Find answers to frequently asked questions about vacuum tube audio equipment and why tube audio may be right for you.

Jolida Tube Amplifier photoIsn’t Vacuum Tube amplifier technology obsolete? 

No. Many people think tube technology is obsolete since solid state has replaced it. One example used to exemplify tube obsolescence is the comparison of the small size and high computing speed of today’s computers and smartphones which has replaced the wieldy 1950’s Enac computer which used 18,000 vacuum tubes, had the power of a calculator and fit in a room the size of 3 double garages. No doubt integrated circuits are a significant technical advancement that has made many of the communication and computing devices of modern times a reality. However, tubes were never designed to be utilized as integrated circuits (on/off switching), tubes were designed for power applications, in essence to amplify. A good example of how tubes create power is your microwave oven which is powered by a vacuum tube. Press the start button and your microwave oven will develop 900 to 1400 watts of power on demand. If that counter top microwave oven used integrated circuits for power, it would be the size of a refrigerator. Tubes are still a $2 billion industry in the U.S. and is utilized in high power applications such as transmitting equipment, radar, RF equipment, x-ray machines, medical equipment to name a few. In relation to audio equipment, vacuum tubes perform superbly as an amplification source. From a technical viewpoint in terms of cost, size, power, reliability and performance, the vacuum tube amplifier is as viable as the solid state amplifier.

Why a Tube Amplifier?

The comeback of the tube amplifier as told by Rick Rosen of Stereophile is not a matter of nostalgia; it is a matter of excellent sound reproduction. Even the average ear can recognize the holographic soundstage, smoothness, and the crystal clear resolution that a tube amplifier can deliver. At low volume levels, the sound is clear and linear; at moderate volume levels, the sound is full and satisfying; and at loud volume levels, the sound will not punish your ears.

I have never used vacuum tubes before and they make me nervous?

In a sense, you have been using tubes all your life, light bulbs. Although the light bulb and the vacuum tube are used in different applications, there are some similarities in how they operate. If you drop a light bulb on a cement floor, it will break; you have to change the light bulb every so often; and last but not least, if a light bulb has been on for an hour and you grab it, then you will burn your hand. So it is with a vacuum tube.

I have heard that vacuum tube amplifiers are not reliable.

All technology has its problems and reliability is an engineering function of design, build quality, maintenance and the appropriate use of the technology. Tube equipment runs from radars, radio transmitters, microwave equipment, cat scanners to heat sealing equipment. Tube technology designs are well understood and have the inherent nature of simplicity and ruggedness. Jolida uses high quality parts and prior to shipping we burn in the amplifiers at a minimum of 48 hours. In addition we test the amplifiers physically and sonically.

Will I have to replace the tubes all the time?

In JoLida hybrid or vacuum tube amplifiers, the main power vacuum tubes should last approximately six years playing at a rate of twenty hours per week. If you are playing at a rate of 8 hours per day, the first power tube should go in about 3.5 years. For the receiving tubes, they should last 10 years or more. The reason for the longevity of the tubes in Jolida amplifiers are for the following reasons:

1. All our tube units have a slow circuit startup. On startup, the voltage to the tubes is fed slowly until full voltage is realized in order to reduce the life-shortening shock of an initial full voltage to the vacuum tubes.

2. All our tube amplifiers have an ultralinear circuit. The basis for this circuit is a maximum of 460 plate volts. The average current production vacuum power tube is rated for approximately 600 volts. Running the vacuum tubes at 460 volts gives a 20% safety factor. In this mode, the tubes run cooler and in turn gives the vacuum tubes longer life.

This is why we will guarantee the vacuum tubes  for 3 months to a year depending on the unit model.

Can I change the sound of an amplifier?

Yes. We think that our circuits are of such quality that changing the tubes will have an effect on the sound.  FYI, the changing of tubes is also referred to as “tube rolling”.  We do recommend that you listen critically to the audio of your system and ask the question, “what change do I want with the sound”? Then either a tube seller or Jolida can help you select a tube that will come the closest to your requirements.

What if I have questions or need service?

We stand behind or products. If there are any questions or matters to discuss you can call us at 301-953-2014 or you can email us at

How long can a tube amplifier last?

If maintained properly, a tube amplifier can last 30 years or longer. If you look in the classifieds for amplifiers for sale over 30 years of age, most of them are tube. The maintenance that has to be done requires the three basis tasks. Keeping the tubes at proper bias, changing the tubes when they have worn down and changing the electrolytic capacitors every 15 years. Please note that every electronic unit having electrolytic capacitors requires timely replacement.

JoLida amplifers are only rated at forty, fifty watts of power output, that doesn’t seem like much power.

Some people consider 100 watts as the minimum wattage for a adequate amplifier. Wattage that is required in a system is dependent on a number of factors such as speaker sensitivity, volume level and the type of music player.  Given that the majority of the speakers manufactured today run between 89 to 91 dB sensitivity, 50 watts is adequate to push these speakers. Also, it is a rule of thumb that one tube watt is equivalent to two or three solid state watts.

Why doesn’t the Jolida Tube amplifiers have more features?

One of the main objectives of Jolida amplifier designs is to maintain the “viability of the volt”, by controlling noise and the maximum bandwidwith of the music signal. We think the accomplishment of these objectives enhance clarity, smoothness, transparency, weight in the midrange and three dimensionality.  In order to effectively accomplish this objective, we had to compromise on some of the features. In specific:

  1. No bass, treble, equalizer or loudness buttons: Each one of these features introduces noise and distortion into the signal path.
  2. Manual selector switching: To achieve remote control switching either dip switches or relays are utilized. We have found that relays placed in the signal path diminishes the three dimensionality of the sound.
  3. No headphone jack: It is not difficult to design in a headphone jack, however a relay is required to cut off the signal to the speakers and shunt them to the headphone jack. Again the relay has a negative impact on the sound.
  4. No automatic biasing: Automatic biasing utilizes a series of resistors in the signal path. It is well known that the use of automatic biasing will lower wattage power and add distortion. The type of biasing we have in our units is either manual or a sensing system. In the sensing system we have a feature called EZ biasing which is simply turning a screw until the LED lights up and the tubes are biased.
  5. Not placing a DAC within an amplifier: We have experimented with putting a full DAC in our amplifiers. We find that the nesting hi power operation near digital conversion in a limited space increases the noise floor. 

How long does it take to break-in a tube amplifier?

To break-in the tubes of an amplifier usually takes about 250 to 300 hours of use so that the tube can reach a stable thermal operating temperature. To speed up this process you can leave the amplifier on for about two weeks and it is your option to either play audio or not. Since Jolida uses high grade copper and silver copper wire for the inputs, the break-in period for this is approximately 250 to 300 hours. When you first turn on the amplifier fresh out of the box, the sound is usually constricted and lacking bass. Over time the unit will progressively open up.