THE POSEIDON PROJECT and the NEPTUNE

As a direct consequence of the international success of our flagship horizon DAC, we decided to trickle down some of the solutions and most of the sound character (or its lack) to the more affordable products.

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During the creation of the amazing, game changing POSEIDON DAC we realized, that it offers the best preamp linestage circuit we ever designed. This is how the NEPTUNE Preamp was born. We removed the digital conversion engine and the preamp as a stand alone device replaced our previously best preamp.

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Enter: THE NEPTUNE PREAMP

 

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We realize that the preamplifier or line stage is almost extinct in today's market , but NOT DEAD YET.
In many cases when you want a very good amplifier, you end up with two monoblocks or one stereo power unit and hence the need for a preamp is always there. Especially it plays out well when the preamp is tubed and the power amplifier is sold state or hybrid. Including the D-Class amps of today.

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Many preamps out there perform the two basic functions: to adjust the volume and to select the sources.

We analyzed the situation and concluded, that there are three more functions which we like to see in a preamp: 

- very high input impedance, to make the sources sound better

- very low output impedance, to make the amps sound better

- balancing of SE signals to drive the XLR balanced amps (like a single ended turntable (phono) driving the XLR monos.)

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The POSEIDON DAC already has most of the preamp functionality in place, so if you can get a Poseidon DAC you dont need a preamp at all.

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From June 2024 we will offer an optional preamp card with PHONO MC tube stage with one MC input and sound quality based on our copper VP-4 which was used as a base design for the NEPTUNE Preamp Phono Card. This card will be retro-fittable to the preamp.

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MSRP list price is 

- 23 000 Euro netto for full Poseidon DAC with preamp

- 23 000 Euro for NEPTUNE preamp with the tube phono stage MC (no DAC)

- 17000 Euro for line stage version of NEPTUNE Preamp (no DAC and no MC input)

- Poseidon with the DAC and Phono MC is not possible due to the lack of space inside.

 

Sound wise, the stand alone NEPTUNE preamp is better than any DAC we ever made used as preamp , as well as  any preamp we ever made. Also better than Poseidon used as Preamp.

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The design criteria were among others:

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1. To maintain the chassis size no larger than that of Pacific or Horizon

2. To offer single ended and balanced topology at the same time, without the need of choosing one

3. To offer volume control, display and remote control to everyone, without the need of choosing

4. To create the volume control circuit that is NO SONIC COMPROMISE. It just can't be bettered in form of any other  technical solution in this price range

5. To offer FOUR single ended and balanced ANALOG inputs, usually one XLR and three RCA's

6. To eliminate the input impedance problems that plague typical preamps

7. To eliminate output impedance weakness that plagues the typical tube products

8. To use easily available tubes, which is important in these VERY troubled times. This is important for us, manufacturers - today, and for you - users - tomorrow.

9. To provide a unique feature of SE analog inputs becoming really balanced at the outputs. So our turntable or tape deck can drive directly the balanced amps. This is done in a very clever way by means of a common cathode phase inverter.

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The resulting PREAMP is a masterpiece of good sound and convenient features.  It has everything it can have, all the important features of the center of home entertainment. It is specifically designed to work well with modern amplifiers, including the very big solid state ones. 

Key highlights

• No silicon anywhere in signal path

• Silver wiring inside

• Copper foil, true metal sheet Lampizator capacitors in the signal path

• CNC milled sub-chassis.

• 6N6P input buffer tubes, 6N6P voltage gain triodes (ECC182 with adapter compatible)

• 6J5 or 6V6 or 6C2C or KR5 or CV1067 or L63 or EL34 or KT66 output driver tubes

• Volume control of the highest possible caliber in every unit with 63 discrete steps

• Channel tracking - within 1% on the volume scale

• All units are truly balanced and SE at the same time

• Zero feedback, neither local nor global

• Zero opamps

• Tube rectified power supply

• Hundreds of tube rolling permutations.

 

Preliminary parameters:

• Weight: 24 kg / 55 lbs net, 40 kg / 90 lbs gross

• Dimensions without tubes: 440 mm W x 550 mm D x 170 mm H (height with tubes 250 mm)

• ​3 x analog input RCA, 1 x analog input XLR fully balanced

• Output impedance: 400 Ohms per phase

• Input impedance 470k per phase. 0,9M balanced

• 1 x analog output pair RCA and 1 x XLR balanced output (working simultaneously)

• Output level: 0dB full level @3V peak sinus 1 kHz  per phase, 6V p-p for balanced

• Mains 110-115 - 220 - 230 - 240 V AC  /       consumption 85 VA

• Frequency response 15Hz-100 kHz @+/- 1,5 dB, >2 Hz-500kHz @ +/-6dB

• Overall amplification factor: 4x (6dB) - tube dependent (max 8x)

• Maximum possible amplitude output: 11V SE, 22V Balanced

• Volume setting to obtain 2 V output with standard digital source of 0dB: -10points  SE, -15 points Bal

• Input sensitivity  @2Vpp output signal and max level setting: 625mV SE, 160 mV Bal

• THD @ 2V output: 0,09% SE, 0,02 % Bal

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Colors:  (sorry: no gold, no anodizing, no car paint (like Mazda Red)

• Matt Black Hole

• Silver Sahara

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The dust cover plate around the tubes on top can be ordered in these colors:

• Copper Powdercoat- for the famous "Duracell  look"  (Black body and copper top)
• Stainless steel mirror-like chrome look
• Black Hole structural matt
• Silver Sahara Powdercoat

Packing in custom hand made flight case

Tube compliment:

1 x 5U4G rectifier or equivalent, 274B, 5Y3, 5C3S, GZ34, GZ37, GZ480, 5AR4WGB

4 x 6N6P dual triode as input buffer or adapter fitted  6900, 12BH7, 7119, ECC182

4 x 6J5 or KR5 or 6C2C single triode as output buffer or 6V6 pentode (without adapter) or EL34, KT66, (or 6888 with an adapter)

All circuit consists of 4 identical mono circuits and each of phases has three tube stages: input buffer, signal amplifier and output buffer. The remote control for the first time in our designs  is not before the tubes or after the tubes but in between stages, making it the most transparent and benign volume control ever.

Remote Control  - CNC milled metal "slab" remote with following buttons: Vol Up, Vol Down, MUTE, Power On/Off, Input select

Display: monochromatic OLED  display in Amber color (dull orange)  (non dimming)

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