Tube amplifiers current

The characteristics curves define the Total Harmonic Distortion composition. Output characteristic of vacuum tube 6L6 in pentode configuration. There are three basic tube amplifier configurations: triode , pentode and a feedback pentode variant called ultralinear. Pentode configuration is more efficient than triode in terms of load power. Triode amplifier has more natural sound because the THD composition has low order harmonics, but has narrow bandwidth and less efficience.

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Content:

• Valve amplifier
• Tubefriendly loudspeakers?
• Common Tube Amp Malfunctions: My amp doesn't turn on.
• Amplifiers, is it better to buy a tube or transistor amplifier?
• The Differences Between Tube and Solid State Amps
• Tube Amplifier Safety
• Building a Stereo Tube Amp
• Why Tubes?
• Current Production Marshall Tube Amps
• Solid-State Vs. Tube Amplifiers (Pre, Power & Guitar Amps)

WATCH RELATED VIDEO: BEAST TUBE POWER AMPLIFIER Unboxing \u0026 Review - Brooks Berdan Ltd.

Valve amplifier

Many of our customers are tube enthusiasts or aspiring tube enthusiasts , hence one of the most common questions we are asked is "Will my speakers run on tubes? We have been unable to find a good, concise discussion of these characteristics online and as a result have decided to write one ourselves. This article will provide a basic explanation as to why some speakers work well with tube amplifiers while some do not. Overcoming misinformation One misleading piece of information with which our customers are often provided is sensitivity.

This specification is commonly misrepresented as "efficiency" which it most certainly is not. Loudspeakers are terribly inefficient and it is likely that virtually no consumer has ever been given an actual efficiency specification. The most efficient loudspeaker designed to date was the Altec Lansing Voice of the Theater, which had an efficiency rating of approximately 3.

No loudspeaker manufacturer would ever publish an efficiency specification because it would discourage and mislead consumers. Be clear on one point: sensitivity and efficiency are not the same thing. Even when using a solid state amplifier, one cannot necessarily equate high sensitivity to high efficiency - the physics are simply more complex than many manufacturers, and sadly reviewers, lead us to believe.

Instead of efficiency, loudspeaker manufacturers provide a sensitivity specification. This figure is supposed to indicate how loud a speaker will play when fed one watt of power, or 2. The problem with this measurement is that the conditions under which it is to be recorded are not well defined and hence the figure does not provide a consistent "apples to apples" point of reference.

For one thing, the input sensitivity gain of the amplifier used to measure the sensitivity is unknown and unspecified. More importantly, while the specification calls for measurement at one meter away, the conditions of the listening room are not defined. It is not clear whether measurement is to occur in an anechoic chamber, a concert hall, a coat closet, or a gymnasium. Each of these rooms will yield remarkably different sensitivity readings at one meter from the speaker.

The most important lesson to learn from the above discussion is that for the purposes of determining tube-friendliness, sensitivity is essentially meaningless. Many tube gurus insist that one must use speakers with sensitivity ratings of 90 db or higher.

This is simply not true. Many speakers with high sensitivity ratings are poor choices for tube amps, just as many speakers with low sensitivity ratings often work quite well. Why is this so? Read on Oh My! What is impedance Impedance, for the purposes of this discussion, may be thought of as the AC equivalent of DC resistance. In other words, as impedance rises, the current required from the amplifier to maintain the circuit's voltage decreases.

More importantly, as impedance lowers, the current required increases. This concept is important for both tube and solid state amplifiers, as will be explained in greater depth later.

Virtually all speaker manufactureres publish a "nominal" impedance rating for their speakers. The term nominal ought to indicate the optimistic and relatively unscientific nature of the figure provided.

Many speakers are rated nominally at 8 ohms but their impedance fluctuates wildly over the audible frequency spectrum. Knowing the nominal impedance is simply insufficient to determine how well a speaker will perform on tubes. Many tube enthusiasts state that a speaker must be nominally rated at 8 ohms or higher in order to be tube friendly - this is an oversimplification and will be clarified later.

Bear in mind that the nominal impedance is only a useful figure in the context of the minimum impedance. Ideally a graph of a given speaker's impedance vs. Let's take a look at such a graph: In the graph above, the solid line represents impedance, and the dashed line phase. Frequency is measured along the horizontal axis in Hz. Impedance is measured in ohms on the left hand vertical axis. Phase is measured on the right hand vertical axis in degrees.

