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Re: What is the most powerful vacuum tube ever made?
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It is a stupid idea to build the desired distortion into an expensive
and hard to replace part of the system.  When you want to build a
high-power amplifier with the bad performance of a tube amplifier,
use a low-power tube amplifier as a preamp and drive a modern Class-D
amplifier with the resulting distorted signal, to have it cleanly
amplified to high power at high efficiency, low weight, etc.

Once you get tired of the "warm sound" you can always remove the tube
amplifier without having to start from scratch.

Re: What is the most powerful vacuum tube ever made?

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I was referring to electric guitar amplifiers, in which the distorting
amplifier and distorting speakers are part of the electric guitar
instrument.

In big (stadium size) events, a low power (100 W) tube amplifier and
also suitable low power speaker is used. A microphone is placed in
front of the speaker to get both the amplifier as well as speaker
distortion and then amplified by a linear chain to the final kW size
output :-).

With signals with high peak/average ratio, you  can quite comfortably
overdrive a tube power amplifier without too much problems, while you
should never let a solid state amplifier chain clip. Thus the nominal
power output must be several times that of a tube amplifier in order
to get the same average audio SPL.



Re: What is the most powerful vacuum tube ever made?
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That is like what I wrote.  Nobody would want to carry a 5000 watt
tube audio amplifier to an event when they can have the same thing
as a 2U rack module weighing 14kg.

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Such an amplifier likely contains (or requires an external) sound
processor that cleverly limits the amplitude without hard clipping.

Re: What is the most powerful vacuum tube ever made?

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Sounds like a bit of a Disaster Area in the making...


--  
Ian

"Tamahome!!!" - "Miaka!!!"

Re: What is the most powerful vacuum tube ever made?
On 08/03/2018 06:09 AM, Ian wrote:
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And terrible songs!

Maybe the OP is planning to be dead for a year for tax reasons.....

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: What is the most powerful vacuum tube ever made?
On 08/03/2018 09:31 AM, Phil Hobbs wrote:
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Thinking about the output device specifics is bikeshedding at this point  
in the design anyway. If one were serious one would be starting at the  
PSU and working forwards. Oh, it's gonna be a complex and glorious PSU  
for sure, with a pretty sophisticated fail-safing system,  
overvoltage/overcurrent protection, and probably uP-controlled startup  
sequencing and bias monitoring.

Or u can just build a house-burning down murder machine I guess.

Re: What is the most powerful vacuum tube ever made?

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Agreed that the PSU is an issue, if you have only a 50/60 Hz single
phase feed, especially due to the lack of high voltage electrolytic
capacitors.

However, if you have a three phase feed (230/400 V in Europe or
277/480 V in the US) the power supply is trivial. Just put a 6 pulse
rectifier after the anode voltage transformer. If you have two
secondaries, put one in wye and the other in delta and you can use 12
pulse rectifier, generating smoother DC and reduce the power factor on
the primary side.

Tubes can take a lot of punishment, so a 30-60 s time delay should be
enough, before switching on the anode voltage, when the cathode has
reached full operational temperature.

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Re: What is the most powerful vacuum tube ever made?
On 08/03/2018 12:50 PM, snipped-for-privacy@downunder.com wrote:
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You're certainly going to need some kind of fast-acting overcurrent/bias  
voltage loss detecting system; self-bias is probably a non-starter and  
at those power levels loss of a bias supply will probably be a genuine  
disaster that'll make the local news at least ;-)

Re: What is the most powerful vacuum tube ever made?

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Power the anode supply contactor (relay) from the bias supply. If the
bias is lost, the contactor will release. Since in a 3 phase supply,
typically there are no big capacitor on the DC side, the anode voltage
will drop quite rapidly. As noted previously, tubes can handle some
punishment.


Re: What is the most powerful vacuum tube ever made?
On 08/03/2018 05:26 PM, snipped-for-privacy@downunder.com wrote:
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Don't forget to protect yer output driver amp tubes too! They'll likely  
need a different lower voltage bias supply but for an amp of this size  
just the driver for the huge final tubes (power triodes, probably?) is  
gonna be like the equivalent of a Marshall stack amp power stage, maybe  
bigger.

And maybe even the drivers for the drivers.

Re: What is the most powerful vacuum tube ever made?
Ian wrote:

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Not at all, I think he and his friends are working happily on that and
the progress is just fine:


https://www.youtube.com/watch?v=vul4SYL4QiQ


    Best regards, Piotr

Re: What is the most powerful vacuum tube ever made?
On Friday, August 3, 2018 at 2:11:15 AM UTC-4, snipped-for-privacy@tubes.com wrote:
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When I worked at the FEL (Free electron Laser) we had a SLAC Klystron that  
was probably 100 MW.  
http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-10620.pdf
(Check out the unibrow in figure 9.)  

George H.  

Re: What is the most powerful vacuum tube ever made?
On Fri, 3 Aug 2018 05:53:16 -0700 (PDT), George Herold

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Isn't that short  peak power, not average power ?


Re: What is the most powerful vacuum tube ever made?
On Friday, August 3, 2018 at 9:28:39 AM UTC-4, snipped-for-privacy@downunder.com wrote:
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Right.  pulsed power.

GH

Re: What is the most powerful vacuum tube ever made?
On Fri, 03 Aug 2018 01:07:29 -0500, snipped-for-privacy@tubes.com wrote:

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Probably an ignitron, possibly a krytron, but the THD specs are
mediocre.

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Why?

The transformers are the problem.  



--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: What is the most powerful vacuum tube ever made?
On 08/03/2018 11:00 AM, John Larkin wrote:
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For the cost of building the most powerful tube amp ever you could buy a  
pretty nice used sports car. Or less expense. Less dangerous. Girls will  
like you better.

Re: What is the most powerful vacuum tube ever made?

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Some old AM or shortwave transmitters ran plate modulated above a
megawatt.


--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: What is the most powerful vacuum tube ever made?
On 08/03/2018 11:47 AM, John Larkin wrote:
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Ya I think they still use them in Mexico and the Carribean to broadcast  
end-times ranting from that kooky old kid-toucher pastor out of SC.

Re: What is the most powerful vacuum tube ever made?
On 08/03/2018 02:07 AM, snipped-for-privacy@tubes.com wrote:
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Sounds like one of those "if you have to ask how you probably  
shouldn't"-kind of projects.

It'll probably be cheaper in parts and labor cost to just buy one off  
the shelf, anyway. I mean off the floor. Reinforced concrete floor.

<https://www.surplussales.com/Microphones-Audio/MicroAudio-7.html

Re: What is the most powerful vacuum tube ever made?
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:-)
Not only in parts and labor cost but also in human lives...

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