Friday, 5 August 2016

Arcadia 7W PSE 2A3 Power Amplifier Upgrade

At the end of last year one of the original SJS Arcadia 7W PSE 2A3 amplifiers, originally built back in 1998, came in for a major service and upgrade.

Following the terminal exit of the main power transformer the opportunity was taken to upgrade and almost rebuild it.

The main power transformer was replaced by an external dual mono PSU, containing 6 mains transformers; two for the HT to the 2A3 power valves, two for the HT to the 6072A-5687 input/driver stage, and two for the negative bias supply for the grids of the 2A3s.



EZ81 rectifiers, choke input and first smoothing cap for the input/driver stage power supply are inside the PSU case


Four umbilical cables connect the psu to the audio chassis



Independent left and right mains switches, with remote switching controlled form the audio chassis


Removal of the power transformer from the audio chassis allowed for a pair of larger chokes to be fitted for the 2A3 HT supply, each channel has NOS GZ37 choke input supply and Elna Cerafine HT caps in the HT, and NOS Mullard EZ81 and choke input supply for the bias supply


Inside there was a major component refresh and upgrade; tantalum resistors, Hovland Musicaps, lots of Black Gates, Jensen 4 pole HT caps, Kemet bias supply caps and silver wiring



Not looking to shabby for it's age, and now fit and ready to go



Arcadia Model 5 Stereo SE 300B Power Amplifier

Following on from the successful launch of the SJS Arcadia Model 3 MM RIAA Phono amplifier, SJS Electroacoustics are pleased to present the matching all new bespoke Arcadia Model 5 stereo singled ended 300B power amplifier.


In common with other SJS Arcadia amplifiers it has been specifically engineered for sonic performance rather than technical specification, and fulfills SJS Electroacoustics primary design criteria:
  • Single Ended circuit topology
  • Pure Class A operation
  • Zero negative feedback
  • Valve rectification and choke smoothed HT power supply
  • Custom made HT T-network power supply capacitors with silver leads
  • Separate mains transformers for HT and filament supplies
  • Point-to-point circuit wiring without PCBs
  • Hand built
  • Real solid wooden frame
  • 4mm aluminium panels, black or natural anodized
  • Soundcare SuperSpiked feet

The Arcadia Model 5 power amplifier is a modern implementation of the classic 6SN7-6SN7-300B topology with a few tweaks, mainly in the psu design, component selection and layout.



The standard version is supplied with large wide bandwidth multi-section IE core output transformers, carbon film resistors and high quality film and copper foil coupling capacitors.

It is possible to upgrade this is stages to the Premier version including:

  • tantalum film resistors
  • Black Gate bypass capacitors
  • Dueland CAST DC coupling capacitors
  • Custom HiB double C-core output transformers
  • Pure silver wire for all point to point connections

Inside an Enhanced version:

Inside a Premier version


Technical Specifications

Input Impedance
100kOhm
Input Sensitivity
400mV for full output
Power Output
8W per channel
Frequency Response
+/-3dB 8Hz-30KHz
Valve Compliment
2 x 6SN7
2 x 300B
1 x 5U4G
Max. Power Consumption
250 Watts
Unit Weight
30 kg 
Shipping Weight
49 kg
(Original Packaging: Customised flight case)
Unit Dimensions
300mm (h) x 450mm (w) x 400mm (d)
Shipping Dimensions
400mm (h) x 545mm (w) x 500mm (d)

(Original Packaging: Customised flight case)



Design Options

The Model 5 SE 300B power amplifier is hand built to order in England, and therefore we are able to offer customisation to meet your aesthetic and sonic preferences. The solid wooden chassis is available in a range of four standard choices; cherry, maple, light oak and walnut with others such as zebra wood available to special order. The chassis panels are available in either natural or black anodised aluminium as standard, with other colours, such as blue, red or gold, available to special order.

Bespoke customisation of the internal components is also possible to meet our clients' specific requirements, whether it be for use of a certain interconnect cable between the phono sockets and the circuit, or replacement of the coupling capacitors, power supply capacitors or resistors, for example, these can be discussed at the point of ordering.