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What is the most powerful audio output tube?



 
 
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  #21  
Old December 9th 16, 08:32 PM posted to sci.electronics.design,rec.audio.tubes
Roger Hayter
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Posts: 1
Default What is the most powerful audio output tube?

boB > wrote:

> On Thu, 08 Dec 2016 09:19:23 -0600, wrote:
>
> >What is the most powerful audio output tube, as far as RMS wattage
> >output?
> >
> >I have gotten some powerful sound from four 6L6 tubes in push-pull
> >parallel. but I want more. I know it's possible to use eight 6L6 tubes,
> >which I believe is called " push-pull parallel - parallel", but I'm
> >looking into other possible tubes.
> >
> >At one time, I thought the 807 tube was more powerful than the 6L6, but
> >after careful research, it's almost identical, but with a different
> >envelope (plate on the top cap).
> >
> >I'm looking to get a full 500W RMS (or more) output (per channel), from
> >all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
> >RMS (per channel).

>
>
> How about a high AVERAGE output wattage ?
>
>
>
> boB


I think you are fighting a losing battle here. About 10 or 20 years ago
I wrote to the editors of the RSGB magazine complaining about "RMS
power" being used in an article they published and they refused to
publish my letter, apparently on the grounds that I was a boring pedant.
Admittedly AM does get a bit complicated when the peak RF power of an AM
transmitter is a real power (not an instaneous peak of a sinewave)
whereas it represents the peak of an audio waveform of which the power
is not determined by the level of this peak. But there is still no
such thing as RMS power.

--

Roger Hayter
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  #22  
Old December 9th 16, 09:45 PM posted to sci.electronics.design,rec.audio.tubes
Michael A. Terrell
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Posts: 318
Default What is the most powerful audio output tube?

wrote:
> What is the most powerful audio output tube, as far as RMS wattage
> output?
>
> I have gotten some powerful sound from four 6L6 tubes in push-pull
> parallel. but I want more. I know it's possible to use eight 6L6 tubes,
> which I believe is called " push-pull parallel - parallel", but I'm
> looking into other possible tubes.
>
> At one time, I thought the 807 tube was more powerful than the 6L6, but
> after careful research, it's almost identical, but with a different
> envelope (plate on the top cap).
>
> I'm looking to get a full 500W RMS (or more) output (per channel), from
> all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
> RMS (per channel).



http://www.g8wrb.org/data/Eimac/8973.pdf A pair will give you over two
megawatts.

--
Never **** off an Engineer!

They don't get mad.

They don't get even.

They go for over unity! ;-)
  #23  
Old December 10th 16, 04:36 PM
John L Stewart John L Stewart is offline
Senior Member
 
First recorded activity by AudioBanter: Jan 2011
Location: Toronto
Posts: 301
Smile

Quote:
Originally Posted by View Post
What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).
--------------------------------------------

Early in my career as I interned for my P.Eng I built a regulated DC power supply. 4.5 KV at One amp ain't easy. And one needs lots of safety systems, otherwise death is a sure thing.

The passers were 3X 304TH, all grids driven +ve. It ran a Philips cooking magnetron continuously, driving an experiment involving active Nitrogen in an evacuated glass vessel, my supervisors Prof JSM (Andy) Anderson's experiment at the time. Was about 1960.

The safety system did operate on one occasion as it discharged the storage caps after a fault. Lots of noise from that explosion. But it saved my ass!
  #24  
Old December 11th 16, 06:42 AM posted to sci.electronics.design,rec.audio.tubes
Jon Elson[_2_]
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Posts: 1
Default What is the most powerful audio output tube?

wrote:

> What is the most powerful audio output tube, as far as RMS wattage
> output?
>

4CX25000A would be good! Hmmm, I think the filament runa about 10 V at 170
A, you can run at least 10 KV on the anode at several amps. The output
transformer would be about the size of a small car.

I was at a Greatful Dead concert in 1969 at the Fox Theater in St. Louis,
and they used the modulator out of an AM broadcast transmitter as an audio
amp. The tubes were about a foot in diameter.