As one can plainly see, the impedance of the measured loudspeaker varies considerably as a product of frequency. Interestingly enough, this speaker has a published nominal impedance of 8 ohms, despite the fact that for large sweeps its impedance measures lower than 4 ohms What are phase angles? Also worth discussing is the measurement of phase on the above graph.

Phase is measured in degrees. The greater the angle in the positive direction, the more inductive the loudspeaker becomes, the greater the angle in the negative direction, the more capacitive.

The above speaker's phase angles are actually not as steep as some others we have seen, but one important consideration is that the speaker is fairly capacitive at around 80 Hz. The combination of low impedance and high capacitance requires that the amplifier generate large amounts of current at that particular frequency.

What Tubes Want Tubes like a resistive load - it's really that simple. A resistive load translates to a flat impedance, and an inductive rather than a capacitive phase angle. A less technical way of looking at an ideal speaker from a tube's point of view is as follows: tubes like consistency. They prefer a speaker that doesn't swing from 8 ohms to 2 ohms and back again. If the impedance is going to dip it should do so gradually, or in small dips. Tubes like a steady load - capacitance is the opposite.

When a speaker behaves in a capacitant manner, it presents an uneven load to the amp, asking for current in sudden spurts. Tubes don't like to pump out current at the drop of a hat. They prefer a consistent and predictable load. Naturally it is sometimes difficult for speaker manufacturers to keep all the aforementioned variables in their ideal ranges. If phase angles must be capacitive, impedance should be high.

The lower the impedance, the flatter it must be, and the less capacitive the phase angles must be. All three variables slope of impedance, value of impedance, value of phase angle together determine how good a match a speaker will be for a tube amp. For this reason, the argument that only speakers with an impedance of 8 ohms or higher will work on tubes is incorrect.

There are many tube friendly speakers whose nominal impedance is 4 ohms. If the speaker's impedance is relatively flat and consistently hovers around 4 ohms, and if the phase angles are only slightly capacative, or better yet inductive, there is no reason why a 4 ohm speaker cannot perform well on a tube amplifier. Some of our favorite tube friendly speakers are 4 ohms! It is also important to recognize that one need not use the 4 ohm taps on a tube amp with 4 ohm speakers.

Many 4 ohm speakers sound their best when hooked up to 8 ohm, or even 16 ohm taps. If the speaker presents a resistive load i. If the speaker requires more current because the impedance is low and and not terribly flat, the 4 ohm taps will likely offer better bass control at the expense of definition in the highs and mids. We encourage you to try your speakers on each of the output taps and hear for yourself the difference.

If the above explanation seems complicated, let's take a look at some more graphs. Visualizing our explanation will make it much simpler to grasp. Let's start with some graphs of speakers that we know are excellent matches for tubes. While the impedance is not flat it is consistently high, never dipping below 8 ohms, and often peaking above 20 ohms.

The result is less current demand on the amplifier in question. At the same time, the phase angles for this speaker are only slightly capacitive, with the exception of the dip at around Hz. However, notice that the corresponding impedance is extremely high, thus somewhat marginalizing the effects of capacitance. The tendency of a speaker's impedance to peak when the phase angles dip is a trend found in many tube friendly speakers. Remember our discussion of sensitivity and how misleading it can be?

Yet they are some of the most tube friendly speakers ever designed. Again we see the trend of a consistently high impedance. This speaker is rated as 8 ohms nominally and its impedance never dips much below 6.

The phase angles for this speaker are even better than those for the Rogers, with only one small saddle at around 80 Hz. Now let's try a speaker with a lower impedance: This speaker has a published nominal impedance of 8 ohms, which might be a little optimistic but nevertheless it only dips below 6 ohms briefly on a couple of occasions and when it does so, the phase angles are either slightly capacitive or inductive. Now let's look at some un-tube-friendly impedance graphs: What we see here is a speaker whose published nominal impedance 8 ohms bears little relation at all to its actual impedance.

For large spreads of the audible bandwidth this speaker measures under 4 ohms. Likewise at around 55 Hz. Taken together these two factors place very substantial demands on the amplifier.

Is it clear now how misleading sensitivity can be when selecting a tube-friendly speaker? Of all of the speakers we have measured thus far, the one with the highest sensitivity has been the worst choice for tubes. Here's another guy that doesn't play well with tubes: In this case the problem is really quite simple - the measured impedance for this speaker is unrealistically low throughout the vast majority of the audible frequency spectrum.

