Author Archives: rob

Class A Stereo power amplifier

Class A Stereo Power Amplifier

Class A amplifiers have always had the reputation of warmth and a great soundstage and although class D amplifiers have made a great way forward in recent years, is there still room for this old design of amplification in the modern world?

Excessive heat,  high power consumption,  very low damping factor and low power output. All these aspects and small amounts of hum does not bring confidence to the discerning audiophile how-ever as always, it is in the listening where this approach to amplification brings a certain joy and pure audio realism that answers the question earlier.

My own reference system now has this amplifier along with the latest MV2 tube pre-amplifier and in terms of preference the Class D N-core 1200 mono block amplifiers which are incredibly good, now comes third behind this stereo power amplifier and the 300B tube integrated amplifier.

The reasons are many but primarilly it is about that elusive holographic presentation, a lack of edge to vocals and instruments such as piano and pure realism to live recordings which gives an accurate sense of space and depth to a recording. 

Digital recordings have a more organic and analogue feel and vinyl takes on an even more beautiful and beguiling nature making you want to explore  your vinyl collection yet again and buy new records.

As with all the masterpiece editions, this model is hand crafted using exotic materials and components. Bolivian Rosewood, copper panels and silver wiring are standard.

This stereo amplifier will soon be complimented with a matching tube pre-amplifier. Watch this space.

To discuss this product please give me a ring.

Price  -  £4000 (SOLD)


Output power   

20W x 2 RMS into 8 ohms 

Damping factor <16
Minimum load 4 ohms
Frequency response and Distortion 10Hz to 30kHz @  0.19% @ 1Khz 1 W 0.2% @ full power
Signal to noise ratio 91dB
Output impedance 0.36 Ohms @ 1Khz 500mV input
Construction Copper top plate and solid Bolivian Rosewood case
Input sensitivity 1.63V RMS
Inputs  2 x RCA inputs
Power consumption 150W
Input voltage 240V/50Hz
Output connectors Silver plated binding posts
Input connectors Un-Balanced RCA 
Input impedance 24Kohms
Size 430W x 370D x 140H (mm)
Weight 14Kg

Class A integrated power amplifier - Image Gallery

300B integrated amplifier

300B Integrated Amplifier

For many years now I have wanted to see how good the 300B tube amplifier design actually is and to see how far this design can be pushed to extract every last drop of it's acclaimed holographic presentation and musicality.

The Masterpiece edition 300B integrated amplifier has more than exceeded my expectations in terms of sheer enjoyment from music, especially live recordings where it exhibits a beautifully "real" sound where musicians and instruments are visible in time and space as a truly cohesive field.

At only 7W output, it is a little low for many low sensitivity loudspeakers and care here is needed to match this amplifier with anything below 90dB how-ever I have also been surprised at how well this amplifier copes with large loudspeakers such as the Voltaire lll which as it happens has  very tube friendly impedance characteristics and easily driven by this amplifier and at high volumes which I generally like to listen to. Also of note is it's ability to deliver a very precise and extended bass rendition without the often terrible bass control of other tube amplifiers. High frequencies shimmer and vocals are simply exquisite with imaging of pin point accuracy and definition.

Having a very high input impedance negates the need of a separate pre-amplifier and the first pre-buffer stage is taken care of by a matched pair of Psvane 6SN7 vacuum tubes. Having tested many 300B tubes I still prefer the Golden Lion version and although the differences are quite small, I have decided the masterpiece edition needed to sound as good as possible.

Output transformers are another very long and difficult subject and after long discussions with NP Acoustics from Vietnam who are passionate about their transformer product, I  am now using them exclusively for both power output transformers and also pre-amplifier transformers and will soon be making a reference pre-amplifier to add to the masterpiece collection. These beautifully made transformers sound amazing and a step up from many other brands that get great reviews.

Internal wiring is again from Duelund Audio both with solid silver foil on outputs and signal cable. This is a design that loves silver especially the very high grade and pure silver!

Encased in a solid burr Elm and a 3mm brass cabinet including dampened standoff material and transformer dampening to ensure the whole structure is virtually free of extraneous vibrations and external spurious emissions. This amplifier is very quiet and has an inky black background during playback.

Having spent the last few years developing headphone amplifiers based around the HiFiMan Susvara Ref headphones, it soon became apparent that this design is also an incredibly good match with high end headphones and using a switched attenuator can also partner with high sensitivity headphones. This is now my reference headphone amplifier and can also be built purly for this purpose for the discerning audiophile headphone fan. 

