control

The remote control too, as the front panel, is realized starting from an aluminum ingot later milled.


The surface is firstly completely brushed, then anodized.

 

 

 

 

 

 

 

 

FL Pre MK3 Technical Data / Specifications

 

Input 2 balanced XLR / 4 unbalanced RCA


Gain range -90 dB / +10 dB
Gain resolution 0.5 dB


Frequency response (1W rms -3dB) 3 Hz ÷ 1 MHz
Slew-Rate (on 8 ohm) > 200 V/μS
THD < 0,05 %
S/N Ratio 95 dB


Input impedance 680pF Unbalanced 51 Kohm
Balanced 30 Kohm


Output impedance Unbalanced 12 ohm
Balanced 50 ohm


Main voltage AC (50-60Hz) 100, 110-115, 220-230,240 V
Power consumption 60 W


Dimensions and weight 420x113x380mm (wxhxd) - 12 Kg
Shipping dimensions and weight 570x270x540mm (wxhxd) - 15 Kg

 

Audia FL Pre MK3 - rear

Audia FL Pre MK3 Preamplifier - rear