What is a tube?

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jerberson12

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What is a tube in a compressor, preamp, guitar amp, etc....?
How does that differ from with or without?
 
When it comes to electronics, there are two different kinds.

Solid State and Tube/Valve.

Its just a different way of amplifying an electronic signal. Tubes came out first, solid state (also known as transistors) came around in the 50's.
 
What is a tube in a compressor, preamp, guitar amp, etc....

it's that glowing glass thing that behringer puts in their gear and charges you double for. if it's an Ultra or Pro model, you better be prepaired to pay triple.
 
In 1906 Lee De Forrest modified a light bulb and made the first tube that amplified sound. All amplifiers are descendants from his modified light bulb. The only tube that's left in most houses is the light bulb and if you have an old tv that's a tube too. Here's that modified light bulb that started it all:

audion.jpg

The big thing with tubes is that they amplify the odd harmonics differently than the even ones. Solid state amplifies all of them the same.

There's a WWII submarine in Pearl Harbor I've been on and the electronics are all tubes. They even had a rack mount tube digital readout. All 19" rack stuff.
 
The only tube that's left in most houses is the light bulb

Which has only one of three required parts and is thus not a thermionic valve.

The big thing with tubes is that they amplify the odd harmonics differently than the even ones. Solid state amplifies all of them the same.

That's a wildly inaccurate statement.
 
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With a Class A tube circuit, its distortion adds both odd and even harmonics, if that's what you mean....
 
well, tubes do tend to emphasize even order harmonics .

So do transistors, if they are used in the same configuration as tubes.

Let's be clear that neither a tube nor a transistor knows what an incoming harmonic is. They don't know that they are related in that manner to a fundamental. They are just signal that the device is being asked to amplify. Such that saying tubes "emphasize" or "amplify" even/odd order harmonics differently is fundamentally ;) incorrect.

Rather, we are talking about the behavior of devices when and if they distort, which adds harmonics. If the device is operated in its linear range, there is little difference in the signal. To add even order harmonics, a device must distort asymmetrically. Many tube designs do this, although it's quite possible and not that uncommon to design a tube circuit that minimizes asymmetrical distortions.

Transistors are subject to the same considerations and thus the same types of distortion. The major difference is transistors are cheap to buy and cheap to operate, so most solid state designs are liberally sprinkled with transistors to eliminate all such distortion, since that is held in most circuits to be an important goal. You could build an all-tube opamp with 20 or 40 tubes that performed like its solid-state counterpart, except with respect to the massive amount of waste heat the tubes generate. In such low distortion circuits, there will be almost no distortion until the limits are reached, when all distortion products, especially high-order distortion products, rise suddenly and dramatically.

Another consideration is that tubes operate at high voltage, so they often have more headroom than a transistor circuit (although that does not have to be so either, it usually is).

Finally, we can consider the behavior of the device as it nears the bleeding edge: tubes tend to "soft" clip. BJTs will hard clip; FETs are more tube-like. That determines the relative amount of high- vs. low-order harmonics, which is actually more important than the even/odd distinction. For example, as passive devices, transformers can only generate odd-order distortion, but mostly low-order and on low frequencies. This is a distortion we like, even though it's 100% odd-order.

In summary, we like tubes because:

- In the simple circuits often used with tubes, they will clip asymmetrically (even-order distortion).

- In the simple circuits often used with tubes, they are allowed gradually distort (soft clip), rather than suddenly overload (hard clip).

- In the complex circuits often used with transistors, the above effects have been minimized so distortion is minimal until a sudden overload (hard clip).

So you see, it's NOT simply because "tubes amplify even order harmonics". Were that so, we would all hate transformers.

Another case study: one time I read one guy disparage a tube mic amp design because the amp used a long-tailed pair circuit. That will suppress even-order distortion. According to this otherwise seemingly technical fellow, it was improper to use any tube circuit design that eliminated the desired even-order distortions. Strangely, he also opposed starved-plate circuits, even though the primary characteristic of such designs is a large increase in even-order distortion, so much that they are described as a caricature of tube sound.

Therefore, there is apparently a mandated amount of even-order distortion a tube design must possess, not too much nor too little, to be considered a "real" tube design.

Nevermind that all of the basic circuits used with transistors to eliminate distortion were developed in the days of engineers trying as diligently as they could to make their tube designs as linear as possible . . . :rolleyes:
 
Great stuff there MSHilarious about the tubes. The main point is that any circuit that is providing amplification will do a few things...not amplify aspects of the sound exactly identical to the original; and distort certain harmonics, frequencies, and aspects of the signal.

Tubes, transistors, transformers, and integrated circuits all have these issues and are often used in conjunction with each other to create a custom sonic signature for each electronic device. Guitar amps are a little more straight forward with tube vs solid state than other audio equipment. You can really tell a difference between a tube guitar amp and a solid state amp mainly because the sound is all about the distortion.

With preamps, compressors, and consoles distortion is an unavoidable side effect that has to do with the sonic character mentioned above. A funny thing that people obsessed with tube preamps don't realize is that the majority of the most coveted preamps are transformers and not tubes like the Neve 1073 and API. And many will argue that even the coveted tube preamps get the majority of their sound from their hand wound transformers, not the tubes.

In a nut shell...a tube is often unbridled and unknowledgeable sonic obsession.

Take a look at those things hanging from the tube guitar amps in the back. The square thing is the transformer...just as important, but you won't have to replace it as often as the tubes.

