Posts Tagged ‘current’

Does Plate Dissipation Affect Valve / Tube Life In Practice ??

Thursday, November 8th, 2012

In general, the obvious connection between higher anode dissipation and shorter tube life holds good, however,  many other factors affect tube life, including accuracy of heater voltages and the efficiency of tube cooling within amplifiers.

The tube leaves the factory with a known amount of cathode coating material which is the source of all the electron emission. In use, this material is used up as it emits electrons when heated by the filament and plate current is drawn.

If plate current is drawn before the cathode is at operating temperature, the surface of the cathode can be damaged (so called ‘cathode stripping’).

This is why the Standby switch should be off when the amplifier is warming up. If, however, the tube is operated for long periods with the filament hot with little or no plate current being drawn, then an oxide-like coating can form on the cathode, effectively blocking the emission of electrons even when normal operation is required (known as ‘cathode poisoning’). TubeSync takes care of this by automatically controlling the bias at both start-up and run conditions.

vacuum tube EL34 valve

Plate dissipation is generally quoted by the manufacturer as a maximum value which, if exceeded could cause damage to the tube and should not generally be used for ‘normal’ operation. The relationship between tube life and plate dissipation follows an exponential curve. Tubes operated correctly at around 30% maximum dissipation can have lives in the region of tens of thousands of hours and can last several decades of years. This figure decreases rapidly as the dissipation increases, in some cased down to hundreds or even tens of hours as they approach or exceed their maximum plate dissipation rating.

Cooling is extremely important as running tubes very hot also increases the risk of arcing and a condition known as thermal runaway, which can instantly destroy the cathode material, making the tube useless. Conventionally biased tubes are most at risk when biased towards ‘Class-A’ operation, as they experience maximum power dissipation when no audio signal is present.

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Tube Amp Testing For Professional Stage Performers – Engineering Tube Talk

Tuesday, February 22nd, 2011

A common requirement for tube amplifiers used for professional and stage purposes is that there should be a high percentage of confidence that one or more tubes will not fail during the performance. Tubes are often thought of in the same manner as light bulbs, in that they are most likely to fail catastrophically at switch on. This means that the moments just after the switch on point constitute the most stressful and potentially damaging periods in the life of the equipment.

In an attempt to guard against this possibility, it is common practice to do one of two things on a regular basis.

1/ regularly remove the tubes and have them commercially tested;

2/ replace the tubes with new stock on a regular basis.

These two methods may give the operator a degree of confidence but in fact, it can be shown that the faith placed in both methods is misplaced.

It is a known fact that removal of a tube from its socket results in a number of potentially damaging mechanical stresses on the metal to glass seals around the pins. Each insertion of an all glass tube will cause micro-cracking of the glass around the pin. This will invariably cause a small leakage of air into the valve, causing ‘gassing’ and eventually leading to its demise.

Removal for testing will also break the intimate contact between the holder and the tube contact pin, resulting in a poorer contact on re-insertion.

Many tube testers apply unreasonable electrical stresses to the tube internal electrodes and it is not uncommon for a known good valve to be damaged during the test. Tube testers can also give erroneous results depending on the way they perform the tests, possibly allowing faulty tubes to show ‘good’ and the good valves to be rejected as ‘bad’.

The second method of ‘blanket replacement’ with new stock on a regular basis can also lead to problems because if the failure distribution curve for tubes is analysed, it can be seen to follow the classic ‘bathtub’ failure curve. This inevitably means that an amplifier which is regularly ‘re-tubes’ will inevitably be considerably more likely to fail during the first hundred hours service than one which has been left untouched.

TubeSync overcomes these problems by performing an ‘in circuit’ test on the tubes every time the amplifier is powered up. The mutual conductance (gm) of the tube is measured by monitoring the cathode current of each valve whilst adjusting the grid bias in fixed steps. The results are tabulated and the new value is compared with previously stored values. A decision is then made on how far the tube has decayed in emission since the last test. Outputs from the device inform the user of the predicted remaining life of the tube.

TubeSync_350

The Scissor Sisters Choose Hiwatt, Hiwatt Choose TubeSync

Friday, October 8th, 2010

The extravagant disco pop group The Scissor Sisters have purchased a Hiwatt amp for recording and live performances. They have just been announced as support to Lady Gaga for the North American leg of her Monsters Ball tour and have a new single “Any Which Way” out now.

scissorsist

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TubeSync Bias Engines Roll Off The Production Line

Friday, August 20th, 2010

Due to popular demand the TubeSync Bias Engine is now in volume production!

TubeSync

For order enquiries please email sales@tubesync.co.uk

Leaky Tubes / Valves Can Blow the HT Fuse In Guitar Amps, TubeSync Can Avoid This!

Thursday, July 1st, 2010

An interesting phenomenon that some ‘leaky’ tubes, removed from conventionally biased amps, appear to improve when run with TubeSync. The reason may be that when the tube gets hot, g1/cathode leak causes a current increase, but it is automatically biased ‘back’ to compensate, which allows the tube to cool down again and thus reduce leakage et al. After a while the leak sometimes reduces or disappears completely – we surmise that the getter  gets a chance to mop up stray gas molecules or the metallic deposit gets ‘boiled off’ the mica supports.  This type of fault in a conventional amp would normally blow the HT fuse, however TubeSync can avoid is and rectify the problem! Cool eh?