Please contact me to discuss this product 


Price   £5000.00 - SOLD



Output power   

7W x 2 RMS 4 ohms Tap

7W x 2 RMS 8 ohms Tap

Tube compliment Pavane 6SN7 and Golden Lion 300B output tubes

Rectifier Svetlana Winged C - 5U4G 

Minimum load 4 ohms
Frequency response and Distortion 10Hz to 30kHz @  0.015% @ 1Khz 1 W 0.2% @ full power
Signal to noise ratio 85dB
Output Transformers NP Acoustics Amorphous core
Construction Brass plate and solid burr Elm case
Input sensitivity 3V RMS
Inputs  2 x RCA inputs
Power consumption 350W
Input voltage 240V/50Hz
Output connectors Rhodium plated binding posts
Input connectors Un-Balanced RCA 
Input impedance 47Kohms
Size 400W x 430D x 290H (mm)
Weight 30Kg

300B integrated amplifier - Image Gallery

Voltiare ll Masterpiece edition loudspeakers

Voltaire ll Masterpiece edition loudspeakers

As with the Regis Mkll Masterpiece edition, the Voltaire ll are also one of my favourite designs and this particular pair was designed around inspiration from Morgan cars which also have an interior design option of Brooklands swede green hide and Zebrano hardwood,  perfectly combining subtle colours with the striking nature of Zebrano. The addition of quilting the hide further compliments the similarities of classic car interior and a Masterpiece edition.

I have really enjoyed building these exquisite loudspeakers with design help from Russell at Revolutions, Scotland's premier Morgan car dealership in Perth  who are now a fully authorised Masterpiece dealer for Robson Acoustics.

Carefully selected cross-over components, silver foil internal wiring over silk and oil dielectric with additional dampening of the cross-over board are just some of the many extra features a masterpiece edition has over standard models along with a 50mm thick baffle and WBT pole connectors and a choice of floor spikes or Panzerholtz dampening feet to suit various flooring and acoustic space.

For further details about this product please contact me.


Price   £8000.00



Technology Scandinavian Birch ply braced construction 
Description 2 way, linear phase, infinite baffle design
Drive Units 1 x 234 mm doped plastic coned
bass/mid range unit
1 x Low mass high precision Ribbon Tweeter
Frequency Response 30Hz to 40KHz +/- 2dB on axis
Impedance 8 Ohms nominal, 5 Ohms minimum
Sensitivity 88dB spl at 1 metre on axis. 2.83V input
Crossover 2nd order bass roll-off
2nd order tweeter
Power Handling 200W peak un-clipped programme
Dimensions Height - 100cm
Width - 28cm
Depth - 39cm
Net Weight 40Kg
Finishes Masterpiece 1 off edition

Bespoke options available on request

Various spike/feet options dependant on floor and room acoustics


Voltiare ll loudspeakers - Image Gallery

Regis Masterpiece edition loudspeakers

Regis Mkll loudspeakers

With the launch of the Masterpiece collection, it seemed perfect to implement a stand mount loudspeaker worthy of this range of exquisite products.

The Regis Mkll is without doubt the finest small loudspeaker I have ever designed, capable of a huge soundstage and musical cohesiveness seldom heard at any price point.

This design uses my favourite ribbon tweeter by Raal of Serbia and a Titanium advanced bass/midrange driver from Morel which provides a perfect partnership via a dampened cross-over using exotic oil capacitors,  foil inductors, cast resistors and solid foil silver wire in silk and oil dielectric from Duelund Audio to give incredible detail and resolution  without fatigue over long listening periods.

Encased in a very stable birch ply cabinet with minimum internal reflections to enable all drivers to perform at their maximum abilities without the typical detrimental cabinet influences.

To compliment the Masterpiece collection the caps and spine were specially selected from Scottish burr Elm which is becoming increasingly scarse and very difficult to sourse. Together with a beautiful distressed hide, this 1 off masterpiece will grace any living space and provide a lifetime of musical pleasure.


Price   £6000.00 - SOLD

Technology Finnish Birch Ply matrix construction
Description 2 way, linear phase, sealed cabinet
Drive Units 1 x 160 mm Titanium advanced woofer with 3" voice coil and damped polymer composite cone.
1 x Low mass high precision Raal Ribbon Tweeter
Frequency Response 40Hz to 40KHz +/- 2dB on axis
Impedance 8 Ohms nominal, 5 Ohms minimum
Sensitivity 87dB spl at 1 metre on axis. 2.83V input
Crossover 2nd order bass roll-off
2nd order tweeter
Power Handling 150W peak un-clipped programme
Dimensions Height - 39cm
Width - 20cm
Depth - 32cm
Net Weight 11Kg
Finishes Masterpiece edition 1 off design - distressed hide and solid Burr Elm hardwood caps and spine.

