The Most Powerful Tube Amplifier Ever Built?

The Most Powerful Tube Amplifier Ever Built

OK – you’ve got the most powerful synths ever, and you’ve got the most powerful computer gear ever, and you’ve got the most powerful kick ass tracks ever – what are you going to play them on?

The NAT Audio Magma, of course – designed to be the most powerful tube amplifier ever built.*

The NAT Audio Magma is capable of blasting its raw power at 4 or 8 ohms with a frequency response of 10-10,000 Hz. To produce this power the Magma relies on three different tubes: the 6N1P-EV, the 6N30P-DR, and the Eimac 450TH.

In order to handle this power, the Magma utilizes an unusual direct-heated NOS amp design that runs into a DC-coupled all-tube circuit, which allows the amp to achieve a damping factor of 20. In addition, the power and output transformers are rated for 1000 watts, and the power supply capacitance is over 500 joules. The Magma weighs in at 88 lbs. and will set you back $55,000 for a pair of the monoblock amplifiers.

*NAT say they have produced the most powerful single ended in the world.


  • Type: Single Ended Class “A”
  • Power Output: 160 Watts @ 4 & 8 ohms; 1 kHz
  • Frequency Response: 10 Hz to 100 kHz; -3dB
  • Input Impedance: 100 kohms
  • Input Sensitivity: 2.7 V RMS for full power output
  • Gain: 22.50 dB at 8 ohm
  • Rise Time: 5 microseconds
  • Noise: 105 dB below rated output
  • Phase Status: Non inverting (0 degrees)
  • Tube Complement: 1x 6N1P-EV, 1 x 6N30P-DR , 1 x 450 TH
  • Power Requirement: 110 VAC or 220 VAC @ 50 to 60 Hz, 450 VA
  • Dimensions: 11.8″ wide x 25.2″ deep x 14.2″ high
  • NET Weight: approx. 88 lbs per piece
  • Price: $55,000 per pair


  • Single Ended pure class A mono block power amplifier
  • Eimac power industrial type direct heated triode 450TH (N.O.S.)
  • DC coupled all tube circuit (only output transformer without capacitors)
  • CE comfortable
  • 160 W of pure class A @4ohms or @8ohms
  • Low global feedback configuration with damping factor of 20
  • High capacity in power supply resulting to over 500joules of energy storage
  • Custom designed power transformer of 1000W encapsulated-low density
  • Custom designed output transformer of 1000W encapsulatedlast generation
  • Full double stabilization of high voltage for driver tubes
  • 6N1P-EV & 6N30P-DR long life military grade tubes for driver purposes
  • Full automatic bias with automatic-adjust (no any adjustment).
  • Variable bias (two mode with 40W & 160W of output power)
  • Balanced DC power to supply filament of output tube
  • Balanced regulated DC power to supply filament for driver tubes
  • Both input and output WBT connectors
  • Input wired with pure 6N silver (99,9999% of silver purity)
  • All aluminum modulated chassis with double 25mm thick front panel

36 thoughts on “The Most Powerful Tube Amplifier Ever Built?

  1. I have seen a Diagram for a 500 watt push pull output (Philips) with the HT at 3KV, response was something like 50Hz to 6Hz and this was more than 20 years ago. Personally I hate valves, they a crap in producing HiFi. If you been brainwashed into thinking valves are the best then you must have more dollars than cents (sense). They sound great in guitar amps and old style radio.. Distortion is what these babies make! You must be crazy to spend 55.000 dollars this old technology. Damping Factor of 20 lol

    1. Zed, I tend to disagree with you.. The quality of any amplifier depends on the quality of the components used to manufacture it..and even this won't help if a person doesn't know how to utilize the piece of equipment in question! That's only my opinion, and my experience as a qualified D-Tech graduate Sound Engineer.. 😉

    2. The funny thing about spec sheets is that they don’t translate into psychoacoustics (ie what your brain hears as live). Once you hear a good tube, you will never go back to that awful, ear fatiguing sound of constantly switching solid state circuitry. I used to be an SS junky based on tech sheets too.

    3. hello
      im not certain that this is the most power tube amplifier
      maybe the most recent and design looking
      in the early 1970s there was a orange kila a 1000 or more watt power pa amp using lots of kt88s
      and i i remember a GEC 2000watt factory pa amp using banks of DA42’triodes
      but i supose these couldnt be classed as hifi amps
      i myself built a big triode audio amplifier using 2 industrial STC tubes with about 3000 volts of ht
      60amps of heater current and 8 KT88s as drivers
      they were forced air cooled and i remember i could measure getting on for 2000 watts into a big load
      anyway its nice to see people are still using big tubes
      thanks peter

  2. Now you all know what I mean when I talk about paper powered amplifiers. Any pure class A amplifier is running a half power in total quiescence (dead quiet). This is a pretty web page, also a technical selling ploy that I hope has become antique. The chinese are trying to dump oddball tubes on our market, and I say that that is what you are viewing here with this ad. Just search and you’ll see them with free shipping and russian tubes. Push pull, – will burn up as soon as you turn them on without the exact right load on the speaker outputs. Now I’m laughing too hard to keep typing…

  3. There are many tube amplifiers making lots more power than this. Production ones include the Altec 260,1570B, and others, the McIntosh MI200 and MC3500, and….about two dozen others.

