Do Vacuum Tube Amplifiers Emit X-Rays at Lower Voltages and Frequencies?

[Salvador]

also I have found out that of all genres classical sounds the best on this and probably many other tube amps.
i think it has something to do with the fact that due to the output having transformers the very low frequencies and the very high get kind of influenced and cut off a bit.

 

[jim hardy]

i think it has something to do with the fact that due to the output having transformers the very low frequencies and the very high get kind of influenced and cut off a bit.

There's volumes written on the subject sound of tubes vs solid state amplifiers and it ranges from very scientific inquiries with spectrum analyzers to utter bilgewater .

One author picked up on these facts
Tube amps resemble a current source because of pentode characteristics and large inductance of the output transformer . They reproduce the input signal as a current waveform.
Solid state amps resemble a voltage source because they employ feedback . They reproduce the input signal as a voltage.
Most lab tests of an amplifier use a resistor load .
For a resistor load, voltage and current waves have the exact same shape.

When there's inductance present , voltage and current waves have same shape ONLY for a sine wave. That's one of the oddities of Mother Nature's favorite shape, the sinusoid , it doesn't change shape when you integrate or differentiate it.
More complex waves such as square or Mozart will change shape.
Now a speaker is a motor with inductance and inertia in addition to resistance.
In a motor current determines torque and voltage determines speed(velocity) .
A motor when driven by a current wave of given shape will not have same motion as when driven by a voltage wave of same shape.

If you have a 'scope try it - set your function generator for square wave and drive a speaker through different amps, observing voltage across speaker.. Repeat with resistor load.

 

[Salvador]

Hmm i'll have to digest some of this , so for inductance if driven with a sinusoidal wave voltage and current run just like they do in a purely resistive load aka together?
I think i confused the inductive load for the capacitive load , hence all the fuss about the smps mains filters producing bad power factor if not corrected.

as for the tubes you mentioned a pentode amplifier but the one I have is using dual beam tetrodes in the output.Now I have to read some papers otherwise I am not that smart at telling he difference between them but I assume there is some.

 

[jim hardy]

so for inductance if driven with a sinusoidal wave voltage and current run just like they do in a purely resistive load aka together?

For an applied sine wave voltage, Inductance gives a phase shift between voltage and current. Shape doesn't change, just current wave shifts toward 'later' by a fraction of a cycle..you've heard the expression "current lags in an inductor" Human ear is not sensitive to phase.
For an applied square wave voltage, inductance will change the shape of the current wave from a square toward a triangle .
http://electronics.stackexchange.co...change-in-current-and-what-is-its-correct-for

If there is significant internal resistance, the current looks more like:

a speaker has resistance of about 70% of its nominal Z,
ie an 8 ohm speaker has ~5.6 ohms of resistance and some inductance.

old jim

 

[jim hardy]

as for the tubes you mentioned a pentode amplifier but the one I have is using dual beam tetrodes in the output.Now I have to read some papers otherwise I am not that smart at telling he difference between them but I assume there is some.

A pentode is just a tetrode with "Suppressor Grid" added close to the plate.
When the plate approaches red hot it'll emit some electrons that would be attracted to the positive screen grid.That's called 'secondary emission'.
The nearby suppressor grid is at same potential as cathode , so it tends to push those secondary electrons back toward the plate where you want them.
That's all explained in the RCA tube manual that(i think) you've downloaded.

Have fun with your tube amps. I love that blue glow ..
picture courtesy of http://gpoint-audio.com/about-valves/

Try a search on loudspeaker inductance, My google seems eager to please
http://users.ece.gatech.edu/mleach/papers/vcinduc.pdf
http://www.eminence.com/support/understanding-loudspeaker-data/
https://www.klippel.de/fileadmin/klippel/Files/Know_How/Literature/Papers/Voice_Coil_ Impedance_04.pdf

old jim

 

[dlgoff]

Now a speaker is a motor with inductance and inertia in addition to resistance.

I know how you like visuals, so I thought I'd share this Physics animations site. And as to the speaker,

A loudspeaker is a linear motor with a small range.

they have the embedded flash player image http://www.animations.physics.unsw.edu.au/jw/flash/speaker_vibrating.swf
loudspeaker page = http://www.animations.physics.unsw.edu.au/jw/electricmotors.html#loudspeakers

 

[Salvador]

I will try to resurrect the other Priboi amp that I have , that one is a 75watt per channel version , i now have one output transformer i have to finish the other one , hopefully.

as for the picture Jim posted of the glowing tubes, i think most of those photo's are a bit edited or taken with some special lens etc because as much as I have observed in real life the tubes never glow as strongly or as beautifully as they seem to in photos.
ans is that blue color from the electrons interacting with the camera or can it be seen directly with naked eyes ? I have never seen blue light from a tube with my eyes in real time.

 

[jim hardy]

ans is that blue color from the electrons interacting with the camera or can it be seen directly with naked eyes ? I have never seen blue light from a tube with my eyes in real time.

Darken the room. It's very real, but not all tube types have it.
6973 Beam Pentodes in my high school project hifi shone wonderfully.

 

[nsaspook]

http://www.jacmusic.com/techcorner/ARTICLES/English-neu/blueglow/blueglow.htm

 

[Salvador]

just if anyone's interested I managed to repair the output transformer , after carefully studying the way it's built I rewound the bobbins that were damaged and now it finally works.
so what started out as a spare not working amplifier to make this one work turned out a lesson learned and two working amplifiers.