Posts Tagged ‘cathode’

Orange Amplification Announces DIVO VT1000 Valve Tester

Thursday, January 31st, 2013

Orange Amplification has released the DIVO  VT1000 Valve Tester, an automatic valve tester that performs a host of diagnostics on both preamp and power amp tubes. The unit has one octal and two nine pin valve sockets to fit pe-amp and EL34 valves. Once inserted, the user presses the start button and the tests are run.

Vt1000 valve tester

VT1000 Details:

Tests run:

  • Heater filament test: Short circuit
  • Heater filament test: Open circuit
  • Heater filament test: Tolerance check
  • Heater cathode insulation: Leakage
  • Heater cathode insulation: Short Circuit
  • Tests for heater current abnormalities
  • Amplification factor
  • Voltage gain
  • Power gain
  • Screen grid test
  • Mutual conductance test
  • Dual test for double triodes
  • Emission
  • Inter electrode leakage
  • Inter electrode short circuit
  • Flash-over (arc detection, high voltage breakdown)
  • Gas ionisation test

Compatible Valves:

  • EL34/6CA7
  • EL34L
  • 6L6
  • 6V6/6v6GTA
  • KT66
  • KT77
  • KT88
  • 6550
  • 5881
  • EL84/6BQ5
  • ECC81/12AT7
  • ECC82/12AU7
  • ECC83/12AX7
  • ECC99
  • 12BH7

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.

TubeSync_225

Orange TubeSync DIVO OV4

Friday, July 13th, 2012

Engine management for your valve amp? It’s here and it works brilliantly

Nick Guppy (Guitarist).

orange-divo-main-460-80

Bias, and how to set it, is probably one of the most contentious issues for many valve amp users, especially those who like to tweak their amp by installing different makes or types of output valve.

Put simply, bias is your valve’s idle adjustment – it’s like making sure your car is ticking over properly. In fixed bias amplifiers, this is achieved by applying a negative voltage to the valve’s control grid – literally a grid of wire that sits between the cathode and plate.

“Once set, the OV4 continually micro-adjusts the bias current for each individual valve, keeping the amp running at peak efficiency.”

When you switch your amp on, electrons are generated at the cathode and pulled towards the plate, causing current to flow. This happens because electrons are negatively charged particles and the plate is energised with a strong positive voltage – opposite poles attract.

Varying the control grid’s negative voltage means this flow of electrons can be slowed to a trickle, or even stopped – like poles repel.

Although people often refer to the negative bias voltage setting, it’s the actual idle current that is important. All valves have an ideal idle current, typically around 30-50 milliamps, and for the amp to operate at its best it’s important that all your output valves are idling equally.

Click here to find out more!

This is done by fitting valves that have been matched in pairs or quartets, however even the best matching doesn’t mean that valves will wear equally, so in order to keep your amp operating at its best, an occasional small adjustment to the bias is sometimes necessary.

Usually these adjustments are at best a compromise; as individual output valves rarely draw the same idle current. What if there was a device that could measure and automatically adjust the bias for each individual valve? Well now there is: the Orange/TubeSync DIVO, which stands for Dynamic Intelligent Valve Optimisation.

It’s been available in OEM format for some time, however retrofitting this to an existing amp isn’t easy and is definitely beyond most guitarists’ capabilities. What was needed was a simple, bolt-on accessory that can be added to any fixed bias amp, and that’s what Orange has now come up with, in the shape of the DIVO OV4.

Built into an aluminium case about the size of a small paperback, the OV4 module comes with both a bracket and strong industrial Velcro fixings. Four piggyback octal sockets, or interceptors as Orange calls them, are connected to a strong nylon multi-pin plug that is located at one end of the module.

There are two small push-button switches, one offering a choice of standard and custom bias settings, while the other is called ‘share the wear’. At the other end of the module there’s an earth connection, together with an RJ45 socket and a standard 6mm jack socket.

The RJ45 socket is where the DIVO OV4’s interface module plugs in, allowing the product to be configured and interrogated from a PC using a small Windows-compatible program. This handy software lets authorised resellers/installers configure the custom bias switch setting, either globally or for each valve individually, as well as a second ‘idle only’ bias current that operates as a progressive standby feature.

Once set, the OV4 continually micro-adjusts the bias current for each individual valve, keeping the amp running at peak efficiency. It also means that you can run any combination of standard octal power valve you like, although pairs, such as 6L6s and EL34s are more useful.

