"JADE 2.1" Line Stage Preamplifier with gold or black nickle knobs

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New JADE DESIGN GOALS

AUDIO CIRCUITS

The JADE has been upgraded with the analog circuit and power supply taken from the Pearl. Signal capacitors have been upgraded to the best metalized Teflon 1300 Volt type that's used in our reference Ruby line stage.Pictures are from original Pearl preamp later renamed New Jade and do not show the two Teflon signal caps.

In addition a new selector circuit board mounts to the back of the input RCA connectors and now uses relay switching for all functions. Front panel selector and tape monitor switches now control the relays which handle the routing of the signal. Previous coax wiring running from the rear to the front selector & monitor switches has been eliminated, reducing the length of the signal path while eliminating much wiring. This also enhances the life expectancy and reliability.

As a consequence the Pearl name has been discontinued and the new product will retain the name of the Jade. The new Jade unit will be available with either the 24K gold plated or black nickel finish on the precision machined brass knobs

Our previous goal in designing the PEARL was to duplicate the sound of the Opal in a one box configuration. Our new goal is to give the new JADE the sound of the Pearl at a significantly reduced cost. We were able to do this by reducing the labor cost of assembly and eliminating the coax wiring previously used to route the analog signal from the rear RCA connectors.

The new JADE comes very close to the OPAL, such that the difference is heard only by straining one's ear in comparative listening test and providing that the accompanying equipment is up to this new performance. For most people, this line stage will be the strongest link in the chain.

POWER SUPPLY

The power supply is built on a separate terminal board and is similar to the Opal in that we have implemented a double pye filter network using two large chokes in conjunction with electrolytic and polypropelene capacitors to maintain an ideal DC voltage. A passive Zener network shunt regulator stabilizes the DC Voltage level. We have again avoided using active feedback in order to maintain the speed of the power supply in relation to the extremely fast analog circuitry. Stability is ensured by the use of a large electrolytic reservoir capacitor and speed is enhanced by using a large [30uf] polypropylene film capacitor as a final filter stage located directly on the analog terminal circuit board. The 200 Volt DC power supply completely eliminates all noise and ripple to below what our test instruments can detect. An AC power line filter is also used to prevent unwanted noise and hash from entering into the unit.

PARTS

We use precision quality parts throughout. Our fixed terminal hand crafted circuit boards are identical to the ones used in constructing the Opal preamp and Topaz amplifier. The ease of replacing parts and the tenfold increase in lifetime durability are added benefits resulting from this board construction. These boards are held elevated from the surrounding metal chassis to avoid any capacitive coupling between components. We import from Denmark our stepped ELMA volume controls that use 0.1% precision metal film surface mount resistors. For selection and tape monitor or processor loop, we have replaced the Shallco switches formerly in the Pearl with relay switching of the analog signal right at the input RCA connectors.

TECHNICAL SPECIFICATIONS

TUBE COMPLEMENT

[ 3 ] - 6SN7WGTA NOS PHILLIPS Dual Triode

[ 3 ] - SPARES INCLUDED 6SN7GTB TUNG SOL

CIRCUIT DESCRIPTION

This line amp uses a grounded grid configuration which is isolated by a cathode follower stage before and after it. All three stages are non-inverting thereby maintaining absolute phase. The grounded grid configuration is known for its extremely wide bandwidth and high speed! Each channel cathode follower is provided with two RCA output jacks to accommodate bi-wiring or bi-amping. All stages are DC coupled and only one capacitor is used in the output stage for DC blocking. No feedback is used and mirror image circuitry is implemented using a separate circuit board for the audio section.

POWER SUPPLIES

A unique design for the power supply was implemented in order to eliminate all ripple & noise while maintaining a constant voltage regulation of the 200 Volt DC power line. A dual pye filter, consisting of  two large chokes, a  large electrolytic reservoir capacitor, several polypropylene capacitors and an array of high power zener diodes are used to provide exceptional power for the analog circuitry. This filter, like the OPAL, is designed using only passive components that allow  the speed of the power supply to keep up with the analog circuitry.  DC for the filaments is supplied using a solid state 3 terminal regulator for hum free operation.