Bespoke options available on request

Regis Mkll loudspeakers - Image Gallery

Masterpiece edition Turntable

Masterpiece edition Turntable


Another exciting project and product development is based around the well known Swiss made Lenco turntable  which fundamentally is constructed extremely well with a precision motor and structure that lends itself to be upgraded and modified to create an incredibly good turntable.

The initial phase involves a complete strip down of every component with certain key parts replaced or modified. The main chassis is resprayed and lacquered before re-assembly and lubricated for longevity and noise reduction. Because the central spindle and platter are already of a very high standard and tolerance, these are polished and retained. The main bearing is either replaced with an upgraded bearing or modified with a new ruby ball bearing and thrust plate. The main motor is stripped down and inspected for wear or noise, re-assembled and lubricated. I have yet to find a motor which has failed these tests or brought back to a new standard.

The high mass plinth is a based around the natural qualities of certain hardwoods and their abilities to exhibit very high levels of resonance and damping control as well as high density and other acoustic characteristics.. This model is made from solid sections of Bubinga hardwood which is incredibly heavy and dense, perfect for reducing micro vibrations within the motor and main turntable structure. This combined with Tungsten carbide ball bearings on Panzerholz dampening feet ensure the combined structure of the turntable is virtually free from extraneous effects and vibrations.

A choice of tonearm boards made from either the same hardwood or Panzerholtz is available with additional dampening and specifically chosen for their acoustic characteristics and density.

Days of sanding and preparation are done prior to a high gloss lacquer finish with further wet sanding, buffing and final polishing before final assembly and soak testing.

A choice of tonearm is also available and from SME, Ikea and Reed along with a select number of cartridges. Please get in touch to discuss this product.


Price   £3500 without arm and cartridge - SOLD

Price  £8000 with SME series V arm - SOLD


Turntable - Image Gallery

Robson HA1

Robson HA1

Years of research into a dedicated headphone amplifier which can drive the most difficult of loads with ease has culminated into a design based around the most dynamic amplifier modules in their class. 

A dual mono design throughout using N-core technology and fully balanced with our own pre-amp internal buffer stage and a 4 pole Swiss Alps volume control. 

Internal wiring uses Duelund Coherent Audio copper and cotton in oil wire for input signal path and Harmonic Technology UP-OCC wire for output signal path. 

The HA1 headphone amplifier has been primarily designed to perfectly match the incredible HiFiMan Susvara and HE100se headphones along with matching headphone cables specifically deigned for each headphone and available as a package deal.

HA1 features

  • N-core technology, dual mono design
  • Specific high quality internal wiring
  • Fully balanced with switchable un-balanced
  • 4 pole balanced Alps volume control
  • Same form factor as the MV3, SA1 and MC1 amplifiers

Please enquire about Burr hardwood front panel options.

PRICE -  HA1 - £1800.00

PRICE - HA1 + HiFiMan Susvara + 3m cable - £5500.00

PRICE - HA1 + HiFiMan HE1000se + 3m cable - £3800.00 


Output power 4W RMS into 30 ohms ohms 

2.5W RMS into 60 ohms 

Class of operation Class D
Minimum load 4 ohms
Frequency response and Distortion  10Hz to 50kHz @  0.0015%
Signal to noise ratio 121dB
Output impedance 1.5 mohms
Peak output current 12 amperes
Damping factor >1000
Power consumption 350W
Input voltage 240V/50Hz
Output connectors Silver plated 4 pin XLR or 6.3mm jack
Input connectors True Balanced  XLR or unbalanced RCA
Input impedance 47Kohms
Size 240W x 320D x 115H (mm)
Weight 5Kg

Robson HA1 - Image Gallery

Robson SA1

Robson SA1

Based around a dual mono design using the incredible Hypex N-core 250W modules and using the same high quality aluminium case as our matching MV3 pre-amp, MC1 phono-stage and HA1 headphone amplifier to give a stunning rack of high end Hi-Fi equipment.

Essentially the same sonic characteristics as our MB2 250W mono block design and using the same high quality components, input buffer stage and internal wiring.

High current and high damping factor to drive the most difficult of loads with ease and accuracy. Incredible imaging and soundstage capabilities along with immense detail retrieval.

SA1 features

  • Rhodium plated pole connectors
  • Duelund Coherent Audio internal wiring
  • Same form factor as matching MV3 pre-amp and MC1 phono stage
  • Highest damping factor in it's class 

Please enquire about Burr hardwood front panels

PRICE   £1200.00 


Output power -Dual Mono design  

250W x 2 RMS 4 ohms

130W x 2 RMS 8 ohms 

Continous output power 50W  x 2 RMS

Class of operation Class D
Minimum load 4 ohms
Frequency response and Distortion 10Hz to 50kHz @  0.0015%
Signal to noise ratio 121dB
Output impedance 1.5 mohms
Peak output current 17.5 amperes
Damping factor >1000
Power consumption 350W
Input voltage 240V/50Hz
Output connectors Rhodium plated binding posts
Input connectors Un-Balanced RCA 
Input impedance 10Kohms
Size 240W x 320D x 115H (mm)
Weight 5Kg

Robson SA1 - Image Gallery


MV4 - Line stage Phono Pre-amplifier

MV4 is a all in one phono stage and line Pre-amplifier using the MV3 and MC1 Phonostage.

