TECHNICAL SPECIFICATIONS

The Circuit Description:

The Linestage I is an active linestage using vacuum tubes as the gain device. Vacuum tubes are also used in the regulation of the power supply. A class A triode circuit is employed in a most straightforward design, with emphasis on keeping the design as simple as possible. This is in accordance to our design philosophy plus the added benefit of very high reliability (the simpler the design equates to fewer parts, equates to less parts to fail). The purity of the signal is kept as intact as possible as it travels through the preamplifier. As the signal enters, it goes to the selector switch, into the gainstage (the vacuum tube), into the attenuator, and out. Quick and short, minimizing the possibility of signal degradation by eliminating one or more stages in the signal path. This is the most straight forward design possible for this purpose.

Frequency Response:		5 Hertz to 250K Hertz, +0, -3db
Input Impedance:		150 Kilo Ohms
Output Impedance:		1200 Ohms
Absolute Phase:		Inverting
Total Harmonic Distortion:		less than 0.4% at 2V
Noise:		Better than 91 db below 2V
Maximum gain:		Greater than 15 db at 1 kilohertz
Tube Complement:		2 6DJ8 or comparable, 2 OA2
Maximum input:		6 Volts RMS.
Inputs:		Six line-level inputs
Outputs:		Two main outputs, one tape output
Dimensions:		Main chassis: 18" W x 14" D x 5.5" H
Power Supply:		8" W x 13" D x 5.5" H
Shipping Weight:		Paramount Statement: 159 lbs. Paramount: 81 lbs. Presence Deluxe 4.0: 78 lbs. Presence Deluxe: 57 lbs.

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The Components and Parts:
The External Power Supply:

The Linestage I is included with an external power supply. It is connected via a dedicated umbilical cord. The power supply is removed from the main chassis to improve on the performance aspect of the unit. A power transformer emits different kinds of spurious radiation that could impede in the uninterrupted flow of the music signal and thus have a degradation in the performance. Removing the power transformer away from the main chassis prevents this from occurring. Though implementing an external power supply is much more expensive, it nevertheless ensures the purity of the signal from spurious radiation from the power supply.

The ON/OFF Switch:

The on/off switch of the Linestage I is actually an electromagnetic circuit breaker. It functions as a regular on/off switch and also as a replacement of your regular A.C. fuse. The electromagnetic circuit breaker provides for a solid contact for the A.C. to go through in comparison to the little thin wire normally found in A.C. fuses. Furthermore, all the connections in the electromagnetic circuit breaker are direct soldered rather than having quick disconnects, ensuring full contact in the electrical junction.

Current Rating of the Bridge Rectifiers:

The current requirements of the Linestage I is relatively small at less than 1 amp. The current rating of the bridge rectifier is at 4 amps. With the optional power supply upgrade, this current rating goes up to 12 amps! Such overkill is not by accident but by design. Aside from having great safety margins in using overly large current ratings, this again ensures the unimpeded flow of electrons to their destination, resulting in a power supply that is quick, instantaneous and responsive to the needs of the music. The bridge rectifiers are made from discrete parts using high quality fast recovery diodes. This translates into a focused, effortless and natural performance with clear and defined presentation at the musical extremes.

Computers Grade Electrolytic Capacitors:

These large 2.0" x 4.125" capacitors provide for vast amounts of power reserves for the Linestage I. Totaling to greater than 180,000 mfd in capacitance, these capacitors ensure that an enormous amount of power is always ready to provide when called for. Having overly large supply of capacitance provides stability and filtering in the power supply, coupled this with the high ampere ratings of the bridge rectifiers provides for power reserves that would seem unfathomable. Computer Grade Electrolytics are choice capacitors for this particular application where large power capacitance, low ESR and high ripple current are needed. Two of these capacitors are found in the external power supply and eight are on the main chassis. The massiveness of the power supply as a whole is perceived with the lowering of the noise floor, creating a space for the music to unfold that is as black as space itself; no grain, milkiness or electronic haze. Rather, just the music itself with all its intricacies and purity possible.