With no audio present, the OV4 can automatically drop the bias current to a lower setting to reduce wear and tear, instantly returning to its higher level when audio is detected.

In the event of a valve fault, a clever algorithm shuts off the affected pair automatically and remembers which valves are at fault, displaying them on warning LEDs, as well as in the software, while also keeping a record of how many hours use the amp has had, both with and without audio.

The jack socket connects to a standard footswitch letting you switch the amp from full power (all four valves on) to half power, moreover the ‘share the wear’ function remembers which pair of valves were switched off the last time and alternates them, keeping wear as even as possible, although if you use two different pairs of valves, such as 6L6s and EL34s, you can use this as a tone option, swapping from one pair to the other. Cool or what?

In Use

Click here to find out more!

Installing the OV4 on an unmolested 1970s Marshall 100-watt Super Lead head, we deliberately plug in an assortment of unmatched power valves – an EL34, a 6V6, a 6L6 and a 6550.

Setting the custom bias measurements for each valve in the DIVO’s software, we use a special piggyback test socket connected to a multimeter to verify the DIVO does actually do what it says on the can – needless to say, it does.

We then install an old set of EL34s and compare these results with a brand new matched quartet of Groove Tubes – the OV4 automatically senses the difference, easily dealing with big variations across the old valves and smaller ones on the new set.

Sonically, the OV4 noticeably tightens up the Super Lead’s midrange focus and attack while also slightly reducing mains hum, indicating that the magic DIVO box is actually making a positive improvement to the amp’s performance.

For owners of most fixed bias four-valve amps, DIVO offers a reliable and simple means of ensuring peak operation at all times; it works efficiently and transparently and should extend the working life of valves way beyond the point when most people would start thinking about replacement.

There was a time when all cars used a mechanical device called a carburettor to spray fuel into the engine – mechanics had to adjust them by hand, using a plethora of vacuum gauges, stethoscopes and experience to get the best results.

Today, this dark art has been replaced by the convenience and reliability of electronic fuel injection and engine management – if your mechanic wants to know what’s happening inside your engine he doesn’t make intelligent guesses any more, he plugs in a laptop instead and the car tells him what’s wrong.

The DIVO OV4 is really like engine management for your valve amp. It’s ready-fitted to the Orange Rockerverb 100, meanwhile this retrofit version is quick and easy for authorised installers to fit to almost any four-valve design.

As there’s presently no competition, it’s difficult to make comparisons, but we think the price is pitched just about right. Those who like to tweak things may be frustrated that the PC interface and diagnostic software isn’t available to the general public, however there is the possibility of damaging your amp if it isn’t configured properly, so this is an entirely sensible decision.

DIVO works perfectly and does an excellent job of keeping even the most wayward valves on the straight and narrow. If you want to get the absolute best out of your amp and improve its reliability, DIVO is almost an essential – it’s a real innovation.

Verdict

A brilliant idea from the UK that could be the way of the future for valve amp design.

TubeSync Fitted To A Mesa Boogie F-50

Thursday, June 9th, 2011

Sensational blues guitarist Mitch Laddie has been out touring with the product fitted to his Mesa/Boogie F-50, which he said sounds “incredible”. “I had totally fallen out of love with this particular amp before Tubesync was fitted but the difference in sound is more than substantial.The response and tone have been improved ten-fold. Very tight, very fat and all round punchier, especially in the low to mid frequencies.”

Mitch & His Mesa F50“I believe the product is very interesting and definitely nothing like anything I’ve seen or used before. The main advantages of the product are that not only does it give you a valve maintenance feature by displaying a light if a fault is found within a valve, but it manages your valves to run at an equal number of milliamps. This means that each valve is working at an equal rate which in theory gives you optimum amp performance.

F50

Above : TubeSync fitted to a Mesa Boogie F-50

TubeSync DIVO A Brilliant Idea From The UK That Could Be The Way Of The Future For Valve Amp Design

Friday, April 1st, 2011

Checkout the TubeSync DIVO review in the April 2011 Guitarist Magazine.

”TubeSync DIVO works perfectly and does an excellent job of keeping even the most wayward valves on the straight and narrow. If you want to get the absolute best out of your amp and improve its reliability, DIVO is almost an essential – it’s a real innovation”.

orange-divo-main-460-80

Hayden Amps New MoFo 100 With TubeSync

Tuesday, March 30th, 2010

Hayden amps launch the new MoFo 100 with TubeSync during Messe Frankfurt 2010

Hayen Mofo 100

The new Hayden MoFo 100 with 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 !!…….

