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Colossus

132.185.144.123
Posted on October 19, 2009 at 04:33:43
WALLACE
Audiophile

Posts: 24
Location: London, UK
Joined: July 31, 2008



This is Colossus (or will be when I get around to building it) - bottom stage is power supply with big chokes and 30,000 microfards worth of capacitance per phase - middle stage is driver supply - again lots of transformers, chokes, capacitors. Top stage will have valves etc.

It's going to be big - 24" by 18" - and this is just for one channel . . I'm trying to keep the mains power under 1kw - that's for about 35 watts of audio output power . .

W.

apologies, if needed, posted on October 21, 2009 at 10:01:13
Lew
Audiophile

Posts: 2685
Location: Bethesda, Maryland
Joined: December 11, 2000
 I apologize for my mild attempt at humor, if it put you off. I am sure I and others would like to know more about your project.

RE: apologies, if needed, posted on October 29, 2009 at 10:27:25
WALLACE
Audiophile

Posts: 24
Location: London, UK
Joined: July 31, 2008
 No apology needed !

The more humour the better !!

I know it's OTT - but you only make your dream amplifier once . .and it's dead easy to get carried away :-)
Oy!, posted on October 19, 2009 at 08:27:17
Lew
Audiophile

Posts: 2685
Location: Bethesda, Maryland
Joined: December 11, 2000
 First remark that came to mind. My grandmother said it best.

Oy is right!, posted on October 19, 2009 at 08:34:49
Jim Dowdy
Manufacturer

Posts: 1168
Location: western North Carolina
Joined: July 22, 2000
 I'm curious: what the proposed tube line-up/circuit?

RE: Oy is right!, posted on October 20, 2009 at 19:18:37
Satelliteman
Audiophile

Posts: 101
Location: Napier - The Art Deco City of the world
Joined: May 21, 2006
 Big enough to power a Flood Fight on a Japanese Squid Boat !
RE: Oy is right!, posted on October 29, 2009 at 07:03:15
WALLACE
Audiophile

Posts: 24
Location: London, UK
Joined: July 31, 2008
 Going to be 8 x 6C3C's per channel. Driver's still a bit in the 'planning' stage. At the moment, it's heading towards a differential mu folllower (the D to A converter driving it is fully balanced so I don't need a phase splitter).

Something like this - but with a triode on the top, not a pentode (6SN7).

http://www7.taosnet.com/f10/mustage.html


That's partly why it's a heafty power supply - there's plus AND minus 500 volts . ..

Totally over the top, but I just can't resist temptation.

RE: Oy is right!, posted on October 30, 2009 at 16:08:27
Lew
Audiophile

Posts: 2685
Location: Bethesda, Maryland
Joined: December 11, 2000
 Not sooo different from an Atma-sphere MA2 or MA3, both of which supply + and -400V to the input and driver stages. With Ralph's help, I configured my MA240s, which use six 6C33Cs per monoblock and are built on MA2 chassis', so that each pair of outputs has its own driver tube, thereby enabling me to separately bias each tube. Over the years since then I added CCSs for each of the driver sections, for a noticeable improvement in sound. My input stage is a pair of 6900s in dual-differential cascode, again with a tube-based CCS on the negative side.

RE: Oy is right!, posted on November 2, 2009 at 07:51:45
WALLACE
Audiophile

Posts: 24
Location: London, UK
Joined: July 31, 2008
 Starting to think the same way ! I'm going for the seperate bias as well - I brought a whole load of moterised pots of ebay last year - I like the idea of setting the bias on a meter and hitting the 'auto' button and watching it all bias up the valves to the correct current.

Or watching the output tubes go into meltdown taking the speakers with them if it doesn't work.

W.

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