Posts Tagged ‘anode’

Never Hang Your Guitar Tubes / Valves Upside Down

Thursday, March 18th, 2010

Never hang your guitar tubes upside down as many horrible things may happen!!!

The heat from the electrodes will go directly to the base pins and cause problems with oxidization. The heat will also cause micro-cracks on the pins of the tube / valve, which could result in failures.

Don't_ hang_ your_tubesSo don’t do it !!…….

Guitar Amp Tubes / Valves The History Of .. EL34 s etc

Thursday, March 18th, 2010

Until the introduction of the germanium transistor in the late 1950’s, there was no alternative form of high quality audio amplification to the thermionic valve (American terminology was always ‘Tube’). The 1960’s, 70’s and 80’s saw a steep decline in the usage of valves for all purposes except audio amplifiers, to the point that, with a few exceptions, they were almost entirely replaced by transistors and integrated circuits. However, since the late 1980’s, valve amplifiers have experienced a renaissance which has, in the last decade grown rapidly year on year.

The unique character of the ‘Tube Sound’ has once again attracted both amateur and professional interest in the areas of High Fidelity (HiFi) amplification, Musical Instrument (MI) amplification (notably the electric guitar) and Audio amplification. The dominance of digital technology now, means that the valve amplifier is seen as new to younger people and as nostalgic to the older generation. Please note it is estimated, that the electric guitar amplification market consume as many as three out of four of the world’s production of audio tubes.

EL34 Valve

EL34 Valve

Many arguments have been put forward as to why tube amplification ‘sounds’ better than digital. Some differences can be proved using measuring instruments, whilst others are down to the nuances of the human ear. Whatever the reason, evidence shows more and more listeners appear to prefer the sound of a tube amplifier.

The demand for tube amplifiers is rapidly growing, with products ranging from a few hundred pounds to several thousand pounds, depending on quality and output power, with tube sales worldwide currently standing at over $100,000,000. Today vacuum-thermionic devices hold sway over the US $100 million worldwide guitar amp business. One rough estimate shows a 10-percent-per-year growth in demand for tubes used in MI instrument amplifiers and high-end audio since the late 1980s, with no apparent slackening.

However, the problems with existing tube amplifier technology is that the circuits used are based on ‘classic’ designs developed in the 1940’s and 50’s and, although more modern technology has occasionally been applied, this is usually confined to regulating the power supplies. One of the principle disadvantages of existing tube amplifiers is that they are very inefficient in converting electrical power into audio power. This is largely due to the ‘classic’ methods of controlling them. All analogue high power amplifiers require a system known as ‘Biasing’ to be applied to them. This controls the output devices and prevents them from ‘Thermal’ overload and eventual destruction. It does, however, incur a heavy cost in loss of output power and increased heat dissipation. In addition valves also need to be used in ‘Matched’ pairs, in order to control distortion of the output signal. This process is time consuming and expensive when carried out on a commercial basis.




PIMP Your Guitar Amp With The TubeSync Bias Engine

Tuesday, March 16th, 2010

Pure tube magic – that warm, uncluttered sound powered by superior amp technology deserves the best. TubeSync takes care of the detail, giving unsurpassed performance from any tubes.

Plugging straight into the tube powered heart of your amp, in perfect harmony with its fine tuned circuitry, TubeSync’s Bias Engine eradicates the need for bias current matching, increases tube life and takes your tubes to their optimum temperature as soon as you power up . . .

and there’s more.

The result: a well honed tone tyrant with none of the problems hampering conventional tube amps; a streamlined orchestrator of analogue magic.

Ashdown Amp With TubeSync

Ashdown Amp With TubeSync


The Bias Engine’s ‘Hot Anode’ cranks up the heat and has you running hot from the very first cord. It knows the optimum temperature for your tubes best performance and gets them there the minute you start playing.


The Bias Engine is easily incorporated into your amp’s systems at manufacture. It removes the need for bias current matching but still achieves the absolute best tone.


Increased manufacturing efficiencies (due to reduced testing) are achieved by eliminating the need for bias current matching.


Fear not the cherry red glow of a failing tube! The Bias Engine continuously monitors the performance of each tube during operation and searches for typical tube failure modes and trends. If the Bias Engine

detects a faulty tube, it can automatically ‘switch out’ the offending tube and run the amp, at half power, until the defective tube can be changed.


Work your tubes at their full potential. The Bias Engine automatically micro-adjusts the bias on each tube to ensure its full potential is realised throughout its working life. The amplitude of drive signals supplied to the grids is dynamically measured and performance is optimised accordingly. Tubes work harder, better and for longer.


TubeSync revolutionises convention by completely replacing traditional testing methods. Every time you power up TubeSync runs an automatic ‘in circuit’ test and assures reliability.


