New JADE Line Stage Preamplifier
SPECIFICATIONS
TUBE COMPLEMENT:
[ 3 ] - 6SN7GT selected Low Noise Matched Triodes [ China ]
OPTIONAL - 6SN7WGTA NOS PHILLIPS Dual Triode
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..
- 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
[ 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 ]
- +/- 0 dB FLAT ... 15 Hz to 200 kHz
- +0 dB/-1 dB ... 7 Hz to 520 kHz
- +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