Jon
  #25  
Old December 12th 16, 07:40 PM posted to sci.electronics.design,rec.audio.tubes
Big Bad Bob
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Posts: 323
Default What is the most powerful audio output tube?

On 12/08/16 08:55, John Larkin so wittily quipped:
> On Thu, 08 Dec 2016 09:19:23 -0600, wrote:
>
>> What is the most powerful audio output tube, as far as RMS wattage
>> output?
>>


[snip]

> https://dl.dropboxusercontent.com/u/.../Tubes/833.jpg


big sucker. 4 terminals, so I'm guessing it's a power triode for RF
output, directly heated cathode. Lots of 'issues' powering it up for an
audio amplifier. You'll need a center-tapped cathode supply, for
starters, and a fixed bias supply for the control grid. Since the
control grid [appears to be] on one of the 'cap' electrodes, it's
probably designed to operate at a positive voltage for class C
operation. So a Class 'A' or push-pull 'AB' might not give you the
results you want. I could see AB2 maybe working, but lots of
experimenting involved in making something like *THAT* "fit".

better to use KT88 or similar [like a Marshall amplifier]

http://www.drtube.com/library/schema...-schemas#Major

http://www.drtube.com/schematics/marshall/200w.gif
(a generic schematic)

4 of them gets you 200W. I guess 8-10 would get you 500W with the right
transformer.


  #26  
Old December 12th 16, 08:18 PM posted to rec.audio.tubes
Peter Wieck
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Posts: 2,414
Default What is the most powerful audio output tube?

I dunno - the OP asked about *AUDIO* output tubes. Kinda-sorta puts transmitter tubes out of the realm of discussion. I still think the KT family is the best avenue to explore - starting with the KT88.

Peter Wieck
Melrose Park, PA
  #27  
Old December 13th 16, 02:21 AM posted to sci.electronics.design,rec.audio.tubes
Big Bad Bob
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Posts: 323
Default What is the most powerful audio output tube?

On 12/08/16 11:18, bitrex so wittily quipped:
> I'd question my sanity if I started thinking about a 500 RMS watt
> all-tube amp though. Well, this guy actually did do something rather crazy:
>
> http://www.chambonino.com/construct/const9.html
>
> Output transformer looks like it weighs about as much as I do.


I like it already.

You win!


--
your story is so touching, but it sounds just like a lie
"Straighten up and fly right"
  #28  
Old December 14th 16, 05:25 PM posted to rec.audio.tubes
Andre Jute[_2_]
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Posts: 631
Default What is the most powerful audio output tube?

On Thursday, December 8, 2016 at 3:20:48 PM UTC, wrote:
> What is the most powerful audio output tube, as far as RMS wattage
> output?


There is a self-contradiction in this question. There are lots of really powerful tubes but they aren't audio tubes; many sound like ****. There is, even today, plenty of choice in quality audio tubes that sound great, but they aren't necessarily all that powerful. In hi-fi, furthermore, it is accepted that you sacrifice some of the available power to operate the tube on the flattest part of its transfer curve, so that mitigates against hogging out all the available power. Also, the most refined audio sound comes from triode tubes, which are pretty inefficient, meaning you need lots or very big, not ones to make any appreciable power.

However, unlike some of the advice that you're getting here from people who've never built or heard a big tube amp, there are ways to get around it. First of all, you can parallel standard tubes like KT88 to your heart's content (well, actually the depth of your pocket, because the custom iron will cost plenty); I had a big OTL KT88 amp built as a modular rack mount system that by rewiring would give any output you wanted; it took up two bays; but it sounded like what it was, a PA system. Even the humble EL34 can build into a very potent amp: I got 96W of high quality audio sound out of parallel push-pull tubes running in class A/B with toroidal trannies in a stereo amp that two people could handle with ease, one with some difficulty; for home use it had 18W in Class A, so the massive oomph was rarely needed.

Next, some of the broadcast tubes sound fabulous, for instance the 845 broadcast triode, and you can parallel triodes in single-ended output for the finest sound of all, zero negative feedback SE, same as you can pentodes in push-pull. For instance, my 80W SE amps were deliberately operated at only a fraction of theoretical output to linearize the sound. I could as easily have chosen your 500W output if I were willing to sacrifice some sound quality; instead I put the time and the money into high-sensitivity speakers.

