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Monoblock amplifiers
Topaz 572M monoblock amplifiers
Product Status

Limited Edition - Maximum production is 4 pairs per year

Each unit comes with a gold plated solid brass nameplate that is individually engraved with its own unique serial number,

Now outputs 45 watts RMS per channel

Wyetech Labs has replaced the 211 output tubes in the monoblocks with the new Svetlana SV-572-10 triodes. These directly heated triodes are almost an exact replacement for the 211-VT4C in respect to the Topaz design. They are somewhat smaller in size, but have a larger plate dissipation (a 25% increase over the 211's). Because of this, we have been able to increase the power out from the amplifier while still operating in pure class A1. In essence this is a high power version of the TOPAZ (572B) stereo reference amplifier. The 572M monoblocks will put out 45 watts of pure single ended DHT power.

Each monoblock contains two channels identical to the TOPAZ (572B). The output transformer windings from each channel are added together to double the power. This method avoids the high frequency loss that would occur if using a higher power single output transformer. It also avoids parralleling output tubes and the negatives inherent in such designs. The dual output windings are controlled by two toggle switches that enable the amplifier to drive into 2, 4, 8 and 16 Ohm speaker loads. This configuration enables the monoblocks to exceed the performance and project an identical sonic signature as the stereo version while doubling the output power. This enhanced performance is the result of the isolation of each channel and its DC power supplies.

Circuit Description

1st & 2nd Stage

The large octal based triodes have lower microphonics and improved resolution over their smaller 9-pin counter parts. Our exclusive use of exceptionally large value Solen polypropylene coupling capacitors is one of the reasons for our extended low frequency response.

Output Stage

Single ended and self-biased, each Svetlana directly heated triode (DHT) drives its own Audio Note output transformer and merges the two outputs to get 45 watts (RMS) of pure CLASS A1 power output. Each monoblock contains two channels identical to the Topaz stereo version. The output transformer windings from each channel are added together using high current toggle switches to allow the selection of speakers rated for 2, 4, 8 or 16 Ohm loads. This is the most ideal (pure) way of doubling the output power and avoids the parralleling of output tubes. It also gives better low and high frequency response than would occur when using only a single output transformer of an equal power rating. The reason for this is the inverse effect ( between the low/high frequencies ) that the amount of iron in the output transformer has on the frequency response.

ALL STAGES Operate in class "A1" single ended and contain automatic self-biasing circuitry NO FEEDBACK of any kind is required from our low distortion linear amplification.

Power Supplies

  • Dual output toroidal power transformer for 572-10 filaments is full wave rectified and DC filtered separately for each output triode using a p (pi) LC choke filter. This provides superior performance that eliminates adjustments by reducing ripple to 0.002 volts. (each filament draws 4 Amps of current)
  • Separate power transformers and filters provide total isolation between the INPUT and OUTPUT stages. The INPUT High voltage power supply (+450V) uses a double p (pi) LC filter network to obtain complete immunity from power supply induced signal aberrations. The 1st stage is further isolated from the 2nd stage using an RC filter network. The OUTPUT High voltage power supply (+1200V) uses a full wave rectifier configuration feeding a double p (pi) LC filter network for excellent regulation as well as superb ripple and noise rejection! It also contains polypropelene in oil capacitors that have double the storage capacitance over that used in the stereo Topaz model.
  • A total of six large chokes are employed in each monoblock power supply and only polypropylene type capacitors are used in the High voltage power supplies.

Mechanical Construction

  • Extremely rugged (12 gauge) all welded steel chassis was implemented to further reduce any possibility of vibration induced signal aberrations.
  • Highly polished showcase chrome and black nickel plating on brass is used to accentuate the chassis styling on this unit.
  • Very high quality pearl enamel baked on finish to further enhance the artistry.
  • Rugged solid brass handles with nickel finish are implemented for ease of handling.
  • A fine mesh screen covers the high voltage transformers and chokes.
  • Tubes are left uncovered to enhance the visual arts.

Circuit Boards

(Hand crafted Vectorboards using precision double turret terminal posts)

The components are mounted on Vector boards which contain swaged terminal post. These posts are divided into two areas. The wiring used is laid out on both top and bottom of the board and is soldered to the bottom layer of the terminal post. This point to point wiring allows the highest possible component density while maintaining the shortest possible SIGNAL PATH! The components are then soldered into place on the top layer of the terminal which allows the replacement of any part without removing the circuit board. High quality Teflon coated Silver plated OFHC copper wiring is used where appropriate and silver solder is used throughout.


(Power on cycle completes in 60 seconds)

Three time-delay relays provide proper power sequencing for stabilized circuitry before use and to provide extended tube life.

  • Standby Sequence - Allows filaments to reach operating temperature before applying high voltage. Can also be invoked manually via the POWER SWITCH.
  • Power Sequence
    1. Applies high voltage to input stages and allows circuit elements to stabilize before next sequence.(red LED lights)
    2. Applies high voltage to output stage. (Green LED lights--red LED turns off)
    3. A few seconds later the auto-mute is disengaged completing the turn-on sequence.

Power Switch Settings

(A 3 position toggle provides the following functions:)

  • Top - ON (auto-sequencing)
  • Middle - OFF
  • Bottom - STANDBY (sequence 1 only)

Impedance Matching

Two high current toggle switches enable setting for 2,4,8 or 16 ohm speakers and can be switched while in operation.


Two sets of RCA input and two sets of WBT output connectors. This feature is useful for Bi-Amping or Bi-Wiring


Tube Complement

  • 1 6SN7GT octal base dual triode
  • 1 6BX7GT octal base dual triode
  • 2 SV-572-10 Svetlana - large triode rated for 125 watts plate dissipation

Frequency Response

(reference to a sine wave at 5 watts RMS/8 Ohm output)

  • +/- 0 dB FLAT (100 Hz to 10 kHz)
  • + 0 dB/ -1 dB (20 Hz to 25 kHz)
  • + 0 dB/ -3 dB (16 Hz to 37 kHz)

Input Impedance

100 KW

Absolute Phase



25dB (0.75V RMS maximum for full output)

Power Output

45 watts RMS each monoblock

Noise & Distortion

below audibility

Stage Width

wide open

Stage Depth

exceptional layering

Perceived Sound Field

precise imaging


crystal clear

Power Consumption

375 watts x 2 = 750 continuous watts


Net: 104 lbs x 2 = 208 lbs ( 95 kg )

Shipping: 238 lbs (108 kg)


16" W x 22" L x 10" H (each monoblock)


The Inner Ear Report

Volume 12, # 2 (2000) - Reviewed by Ernie Fisher

…the Topaz amps are closer to the “real thing”, the music, than any other amplifiers we have auditioned…

Review Download


Limited Warranty

Tubes: 1 Year Components: 3 Years Parts & Labour

Extended Warranty

(See warranty registration)

Components Only: 20 Years Parts & Labour

Price (USD)
$ 17,500
Price (CAD)
$ 23,500