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.

tubesync_amp_02

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 www.kbodynamics.com and www.hiwatt.co.uk.

Hiwatt produce classic British custom amps both guitar and bass.

Tube Failure Modes, Within Amplifiers

Tuesday, August 11th, 2009

Catastrophic Failures. These are failures that occur suddenly, without warning, making the equipment unusable.

Examples of catastrophic failures are: –

  • Glass failure, loss of vacuum due to mechanical damage or thermal stress.
  • Heater failures open circuit or partial short circuit due to excessive heater voltage or high initial surge current and normal on off cycling over many thousands of hours.
  • Arcing, due to low cathode temperature, causing damage to the cathode and grids.
  • Bias failure due to component leakage or valve characteristic spreads using fixed or auto bias.

Degenerative Failures. The slow but eventual, deterioration of all tubes, which can contribute to the end of life of the tube.

Examples of degenerative failures: –

  • Gas is present in all tubes and if the tube is used within its characteristics should not be a problem, however excessive dissipation can liberate gas from the tube structure and lead to eventual premature failure.
  • Getters are patches of evaporated metal, which are deposited on the inside of the glass. The purpose of the getter is to absorb any gas that may be evolved during the life of the tube and work best at normal glass bulb temperatures.
  • Spurious emissions are uncontrolled unwanted emissions usually caused by gas released due to excessive dissipation and elevated temperatures.
  • Inter electrode leakage. This is current, which flows between the electrodes of the tube, which are not connected in any way. The cause is metallic vapours released by the hot metallic structure of the valve being deposited on the insulating micas and eventually leading to a conductive path.
  • Cathode depletion can occur due to arcing, which can strip the cathode coating reducing the active area of the cathode. Arcing will vaporise the cathode material and generate gas, which can poison the cathode material. This can also be caused, by passing excessive cathode current before the heater has reached its normal operating temperature.

Subjective Failures. These are tubes, which will normally pass tests but do not perform satisfactorily due to for example: – hum level, microphonics and noise.

Examples of subjective failures: –

  • Hum is an unwanted mains frequency signal, which is superimposed on the wanted signal.  It can be caused by heater to cathode leakage or due to electrostatic or electromagnetic fields within the equipment.
  • Microphonics is defined as a signal originating inside the valve caused by mechanical vibrations being amplified by the tube.
  • Noise is a signal originating from inside the tube, but not due to hum or microphonics. It can be due to intermittent short circuits, open circuits or arcing due to leakage paths between the electrodes.

Characteristic Variables. These are variations or spreads in the tube characteristics, due to manufacturing tolerances and follow a normal distribution curve.

Examples of characteristic variables: –

  • The Standard is usually a tube that complies with the manufactures published data. The Upper and Lower limits are values that any tube within these limits can be considered acceptable for normal use.
  • Characteristic Spreads is the degree of deviation from the standard tube.
  • Design Tolerances is the normal variations of standard parts, which a well-designed piece of equipment will operate correctly.

The Solution Is ……….TubeSync!

TubeSync Amp Biasing

TubeSync Amp Biasing


www.kbodynamics.com

The Advantage Of TubeSync Over Fixed Or Auto Bias

Tuesday, August 11th, 2009

TubeSync has many advantages over other bias methods. An amplifier with fixed bias needs to be set manually and adjusted frequently to maintain the correct bias. Also unless each tube has its own bias setting, at best the results can only be a compromise due characteristic spreads in the valves, which in push pull amplifiers can lead to saturation of the output transformer on high signals due to DC magnetization of the core due to unbalanced anode currents. TubeSync continuously monitors the bias current and ensures perfect DC balance. Auto bias can compensate for valve characteristic spreads providing the characteristics of the valves are closely matched. However auto bias introduces loses by subtracting the bias voltage from the power supply voltage and with some types of valve the losses can be considerable and this means that the anode of the valve has to be operated at a much higher voltage to compensate for the auto bias losses.

TubeSync Amp Biasing

Using TubeSync these losses are eliminated and the HT power supply voltage can be reduced or the amplifier can deliver more output power due to having all of the power supply voltage available to supply the load. TubeSync can compensate for much large spreads in valve characteristics without the need to use specially selected or matched pairs of valves and still maintain the linearity of the output stage.