Diy HiFi Supply EZ Preamp Kit

The EZ kit from Diy HiFi Supply is a a linestage pre-amp with an adjustable gain from 6, 12, 18, 22 and 30db. Input impedance is 400k+ depending on the gain setting chosen and consequently measurements vary with different tubes fitted. This is not my own unit but for Val I know who asked me to build this pre-amp with some special custom modifications.

Upgrades :-

Blackgate PSU Caps for HT and Heaters
Calrity Caps for Audio Coupling
Wima FKP Flim PSU By-Pass Caps
Gold Plated Silver Audio Wire in Teflon
Seiden Selector Switch
Japanese Step Attenuator
Silver WBT Style RCA Sockets
Custom Made Wooden Knobs


Sound is mid range focused and very slightly forward with certain tubes. I tried various tubes and the best two were an Amperex 6922 and Siemens 6922 (Ecc88). It is detailed and very dynamic, esp with these custom mods but lacks the ultimate wide bandwidth, bottom end weight, big full sound and slam of some other pre-amps I have heard. It suits my Martin Logan's in a small room as these can sound a little too lazy and laid back on some amplifiers. This pre-amp brings them to life in the mid range. It is quite an upfront exciting sounding pre-amp. Bare in mind it is also possible to make this pre sound completely the opposite, ultra warm, lazy and dark, with a 6CG7 tube I discovered.

The sound as with any unit is very much system and room dependent. You cannot take any component in isolation but must consider it as part of a complete system when evaluating the sound. Also bare in mind this unit has some custom parts which will alter its default character and you need to select a tube that suits your own system and taste. On my own Hi-Fi with the Amperex 6922 it is a good match. The dynamics remind me of the Aikido pre-amp, lively and fast. On Ian W's system with Tannoy Canterbury 15 and a David Berning power amp the sound was more forward with a strong focus on the mid band. On Dave H's system using Impulse H2's and a Russian Push-Pull Tube amp again it has a slightly forward mid band. If you are not careful in matching it could become a little fatiguing after a while. The WAD pre2 had a similar characteristic and that used a single Ecc88 tube so maybe it is a characteristic of this tube type. So best to avoid bright forward sounding speakers and power amp. With a more laid back and natural sounding speaker or tube power amp would be a good match.

This is a nice little pre-amp which is fairly easy to build and perfect for a beginner. It should suit a tube power amp better than most solid state amps. It has more than enough gain at its lowest setting to drive anything, even a low power SET amp. The gain can be increased further by a jumper selection on the board.


Diy HiFi Supply EZ Preamp Kit
Diy HiFi Supply EZ Preamp Kit
Diy HiFi Supply EZ Preamp Kit
Diy HiFi Supply EZ Preamp Kit