Next time you see one of the utility trucks (4 guys standing around drinking coffee) in your area, go talk to them. See where all three wires are terminated on the distribution transformer. Feeding two or three homes. Here's another plan, just for fun, call your local electrical utility, ask for the service department, when they ask why, tell them you want a quote for 3 phase hook up at your residence.
Utilities aren't bound by the National Electrical Code, they do pretty much what they want. But I know at Alyeska, we were required to have a ground wire in the ditch even when pulling single phase 4160 or 7200 for distant cathodic protection systems along the buried portions of the line. It was terminated to a ground rod (ridiculous) at each station and then it and the two hots were fed to the step down transformers and then the cathodic protection equipment. Equipment grounding conductor until reaching the ground rod, then it became a grounding electrode conductor and was terminated on the SECONDARY side of the transformer.
The MC3500 used 8 X 6LQ6 / 6JE6C which is a big sweep tube. Google McIntosh MC3500 to find the schematic. The MI200 is believed to use a pair of 8005 transmitting tubes. I have never seen the schematic.
The McIntosh amps used dual primaries feeding both the plates and cathodes. New or cloned transformers today would be very pricey. My advice if you want to build the big one is to search for available transformers first, then find the tubes to drive them, then figure out what kind of power will be needed to feed it all. Figure all of this out before buying anything! If you haven't built a tube amp before don't even think about building anything this big. I have been building them since before high school, and I still blow stuff up. Building an amp of this magnitude will cost at least $1K and that is on a tight budget. The probability of first time success isn't 100% even with a known good circuit and an experienced builder. The probability of a visit from the fire gods or the smoke monster is definitely non zero! The voltages involved are lethal, and the energy levels can lead to exploded parts (as I found out when cranking 100+ WPC out of the red board).
Plitron makes a 400 watt toroidal OPT, the PAT-4141-00. It weighs 23 pounds and costs $408 EACH! I have a pair of similar OPT's that were made by Plitron for guitar amp use. They sold them surplus for $125 each.
Hammond makes a 280 watt OPT, the 1650W. It weighs 28 pounds and costs $240 each.
You will still need a power transformer, tubes, a substantial chassis, and all of the small parts. This is not going to be a budget amp.
Yes, we used to skip school and go swimming in the one off of Galoway. The shortcut when I had to walk home went past all 4 lakes (rockpits that filled with water) and through Tropical Park racetrack, then down the train tracks under the Palmetto Expressway. At least two of those rockpits have been filled back in and expensive homes are their now. The pits were dug to make concrete. This is still going on west of the Turnpike extension in west Dade.
No, that describes a proper two-phase system: two signals of equal magnitude, 180deg out of phase. The confusion is due to the fact that:
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That's actually an unbalanced four phase system. Unbalanced polyphase systems are a real
because this leads to high frequency circulating currents, current in the neutral, and poorer power factors. Cutting out half your phases is way worse than imbalanced loads.Sometimes you see quadrature signals referred to as "two phase", but they shouldn't, they really shouldn't.
Call it what you want but here in the USA the 120V/240V system you describe is called "Single Phase". Equipment meant for 240V use is called "Single Phase". I'm not confused.
Can you find me a contrary example?
Cheers,
Michael
^^^^
Just because electricians and electrical engineers weren't talking to one another a century ago is no reason for me to continue misusing the terminology.
You can't call a push-pull amp "single ended" because some would mischaracterize a balanced, two-phase system as "single phase". It doesn't work.
Just because electricians and electrical engineers weren't talking to one another a century ago is no reason for me to continue misusing the terminology.
You can't call a push-pull amp "single ended" because some would mischaracterize a balanced, two-phase system as "single phase". It doesn't work.
I've been both electrician and EE for a good part of the century and I've never heard 120/240 called anything but single phase, except in a naive way based on the center tap. To counter your amp analogy, how does adding a center tap to a transformer make another "phase" ?
The old books I have on power engineering depict "two phase" as a 2-coil system 90 degrees apart. It looks more like 1/2 of 4-phase (not 2/3 of a 3 phase but it probably could be used that way as well...)
