Tube Amp 101

[dcow90]

I'm making the move to tube. I've read a lot about tone and features but many places fail to mention tube care. Can anyone give me a quick caring for your tube amp rundown or anything else I may want to know about the journey to tube amps?

Any help is appreciated. Thanks!

 

[coppa]

#1 it only sounds good when its too loud
#2 never run it without a speaker plugged into the speaker output jack
#3 always match the speaker impedence correctly
#4 turn on power 30 seconds later take it off standby
#5 replace the tubes before they blow if you can

as long as you follow the first 4 there isn't much maintenance other than changing tubes every year or two.

tube care? dude tubes are still used in military electronics because they will survive a nuclear holocaust. just replace evey year or two and thats about it for most people.

 

[MrMarkIII]

Not to disagree, but to amplify: tubes survive nuclear explosions better than solid-state electronics because they are a bit less prone to the effects of the Electro-Magnetic Pulse (EMP). Not because they are physically more robust.
This also why a '67 VW Bug would survive better than a 2008 Caddy. Much simpler electronics. Any integrated circuits will still fry, unfortunately. Especially if the amp is plugged in at all. Putting your amp on "Standby" won't help when the bombs start to fall. :wink:
Mechanically, one should still treat tubes the same as light bulbs - thin, fragile glass bottles filled with vacuum.
Of course, in the event of a nuclear holocaust, your first concern may not be the next blues jam meet-up.
Cheers!

 

[ja22y]

I'm making the move to tube. I've read a lot about tone and features but many places fail to mention tube care. Can anyone give me a quick caring for your tube amp rundown or anything else I may want to know about the journey to tube amps?

Any help is appreciated. Thanks!

Class started.
Caring for amp also means knowing what you're doing. Maybe this is 102 but:
- Learn about the different type of tube (pre, power, rectifier)
- Get a bias tool or atleast learn what biasing is.
- Train to hear tonal different of pre tube distortion vs power tube breakup.
- Understand 'sag' and natural compression
- Tube position V1, V2, Vxxx

welcome to the board.

 

[dcow90]

Thanks. What is tube poisoning?

 

[coppa]

Not to disagree, but to amplify: tubes survive nuclear explosions better than solid-state electronics because they are a bit less prone to the effects of the Electro-Magnetic Pulse (EMP). Not because they are physically more robust.
This also why a '67 VW Bug would survive better than a 2008 Caddy. Much simpler electronics. Any integrated circuits will still fry, unfortunately. Especially if the amp is plugged in at all. Putting your amp on "Standby" won't help when the bombs start to fall. :wink:
Mechanically, one should still treat tubes the same as light bulbs - thin, fragile glass bottles filled with vacuum.
Of course, in the event of a nuclear holocaust, your first concern may not be the next blues jam meet-up.
Cheers!

yeah i know i know but do you really want to take chances...when the enemy comes?. :shock:

 

[MrMarkIII]

Thanks. What is tube poisoning?

A little Google is a dangerous thing:

"Cathode stripping is perhaps a slightly misleading description. Cathode bombardment would be more accurate - remember that we are considering damage to the cathode emissive surface.

"The vacuum in a valve is not perfect, so there are copious stray gas molecules randomly floating between the anode and cathode. If an electron should be accelerated towards the anode from the cathode, there is always a chance that it will strike a gas molecule and have sufficient energy to remove an electron from that molecule, rendering it positively charged and attracted to a lower potential such as the cathode. The problem is that the ion is not merely a single electron, it's a molecule with a nucleus composed of (heavy) neutrons having considerable momentum when it strikes the cathode emissive surface.

"If the only force on particles between the cathode and anode was the accelerating electrostatic force of the anode potential, then the repellant force of the electron cloud above the cathode surface would be sufficient to completely prevent damaging cathode bombardment. However, Brownian motion means that some ions have additional momentum, and that tips the balance in favour of cathode bombardment.

"We need to prevent/reduce ion bombardment, preferably by not producing positive ions, or by maintaining a protective space charge around the cathode emissive surface. In general, that means that we shouldn't allow the anode to become positive before the cathode is able to develop a space charge."

Glad you asked? :shock:

 

[MrMarkIII]

Perhaps this will make it even more crystal clear:

"Power-grid vacuum tubes operate by a thermionic emission process. In a vacuum tube, we commonly call the electron emitter a "cathode". The cathode can be directly heated or a filament-cathode. Another type is the indirectly heated, or heater-cathode type of electron emitter.

