There are some tubes however that can run at very very low voltages, using some of those into a directly driven sensitive high-impedance speaker should be OK surely?
Some regular tubes even work at very low voltages - I can hear mine still after switch off for a while - as the HV takes a tumble and gets very low indeed!
tubes which can be operated at safe (very low) voltages - in some extreme cases even as low as 12V - do indeed exists.
But (even setting aside performance considerations) with those you can not do anything more than a preamp or perhaps an headphone amplifier.
In order to deliver enough power to drive a loudspeaker (even an high-sensitivity one) you need much higher voltages. Even if designed to use the least possible voltage, a power amp will require at least some > 90V. Which are really a little in tube terms, but nevertheless more than enough to be dangerous and not suitable for being handled by a child without risks.
Moreover, electrical shock risks apart, there are several other reasons why tubes must be kept out of the reach of children.
Tubes gets hot. Many perhaps not so much, bet usually enough to hurt (...the soldering iron which is almost unavoidably required is even more hot and dangerous with this respect).
Tubes are made out of a fragile glass envelope with high-vacuum inside. If the envelope gets broken, it'll implode!
The resulting glass debris can be very dangerous (especially if they ends up in the eyes...). Moreover, some tubes may contains poisonous substances inside their envelope.
I'd not let any child mess with any tube. At least not without strict & competent adult supervision.
But (even setting aside performance considerations) with those you can not do anything more than a preamp or perhaps an headphone amplifier.
In order to deliver enough power to drive a loudspeaker (even an high-sensitivity one) you need much higher voltages. Even if designed to use the least possible voltage, a power amp will require at least some > 90V. Which are really a little in tube terms, but nevertheless more than enough to be dangerous and not suitable for being handled by a child without risks.
Moreover, electrical shock risks apart, there are several other reasons why tubes must be kept out of the reach of children.
Tubes gets hot. Many perhaps not so much, bet usually enough to hurt (...the soldering iron which is almost unavoidably required is even more hot and dangerous with this respect).
Tubes are made out of a fragile glass envelope with high-vacuum inside. If the envelope gets broken, it'll implode!
The resulting glass debris can be very dangerous (especially if they ends up in the eyes...). Moreover, some tubes may contains poisonous substances inside their envelope.
I'd not let any child mess with any tube. At least not without strict & competent adult supervision.
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Hi,
Can anyone give me information about this tube? Can it be used for tube amp?
The only info that I found is this datasheet but it's in Russian which I don't know.
http://www.155la3.ru/datafiles/v2_006_25_tu.pdf
P/S: If I post this in the wrong place please forgive me.
Can anyone give me information about this tube? Can it be used for tube amp?
The only info that I found is this datasheet but it's in Russian which I don't know.
http://www.155la3.ru/datafiles/v2_006_25_tu.pdf
P/S: If I post this in the wrong place please forgive me.
Great link
Thanks Pedroskova, the Naval Electrical Engineering Training Series(NEETS) link is great.
1000 watt amp
Thanks Pedroskova, the Naval Electrical Engineering Training Series(NEETS) link is great.
1000 watt amp
Hi,
Can anyone give me information about this tube? Can it be used for tube amp?
The only info that I found is this datasheet but it's in Russian which I don't know.
http://www.155la3.ru/datafiles/v2_006_25_tu.pdf
P/S: If I post this in the wrong place please forgive me.
This Russian B2-00,6/25 is High Voltage Rectifier tube (Kenotron)(Diode) and is intented for Radar impuls PSU and similar apllication,with Indirect heated filament 5V/3,9A+-0,4A.Think is very hard to use for Audio apllication.Good Luck
I purchased a copy of Valve Amplifiers, by Morgan Jones, Elsevier, 2003 (latest edition), following recommendations here at diyAudio. It has pretty much most of the things I wanted to read about, but I am very surprised at the fact that Chapter 5, on Power Supplies, uses transistor circuits almost exclusively in the schematics for the chapter. I have no idea why he did this, as most audiophiles are of the opinion that a good tube amplifier should have a tube power supply since it is felt that the power supply does contribute to the sound quality. And, in any case, the book is called Valve Amplifiers, not Amplifiers in general. Does anyone have any idea why he wrote the chapter that way? To me, this makes the book very much incomplete and borderline ludicrous.
I know this is supposed to be about online resources. However, some people have brought up books, and I wanted to point out that several of them are actually the same book. Namely, Van Valkenburgh's Basic Electricity and Basic Electronics are functionally the same as both the Navy's and the Army's Basic Electricity and Basic Electronics courses.
My understanding is that Valkenburgh et al. developed those course materials for the Navy in the early '50's. That course was later made available to the public in both the original Navy form, and by Valkenburgh directly. The presentation differs somewhat (Valkenburgh has more illustrations and makes more use of repetition / review), but the topics are covered in the same order and using the same language.