Wikipedia isn't always right, but this time it lines up with my own recollection:
"Two-phase electrical power was an early 20th century polyphase alternating current electric power distribution system. Two circuits were used, with voltage phases differing by 90 degrees. Usually circuits used four wires, two for each phase. Less frequently, three wires were used, with a common wire with a larger-diameter conductor. Some early two-phase generators had two complete rotor and field assemblies, with windings physically offset by 90 electrical degrees to provide two-phase power. The generators at Niagara Falls installed in 1895 were the largest generators in the world at the time and were two-phase machines."
Two-phase electric power - Wikipedia, the free encyclopedia
Tubelab maybe its time to switch to 3 phase wall outlet.In USA(110v) ewerything that exced 500w continous consumpsution must replaced with 3 phase suply(3x200V).Here in Europa (220v)ewerything over 1KW must be replaced with 3 phase main nec(3x380v).BTW many advantages 3 phase primary/3 phase secondary Psu haveulsating freqency from full wave rectifier its 360 hz(USA) so smothing fillter is not so critical in comparison with 120 hz from monophase(110v).Comon primary curent is divided in 3,plus primary voltage is not 110v but 3x200v(Primary curent more down)IN extreme cases it is posible to have 3phase primary and 4phase secondary from same transformer.One of the tube which I recomend for High power SE or PP is tetrode QB5/1750(got wery good expirience from high power AM transmitter with this tube).5,6 KV UBA and ower 5KW output with 4 tubes).Or Rusiann big power pentode GU81M.Salute Tubelab
3 phase is not commonly available for residential use in the United States, but there are some very rare exceptions usually for the extremely wealthy or connected. In the case where a house/mansion is large and I mean very large, (say 15 thousand sq ft and up) and geothermal groundwater heat pumps are employed for heating/cooling AND the local HV distribution is already 3 phase then sometimes the local power company may be persuaded to provide 208V 3 phase service at 400A and up. Where Tubelab lives that is definitely not the case. (I remember the last time this issue was discussed.) My neighborhood has 3 phase distribution, but I doubt anyone here has or can get actual 3 phase to their homes. My house is recently rewired/new service and has single phase 240V with neutral center tap. Everything major in my house (heat, hotwater, and stove) is gas so the only place I have 240V directly available is in my lab space and the garage - and even there I don't normally use it. I have 15A and 20A wall outlets, many on dedicated or modestly shared circuits.. (The 30A receptacles are hideously expensive/non-standard and I don't need them.)
Note Banat, there is no requirement here in the USA that any high current loads in a domestic situation be designed for 3 phase power, and the standard is not supported by any local power companies..
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Again:Totaly strange to me that Electric Power Delivery system in USA,think the major reason for that system is personally people Safety issue determined with some USA federal LAW established long time ago.What is actually behind that regulation don`t know exactly- but think money(profit).Here in my country(Serbia) people can chose betwen two option for home electric power use.First is so called Monophase system- 1x 240v~ and second 3x400v~.Many people chose(over 50%) this 3 phase electric system for domestic use beacose even in smallest villages distribution system and all over the street and country is 3phase configured and many domestic electric aparatures too.But nothing is ideal even here mainly from three reason
rices for 1kw/h is higher and higher every 6 monts,and if I goes with electric power consumption in so called `blue zone`or`red zone`prices for 1kw/h is more higher(penalty issue/again money),Second EPS(Electro Privreda Srbije) switched from old standard 3x380v~ to `new`European standard 3x400v~ and many old standard fabricated Electric Units(aparatures) don`t hold.Symple 220v electric bulb(solid fabricated) last for month or two maximum.Third -electric delivery Net is Old(special in small villages ) and total power breakdown is not rare,special during somer storm and winter rising electric consumption,but there is some advantages for tube high power RF(pirat)transmitter and high power tube audio. Good Luck
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Yes that old Philps 1kw amp can run the speaker.Output transformer is hiden behind output tubes.But even RF modulator have this huge output transformer too(with diferent primary/secondary windings ratio and isolation issue).
I also would like to say "Zdravo Banat".