TubeSync_250

Hiwatt Amplify Their Success With TubeSync

Thursday, April 1st, 2010

IT TAKES more than sex, drugs and rock ‘n’ roll to make a guitarist sound great. John Hill meets North East amplifier makers at the cutting edge of technology.


Hiwatt & TubeSync

ANDY Fallon and Colin Arrowsmith are not guit- arists. Their affair with the valve amplifier isn’t born of a youth spent practising solos or arguing over kit specifications next to the counter of their local guitar store.

In fact, Andy’s experience lies in automotive and military engineering, while Colin is an expert in microelectronics.

However, their contribution to a piece of kit beloved of the White Stripes, The Who and Black Sabbath has attracted the attention of major international amp-makers.

Andy and Colin are co-founders of KBO Dynamics, a Consett company created to market technology designed to improve audio and guitar amplification.

They are the men behind TubeSync, a “tube management system” which monitors the performance of valve amplifiers to avoid meltdowns while maintaining sound.

The product won the innovation award in the Durham and Wearside heat of the nebusinessawards 2009, run by The Journal and Evening Gazette.

KBO co-founder Andy said: “We were looking for a niche market. Neither of us plays the guitar, but we did a lot of brainstorming.

“Colin worked with microelectronics, but he’s also an expert with valve technology. We realised very quickly that the biggest application for valves was inside guitar amps.”

The valve amp isn’t exactly a rapidly advancing technological product. The technology was developed between the world wars and uses a series of vacuum tubes to regulate a signal. It was present in items from TVs to radios, but fell out of favour in the 70s.

The resurgence of such equipment has been prompted by high-end users in the audio and guitar amp market, who praise its natural sound.

Andy said: “There’s a warmer, more rounded tone to it. Anyone who’s serious about playing a guitar would only use a valve amp.”

When they developed TubeSync, the pair didn’t set out to change the sound. Instead, they set their sights on the downside, the problems that plague valve amp users looking for that special sound.

He said: “The closest you can compare it to is an engine management system on a car. It’s like having a maintenance technician looking after your amp 24/7 without you noticing it. It’s continuously monitoring the circuit, looking for faults.

“We got a market research report from Think M in Newcastle. It conducted a series of live interviews with OEM companies and guitarists.

“We looked at the problems people were talking about, but we didn’t change the sound.

“It can detect faults. It can disconnect a pair of valves if it finds one is faulty. You normally have to buy valves in matched pairs and you need to take the amp to a technician to tweak it, but with TubeSync you only need to buy one valve if one fails and it can tweak the system for you.

“One faulty valve can blow up the output transformer. TubeSync can detect this and prevent catastrophic damage.”

KBO had support from a number of North East backers. It won £90,000 from NorthStar Equity Investors’ Proof of Concept fund, developed its prototype with help from Business Link and got £20,000 from the North East England Investment Centre. The process was then advanced by a grant of £20,000 from One North East.

In all, Andy estimates the product has taken 18 months and around £200,000 to develop.

He said: “We built and developed it from the bottom up. We tried to use components that were available in the marketplace and we created our own unique algorithm.

“We don’t think there’s a similar product to this on the market and we’re hoping to receive a patent in the next couple of months.”

Right now, KBO is on the hunt for buyers. The team has just returned from the international Musikmesse instrument trade show in Frankfurt, where they saw a live band perform using TubeSync technology for the first time.

He said: “It was being used by a band playing Pinball Wizard by The Who. We’re expecting to see the technology on stage properly some time this year.

“The lead time on the product is about eight weeks so it could well be appearing in the summer.”

British amp manufacturer Hiwatt, whose users include Arctic Monkeys, The Killers and The Kooks, has incorporated TubeSync into its amps and Andy says that others, such as fellow Brits Orange, are keen.

The company is talking to manufacturers about fitting it in amps this year and down the line it may create variants of the product that could be fitted by amp technicians or even end users.

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TubeSync For Valve / Tube Amps What am I ?

Friday, March 19th, 2010

About me:

I am a revolutionary new amp component, enhancing amp performance resulting in pure valve magic. My superior amp technology overcomes many of the problems associated with conventional tube amplification. With a little help from me there is no need for bias current matching, I can increase tube life and take your valves to their optimum temperature as soon as you power up. I can be easily integrated into any guitar valve amplifier. I take care of the detail, so you can concentrate on becoming a master of the strings . . . You can find a lot more about me on my main website www.tubesync.co.uk

The TubeSync Bias Engine

The TubeSync Bias Engine

Eliminates the need for bias current matching of output tubes

Increases manufacturing efficiencies

Micro-adjusts the bias on each tube to ensure its full potential is realised

Maintains optimum performance

Increases tube life

Assures reliability

Reduces quiescent power consumption

TubeSync

TubeSync

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.

THE SOLUTION IS ……..

EL34

EL34

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

POWER UP HOT

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.

JUST PLUG IN AND PLAY

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 EFFICIENCIES

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

ROOTING OUT THE RENEGADE

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.

HARDER, BETTER, LONGER

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.

RAISING THE BAR

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

MINIMUM POWER, MAXIMUM OUTPUT

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