"The cathode, regardless of sub-category, uses a material easily able to "give-up" electrons with heat. The cathode is heated in a nearly perfect vacuum to temperatures above 1000K (we would see that as a red glow) to as 2600K (a yellowish-white glow). This heat supplies energy to loosely bound electrons at the cathodes surface, causing some electrons to escape the material. These electrons form a cloud suspended around the cathode.

"Positive ions are formed through ionization of residual gasses. High anode voltages speed formation of positive ions. The space charge (electron cloud) surrounding the cathode repels positive ions, and keeps the ions from poisoning the cathode. When positive ions contaminate the cathode, electron emission is reduced.

"Tungsten has the highest melting temperature of any metal, above 3600K. Tungsten has the ability to operate at high temperatures for many hours without evaporation of materials becoming a major problem. Tungsten is one of the few materials able to withstand total depletion of the electron cloud in a vacuum tube. Tungsten emitters are not damaged by stripping away of electron clouds, and the resulting cathode bombardment by positive ions. This immunity to damage means emission life is not shortened by excessive current, operation before full temperature is reached, or low filament voltage.

"If a cathode material sensitive to positive ions is operated with excessive HV, or has excessive cathode current for the cathode operating temperature, it will suffer emission failure. This is why indirectly-heated tubes or oxide-cathode tubes must have long controlled warm-up times before any cathode current is drawn. We must NEVER operate the 3CX1500A7/ 8877, 3CX800A7, or other oxide-cathode tubes at reduced heater voltage! This would allow the cathode's protective electron cloud to be depleted, and nothing would prevent positive ions from striking and poisoning the cathode."


My brain hurts. :shock: :shock: :shock: :shock: :shock: :shock:

 

[MrMarkIII]

Perhaps this will make it even more crystal clear:

"Power-grid vacuum tubes operate by a thermionic emission process. In a vacuum tube, we commonly call the electron emitter a "cathode". The cathode can be directly heated or a filament-cathode. Another type is the indirectly heated, or heater-cathode type of electron emitter.

"The cathode, regardless of sub-category, uses a material easily able to "give-up" electrons with heat. The cathode is heated in a nearly perfect vacuum to temperatures above 1000K (we would see that as a red glow) to as 2600K (a yellowish-white glow). This heat supplies energy to loosely bound electrons at the cathodes surface, causing some electrons to escape the material. These electrons form a cloud suspended around the cathode.

"Positive ions are formed through ionization of residual gasses. High anode voltages speed formation of positive ions. The space charge (electron cloud) surrounding the cathode repels positive ions, and keeps the ions from poisoning the cathode. When positive ions contaminate the cathode, electron emission is reduced.

"Tungsten has the highest melting temperature of any metal, above 3600K. Tungsten has the ability to operate at high temperatures for many hours without evaporation of materials becoming a major problem. Tungsten is one of the few materials able to withstand total depletion of the electron cloud in a vacuum tube. Tungsten emitters are not damaged by stripping away of electron clouds, and the resulting cathode bombardment by positive ions. This immunity to damage means emission life is not shortened by excessive current, operation before full temperature is reached, or low filament voltage.

"If a cathode material sensitive to positive ions is operated with excessive HV, or has excessive cathode current for the cathode operating temperature, it will suffer emission failure. This is why indirectly-heated tubes or oxide-cathode tubes must have long controlled warm-up times before any cathode current is drawn. We must NEVER operate the 3CX1500A7/ 8877, 3CX800A7, or other oxide-cathode tubes at reduced heater voltage! This would allow the cathode's protective electron cloud to be depleted, and nothing would prevent positive ions from striking and poisoning the cathode."


My brain hurts. What little there is. :shock: :shock: :shock: :shock: :shock: :shock:

 

[212Mavguy]

Another way to learn more about tube guitar amps is to periodically read up on them. There are quite a few books out on vacuum tube theory and tube guitar amps in general. One that is pretty good reading is called "The Tube Amp Book 4.1th Edition" by Aspen Pittman. The money spent is well worth it. Peace.

 

[recycledsound]

Tube Amps 101 2 DVD set with BONUS CD of printable material, at only $39.95 it is less expensive and WAY better than any book!

Want to know about tube amps - ya oughta check it out!

www.recycledsound.net

 

[Moot]

...glass bottles filled with vacuum.

Hee, hee... thats funny

 

[Anonymous]

Post removed.

 

[Steve P]

I'd like to add "don't use your amp as a beer coaster" to the list.