Less power input, same big output. TubeSync reduces quiescent power consumption by an average of 20% compared to conventional amplifier biasing techniques.

Hiwatt Underline Reliability Repuation With TubeSync

Thursday, February 18th, 2010

Famed for their legendary reliability and tone, Hiwatt have gone one step further in the reliability stakes by employing TubeSync® technology in their already bulletproof amplifiers.


Over the last year, Hiwatt and UK based KBO Dynamics have developed their own version of a pioneering technology called TubeSync®, which Hiwatt will launch at Frankfurt Musikmesse 2010 in March. The technology has been developed in order to overcome problems associated with conventional tube amplification such as biasing, tube longevity and overall reliability. What the collaboration has achieved is to improve amplifier design without changing the fundamental amplification process yet retaining the classic Hiwatt tone and sound.

Although not an integral part of the amplification process, Tubesync® is connected to the heart of the amp’s circuitry, constantly testing and monitoring; it’s like having an amp technician working full time inside the box every time the amp is powered up. This technology eliminates the need for tube bias current matching, increases tube life by micro-adjusting the bias on each tube, predicts tube failure and can, in the event of a catastrophic tube failure, even run the amp at half power. The result is the eradication of many of the problems hampering conventional tube amplifiers and peace of mind for the musician wise enough to have taken this route.

KBO Dynamics Chief Exec Andy Fallon: “It has been a pleasure working with Hiwatt who have been extremely receptive to change and have embraced the new technology. They have seen the benefits it can bring to them and of course, their customers, and we are looking forward to further exciting collaborations. This technology genuinely has raised the bar concerning reliability and classic tube amps, and what’s more. It’s been developed exclusively in the UK .”

For more information on TubeSync® technology, please visit and

Hiwatt produce classic British custom amps both guitar and bass.

What People Say About TubeSync

Tuesday, September 8th, 2009
What I like about TubeSync is that gives us the opportunity to create our own features which enables us to have our own unique USPs.

(Marketing Manager)

Not changing the sound is very important to us because the sound is the main reason why customers buy our amps. TubeSync offers a long list of benefits without changing the sound. Amplifier reliability is a big one for us as some of our order designs have design problems which can result in field failures. Failures are very costly and results in a large amount of hassle for both us and our customers especially when an amp output transformer blows up! The TubeSync reliability features is what we like best, it saves time, money and of course our reputation.

(Lead Development Engineer)
TubeSync does what it says on the tin! We are looking to incorporate it into our next generation of amps!

(Technical Director)

Not matching tubes that’s a big one – it’s a pain in the neck – it’s key to getting a successful tube amp ‘fantastic’. if you don’t need to use matched pairs and there’s no need to bias, then that’s amazing, the efficiency savings on the factory floor will be a awesome. Who needs a Six Sigma Black belt!

(Amplification Product Line Manager)

You’re saying all of the things that we hear on a regular basis, i.e. ooh, tube longevity – these are things that crop up that keep me awake at night. I’d say it’s pretty unique

(Marketing Manager, Guitar Amplifier Manufacturer)

We are currently going for the ISO 14001 environmental accreditation. The energy savings resulting from TubeSync will be part of our continuous improvement plan. If everyone does their bit, the world will be a much greener place.

(Operations Manger, Guitar Amplifier Manufacturer)

There is only so much power a tube can throw out before it dies. So it’s an efficiency thing? It gives you more power for less heat? Useful, yeah

(Lead Development Engineer)

TubeSync can optimise the running temperature of the tube down considerably, and as a function of that, the life of the tube increases. And that’s something that’s far more interesting than putting more power through it.

(Technical Director)

The Advantages Of TubeSync In Guitar Amps

Thursday, September 3rd, 2009
Eliminates tube matching

Eliminates the need for bias current matching of amplifier output tubes,this increases manufacturing efficiencies, due to reduced testing.

Reduced tube cost

Eliminates the need to purchase tubes in ‘matched pairs’ and replaces conventional biasing components.

Increased tube life

Automatically micro-adjusts the bias on each tube to ensure the full potential of each tube in the system is realised throughout its working life.

Reliability assurance

Replaces conventional tube testing methods by performing an ‘in circuit’ test every time the amplifier is powered up.

Half power back-up

If TubeSync® detects a faulty tube, it can automatically ‘switch out’ the offending tube and run the amp at half power, until the defective tube can be replaced. tubesync rendering white

Maintains optimum performance

Dynamically measures the amplitude of the drive signals supplied to the grids of each output tube and optimises performance accordingly.

Simultaneous distortion

Maintains the classic warm sound of the amplifier by ensuring tubes distort symmetrically.