From 80 Hz. Even though the phase angles are relatively harmless, the impedance is so low that only a high inductive load would make a difference. This speaker requires an amplifier stable into very low impedance, and which is capable of outputting large amounts of current on demand.

Let's have a look at one more: In this example what we see is an impedance which mimicks a rollercoaster - up, then down, then up, then down again. A giant peak between 1 and 5 k, on either side of which we measure impedance under 4 ohms guarantees erratic performance with tubes. As in past examples we also see a relatively capacitant phase angle intersecting with a fairly low impedance, demanding high current output from the amplifier. What is Back EMF?

Back EMF is one variable which is difficult to gauge from impedance graphs but contributes significantly to how tube-friendly a given speaker will be. Consider for a moment how a loudspeaker operates: an amplifier excites a loudspeaker driver by sending it current. Now look at the process in reverse: if you excite a loudspeaker driver by pushing on it gently, for example you will send some current from the speaker to the amplifier.

Tubefriendly loudspeakers?

Vacuum Tube Amplifiers. This article covers commonly used vacuum tube amplifier configurations with emphasis on types used in veteran radios and veteran communication equipment. The article discusses each configuration first at a fairly elementary level, aimed at readers with limited technical insight or readers who just want an overview of the amplifier type. After this, some of the stages are discussed in more depth, to give readers who are interested in this a deeper knowledge of how the stage is built and dimensioned. For a general overview, these parts, which are in blue , can be skipped. Prerequisite: The reader should have basic knowledge of superheterodyne concepts , vacuum tube technology , and biasing methods. The vacuum tube as amplifier.

Common Tube Amp Malfunctions: My amp doesn't turn on.

Audio amplifiers are required in nearly all playback environments and many recording situations as well. There are plenty of amplifier types out there, and a major distinction between amplifiers is the use of solid-state circuitry versus tube circuitry. What are the differences between solid-state and tube amplifiers? Solid-state amps use solid-state transistor-based amplifier circuits, while tube amps use vacuum tube amplifier electronics. This difference is apparent in power amps, preamps and other amplifier types as well. It also yields other general differences between solid-state and tube amps. A signal is a time-varying voltage or current.

Amplifiers, is it better to buy a tube or transistor amplifier?

These two Op-Amps accomplishes the signal phase inversion and the balanced drive signal. The second Op-Amp works as both as a phase splitter and as a driver for the second output tube. The first Op-Amp is configured as a non-inverting amplifier with a gain of In contrast, the second Op-Amp is configured as a inverting amplifier with also a gain of

The Differences Between Tube and Solid State Amps

The reputation of the tube amp is so great, that the best possible compliment for a transistor amp is often to say it has a "tube sound". You've probably heard about the electric guitar tube amp, they're the most popular ones. Obviously, tube amplifiers or tube amplifiers have not only advantages: the counterpart is to be cumbersome, heavy and often very showy aesthetically speaking. A tube amp works in a completely different way from a transistor amp also called a solid state amp. In fact, tube amps work in high voltage several hundred volts compared to a few tens of volts in transistor amps.

Tube Amplifier Safety

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Building a Stereo Tube Amp

It was bound to go sooner or later. The back of an amp should indicate the wall voltage for which the amp is designed. The closer to new an amp is, the higher its optimal operating voltage. Depending on where you live, wall voltages fluctuate on a daily basis, and range from to volts!

Why Tubes?

RELATED VIDEO: DIY Tube Amp sounds better than a normal Amp?!

I am on the search for a good and affordable integrated tube amplifier to use with my new Klipsch Heresy IV speakers. After some initial research I found 5 tube amps that seem to offer remarkable value for money. I even got a bit over-enthusiastic and ordered three of them to test myself. It is one of the China made tube amplifiers that is highly acclaimed and reported to perform very well for the money. What I found especially intriguing about this amp is that it is a true no-feedback, single-ended, class-A B design.

Current Production Marshall Tube Amps

At TestHiFi we discuss and develop ways to measure aspects of music reproduction. Sometimes, working on my own loudspeaker projects, such aspects draw attention. About such an event I want to write this time. It is good enough to show the most important voicing aspects clearly. It also has low output impedance.

Solid-State Vs. Tube Amplifiers (Pre, Power & Guitar Amps)

Watt's the Deal? There is no such thing as a perfect amplifier. All audiophiles and their associated equipment have specific needs, but in each case there is such a thing as a best amplifier - the one that makes you happy.