Hand crafted using the same high quality components as the standard MV3 and MC1 models and using Duelled Coherant internal wiring and high end connections for RCA's.

For people who are passionate about vinyl, this model creates incredible soundstage and realism in your vinyl collection.

Comes as standard with 100 Ohm loading for MC cartridges.

For MM and different MC loadings, please specify upon ordering. 

MV4 features

  • Combined MV3 and MC1 amplifiers
  • High quality capacitor and resistors in signal path
  • Duelund Coherent internal wiring
  • All tube design throughout
  • Bespoke cartridge loading

Please enquire about Burr hardwood front panels

PRICE   £2200.00


Vacuum tube compliment 7 x JJ or Tung Sol 12AX7
Input Impedance Line in 47Kohm      MC in 100 Ohms 
Output Impedance 150 Ohms
Inputs Line in RCA and MC in Phono
Output Unbalanced RCA
Gain 22dB
Power Consumption 45 VA
Frequency Bandwidth 10Hz - 45KHz
THD 0.3% 1KHz 4V ref
S/N 88dB
Dimensions 380W x 320D x 130H
Weight 9Kg

MV4 - Image Gallery



Our latest Preamplifier is a full tube line stage design using 4 x 12AX7 specially selected tubes.

MV3 follows in the footsteps of the incredible MV2 using the same principles of minimum of active parts and high quality passive components in the signal path. A no compromise design and attention to components and internal wiring brings a product worthy of the Robson brand and a great match to our range of power amplifiers.

Volume is controlled via a Khuzmo 48 stepped attenuator  and series shunt resistor. No other manufacturer would use components such as this and many other parts as standard in a product in this price range.

MV3 features

  • Khuzmo 48 way stepped attenuator as volume control
  • Low ripple power supply on the anode
  • R-type transformer
  • Duelund Coherent internal wiring
  • SE model upgrade to high end signal capacitors

Great design and the use of very high quality components has created a pre-amplifier of exceptional abilities and able to drive the most difficult of power amplifier loads to below 10Kohms.


Standard model    £1600.00

SE model                £2000.00


Vacuum tube compliment 4 x JJ or Tung Sol 12AX7
Input impedance 47Kohm
Input Unbalanced
Output Unbalanced
S/N 88dB
Frequency Bandwidth 10Hz - 45KHz
Dimensions 240W x 320D x 117H 
Weight 7Kg

MV3 - Image Gallery



Our flagship reference Pre-amplifier to compliment our mono block power amplifiers and Phono stage Pre-amplifiers.

As standard hand made using very high quality components in the signal path, our MV2 valve pre-amplifier will compete with the very best products out there regardless of cost.
Again……listening is believing!!

Design specifications include dual mono power supplies with each channel supplied by it’s own high voltage and filament rails via a tube rectifier and feeding separate regulators to give incredible stereo separation.

A very simple but pure signal path based around the 6SN7 audio tube and using a single output capacitor which can be specifically chosen for it’s integration to solid state or valve amplifiers based on input impedance compatibility.

MV2 features :

  • Dual mono design
  • Tung-Sol vacuum tubes upgradable to Black Treasure or Pavane
  • Khuzmo 48 way stepped shunt attenuator
  • Duelund Coherent Audio internal wiring
  • Miflex paper/oil output capacitors

Purity of signal path is critical in the design of any amplifier to give incredibly black backgrounds and the retrieval and portrayal of the tiniest musical passages and notes.

If you have never heard a valve based pre-amplifier of this class you will be amazed at how much information you may be missing in your vinyl or digital music collection.


Standard Model   £2600.00

SE model  £3000.00



Vacuum tube compliment 4 x Tung-Sol 6SN7GTB

1 x 6X5 Rectifier tube

Input impedance 47Kohm
Output Impedance 150 ohms
Inputs 2 x RCA Line inputs
Output RCA Line out
Frequency response 10Hz - 50KHz
Power consumption 50VA
Gain 22dB
THD 0.3% 1Khz / 4Vef
S/N Ratio 88dB
Dimensions 380W x 320D x 130H ( without tubes )
Weight 11Kg

MV2 - Image Gallery