Reduced power consumption

Reduces quiescent power consumption when compared to conventional amplifier biasing techniques by an average of 20%.

NEW ‘ Hot Anode’

TubeSync® knows the optimum operating temperature of your tubes, so there is no need to warm up your amp. TubeSync® will get you to where you need to be just as soon as you start playing.


Unique algorithms can be incorporated to tailor optional performance characteristics and features to customer requirements.

Conventional Tube Biasing

Wednesday, July 8th, 2009

A very important feature of any thermionic tube circuit is known as ‘biasing’. It has already been mentioned that a negative voltage applied to the control grid of the valve will restrict or prevent the current flowing between anode and cathode. This is also known as a ‘bias’ signal, as it is used to control the amount of current which flows under ‘no-audio-signal’ conditions (quiescent conditions).It is common practice to operate tube amplifiers in a state known as ‘Class A-B’. This means that when no signal is present, a relatively small amount of D.C. current is allowed to flow in each tube to reduce distortion of the amplified signal to a low level. The amount of quiescent current allowed to flow is obviously very important to maintain optimum operating conditions. Too much current will cause harmonic distortion, increase heat dissipation in the anode, reduce audio output power and reduce the operational life of the tube. Too little current will cause severe harmonic distortion and, under extreme conditions, could cause a condition known as ‘cathode poisoning’, which also reduces the effective operation life of the tube.

Conventional Methods of Biasing Fall Mainly into Two Categories

– (1) Cathode (or ‘automatic’) Bias in an attempt to automatically control the quiescent current flow in the tube, a high power resistor is connected in the cathode circuit to signal ground.  The grid is connected via a high tube of resistance (usually 500k Ohms or greater) to earth or signal ground.  The principle of operation is that when current starts to flow through the tube (and the cathode resistor), a volt drop, proportional to the current will occur across the resistor.This will effectively make the cathode more positive than the signal ground (control grid potential). In effect, this is exactly the same as making the control grid more negative than the cathode. The grid will therefore begin to restrict the flow of current until equilibrium is obtained. The value of this current will be proportional to the value of cathode resistance. Any tendency for the current to increase or decrease due to aging or external conditions will be countered by the resultant change in control grid voltage.

Disadvantages of Cathode Biasing

Cathode biasing has been used in audio amplifier circuits for many years, and although fairly effective, it also has several serious drawbacks notably:

  • In high power amplifiers, the value of the cathode resistor must be made relatively large, which results in them needing to dissipate several Watts of heat (adding to the general heat dissipation within the amplifier chassis).
  • Reduced operating efficiency.
  • A significant amount of audio signal power is ‘lost’ in the resistor, thereby reducing the audio output power for any given input power.
  • It is necessary to bypass the cathode resistor with a capacitor in order to preserve the audio amplifying properties of the tube. This capacitor is in the audio signal path and therefore has a restricting effect on certain frequencies.

(2) Fixed Bias

Higher power amplifiers tend to use fixed bias due to the disadvantages of cathode biasing already mentioned. It has a tendency to be used in guitar amplifiers where distortion due to maladjustment comes second to higher output power. Fixed bias incorporates an external negative supply to the grid, which is controlled by a manually adjusted trimmer resistor. It is common practice to supply more than one of the tubes from the same adjustment.

Disadvantages of Fixed Biasing

Setting the bias conditions requires technical knowledge and skill; therefore this operation should be performed by an audio technician.

  • Once set any tendency for the current to increase or decrease due to tube aging or external conditions cannot be catered for, therefore conditions can only be optimum immediately after adjustment.
  • Frequent adjustments are necessary throughout the life of the valves to preserve optimum performance.
  • If a single bias control is used, at best one, or possibly none of the output valves will operate under optimum conditions.
  • Maladjustment of the bias control or slight leakage in grid coupling capacitors could result in severe (very costly) damage to the power supply, power output tubes or output transformer.

Heating Effect

It is a misnomer to assume that because tubes rely on thermionic emission for their normal operation, that they cannot overheat. Power output tubes are especially vulnerable to the effects of overheating due to their high anode dissipation under normal driven conditions. Any extra heat generated due to the effects of faulty coupling components, incorrect biasing or poor design can seriously shorten their operational life. Common conditions which cause overheating are:

  • Faulty (high leakage) grid coupling capacitors – if cathode bias is used this can be offset to some degree by the automatic compensating effect of the cathode resistor, although overheating and destruction of the resistors may occur before audio distortion is noticed by the listener. In a fixed bias system, it is almost certain that severe damage will result.
  • Failure of the cathode resistor by-pass capacitor in cathode bias systems.
  • Bias voltage maladjustment in ‘fixed bias’ systems.
  • Gas in the valve envelope (‘soft valve’)