On Fri, 3 Aug 2018 11:47:41 -0400, bitrex <user@example.net> wrote:>On 08/03/2018 09:31 AM, Phil Hobbs wrote: >> On 08/03/2018 06:09 AM, Ian wrote: >>> On 2018-08-03, oldschool@tubes.com <oldschool@tubes.com> wrote: >>> >>>> I'm looking into building the most pewerful tube audio amplifier >>>> possible. >>> >>> Sounds like a bit of a Disaster Area in the making... >>> >>> >> And terrible songs! >> >> Maybe the OP is planning to be dead for a year for tax reasons..... >> >> Cheers >> >> Phil Hobbs >> > >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.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.>Or u can just build a house-burning down murder machine I guess.
What is the most powerful vacuum tube ever made?
Started by ●August 3, 2018
Reply by ●August 3, 20182018-08-03
Reply by ●August 3, 20182018-08-03
On 3.8.18 18:49, bitrex wrote:> On 08/03/2018 11:45 AM, Rob wrote: >> bitrex <user@example.net> wrote: >>> 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. >> >> :-) >> Not only in parts and labor cost but also in human lives... >> > > Starting at the output devices is bikeshedding, anyone who was > serious/non-crazy would be thinking (sleepless nights in horror) at what > the cost in design time and parts to make a safe reliable PSU for such > an amplifier would be to start.To stay in the style: A sturdy transformer, some mercury-arc rectifiers, a hefty swinging choke and a bunch of oil capacitors. -- -TV
Reply by ●August 3, 20182018-08-03
On Fri, 03 Aug 2018 07:34:12 +0100, Mike Coon wrote:> In article <kjr7mdte459o2ll2fo8mp48j98afrfisks@4ax.com>, > oldschool@tubes.com says... >> >> What is the most powerful vacuum tube ever made? >> >> I'm looking into building the most pewerful tube audio amplifier >> possible. I'll be using 4 tubes in push-pull parallel. (per channel). >> My goal is at least 5000 watts RMS per channel (if possible). I will >> likely rewind some pole pigs (power pole transformers) for output >> transformers, >> and possibly use one of them in reverse for the power supply >> transformer, which should supply 3250 to 7500 volts to the plates (or >> up to 15KV if I use a different pole pig rated for higher primary >> voltage). > > Water-cooled loudspeakers? >Good question. :-) The OP's an hammerchewer with his talk of using BFO transformers. I'm not surprised I didn't see the OP since I'm guessing I must have killfiled him some time back. If his plan is to annoy the neighbours, he could scale his BFO Amp requirements back by a good 16 to 20dB using horn loaded pressure transducers just like the old cinema houses used to do when filling a large auditorium with high level sound using just a 5W rms valve amplifier. If he's ok with a cardioid sound field, he could gain an extra 3dB by loading the pressure transducer diaphragm(s) front and back with a matching pair of horns each. There's no point in wasting energy and money on superfluous matching transformers when you can use paralleled valves (vacuum tubes) in a DC coupled push-pull bridged output configuration fed from a voltage doubled 240v rms supply with +/-300 volt HT rails. That's a configuration that should drive a 16 ohm speaker load to 5KW rms with some margin to spare. :-) Of course, he could save himself the bother of floating heater supplies and the sheer quantity of 807 valves or whatever readily available valves he can get his hands on if a 10KW am Tx high level modulator amplifier doesn't float his boat by building a solid state equivalent of the DC coupled valve design using high voltage high slew rate power fets instead. As I said above, the OP's an 'ammerchewer. -- Johnny B Good
Reply by ●August 3, 20182018-08-03
On Thursday, August 2, 2018 at 11:11:15 PM UTC-7, olds...@tubes.com wrote:> What is the most powerful vacuum tube ever made?Varian made 23MW (klystrons, I think) for SLAC, and that two-mile accelerator is still in service, so they're probably rebuilding 'em from time to time.