  4. A little place in North Hollywood made a nice Class-A tube amp back in in the 1970’s that used two Eimac 1000Z tubes and would easily top 1.5KW rms output!
    Of course it had a plate transformer that weighed 200 lbs, a 2nd
    transformer (for the filaments) that added another 40 lbs to the total..
    ..I think they were called Kenton Audio Laboratory..and the amp was
    dubbed “The Theater Reference Amp”. We had a pair of them at KPFK-FM studios in the listening room..driving a pair of stadium-series (double 15″ drivers) Klipsche Horns. Sounded great!

  5. We market a SET from SAC Thailand the GM 70 which uses 2 ULANOV GM70 output tubes which boasts 70W pure class A output, bandwidth
    20hz – 30KHz (-3dB) AT FULL POWER ( 5Hz – 70KHz @ 1W) and less than 5% distortion at FULL POWER (0.08% @ 1W), at a mere £8000 dollars a pair. as about 1/7 of the price I know where I would put my money!

  6. also whatever STUDIO you would get for $55K or even twice that would be more CRAP DAW from today's digital losers studios, not REAL equipment or ability…then there's talent…oh forget it!

  7. Hi

    Thats looks very nice done amp, I have my doubts about most powerful amp, I so and amp with a 4CX1500B tube that pull out like 4Kw.
    I like the amp but I think you should change the most powerful part.

    1. Hi

      I do agree.. Young sound enthusiasts don't have any idea, anymore of what a really powerful amplifier is, these days, and also, they don't understand that there is a significant difference between one Transistor watt, and one Valve watt!

  8. Your line of "most powerful ever built" is complete nonsense, and an absolute lie. It surely looks like a good design and well built SET, and has quite a bit of output for that topology, but you really need to do a *little* research before making statements that make you look like a complete idiot.
    And to Zed- have you heard any modern high end tube amps? The well designed examples simply make music. I, for one could care less about distortion figures when a system sounds dry and fatiguing.

  9. >.< LOL cant believe the pore person writing this is that stupid.
    single 813 has more power than that and i just built an amp with 4 of them !
    that is over priced junk. but to be quite honest that tube is orgasmic…. !

  10. May be they use platinum wire in the transformers,and golden ones for point-to-point wiring! The market for such high-end toys is very small,to say the least…

  11. I´ve seen "crappy" paintings costing much more n this amplifier, and I am pretty sure there has been MUCH less work involved in producing em.
    So is this amp worth the money? No idea…
    You cannot judge a amplifier on its looks, specifications or pricetag.
    That is entirely impossible.
    Only thing I can say is that 160W single ended cost more than 500W AB-push-pull.
    Normally, all those high power amps are only needed because most speakers trade efficience
    for something that givs them a edge in some other form and things (in this respect) went wrong a long time ago. Just remember, a few acoustical watt in your livingroom would blow your head off and deafen you for the rest of your live!!
    So, if I really want that, I would rather spend 50000,00 on the speakers and 4900,00 on the amp and max 100,00 on decent cables (just to put things into proportion).

  12. Offcourse, most powerfull is nonsense, furthermore power is no measure of performance and has usually to be traded against a variety of other parameters of importance.
    Even power in a car-engine has to be traded against other parameters (wich also led to the highly unfortune horsepower-maxed designs of most of todays cars).

  13. My Kenwood Transistor Home theatre has about ten times the output wattage of this tube amp..220 watts x 7, plus 2 x 350 watts for the subs.. -I personally know about 55 KW Class-D Valve Amplifiers used for open-air concerts in South-Africa, and are also currently busy with my own 4+ KW Self-Designed Tube amplifiers, of which I will post some diagrams, later this year!

    My Car sound system's output wattage is 2050 Watts RMS (Total) at a stable 8 Ohms… -160 watts…..oh shame!

  14. -Are the Tube amps, though? -Remember: A single tube Watt is about equal to 2 or 3 Transistor watts, as Tubes operate at High Voltage and also has a much higer output current than a Solid-State amp of the same Wattage..