...Transformers Rock!

thedawstudio.com
 
What is a tube in a compressor, preamp, guitar amp, etc....?
How does that differ from with or without?

wtf? there has been WAY too much geek-speak in this thread. let me break it down for you:

An essay on tubes​

While many learned professors have abandoned hope of ever discovering the truth behind tubes, I for one feel that it is still a worthy cause for examination. Advancments in tubes can be linked to many areas. Though tubes is a favourite topic of discussion amongst monarchs, presidents and dictators, tubes is featuring more and more in the ideals of the young and upwardly mobile. It still has the power to shock socialists, obviously. Complex though it is I shall now attempt to provide an exaustive report on tubes and its numerous 'industries'.

Social Factors

While some scholars have claimed that there is no such thing as society, this is rubbish. When J H Darcy said 'fevour will spread' [1] she borrowed much from tubes. While deviating from the norm will always cause unrest amongst ones peers, tubes raises the question 'why?'

Did I mention how lovely tubes is? Just as a dog will return to its own sick, society will return to tubes, again and again.

Economic Factors

Derived from 'oikonomikos,' which means skilled in household management, the word economics is synonymous with tubes. Of course, tubes fits perfectly into the Custard-Not-Mustard model, making allowances for recent changes in interest rates.
National
Debt

tubes

When displayed this way it becomes very clear that tubes is of great importance. My personal view is that the national debt will eventually break free from the powerful influence of tubes, but not before we see a standardised commercial policy for all. A sharp down turn in middle class investment may lead to changes in the market.

Political Factors

Politics, we all agree, is a fact of life. Contrasting the numerous political activists campaigning for the interests of tubes can be like looking at tubes and ones own image of themselves.

We cannot talk of tubes and politics without remembering the words of nobel prize winner Xaviera H. Amster 'The success of any political system can only truly be assessed once the fat lady has sung.' [2] One cannot help but agree when faced with tubes, that this highlights an important issue. It would be wise to approach the subject with the thought that 'if you don't have anything nice to say, don't say anything at all'. However this can lead to missing out important facts.
One thing's certain. The Human species liberally desires tubes, and what's more human than politics?

Conclusion

To conclude, tubes is both a need and a want. It enriches, influences the influencers, and never hides.

The final say goes to the award winning Nicole Beckham: 'I demand tubes, nothing more nothing less.' [3]

[1] J H Darcy - The Spaniard - 1988 - PPT

[2] Amster - The Popular Vote - 2002 Worldwide Publishing

[3] Sham Magazine - Issue 124 - Monkey Books
 
then there's "in the tube":
SuperStock_1760-1520.jpg


To answer the original question :

Tube stuff is supposed to have a warm sound. Some of the cheap tube stuff is bullshit, some of it is actually ok. Just use your ears.
 
wtf? there has been WAY too much geek-speak in this thread. let me break it down for you:

An essay on tubes​

While many learned professors have abandoned hope of ever discovering the truth behind tubes, I for one feel that it is still a worthy cause for examination. Advancments in tubes can be linked to many areas. Though tubes is a favourite topic of discussion amongst monarchs, presidents and dictators, tubes is featuring more and more in the ideals of the young and upwardly mobile. It still has the power to shock socialists, obviously. Complex though it is I shall now attempt to provide an exaustive report on tubes and its numerous 'industries'.

Social Factors

While some scholars have claimed that there is no such thing as society, this is rubbish. When J H Darcy said 'fevour will spread' [1] she borrowed much from tubes. While deviating from the norm will always cause unrest amongst ones peers, tubes raises the question 'why?'

Did I mention how lovely tubes is? Just as a dog will return to its own sick, society will return to tubes, again and again.

Economic Factors

Derived from 'oikonomikos,' which means skilled in household management, the word economics is synonymous with tubes. Of course, tubes fits perfectly into the Custard-Not-Mustard model, making allowances for recent changes in interest rates.
National
Debt

tubes

When displayed this way it becomes very clear that tubes is of great importance. My personal view is that the national debt will eventually break free from the powerful influence of tubes, but not before we see a standardised commercial policy for all. A sharp down turn in middle class investment may lead to changes in the market.

Political Factors

Politics, we all agree, is a fact of life. Contrasting the numerous political activists campaigning for the interests of tubes can be like looking at tubes and ones own image of themselves.

We cannot talk of tubes and politics without remembering the words of nobel prize winner Xaviera H. Amster 'The success of any political system can only truly be assessed once the fat lady has sung.' [2] One cannot help but agree when faced with tubes, that this highlights an important issue. It would be wise to approach the subject with the thought that 'if you don't have anything nice to say, don't say anything at all'. However this can lead to missing out important facts.
One thing's certain. The Human species liberally desires tubes, and what's more human than politics?

Conclusion

To conclude, tubes is both a need and a want. It enriches, influences the influencers, and never hides.

The final say goes to the award winning Nicole Beckham: 'I demand tubes, nothing more nothing less.' [3]

[1] J H Darcy - The Spaniard - 1988 - PPT

[2] Amster - The Popular Vote - 2002 Worldwide Publishing

[3] Sham Magazine - Issue 124 - Monkey Books

This is 100% on the mark. Nothing more to be said about tubes. :)
Well said dude.
 
How come you guys know all these stuff?

Arent you supposed to be a recording engineer? not an electrician?
 
How come you guys know all these stuff?

Arent you supposed to be a recording engineer? not an electrician?

Any experienced audio engineer will have a good knowledge of electricity, because it is essential to recording. Almost everything in recording has to do with electricity.
 
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