Stemfoort SF-200 Passive Line Power Amplifier


Stemfoort SF-200 Passive Line Power Amplifier

The SF-200 is a passive line power amplifier offering a direct signal path for all your analogue inputs. Unlike a conventional integrated amplifier with a built in pre-amplifier, the SF-200 is completely passive. This allows the signal to go straight from your CD player, DAC or streamer through a volume control and direct to the power amplifier. The use of a passive input is maximised by a carefully developed high impedance FET input stage on the power amplifier. The SF-200 uses a sophisticated low gain high sensitivity circuit, matched to the specification of a line level input.

Dynamic and in Control

The SF-200 is a wide bandwidth design reaching frequency extremes of 6Hz – 120kHz. This allows your music to retain all the low level detail and nuances that create the authentic atmosphere of a recording. This wide bandwidth capability provides excellent dynamic performance for high resolution music streaming such as 24/192, DSD and SACD formats.

With hi-res music formats available, it is important to have an amplifier capable of handling a greater dynamic range. The SF-200 uses a large power supply providing impressive tone bursts and 100 Watts per channel output. Plenty of current is on tap, resulting in greater control of loudspeakers and powerful deep bass when required

It’s all in the detail

The SF-200 has a number of hidden features providing a high level of design sophistication.

All inputs are relay switched keeping the signal path as short as possible. A motorised analogue volume control is operated by a supplied remote control or can be manually turned. This is a high quality component to ensure the least possible signal degradation.

The amplifier output stage has a fast acting protection circuit just in case a wrong connection has been made or there is a disruption to the mains supply.  A unique feature of the SF-200 is its ability to remain operational even if the mains voltage drops 30%. This feature is the result of developing a very stable and robust power supply and amplifier circuit.

Military specification signal wiring has been used to eliminate interference from power supplies, whilst the custom designed transformer sits inside a steel sub assembly to reduce noise and vibration. Quality components are used throughout, chosen for reliability and performance, low inductance resistors replace standard components in critical areas of the signal path.

Construction credentials

Top grade materials are used throughout the SF-200’s body work. The front panel is a solid 10mm thick pre-milled aluminium plate, a high grade material normally used for medical instruments, aerospace and robotic systems. Other case materials are steel or aluminium that have either been anodised, galvanised or powder coated to protect the finish and maintain appearance during many years of use. All fine finishing is carried out at our own factory to ensure complete quality control.

The Stemfoort SF-200 is designed and manufactured in Britain by J E Sugden & Co Limited. Each amplifier is handmade by a single highly skilled technician with many years experience. All circuit boards are hand soldered and we do not use any surface mount components that can degrade sound quality. A rigorous and continuous test procedure is carried out during construction. This includes power amplifier module pre-test, sub assembly test, built chassis test and final bench and specification test.


Front panel controls – Input Selector Switch, Motorised volume control, Power on push switch, Circuit ready indicator, Remote control sensor, Solid aluminium knobs with machined indicator.

Rear panel connections – Mains power inlet socket with accessible fuse tray, Two pairs of gold plated threeway loudspeaker binding posts & Five stereo gold plated phono inputs.


Power output – 100 Watts per channel, both channels working.

Frequency Response – 6Hz-120kHz +/-1dB.

Noise Level – Greater than 85dB.

Input Sensitivity – 350mV.

Weight – 16 kgs.

Size – 115mm x 430mm x 360mm (HWD)

Recommended Retail Price – AUD$5,495.00.

E. & O. E.