  15. The problem here is the lead question .”Most powerful Tube Power Amp.” What the manufacture is claiming is it’s the most powerful production SET amp (Single Ended Triode) One Tube Directly Heated. synthtopia asked a question the manufacture never claimed and after reading the comments most of its followers have not a clue what SET Amps are. Ive had built 2A3, 300B, 211, and 845’s These SET’s power range from 3 to 50 watts. To get 160 watts out of one tube is quite impressive with its specs. I would like to pose this question to you “SS” people out there. How many watts can you get out of a single transistor? Answer; 60 crappy watts? Actually I don’t know. and don’t care.

  16. Tubes are the Kings of high power RF applications (3CX15000A7 for ej.), and please don’t talk about MOSFET RF power amplifiers, however we are entering into the Digital Era for say the last.

    As for those people who say Solid-State audio amplifiers are crap compared to Tubes audio amplifiers, is like say that Plasma TV’s are crap compared to the CRT’s, also they never heard a High-End Reference audio amplifier, and yes Audio Analyzers talks for itself, but an audio tube fan-boy will never trust the audio analyzer results when a High-End SS AF Amp outperform a tube amplifier.

  17. With way too less bucks than 55K one can get a full set tube amp Macintosh system, player and speakers which produces a legendary sound…

  18. Just to clarify, the claim is the most powerful single power tube tube (direct heated) single ended triode (DHT SET). This is not the same as a push pull or paralleled SET.

  19. I’ve used both solid state and valve, I still prefer my 2x phase linear 700b’s that are pushing
    780watt rms per channel x 4.
    But the issue is what sounds good,Phase Linear sound pretty good to my ears and
    have sufficient headroom to avoid clipping,if you like ‘furry’ harmonically inaccurate mixes,go ahead use valves,but your cd buying public will mostly hear your product through solid state devices,mixing for the tiny amount of folk with similar valve amps is plain stupid.The Best studios avoid valves in monitoring applications..FACT!!!

  20. Mass-produced or kit.? There was a mono kit in 1956 that used 2 (4-1000a)tubes. It produced 3040 watts @ 5000v. Class A amp 2% Thd if carefully assembled. The tubes could be pushed to 6000 volts (safely) producing better than 4400 watts.

  21. I love tube audio amps but…
    So sick of lies & misinformation. A output transformer rated for 1000W would huge & weigh 200lbs or more. It would be unnecessary & wasteful in a 160W amp. Exaggerated specs & price from a greedy company, this sort of thing goes on everywhere in the audio industry.
    Also to those misinformed folks saying stuff like 1W of tube power is = to 2 or 3W of SS power, that simply is not true. People saying this stuff certainly have no knowledge of the laws of electricity, such as Ohm’s law or others. 1W is 1W regardless of where it comes from. Tube amps distort more which can make them sound louder, but its an auditory illusion. It has nothing to do with the amp’s power delivery in W.
    The industry preys on the growing lack of knowledge in the consumer market, especially in the USA, where very few people have any knowledge of the science of electronics engineering, & people are generally not well educated. Sadly, the USA general population seems to be getting more & more ignorant, & have less & less common sense.

  22. A Class A amplifier is a relatively simple amplifier class as well as solid state and tube. The defining principal of class a operation is that all the amplifiers output devices must be conducting through the whole 360 degrees cycle of a waveform. Class A can also be broken down can also be broken down into single ended and push/pull from the basic diverges from the explanation above by utilizing output devises in pairs. While both devices are conducting through the complete 360 degree cycle, one of the devices will shoulder more of the load during the positive portion of the cycle; while while the other handles more of the negative portion of the cycle; the primary advantage of this arrangement is reduced distortion relatively single ended designs, as even order harmonics are canceled out. In addition to single ended push/pull designs are less susceptible to hum; single ended designs tend to require special attention to power supply to migrate this issue.

  23. Most powerful tube amp???? A Marshall Major will give you 200 watts.
    55 grand a pair – maybe to some NBA jack-off with more money than god.

  24. Back in ’85 or ’86 I built a custom pair of SET monoblocks using Eimac 3CX2500 triodes. It took almost a month to hand wind the toroidal output transformers.

    1. I am interested on building an amplifier with 3CX2500 tube.I would really like to send me some kind of schematic if you like with some data about the output transformer and the grid bias of the tube. I want to ask you also what did you do to prevent hum

  25. Why does it say Frequency Response: 10-10,000 Hz and then later on Frequency Response: 10 Hz to 100 kHz; -3dB so Which is it? 10,000Hz is 10kHz not 100kHz, Maybe the writer is bad at math? If its 10kHz its crap and if its 100kHz its awesome big difference in the two.

  26. a) kickass track ? hmm with a damping factor of 20 LOL ok try it … you will easily find your woofer cones at the corner of Milton and Broadway ( convenient location if there was ever one ) in beautifull Banff British Columbia .. the smoke makes em easy to spot.

    Seriously .. 20 ? That’s totally inadequate.

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