Actually, it looks rather like Final's battery powered wiring monstrosity. But who cares about looks? It sounds wonderful!
It's a "minimal" inverted circuit I found here:
http://www.decdun.fsnet.co.uk/gainclonecircuits.html
Differences to the above schematic are: I use an attenuator on the input (not the 56k resistor), I don't have an input capacitor, I used single 220k feedback resistors, and I left out the ground filter.
Just now I bypassed the Panasonic FC 1000uF PSU caps with 1uF Auricaps, and the sound was transformed. Before it was merely "good solid state" - now it's simply "excellent". The PSU cap bypass got rid of the grain I was hearing in vocal sibilants, added warmth, and improved soundstaging.
Before this last tweak it was a tossup whether my tweaked Belles 150a or the GC sounded better. Now I'm pretty sure the GC has come out on top.
I built the amp as a dual mono circuit sharing one heatsink, completely point-to-point. I used way more heatsink than required; it's stone cold. In fact, I used a lot more of everything than required. The whole shebang weighs around 30 pounds.
PSU
surplus 10A line filters
Plitron 300VA 18V secondaries
10A bridge rectifiers
1000uF Panasonic FC caps (electrolytic)
1 uF Auricaps (metallized polypropylene)
chip
LM3875 insulated version
Riken metal film resistors
generic 16 ga primary wire, CAT5
DACT 50k attenuator
My speakers are DIY - the infamous Parts Express 69 cent surplus TV drivers, in a open baffle line array of 9 per side, roughly 95 dB sensitivity. Drivers are tweaked with coating and foam strip damping.
Source is a Dan Wright modified MSB Link, fed by an M-Audio AP2496 sound card via a Monarchy DIP.
I could get some pictures up of the amp for you to admire, but trust me, it's a horrendous looking rat's nest, a short circuit waiting to happen.
Sincere thanks go to National Semiconductor for engineering such a great chip, Peter Daniel for inspiration, Thorsten for prosetylizing, Decibel Dungeon for schematics and instructions, 47 Labs for starting the craze, RJM, CFraser, the Thor-amp page, and everybody else in the Top 20 of Google "Gainclone" links!
Cheers,
Andrew
It's a "minimal" inverted circuit I found here:
http://www.decdun.fsnet.co.uk/gainclonecircuits.html
Differences to the above schematic are: I use an attenuator on the input (not the 56k resistor), I don't have an input capacitor, I used single 220k feedback resistors, and I left out the ground filter.
Just now I bypassed the Panasonic FC 1000uF PSU caps with 1uF Auricaps, and the sound was transformed. Before it was merely "good solid state" - now it's simply "excellent". The PSU cap bypass got rid of the grain I was hearing in vocal sibilants, added warmth, and improved soundstaging.
Before this last tweak it was a tossup whether my tweaked Belles 150a or the GC sounded better. Now I'm pretty sure the GC has come out on top.
I built the amp as a dual mono circuit sharing one heatsink, completely point-to-point. I used way more heatsink than required; it's stone cold. In fact, I used a lot more of everything than required. The whole shebang weighs around 30 pounds.
PSU
surplus 10A line filters
Plitron 300VA 18V secondaries
10A bridge rectifiers
1000uF Panasonic FC caps (electrolytic)
1 uF Auricaps (metallized polypropylene)
chip
LM3875 insulated version
Riken metal film resistors
generic 16 ga primary wire, CAT5
DACT 50k attenuator
My speakers are DIY - the infamous Parts Express 69 cent surplus TV drivers, in a open baffle line array of 9 per side, roughly 95 dB sensitivity. Drivers are tweaked with coating and foam strip damping.
Source is a Dan Wright modified MSB Link, fed by an M-Audio AP2496 sound card via a Monarchy DIP.
I could get some pictures up of the amp for you to admire, but trust me, it's a horrendous looking rat's nest, a short circuit waiting to happen.
Sincere thanks go to National Semiconductor for engineering such a great chip, Peter Daniel for inspiration, Thorsten for prosetylizing, Decibel Dungeon for schematics and instructions, 47 Labs for starting the craze, RJM, CFraser, the Thor-amp page, and everybody else in the Top 20 of Google "Gainclone" links!
Cheers,
Andrew
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