Reply by ●August 3, 20182018-08-03
On Thursday, August 2, 2018 at 11:11:15 PM UTC-7, olds...@tubes.com wrote:> What is the most powerful vacuum tube ever made?Don't know how many of 'em exist, but reportedly these folk got higher power than you'll need, <https://www.slac.stanford.edu/pubs/slacpubs/7000/slac-pub-7232.pdf> but the 535 kV power (and 700A electron gun) will not be compatible with most power utilities' offerings.
Reply by ●August 3, 20182018-08-03
On 08/03/2018 12:56 PM, Tauno Voipio wrote:> On 3.8.18 18:49, bitrex wrote: >> On 08/03/2018 11:45 AM, Rob wrote: >>> bitrex <user@example.net> wrote: >>>> 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. >>> >>> :-) >>> Not only in parts and labor cost but also in human lives... >>> >> >> Starting at the output devices is bikeshedding, anyone who was >> serious/non-crazy would be thinking (sleepless nights in horror) at >> what the cost in design time and parts to make a safe reliable PSU for >> such an amplifier would be to start. > > To stay in the style: A sturdy transformer, some mercury-arc rectifiers, > a hefty swinging choke and a bunch of oil capacitors. >Yeah, 1920s-style. I'm sure there's someone out there who daily-drives a Model T, too. Bob Pease daily drove a 60's Beetle.
Reply by ●August 3, 20182018-08-03
On 08/03/2018 12:56 PM, Tauno Voipio wrote:> On 3.8.18 18:49, bitrex wrote: >> On 08/03/2018 11:45 AM, Rob wrote: >>> bitrex <user@example.net> wrote: >>>> 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. >>> >>> :-) >>> Not only in parts and labor cost but also in human lives... >>> >> >> Starting at the output devices is bikeshedding, anyone who was >> serious/non-crazy would be thinking (sleepless nights in horror) at >> what the cost in design time and parts to make a safe reliable PSU for >> such an amplifier would be to start. > > To stay in the style: A sturdy transformer, some mercury-arc rectifiers, > a hefty swinging choke and a bunch of oil capacitors. >You could look at the Westinghouse FG-10 design as a ballpark for the size power supply you'd need for two channels at 10kW total. "sturdy transformer"? There are _several_ very sturdy-looking iron transformers in it at the bottom of the cabinet, each one looks to be about the size of a microwave oven. You're not running this hypothetical amp off a 120V wall socket, sorry to say.
Reply by ●August 3, 20182018-08-03
On 08/03/2018 12:50 PM, upsidedown@downunder.com wrote:> On Fri, 3 Aug 2018 11:47:41 -0400, bitrex <user@example.net> wrote: > >> On 08/03/2018 09:31 AM, Phil Hobbs wrote: >>> On 08/03/2018 06:09 AM, Ian wrote: >>>> On 2018-08-03, oldschool@tubes.com <oldschool@tubes.com> wrote: >>>> >>>>> I'm looking into building the most pewerful tube audio amplifier >>>>> possible. >>>> >>>> Sounds like a bit of a Disaster Area in the making... >>>> >>>> >>> And terrible songs! >>> >>> Maybe the OP is planning to be dead for a year for tax reasons..... >>> >>> Cheers >>> >>> Phil Hobbs >>> >> >> 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. > > 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.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 ;-)
Reply by ●August 3, 20182018-08-03
On Fri, 3 Aug 2018 19:50:08 +0300, Tauno Voipio <tauno.voipio@notused.fi.invalid> wrote:>On 3.8.18 16:48, upsidedown@downunder.com wrote: >> On Fri, 3 Aug 2018 16:20:43 +0300, Tauno Voipio >> <tauno.voipio@notused.fi.invalid> wrote: >> >>> On 3.8.18 15:12, Rob wrote: >>>> Tauno Voipio <tauno.voipio@notused.fi.invalid> wrote: >>>>> On 3.8.18 11:28, Rob wrote: >>>>>> oldschool@tubes.com <oldschool@tubes.com> wrote: >>>>>>> What is the most powerful vacuum tube ever made? >>>>>>> >>>>>>> I'm looking into building the most pewerful tube audio amplifier >>>>>>> possible. I'll