"Ruby" XM 300B Reference SET Monoblock Amplifier



Ruby XM 300B Reference SET Monoblock Amplifier Ruby XM 300B Reference SET Monoblock Amplifier Ruby XM 300B Reference SET Monoblock Amplifier Ruby XM 300B Reference SET Monoblock Amplifier



This edition of the Ruby XM 300B is very similar to the Ruby XR 300B with the main difference being it uses two output tubes in a parallel configuration while the more powerful Ruby XR 300B uses a series-parallel configuration. This XM model lowers the power output to 60 percent of the XR model while maintaining the absolute reference pedigree of the Ruby XR model.

It also includes the XR designed first gain stage using a 5687 double triode in parallel which lowers the noise level by 3db's.

This edition also has the same lowest noise floor as the XR model making these two models leading the SET competition in this regard.

The Ruby XM 300B monoblocks that we are now building are gold anodized with blue ink filled engraved lettering as shown in the picture above.


The Ruby series of products reduces overall noise levels to unprecedented levels resulting in heightened dynamics to accommodate the ongoing increase in resolution in analog and digital recordings.

The fact that there are quite a variety of new 300B tubes being manufactured today gives the user a varied choice in selection and voicing of his system, including the EML 300B XLS and the KR 300B XLS with a filament current of 1.5 and 1.8 amps [ standard 300B is 1.2 Amps ]


The Ruby XM 300B monoblocks comes shipped with the Emission Labs EML 300B-XLS.




[1] 5687WB Dual Triode JAN NOS Philips USA - VOLTAGE GAIN STAGE - T1
[1] 12B4A Single Triode JAN NOS GE USA - DRIVER STAGE - T2
[1] Svetlana 6D22S high current high voltage 6KV rectifier - - 30 second high voltage ramp up until final bias is obtained. - - - The 6D22S is preceded by a Solid State Bridge Rectifier rated @ 12,000 Volts 1/2 Amp.
[2] Emission Labs EML 300B-XLS with Gold plated GRID and tube pins


This stage operates in pure class "A1" single ended plate loaded with independent automatic biasing circuitry for each triode . Both triodes are wired in quasi parallel to take advantage of the 3 db noise reduction using this configuration.


This stage also operates in pure class "A1" single ended plate loaded with automatic self-biasing circuitry. This stage operates with high bias current and high voltages needed to drive the two 300B output tubes and do so without driving the 300B grids positive to insure no grid current drive is required. The AC signal is coupled to the 300B grids via 2 metalized high voltage, high capacitance Teflon signal capacitors with self healing ability.


Both output tubes operate in pure class "A1" single ended self-biased isolated circuitry while the two plates are tied together to drive the output transformer.

The LED bias meters show the status of each output tube that continuously adjust the bias automatically.

If either of the 300B tubes go out of the normal range it's corresponding red LED will turn on suggesting that this tube should be replaced. The left tube fault light is designated FL and the right tube is designated FR.

If the FL or RL red LED's come on then it's time to change that 300B tube


Dual triple digit LED bias meters read up to 99.9 Volts using a blue readout for constant monitoring.

A LCD hour meter [99,999.9 hours] is now incorporated to keep track of usage, especially important with monitoring the life of output tubes.

GROUND LOOP HUM NOT A PROBLEM: No ground lift switch on all wyetech amplifiers. We employ a special network that does not remove ground safety from the chassis. As a consequence Wyetech MONOBLOCK amps don't suffer from ground loop hum pickup!

The 300B filaments, which also act as the cathode for each triode, require isolated pure 5 volt DC power supplies. Each of the two supplies have a separate 7 volt AC secondary winding connected to a full wave bridge rectifier followed by a 10,000uf filter capacitor and terminated using a solid state 5 volt regulator chip.

Impedance settings of either 4 or 8 ohms is selectable via a toggle switche located on top rear of each chassis.


Two Toroid power transformers are used in each monoblock with input AC power operation for 115V-120/230-240V 50-60 Hz selected via an internal toggle switch.

Separate DC power supply filtering provide total isolation between the INPUT and OUTPUT stages. This consist of a quadruple-4 (pi) filter for both the front end supply and the output 300B stage supply.

A bridge rectifier rated at 12,000 Volts DC provide the needed voltage and current, that in turn feed the 6D22S [6Kv rating] rectifier tube that enable the voltage to slowly ramp up due to the 30 second delayed warm up time of the 6D22S.

Custom made polypropylene in oil capacitors with special screw connectors allow easy assembly or removal from Printed Circuit Board

The use of pure LC filter networks with 10 very large polypropylene in oil capacitors, 3 large polypropylene capacitors and six large chokes provide an unparalleled ripple reduction and purity of design identical to it's big brother the XR model but with different DC voltages.

Rectified, filtered and regulated 12 Volt DC provides the power for the input tube filaments of the 1st and 2nd stage. This also contributes to lowering the noise floor.

An Analyst Plus AC Power Oval power cord is supplied with each Ruby monoblock amp


Extremely rugged all welded steel chassis with 4 mm aluminum top and bottom plates provide a solid firm structure by design. Think of a picture frame doubled up and back to back with the flat top and bottom pieces flush mounted and bolted with 28 stainless steel dress machine screws. This reduces any possibility of vibration induced aberrations affecting the operation of the amplifier tubes.