The transients extends to the highest high and the lowest low with blazing speed and recovery. Bells and cymbals are recreated with such realism that you can almost see the thickness of the instrument and smell the brass. Bass plunges to the very bottom depths with such speed, authority and weight while retaining the very subtle nuances, giving such texture and delineation to the bass notes you never have thought you would be able to experience.

The Dedicated Umbilical Cord:

Measuring at almost 3/5 ths of an inch, the dedicated umbilical cord uses four pairs of twisted wire with each air having a full 100% shield and a drain wire plus an overall shield and a drain wire. Using high quality copper ensures signal purity as well as proper physical characteristics for the intended application. The 100% shield prevents signal loss and provides coverage for optimum protection against radiated emissions and ingress at audio and radio frequencies. The shielding ensures that the power from the external power supply would remain as pure and undiluted as possible from the spurious radiation in the environment. The individual shielding for each twisted pair of wire further ensures that each pair would not contaminate each other.

The Main Chassis:

The main chassis is made out of .06 inch thick cold rolled steel. It is then plated with copper all over as per MIL-C-14550B Class 2 specification. The combination of steel and copper provides for the best protection against spurious radiation in the environment. In such a protected environment, the audio circuitry can perform to its maximum potential and not be subject to any degeneration from the external spurious radiation. Furthermore, copper plating lowers the resonant frequency of the steel chassis to a level that does not detract from the harmonics of the musical signal.

Dual Mono Construction:

The Linestage I incorporates a true dual mono construction on the main chassis. This means that all controls and components are repeated for both the Left and the Right channels. This approach greatly enhances the channel separation. Separating the components for the left and right channels decreases the possibility of the crosstalk between channels. Crosstalk can lead to poor focus and stability of the presentation. It can further degrade the soundstage presentation, making the soundstage both narrower and shallower. It can also lead to smear and grain and inability to have clear delineation of the different instruments and their location in the performance. Having great channel separation is one of the key aspects to great sonic performances. The minimizing of the crosstalk is essential. Though relatively rare in the High End industry, true dual mono construction is effectively the best way to minimize crosstalk.

Separate Mounting Platforms:

In adherence to the true dual mono construction philosophy, the Linestage I employs separate Left and Right Mounting Platforms. These are made from the same material as the chassis and is also plated with copper. These platforms are shaped in an L figure with one of the planes held vertically to provide for further shielding from the other channel. It houses the separate circuit boards in its underside (for further shielding) and attenuators and selector switches, along with the other computer grade electrolytic capacitors.

Short Signal Path:

As one would look inside the Linestage I, four long stainless steel rods would be apparent. These rods extend the controls for the volume and selector switches which are located at the very back of the unit. Keeping the switches at the back helps maintain very short signal path in the unit. The shorter the signal path, the less possibility of sonic degradation from various sources, including the wire itself. Even on the circuit boards, the copper traces are kept to a very minimum length.

The Use of Damping Materials:

The use of damping materials is employed on the main chassis, its cover, the external power supply and its cover. Circular damping materials along with other vibrations absorption devices help tune the units’ overall performance. Vibrations can play a significant role in a chassis sonic signature. The Linestage I is no exception. Extensive listening test were conducted to determine where and how much damping material would be needed to produce the overall balance in the chassis.

High Grade RCA Connectors:

These gold plated solid body RCA connectors provide performance levels that are truly in the very High End. The solid body construction ensures that there is no gap or breach in the flow of electrons. The gold plating provides for superior contact and resistance to oxidation. These High Quality Gold RCA’s are chosen primarily for their sonic performance, edging out even more expensive counterparts.

The Use of High End Wire:

The Linestage I uses custom wire from High End Wire Manufacturers. The Linestage I employs various sized gauges in the signal path. These wires provide for exceptional performance over regular O.E.M. wire manufacturers. Specific gauge wire from specific wire manufacturer is used in specific areas of the signal path. In particular parts of the circuit, up to 12 gauge size are used! Their high level of performance compensates for their relatively expensive costs.