be using 4 tubes in push-pull parallel. (per channel). My >>>>>>> goal is at least 5000 watts RMS per channel (if possible). I will likely >>>>>>> rewind some pole pigs (power pole transformers) for output transformers, >>>>>>> and possibly use one of them in reverse for the power supply >>>>>>> transformer, which should supply 3250 to 7500 volts to the plates (or up >>>>>>> to 15KV if I use a different pole pig rated for higher primary voltage). >>>>>> >>>>>> Not a good idea to use tubes for that. What you want to have is available >>>>>> off-the-shelf both as PCB modules and 19" rack modules, it will be >>>>>> much lighter, much cheaper, much safer and it will work much better! >>>>>> >>>>>> e.g.: http://www.fullfataudio.com/products/ffa-10000/ >>>>>> >>>>>> And when you would use tubes, you would not make the most powerful >>>>>> tube audio amplifier with a measly 5000 watts. Much more power was >>>>>> produced in modulator amplifiers of classic AM transmitters with an >>>>>> RF output of 100 times that. See the documentaries on WLW and info >>>>>> on even stronger AM transmitters outside the USA. >>>>> >>>>> >>>>> A rule of thumb for the AM transmitter modulator is that >>>>> the audio power needs to be at least half of the DC input >>>>> power to the Class C power amplifier. >>>> >>>> It is clear that with his 5000 watts he is about two orders of magnitude >>>> short of the most powerful tube audio amplifier ever made, let alone the >>>> most powerful tube audio amplifier possible. But maybe it would still >>>> be the most powerful, who knows? >>> >>> My guess is that the most powerful audio amplifiers have been >>> modulators for big AM transmitters. The biggest I have seen >>> is 200 kW modulator in the late Lahti AM station in southern >>> Finland. The transmitter was made by Brown Boveri & Cie (BBC). >>> >>> At least Radio Moscow has run AM on 1 MW power level, maybe >>> also VOA in the years gone by. This would need an audio power >>> of around 700 kW, if the power amplifier is not run as a linear >>> amplifier, which is pretty wasteful at this power level, due >>> to the bad carrier-level efficiency of an AM linear. >> >> At least the 500 kW short wave AM/SSB Brown Bovery transmitters >> commissioned in the 1980's in Pori, Finland, used audio controlled PWM >> to generate the final RF tube anode voltage. So no need for a huge >> power audio amplifier or huge modulation transformers. >> >> I do not know what they use in the on site 600 kW AM medium wave >> transmitter. > > >Pori has been down since over a decade ago, see: ><https://yle.fi/uutiset/osasto/news/yle_ends_short_wave_broadcasts/5756519>.After that it was leased to China Radio International (ex. Radio Peking). At least the medium wave transmitter at 963 kHz has been used quite recently.
Reply by ●August 3, 20182018-08-03
On Fri, 3 Aug 2018 15:06:20 -0400, bitrex <user@example.net> wrote:>On 08/03/2018 12:50 PM, upsidedown@downunder.com wrote: >> On Fri, 3 Aug 2018 11:47:41 -0400, bitrex <user@example.net> wrote: >> >>> On 08/03/2018 09:31 AM, Phil Hobbs wrote: >>>> On 08/03/2018 06:09 AM, Ian wrote: >>>>> On 2018-08-03, oldschool@tubes.com <oldschool@tubes.com> wrote: >>>>> >>>>>> I'm looking into building the most pewerful tube audio amplifier >>>>>> possible. >>>>> >>>>> Sounds like a bit of a Disaster Area in the making... >>>>> >>>>> >>>> And terrible songs! >>>> >>>> Maybe the OP is planning to be dead for a year for tax reasons..... >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>>> >>> >>> 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. >> >> 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. > >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 ;-)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.