This is nice because the list price for Valkenburgh is $70, while the Navy's books are only $15.
Interestingly, the Naval course was later used as the basis for the Army's course. I have a copy of the Army's Basic Electricity from 1977 and the text is exactly the same as the Navy's Basic Electricity from 1970. There's even drawings of ships on the cover and references to the naval promotion schedule.
My understanding is that Valkenburgh et al. developed those course materials for the Navy in the early '50's. That course was later made available to the public in both the original Navy form, and by Valkenburgh directly. The presentation differs somewhat (Valkenburgh has more illustrations and makes more use of repetition / review), but the topics are covered in the same order and using the same language.
This is nice because the list price for Valkenburgh is $70, while the Navy's books are only $15.
Interestingly, the Naval course was later used as the basis for the Army's course. I have a copy of the Army's Basic Electricity from 1977 and the text is exactly the same as the Navy's Basic Electricity from 1970. There's even drawings of ships on the cover and references to the naval promotion schedule.
Actually, he discusses tube regulators in that chapter, but explains carefully why performance considerations would discourage their use. If one wants to optimize the performance of the amplification, one wants the tightest, purest DC possible, which is not the strong point of tube regulators.
You'll see a similar conclusion reached in Allen Wright's preamp book, the difference being that Morgan uses series regulators, Allen uses shunt regulators.
Regulators when?
I have also found that regulators are less than stellar in many applications. The one exception is low current, early preamp stages. There, a shunt regulator, isolated from the stage by a further RC filter (bybassed) gives excellent performance by isolating the most sensitive stage(s) from the power line variations--which are random in frequency and size, but non-periodic and slow enough to be filtered by the regulation.
I have come to use--on an almost regular basis--tube regulators for the first stage of phono or mic preamps. It adds a presense to music--don't know any better way to explain it.
I have also found that regulators are less than stellar in many applications. The one exception is low current, early preamp stages. There, a shunt regulator, isolated from the stage by a further RC filter (bybassed) gives excellent performance by isolating the most sensitive stage(s) from the power line variations--which are random in frequency and size, but non-periodic and slow enough to be filtered by the regulation.
I have come to use--on an almost regular basis--tube regulators for the first stage of phono or mic preamps. It adds a presense to music--don't know any better way to explain it.
Here is a great resource for new people, I have the real copy.
Enjoy
http://jricher.com/NEETS/14178.pdf
Enjoy
http://jricher.com/NEETS/14178.pdf
In Allen Wrights Preamp Cookbook, he says that valves are more linear than transistors.
Is anyone aware of some support for this? I have soft copies of Radio Designers Handbook etc, could someone point me in the right direction of a few lines on the subject?
I need to reference it for some uni work.
Thanks
Charlie
Is anyone aware of some support for this? I have soft copies of Radio Designers Handbook etc, could someone point me in the right direction of a few lines on the subject?
I need to reference it for some uni work.
Thanks
Charlie
Morgan's book on valve amplifiers (3rd edition) talks about his attempt to determine average linearity of transistors through profiling their curves. He makes the comment that the final result was like throwing random spagetti at a page--thus supporting the 'non-linearity' problem of transistors, and resulting in the reason that large amounts of NFB are required for transistor amplifiers. (If I remember all his points correctly.)
From the quantum mechanical point that makes sense. Transistors require energy to get over the junction hump--and this is not a linear process, based on the quantum function difference of the junction potential. Valves, on the other hand, are current limited by the space charge effects existing in the vacuum and require no energy to emiss--rather they need potential to retard emission. Thus for tubes, geometry, which can be varied by the manufacturer, plays a huge factor in the linearity--and tubes were designed to be primarily linear.
Both valves and transistors need energy to get charge carriers past potential barriers. Transistors use voltage to do this, and so have an exponential response. Valves use heat to get electrons from the Fermi level past the surface barrier, so also have a partly exponential response to cathode temperature. Once out, the electrons form a space charge which then gives a 3/2 power response to voltage (modified by details of device geometry, ageing etc.).
It may be true to say that valves are more linear, but BJT are more predictable as there is a precise relationship between current and gm. Triodes gain extra linearity from feedback, as the anode voltage and grid voltage have similar effects apart from scaling. The predictability of BJT means that you can build (and simulate) complex circuits. Simple circuits may work better with valves. Horses for courses.
It may be true to say that valves are more linear, but BJT are more predictable as there is a precise relationship between current and gm. Triodes gain extra linearity from feedback, as the anode voltage and grid voltage have similar effects apart from scaling. The predictability of BJT means that you can build (and simulate) complex circuits. Simple circuits may work better with valves. Horses for courses.