Extensive Grounding Network:

The grounding topology used in the Linestage I is directly derived from the First Sound Passive Unit. This particular grounding technique is unique to the whole electronics industry and can only be found in the First Sound passive and Linestage I products. Such extensive topology provides for quieter backdrop for which the music can unfold in its entirety. It further establishes the quick and controlled bass response and the full bodied expression of the high frequency. Within the grounding topology, ground wires reach up to a maximum size of 9 gauge! The ground leg of the signal has not been neglected and given meticulous attention in its implementation. The importance of proper grounding cannot be over emphasized. There is a delicate balance in the relationship between the positive and negative legs of the signal. With the experience gained from the extensive wiring topology of the First Sound Passive, the Linestage I has stretched the limits of grounding networks for linestage applications beyond state of art.

Attenuator:

The Linestage I uses an array of discrete resistors on a switch to set the volume level. This is called an attenuator. These hand made attenuators are superior to any volume potentiometer (commonly known as a "pot") with regards to the manner of providing attenuation. The resistance in a pot is done through having a film of carbon spread over a plastic film. The thickness of the carbon would vary from one end to the other thus providing the means of attenuation. An attenuator on the other hand has discrete resistors with specific values to set the attenuation level. The performance of a specific resistor is infinitely better than having carbon on a plastic film. The switch used in the attenuator of the Linestage I is the same switch used to select the inputs. This switch is a very massive, having a current carrying capacity of 25 amps! The very high rating ensures the uninterrupted, low loss delivery of the signal in the full frequency spectrum. Only premium quality Holco metal film resistors, along with Vishay thin foil resistors are used. Though these are among the most expensive resistors available, they are used primarily because of their sonic excellence. In the construction of the attenuator, each resistor is looped once through the solder lug then crimped. After which it is then soldered. The extra step of looping the resistor leads through the solder lug ensures mechanical reliability and optimum contact between the surfaces. The tedious process of hand assembling each attenuator is rewarded by the clear and focused delivery of the performance. The lack of grain, searing, rounding of the edges and loss of the inherent subtlety of the musical instruments are some of the obvious aspects achieved when using an attenuator.

Holco Resistors:

These resistors were specifically chosen for their sonic performance. In this particular application, there are very few other resistors that could outperform them, often costing 20-40 times more. Their outstanding musical qualities are gaining notice in the High End industry as more companies discover their qualities. Holco resistors are made with no ferrous material. Utilizing the closely controlled production process, the metal film is vacuum deposited on a ceramic substrate whose ends are gold plated. This is then joined to the copper end caps and leads. These resistors are used for the attenuators discussed above.

Caddock and Vishay resistors:

These premium brand name resistors, though very expensive, are at the top of their field. Using metal film foils as the resistive element provides for an unparalleled performance. Due to their excellence, these the only resistors employed in the main circuit. Using anything less would result in a sharp decrease in sonic performance.

Non-magnetic Hardware:

These are used throughout the unit.

Upgrade Options:

The First Sound Linestage I has various options available to its owners. From the starting model Presence to the top of the line model Ultimate Paramount, various options are available as upgrades. The owner of the Presence model can continually add on options that raise the level of performance all the way up to the Ultimate Paramount level of performance. This provides a gradual and convenient path for attaining a desired level of performance without having to have to sell current unit at hand. This further provides for an opportunity to see the difference between each level of options/performance, giving an added dimension in developing ones high end system.

We at First Sound are very proud of our products. If there are areas of the product that has not been covered or leaves certain questions unanswered (or raised new ones), please feel free to contact the factory. We would like to assist you in the best way possible to help you make an easier and intelligent decision for your next linestage purchase.

You are cordially invited to listen to a First Sound Linestage I at a dealer nearest you. Give yourself an opportunity to witness the sonic presentation of the culmination of all that has been discussed in these pages.

Information herein are subject to change without notice.