I just joined DIY audio last month and have read some of your posts. I wanted to tell you I have been to Serbija and I visited the Elektronska Industrija factory in Nis during a production run of the KT90 back in 1992. I was wondering if you are near Nis and if you know Bukumira Blagomir or Arandelovic' Sinisa ?
Dovid'jenja,
Ron
I just joined DIY audio last month and have read some of your posts. I wanted to tell you I have been to Serbija and I visited the Elektronska Industrija factory in Nis during a production run of the KT90 back in 1992. I was wondering if you are near Nis and if you know Bukumira Blagomir or Arandelovic' Sinisa ?
Dovid'jenja,
Ron
Man, I'd forgotten about those gnats. We don't have them in Cali. but they were an unfortunate fact of life growing up in Florida, along with the state bird (Mosquito). The gnats like to drink out of your eyes and fly up your nostrils - very annoying. Once in a while, you'd get a guardian angel dragonfly that would perch on your shoulder and nab gnats, but never enough of them to really make a difference.
Hi Stefano 1970 !
Sory but need some time to provide this schematic to you , since now I am very busy with some very different work .
In the mid time here is the schematic + service manual (pdf) for Philips EL 6471 Power Amp since this topic is primary dedicated for this power Amp : http://83.117.57.34/nvhr/Philips_EL6471.pdf
Best Regards
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'' Zdravo'' Elektron Ron !
Must say that electron tube factory EI Nis is now in big trouble , production of tubes is at zero .
I live in region of Banat (Vojvodina) which is part of Serbija, and is about 250 Km far from Nis , and this two gentleman personally I don`t know .
Dovidjenja i Svako Dobro !
Thanks for the info, Banat. Mr. Bukumira designed the KT90 and Mr. Arandelovic' was the director of the EI factory. Those KT90's were, IMHO the best octal based output tube at that time, made with hardened glass and gold grids. I very much regretted my government's decision in 1992; but that is another story we cannot discuss here. Now I'm using 16 KT120's to build a 1kw amp.
AVE...
I have a small, probably stupid suggestion about cooling.
Put the amp in metal box, fill it up with mineral oil or liquid silicon, and pump it trough heat exchanger. Secondary system would circulate the water to take heat from oil. Use a cooling column of the type used in power plants. Secondary system can be placed away from primary. Immersing the whole amp in oil or liquid silicon will have four advantages:
- simplified lamp cooling design;
- better heat exchange between parts and coolant;
- electrical insulation (no water near electricity) and protection against shorts and accidental HV discharges;
- tank filled with oil would act as additional heat sink in case of pump malfunction. It will take some time to heat up coolant in the system to dangerous levels.
3-phase installation is required in my country for electric stoves, if their input power is above 2.5kW or 3kW, I don't really remember. The cost for such connection is about 5-10k PLN...
I have a small, probably stupid suggestion about cooling.
Put the amp in metal box, fill it up with mineral oil or liquid silicon, and pump it trough heat exchanger. Secondary system would circulate the water to take heat from oil. Use a cooling column of the type used in power plants. Secondary system can be placed away from primary. Immersing the whole amp in oil or liquid silicon will have four advantages:
- simplified lamp cooling design;
- better heat exchange between parts and coolant;
- electrical insulation (no water near electricity) and protection against shorts and accidental HV discharges;
- tank filled with oil would act as additional heat sink in case of pump malfunction. It will take some time to heat up coolant in the system to dangerous levels.
3-phase installation is required in my country for electric stoves, if their input power is above 2.5kW or 3kW, I don't really remember. The cost for such connection is about 5-10k PLN...
Actually a 3-phase tranformer can be built with a single EI core. The difference is that it's not a standard E, all three legs have the same width, and each holds one bobbin with windings for that phase. The trick is that the current in all phases always averages the same, so does the magnetic field, assuming all phases are equally loaded. A 3-phase transformer built this way is approximately twice as big as a single phase transformer, for equal power draw per phase.
Also, alternators are 3-phase because the resulting ripple from full-wave rectification is very small, sufficient that no filtering is required.
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