None of this throws up insuperable technical problems. The biggest problem of big amps is in fact the availability and cost of very high voltage connectors for the separate components, or the monstrous weight if you build the thing in one unit. For my 80W SE amp, Menno van der Veen designed the transformers for me, and Plitron wound them, and listed them for the intrepid. But it is long since broken up as too heavy, too hot, too large, too dangerous, just too unnecessary. The booster amp, 3.8W of SE 300B, with a bicor horn turned out to produce all the sound pressure I actually need. (A booster amp is a complete small power amp you use to drive a much larger power amp.) Don't laugh. When a sports field across the street from my house annoyed me with their unshielded PA, I coupled my 3.8W 300B SE amp and bicor horns to the stairwell in my four-storey town house, opened the front doors, and blasted their premier event of the year into incoherence. They scrapped the offending PA the next day.

***
If you're just building a humongous amp to prove you're a swinging dick, great, I admire initiative and balls and magnificent obsessions. But if you have a real problem to solve, like x sound pressure in y spatial volume, I suggest you redefine your need working backwards from the speakers: if your speakers are sensitive, a Bessel Array or bicor horns, the amp soon gets down to a practical size and electrical requirement and the costs start approximating reality as she is lived.

For a Bessel Array, try the brief introduction he
http://www.audio-talk.co.uk/fiultra/...n%20BESSEL.htm
And the smallest of my bicor horns looks like this inside:
http://www.audio-talk.co.uk/fiultra/...20T91HWAF3.jpg

Andre Jute
  #29  
Old December 14th 16, 06:16 PM posted to rec.audio.tubes
Big Bad Bob
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Posts: 323
Default What is the most powerful audio output tube?

On 12/14/16 08:25, Andre Jute so wittily quipped:
> For a Bessel Array, try the brief introduction he
> http://www.audio-talk.co.uk/fiultra/...n%20BESSEL.htm


too brief, though you piqued my curiosity.

Then I went he
http://www.angelfire.com/sd/paulkemble/soundf.html

and my curiosity 'peaked'. Interesting, but why do you WANT "that much"
sound pressure now?

my ears bleed just thinking about it...

  #30  
Old December 14th 16, 07:48 PM posted to rec.audio.tubes
Peter Wieck
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Posts: 2,414
Default What is the most powerful audio output tube?

On Wednesday, December 14, 2016 at 12:15:06 PM UTC-5, Big Bad Bob wrote:
> On 12/14/16 08:25, Andre Jute so wittily quipped:
> > For a Bessel Array, try the brief introduction he
> > http://www.audio-talk.co.uk/fiultra/...n%20BESSEL.htm

>
> too brief, though you piqued my curiosity.
>
> Then I went he
> http://www.angelfire.com/sd/paulkemble/soundf.html
>
> and my curiosity 'peaked'. Interesting, but why do you WANT "that much"
> sound pressure now?
>
> my ears bleed just thinking about it...


If you want an excellent example of a really *bad* array, look at the Bose 901 in any of its iterations. Bleeding ears are very nearly a certainty with such a device. Further, as this case illustrates all to well, William of Occam had it right: Eschew needless complexity. There is no valid reason other than as a tour-de-force to create such an array in a non-specialized application when many and far better alternatives are available, including any of several well-established planar options.

As to very large tube power-amps, given the inherent physical and safety issues involved mixed with the very real costs mixed with the time involved - this is almost why PERT would be a better project management tool than CPA.. CPA is designed to reach a specific goal by a specific time. PERT is designed to reach a specific goal by the most effective process - time not being at issue. Getting a man on the moon was done via PERT, developed by the US Navy for their ballistic missile (Polaris) program. Coupled with CPA/M it became the tool-of-choice for complex projects delving into uncharted processes.

