MartinT
13-02-2012, 08:26
This is a Leak Stereo 20 Power Amplifier in gold finish, originally purchased rebuilt from Graham Tricker (GT Audio) around 1992 or so, and then further modified by me.
Modifications: I replaced the two electrolytic reservoirs with large RATA SPX003 32uF + 32uF polypropylene caps and the GZ34 rectifier valve with a RATA fast solid state rectifier (this is easily changed back if required), giving it incredible speed and dynamics. The circuit is modified according to a Hi-Fi World article: it involves essentially changing the biasing of the phase splitter stage to allow direct coupling from the primary stage, reducing gain (a blessing) and fitting the more linear ECC82 valve for the original ECC83 type. I also added resistors to isolate the transformer windings from the output valve screens. I have the notes (http://www.mtc.me.uk/leak_stereo_20_mods.htm) on these mods but sadly not the original article.
Sound quality: I will say it again for anyone who believes that I am a total sand-head: the Stereo 20 has the best midrange of any amplifier I've ever heard. It simply soars, it's liquid, detailed and makes female voice sound extraordinary. Bass is strong, textured, deep and more powerful than the Rogers and treble is sweetly extended and ultimately a touch rolled off. Respect for those transformers, they were superbly well designed. I think the EL84 output valves have a lot to do with it. This was the pinnacle of valve design in its heyday and it sounds bang up to date now.
http://www.mtc.me.uk/images/Leak_Stereo_20.jpg
I'm including a full set of replacement valves as well as 2 x GZ34 (one Mullard) should you wish to revert to valve rectification.
£350 collection only from either Basingstoke (home) or Ascot (work). It's tested working and the buyer can hear it connected up if they would like. I'm very sad to see this amp go but I'll be glad to find it a home and some loving care.
Modifications: I replaced the two electrolytic reservoirs with large RATA SPX003 32uF + 32uF polypropylene caps and the GZ34 rectifier valve with a RATA fast solid state rectifier (this is easily changed back if required), giving it incredible speed and dynamics. The circuit is modified according to a Hi-Fi World article: it involves essentially changing the biasing of the phase splitter stage to allow direct coupling from the primary stage, reducing gain (a blessing) and fitting the more linear ECC82 valve for the original ECC83 type. I also added resistors to isolate the transformer windings from the output valve screens. I have the notes (http://www.mtc.me.uk/leak_stereo_20_mods.htm) on these mods but sadly not the original article.
Sound quality: I will say it again for anyone who believes that I am a total sand-head: the Stereo 20 has the best midrange of any amplifier I've ever heard. It simply soars, it's liquid, detailed and makes female voice sound extraordinary. Bass is strong, textured, deep and more powerful than the Rogers and treble is sweetly extended and ultimately a touch rolled off. Respect for those transformers, they were superbly well designed. I think the EL84 output valves have a lot to do with it. This was the pinnacle of valve design in its heyday and it sounds bang up to date now.
http://www.mtc.me.uk/images/Leak_Stereo_20.jpg
I'm including a full set of replacement valves as well as 2 x GZ34 (one Mullard) should you wish to revert to valve rectification.
£350 collection only from either Basingstoke (home) or Ascot (work). It's tested working and the buyer can hear it connected up if they would like. I'm very sad to see this amp go but I'll be glad to find it a home and some loving care.