Do pre amp tubes glow?
You can also look for a purple glow that is very focused on a specific component inside the tube. Do not confuse this with a blue glow that is near the glass. If you see the purple glow, the tube is not functioning properly and should be discarded. Preamp tubes can become microphonic when they are going bad.
Are power tubes supposed to glow?
The tube is fine! It actually indicates that the vacuum inside the tube is very good, which is what allows this phenomenon to occur. It will not have any effect on the performance or tone of the amp. HOWEVER: If you notice a red glow on the metal plates of the tubes, turn off the amp immediately.
Do all vacuum tubes glow?
Gas-filled tubes Their distinctive orange, red, or purple glow during operation indicates the presence of gas; electrons flowing in a vacuum do not produce light within that region. These types may still be referred to as “electron tubes” as they do perform electronic functions.
Should vacuum tubes glow?
Blue Glow – We often get asked if blue glow inside of a vacuum tube is a sign of a defect. Thankfully, it is rarely a sign of a defect at all. The proper function of gas types such as thyratrons, voltage regulator and voltage reference tubes, requires the presence of this glow as an indication of proper tube operation.
What color should amp tubes glow?
This type of glow is usually violet in color and most noticeable around the inside surface of the glass bulb. It is most pronounced on power tubes and is the product of electron bombardment of the glass taking place within the tube.
What color should amp tubes be?
Within your tubes, sits a heater filament and when working optimally, will illuminate with a satisfying warm orange glow. These filaments when glowing, emit electrons at high temperature producing heat for the tube which is needed to maintain the amplifiers optimal tone.
How do you make a vacuum tube glow?
5 Answers. You can use AC or DC voltage to power the filament of a vacuum tube. The filament will glow when powered up which is what you are referring to as “lighting up”. So a battery is fine.
Why do amp tubes glow?
Sometimes you may notice a blue hazy glow inside your amp tube. This glow is rarely a sign of a defect and is fairly common especially in modern power tubes. This type of glow is called Fluorescence. This phenomenon is due to electron bombardment of the glass taking place within the tube.
How do I know when to change my tubes in my amp?
A: These are the most common signs that tubes need replacement:
- Excessive noise (hiss, hum) including squealing or microphonic tubes.
- Loss of high end.
- A muddy bottom end; Sounds like there is too much bass and note clarity is lost.
- Erratic changes in the overall volume.
- The amp doesn’t work!
What does a bad tube look like?
The purple glow around wires or other elements indicates leakage and a tube with this should be discarded. Perhaps the most obvious thing to look for is any loose parts that have broken off inside the bottle. You can gently shake the tube as well and listen for rattling.
How do you tell if a tube is bad in an amp?
Sometimes you will hear strange sounds, loss of power, or heavily distort sound. These are signs that a tube is failing. Often power loss that seems like the amp is performing at half power or less will be one or more bad power tubes, or even a dying phase inverter tube.
What do you need to know about 12AX7 tubes?
12AX7 is a small signal tube with high gain. Tubes such as 12AV7, 12AU7, 12AT7 are siblings of pin-compatible tubes with differing gains. 12AX7 is the big brother of them all with the highest voltage gain (mu). 12AX7 allows the amp designer the freedom to build high gain amplifier circuit with less components.
Is there a quieter version of the 12AX7?
These quieter version of the 12AX7 are only beneficial when used as the input tube in a preamp. The noise floor is very low at the input tube and so the quieter the input tube the better. The 5751 version of the 12AX7 was created as a military spec tube. This tube was given extra support internally and had matched triode sections.
How long does a triode 12AX7 tube last?
A matched triode tube is ideal for use in the phase inverter circuit. How Long Do 12AX7 Tubes Last? A 12AX7 tube usually lasts a very long time. 1 to 5 years or more is not unreasonable, depending on how it is used. A tube wears out mainly due to usage and heat.
What kind of damper do I need for 12AX7?
Tube dampers can be slipped over the tubes in order to prevent the ring of a microphonic tube. Dampers can also help with mechanical noises that might be heard from noisier tubes. Eurotubes makes a great damper that can be reused with any tube you install to prevent any noises and are extremely affordable.