Speakers are an exercise in moving air. Not in large distances, but in many, very small movements so as to attempt to duplicate sounds recorded somewhere else. Complex sounds in considerable volume require complex means to reproduce - also in considerable volume *relative* to the listening area. If we exclude headphones (no one needs 500W for headphones), the amount of energy required to move sufficient air will be proportionate to the volume to be filled, but that proportion will not be linear.

My personal gold standard for testing a system is this:

https://www.discogs.com/Saint-Sa%C3%...elease/7664706

Recorded right down the street from where I was living at the time. My listening room was then 16 x 27 x 9.5 feet (~4,100 c.f./410 c.m.), so not a small venue. Today it is 17 x 28 x 10 - a touch more difficult. I could do a credible reproduction in the former location with a 425 watt/4/rms amp into AR 9 speakers. Today, it is a 225 watt/6/rms amp into big maggies (MGIIIa).

Between the two ARs, I had 570 square inches of active radiating surface. Between the two Maggies, I have 2,550. Maggies, albeit power-pigs, are spoilers and will ruin a listener forever. But, the point is that single-source/single-driver speakers simply cannot move enough air to make a dent in complex sources at complex volumes in challenging settings - may as well not even waste one's time. Bessel Arrays are possible options - but pretty much doomed to failure unless taken as an exercise in their own right. And, as it happens, when proposed 'back in the day' they were listed as a "high-powered option".

(My, but this is turning into a bit of a rant)

As it happens, the differences between tubes and SS are being discussed in another forum, and citing all kinds of sources, one of which is: http://www..dwfearn.com/tubes_vs_transistors.html Note the date.

Solid-state has evolved considerably in the last 44 years. To the point where the actual differences between the two, while real, are to where one will be challenged to say which is a superior option for the reproduction of music. Tube technology and/or topology has not evolved in any meaningful way over that same time. I would suggest that the OP go ahead and purchase a couple of 500 watt Class D modules (https://www.amazon.com/1000W-Stereo-...X6CTSDKFRGB39M as a full kit) and see what 500 watts sounds like before spending perhaps 20 x that cost for a similarly powerful tube device.

I am emphatically *not* attempting to discourage the OP from pursuing a dream. What I am suggesting is that the OP do the research (other than here), perhaps check in a few of the DIY venues for similar projects, get some advice from those that have done it. I would also strongly suggest getting in touch with Patrick Turner ( http://www.turneraudio.com.au/ ) who is a past-master at specialty and exotic tube amps, winds his own transformers and might be convinced to wind again for others (at a cost, but well worth it). In other words, set a goal and make a plan to reach it.

Many of us here have the solder scars and history to show for some passing acquaintance with the means, methods and related skills and processes associated with the tube hobby. Several glaring examples do not, having a more developed Munchhausen complex to make up for that lack. Writing for myself, my preference is towards the restoration, care and feeding of vintage equipment designed by others but open to improvement. I have designed and built one (1) amp 'from parts' for myself, and have the makings (Iron) for one other. The former is based on the venerable 6BQ5 in PP. For the other, I am torn between several from the 6V6 at one end and the 5881 at the other. It will be some years. But, the point, again, is that there is very little new under the sun in tubes. No need to invent the wheel from scratch when there is so much knowledge and material available that needs only to be refined and executed.

Rambling back to speakers: one wants speakers to be able to handle the most quiet passages with grace and clarity, yet bring that same grace and clarity to those that are 30dB louder. And electronics that are capable of the same. Many speakers 'break up' if required to produce across that range cleanly.

Gets down to Horses for Courses. If one lets the amount of power available drive the choice of speakers, one severely limits one's choices and options, as well as severely limits the types of signal as may be processed cleanly. If, on the other hand, one lets the speakers drive the power requirements, then the choices are near-infinite. And why I fully support the concept of a 500 watt tube amp - overcoming the primary fault of tube amplifiers everywhere *NOT* enough power. I am _always_ curious of what can be done with various parts-and-pieces. Over the next several months, I will be culling the herd developed by this curiosity and parting with five power amplifiers, two pre-amps, two tuners and various other bits and pieces. All fun. None very costly, none very significant. But, to repeat, all fun. And I have to make room for the next lot!

End ramble/rant.

Peter Wieck
Melrose Park, PA
 




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