MECHANICAL CONSTRUCTION

  • Machined aluminum plates [1/4” & 1/8” thick] bolted to square post are used to construct the preamp chassis. This provides excellent shielding from external radio frequency fields.
  • Hard GOLD or BLACK NICKEL plated solid machined brass knobs for smooth operation of switches..
  • Gold plated machined brass holder with 3M rubber feet inserts accentuates the styling and allows proper air flow for the vents under the chassis.
  • The stepped Volume control has gold plated contacts with surface mounted 0.1% precision metal film resistors.  [channel balance within +/- 0.05db]
  • Balance control uses a sealed Electroswitch with silver plated contacts and 1% precision resistor networks.
  • Selector and Tape Monitor switches now control relays located next to the RCA connectors
  • Tape Monitor switch can also function as a processor loop
  • OCTAL SOCKETS are hard wired to turret terminals which are then soldered to the PCB board making them easily replaceable. This insures many decades of operation while ensuring a lifetime of serviceability.
  • Noiseless TOROIDAL power  transformer and NKK rugged quality toggle switches
  • Non magnetic stainless steel and brass hardware is used  throughout.
  • Automotive high gloss paint finish.

CIRCUIT BOARDS

New Jade circuit board

[ Hand crafted PCB's using precision double turret terminal posts ]

Our fixed terminal hand crafted printed circuit boards are a new technology used in construction and is a first in the industry. Again Wyetech Labs is at the forefront and is always looking for ways to improve reliability and construction.

Most of the components are mounted on double turret terminal post. The OCTAL TUBE SOCKETS are also hard wired to these fixed terminals which in turn are soldered to the printed circuit board. This makes the tube sockets easily replaceable should the need ever arise. The muting relay and 555 timer chip are mounted in premium gold sockets which are soldered to the board for ease of replacement

The double sided printed circuit board [ PCB ] has been manufactured with the same high standards as that found in the Sapphire amplifier. It has full solder masking on both sides of it's premium glass epoxy board with white silk screening that identifies parts and there placement for fast efficient hand soldering and assembly. These boards are held elevated from the surrounding metal chassis to avoid any capacitive coupling between components.

We also use WECO screw terminal connectors to fasten wires to the PC board to facilitate easier replacement of parts for future reparability and long service life. This technique will result in much faster trouble shooting and repair in the event of a failure and thereby reduce the labor and cost of any necessary repair.

High quality Teflon coated silver plated OFHC copper wiring is used where appropriate to make connections to and from each board and silver solder is used throughout.

AUTOMATIC POWER SEQUENCING & MUTING: 

To allow circuit stabilization and quite operation a 45 second automatic muting is activated during power up. Muting is accomplished using a 2-pole relay that shorts the preamp outputs. When disengaged the muting circuit is not in the signal path.

SELECTABLE GAIN CONTROL

Overall amplifier gain is controled by a toggle switch for each channel. It can be swirched between HIGH [ 13db (4.4x ] and LOW [ 5.5db ( 1.85x ] gain..

To change the gain settings, you must remove the top cover [ see page 2 for proceedure ] the analog board on the left contains the left and right channel switches to select high or low gain..

FREQUENCY RESPONSE

[ reference to a sine wave at 3.5 Vrms output ]

1. +/- 0 dB FLAT ...   15 Hz to 200 kHz
2. +0 dB/-1 dB ...   7 Hz to 520 kHz
3. +0 dB/-3 dB ...   3 Hz to 950 kHz

INPUT IMPEDANCE 50K ohms minimum
ABSOLUTE PHASE non-inverting
CHANNEL BALANCE CONTROL 11 position for +/- 5 dB adjustment in 1 dB steps
ATTENUATION 24 position stepped volume control [ -60 dB to 0 dB]
OUTPUT IMPEDANCE 600 Ohms
RATED OUTPUT 3.5 Vrms [ maximum = 8.5 Vrms ]
SLEW RATE Greater than 25 Volts/microsecond.
OUTPUTS 2 pre-amp outputs, 1 tape output, 1 line level output.
INPUTS 4 line level inputs, 1 tape input.
POWER REQUIREMENTS Switch selectable 115/230 Volt  50/60 Hz 35 Watts
NET WEIGHT 18 LBS. ( 7.8 KG)
SHIPPING 23 LBS. ( 10 KG.)
DIMENSIONS 17” W x 14 1/4” D x 4 1/4” H
LIMITED WARRANTY TUBES: 1 YEAR PARTS
COMPONENTS: 5 YEARS PARTS & LABOR

* 24 CARAT GOLD PLATED SOLID BRASS NAMEPLATE WITH ENGRAVED SERIAL NUMBER