1000w class A

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Tubetec

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Nov 18, 2015
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I keep an eye on another forum which shall remain unnamed ,
some jack ass claims he has 8 mono blocks each with 1000w class A ,
Lets do a very basic calculation based on the venerable Sugden A21a
Its 11kg and outputs 23 watts pure class A power ,scale that up 42 times to around 1kw
So each amp weighs 462 kilos and streams 500 watts in heat quiescent ,
theres no point in even argueing with a fantacist douchebox like that , away with the fecin' fairies .
 
Thinking about it again wouldnt 25% effeciency be more like it , 50% you might get if you had an output transformer . So the guy has something approaching four tonnes of amplification minimum and 4kw of latent heat to shift , does the guy wander round the house bollock naked or live at the north pole .
 
Tubetec said:
Thinking about it again wouldnt 25% effeciency be more like it , 50% you might get if you had an output transformer . So the guy has something approaching four tonnes of amplification minimum and 4kw of latent heat to shift , does the guy wander round the house bollock naked or live at the north pole .
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THAT's why the ice is melting there ;-)

Michael
 
The biggest commercial class A amps that I recall were made by Krell (apparently still in business). Several hundreds of watts class A.

I find it amusing that they characterize the sound quality as "warm".... ;)

Krell_Solo_375_XD_Mono_Amplifier_Front-2.jpg
 
Bricasti did a "pretty decent" class A amplifier, it's "a good" 100 Watts.

I build a 2x 10W class A Nelson Pass design with balanced inputs, I thought it would be not so bad.... wrong, it sucks 270W from the socket (measured) and it runs bloody hot. It sounds amazing on my DIY single driver broadband monitors, I tried swapping back to a 2x 65W class AB (Cambridge P500) amp, but no, no, no, no...

I tested the powersupply (+17 -17) on my bench with 200 Watts of halogen bulbs.
I can't find the picture anymore, it looked like I just invented nucliar fusion on my workbench :oops:
 
Yeah Krell I have heard of alright , those boxes are on a completely different scale to regular hifi units.
I did find a Hifi tube amp for sale in local adds here before , it had 8 pairs of 6550 and you probably would have needed an engine hoist to get it off the ground and into a van , its also required its own extra heavy duty mains cable installed back to the utillity box or they did'nt guarantee it would meet spec . Cant remember now the make of it, maybe it was Audio Research , A very very expencive space heater , suppose you want to run it in a hot climate , you'll probably be spending as much again on electricity in cooling , I think I calculated roughly a Killowatt was the standing dissipation . Sold for only a couple of thousand in the end , might have cost 12-15 grand new .

At one point way back I lived with a couple of musician buddies in a big old house , fairly run down part of town with a lot of traffic noise , the band could amp up anytime people came round for a jam .
I had the top floor to myself , my pair of Quad II's would be kept powered permanently during winter months ,it was just perfect to keep the room at a comfortable temp . I was able to keep away from much of the drinking madness of my two housemates tucked away up stairs.
Both those guys are toast now .
 
Speaking to exotic tube amps I recall one from back in the day that used a truckload of tubes in parallel to obviate the need for an output transformer. That was also another room heater.

JR
 
The obvious high power tube amps of history are radio transmitters, and those if I recall are almost universally class B. You can get a 1kW radio transmitter in a truck, but probably not a pickup.
 
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emrr said:
The obvious high power tube amps of history are radio transmitters, and those if I recall are almost universally class B. You can get a 1kW radio transmitter in a truck, but probably not a pickup.
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The famous valve for transmitters (in the U.K at least) was the STC 4212E. I believe the Japanese hifi enthusiasts like the for class A amps & a single valve is good for 75W in class A & 1kW in push pull !!
 

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I think for a SE amp the size of the transformer very quickly gets out of hand for large transmitting valves , you also have a few killovolts to be worying about .
 
I was in a 5kW water cooled Western Electric transmitter from the late 1930's once, 25-30 feet long, 5 feet deep 6 feet high, and the large power transformers were freestanding in a cage behind it.
 
JohnRoberts said:
Speaking to exotic tube amps I recall one from back in the day that used a truckload of tubes in parallel to obviate the need for an output transformer. That was also another room heater.

JR
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Atma-Sphere. I own 3 sets of them, gutted and rebuilt with better front end topology. The largest uses 20 power tubes per amplifier, 6AS7G. They require their own 15amp AC circuit each.... and impossible to use in hot weather.
 
emrr said:
The obvious high power tube amps of history are radio transmitters, and those if I recall are almost universally class B. You can get a 1kW radio transmitter in a truck, but probably not a pickup.
Click to expand...

Most radio transmitter amplifiers are class C. That's how you get the high power, it's tuned to a very narrow band to be fed into an antenna.
 
Jen said:
Atma-Sphere. I own 3 sets of them, gutted and rebuilt with better front end topology. The largest uses 20 power tubes per amplifier, 6AS7G. They require their own 15amp AC circuit each.... and impossible to use in hot weather.
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Hi Jen, I have a pair of Atma-Sphere MA-1 amps and would be most interested in your revised front end schematic and reasoning behind the changes. And yes, they are perfect for our cold Colorado winters!

Getting rid of output transformers makes for amazing improvements to OTL amps. These include microsecond risetimes, low distortion, extended frequency response, and no loss of micro signals as you do in transformers,. See Menno van der Veen's books, where he points out the common transformer problems.
 

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