philv
11-07-2025, 15:10
Absolutely stunning amplifier.
Quoted from the original ad by Rabski
I wanted the opportunity to do another of these, and it came about courtesy of a dead Stereo 20 that was very unloved and appeared to have been stored in damp conditions at some time. Basically, it is now what Leak might have done with the Stereo 20, had cost been less of an issue. It combines the standard, later Stereo 20 circuit, a significantly upgraded power supply section (more in line with the TL12+), revised internal wiring and layout, substantial component upgrades, a good dose of foo, and modern safety earthing. Another one I’d love to keep, but as always, it’s madness here with the amount of stuff.
I started by stripping it totally, including dismantling the transformers. The chassis and transformer covers were blasted and powder coated in metallic dark grey and the transformers gently heated overnight, thoroughly tested and reassembled. All components were removed from the main board, which was then ultrasonically cleaned. Apart from the transformers, every single electronic component is new. Among the upgrades, the power supply now has a large choke fitted (visually, the main difference from standard). The wiring is all point-to-point and re-routed, including separating the filament supplies, HT wiring and output wiring. Signal and speaker wiring is in Neotech ‘single crystal’ UP-OCC and power is in high-purity copper. The valve sockets have been replaced with ceramic types and chassis fixings are now with plated allen bolts. Resistors are nearly all Kiwame, coupling capacitors are Audio Note and the negative feedback loop uses silver-mica capacitors, with closely matched components. The mains socket has been replaced by an IEC using the original mounting hole and there is a new-type mains fuse and a push-button on/off switch. The HT is also now internally fuse protected, a proper mains safety earth has been added, and the original mains output and preamp sockets have been retained for looks but disconnected for safety. Speaker connections are now 4mm sockets/binding posts, and inlet sockets are gold-plated RCAs.
For valves, the gain stage valve is an early US JAN 5751 and the second stage a pair of Siemens ECC83. These are lightly used, test good and are from my own collection. The power valves are matched set of NOS Siemens and the rectifier an NOS Brimar. These were all chosen to balance out the tonal presentation. The rectifier is also now a GZ32, which together with the power supply redesign means the output valves are running a slightly lower plate voltage than original, to give longer valve life and better reliability. Cosmetically the chassis is good, but the transformer covers have a bit of 'acne' where the surface didn't take the powder coating perfectly. It looks tidy enough, just with a bit of ‘patina’. The pictures should show it, as well as the naughty bits underneath. Please note that as per the original, there is no bottom cover (this helps ventilation) so it needs to be placed to avoid any prying fingers.
'Sonically and electrically it is excellent. I have run it here for a couple of hours and it’s a belter. It has the typical Stereo 20 presentation, just with a bit more of everything. It’s very, very far from a laid-back sort of ‘valve’ sound and has great dynamics, extension and bass. It’s relatively high gain (as it sticks to the original main circuit), but the input impedance is now loaded at 100K for easier matching with attenuators and preamps. It’s very difficult to price this, but in view of the specification (and the value of the parts and valves), I think £900 seems fair. Collection (and, of course, audition) from Kettering or meet up anywhere reasonably close is fine. Plus, I'm out and about a fair bit, so meeting up somewhere may be possible. Sorry, but commonsense dictates no courier. It’s too large, heavy and breakable and packing would be a nightmare.
If you still think valves are all soft and cuddly, this will surprise you. A lot.'
The only changes i have made is to swap the power tubes for a very nice teste matched quad of Mullard el84.
Measurements can be supplied.
Collection from eton wick/windsor.
Quoted from the original ad by Rabski
I wanted the opportunity to do another of these, and it came about courtesy of a dead Stereo 20 that was very unloved and appeared to have been stored in damp conditions at some time. Basically, it is now what Leak might have done with the Stereo 20, had cost been less of an issue. It combines the standard, later Stereo 20 circuit, a significantly upgraded power supply section (more in line with the TL12+), revised internal wiring and layout, substantial component upgrades, a good dose of foo, and modern safety earthing. Another one I’d love to keep, but as always, it’s madness here with the amount of stuff.
I started by stripping it totally, including dismantling the transformers. The chassis and transformer covers were blasted and powder coated in metallic dark grey and the transformers gently heated overnight, thoroughly tested and reassembled. All components were removed from the main board, which was then ultrasonically cleaned. Apart from the transformers, every single electronic component is new. Among the upgrades, the power supply now has a large choke fitted (visually, the main difference from standard). The wiring is all point-to-point and re-routed, including separating the filament supplies, HT wiring and output wiring. Signal and speaker wiring is in Neotech ‘single crystal’ UP-OCC and power is in high-purity copper. The valve sockets have been replaced with ceramic types and chassis fixings are now with plated allen bolts. Resistors are nearly all Kiwame, coupling capacitors are Audio Note and the negative feedback loop uses silver-mica capacitors, with closely matched components. The mains socket has been replaced by an IEC using the original mounting hole and there is a new-type mains fuse and a push-button on/off switch. The HT is also now internally fuse protected, a proper mains safety earth has been added, and the original mains output and preamp sockets have been retained for looks but disconnected for safety. Speaker connections are now 4mm sockets/binding posts, and inlet sockets are gold-plated RCAs.
For valves, the gain stage valve is an early US JAN 5751 and the second stage a pair of Siemens ECC83. These are lightly used, test good and are from my own collection. The power valves are matched set of NOS Siemens and the rectifier an NOS Brimar. These were all chosen to balance out the tonal presentation. The rectifier is also now a GZ32, which together with the power supply redesign means the output valves are running a slightly lower plate voltage than original, to give longer valve life and better reliability. Cosmetically the chassis is good, but the transformer covers have a bit of 'acne' where the surface didn't take the powder coating perfectly. It looks tidy enough, just with a bit of ‘patina’. The pictures should show it, as well as the naughty bits underneath. Please note that as per the original, there is no bottom cover (this helps ventilation) so it needs to be placed to avoid any prying fingers.
'Sonically and electrically it is excellent. I have run it here for a couple of hours and it’s a belter. It has the typical Stereo 20 presentation, just with a bit more of everything. It’s very, very far from a laid-back sort of ‘valve’ sound and has great dynamics, extension and bass. It’s relatively high gain (as it sticks to the original main circuit), but the input impedance is now loaded at 100K for easier matching with attenuators and preamps. It’s very difficult to price this, but in view of the specification (and the value of the parts and valves), I think £900 seems fair. Collection (and, of course, audition) from Kettering or meet up anywhere reasonably close is fine. Plus, I'm out and about a fair bit, so meeting up somewhere may be possible. Sorry, but commonsense dictates no courier. It’s too large, heavy and breakable and packing would be a nightmare.
If you still think valves are all soft and cuddly, this will surprise you. A lot.'
The only changes i have made is to swap the power tubes for a very nice teste matched quad of Mullard el84.
Measurements can be supplied.
Collection from eton wick/windsor.