Power Amplifier Kits
 World Designs 2018

For built versions of our pre-amplifiers and power supplies please visit our Build Service page. All of our pre-amplifiers require a PSU3 power supply and

are an excellent match for our phono stages and power amplifiers.

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Pre3 CF

Pre3 CF is a valve pre-amplifier featuring low output impedance drive to suit any power amplifier.

This 5 input line level cathode follower (CF) pre-amplifier has a voltage gain slightly less than unity and provides an elegant method of

matching modern sources to power amplifiers. The Pre3 CF can be configured by the user to use a cathode load resistor or a Constant

Current Sink (CCS). The CCS provides an improvement in technical performance when driving long leads between the pre and power

amplifiers.

The Pre 3 CF is offered in standard and XL versions. The XL version has a gold plated valve base, upgraded audio cabling, valves and

Vishay / Soniqs capacitors in the audio path. 

The Pre3 CF requires a separate power supply, the PSU3. Please see below.

External dimensions with valves: W135 x D314 x H82mm. Weight: 1.3kg

Standard version £360

XL version £430

    

PSU3

PSU3 is a high performance choke power supply with separate HT and Heater feeds for the Pre3, Pre3CF, Pre4 and Phono3 pre- amplifiers and phono stages. The PSU3 supplies the correct, smoothed, HT voltage for each unit. It can be used with either unit individually or both together. Outputs are via low impedance, multi-way sockets &  plugs and umbilical cables supplied for use with our pre-amplifiers and phono stages. Offered in a single version only, the PSU3 features full Star Earthing and is supplied with Ultra Fast, Low Noise, Schottky Heater Diodes. External dimensions with valves: W135 x D314 x H82mm. Weight: 2.1kg

PSU3  £299

   

Pre-Amplifier Kits

Pre4

The Pre4 is derived from the highly acclaimed Pre3 pre-amplifier, now providing remote control of volume, input selection and a mute function. In addition the Pre4 now has variable gain (up to +21dB) to match with a wider range of source components and an optional balanced output for driving long interconnect cables.

Pre4 is an innovative valve pre-amplifier featuring low impedance drive to suit any power amplifier. This 5 input line level preamp is

essentially an SE triode power amplifier in concept. Pre4 uses an ECC82 double triode arranged as input voltage amplifier and power

output amplifier stages, the latter driving large output transformers.

The use of output transformers not only provides a low impedance drive but also avoids any possibility of slew rate limiting in the output

stage making the performance independent of the capacitance of interconnect cables. Thus the Pre4 will successfully drive long cables

connecting to power amplifiers near the speakers if you wish. Twin pairs of outputs allow easy connection to power amplifier and

headphone amplifier, or bi-amping. The output can be configured to provide a balanced line connection between the Pre4 and the power

amplifier.

Another advantage is due to the interwinding screens used in this advanced design. Effectively the primary and secondary windings are

isolated from each other allowing us to break the ground connection between preamp and power amp thus avoiding the possibility of hum

loops.

The Pre 4 is offered in standard and XL versions. The XL version has upgraded audio cabling, valves and Soniqs capacitors in the audio

path. 

The Pre4 requires a separate power supply, the PSU3. Please see below.

External dimensions with valves: W220 x D314 x H82mm. Weight: 4.5kg

Standard version £725

XL version £795

    

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Pre3

Pre3 is a valve pre-amplifier featuring low impedance drive to suit any power amplifier. This 5 input line level preamp is essentially an SE

triode power amplifier in concept. Pre3 uses an ECC82 double triode arranged as input voltage amplifier and power output amplifier

stages, the latter driving large output transformers.

The use of output transformers not only provides a low impedance drive but also avoids any possibility of slew rate limiting in the output

stage making the performance independent of the capacitance of interconnect cables. Thus the Pre3 will successfully drive long cables

connecting to power amplifiers near the speakers if you wish. Twin pairs of outputs allow easy connection to power amplifier and

headphone amplifier, or bi-amping. The output can be configured to provide a balanced line connection between the Pre3 and the power

amplifier.

Another advantage is due to the interwinding screens used in this advanced design. Effectively the primary and secondary windings are

isolated from each other allowing us to break the ground connection between preamp and power amp thus avoiding the possibility of

hum loops.

The Pre 3 is offered in standard and XL versions. The XL version has upgraded audio cabling, valves and Soniqs capacitors in the audio

path. 

Read the Hi-Fi World review of the Series 3 (Pre3/Phono3) on our Reviews & Gallery page.

The Pre3 requires a separate power supply, the PSU3. Please see below. External dimensions with valves: W135 x D314 x H82mm. Weight: 4.2kg

Standard version £525

XL version £595