Vacuum Tubes

Tubes that are provided with your unit

Linear Tube Audio sources the best tubes we can find for use in our production units, tested and curated to provide the best experience for our customers. When you buy an LTA amplifier, know that it will come supplied with the highest quality, premium tubes we can find.

Additional Tube Burn-in

The tubes will have been burned in approximately 168 hours.  They will continue to improve with additional burn-in as you play the equipment.  Some customers have reported 2-300 hours are required for full tube burn-in.

Tube Quality and Sound Quality - Upgrading Tubes

As tube quality increases,  ZOTL amps’ sound quality increases.  ZOTL amps act as platforms for tube quality.  The better the tubes, the better the sound.  Also, the same tube, from different manufacturers, can change the sound. It might not be better, just different.  LTA goes to great lengths to source the standard vacuum tubes to ship with our amplifiers. 

LTA Tube Upgrades

LTA also looks for tube upgrades for our different pieces of gear.  We test upgrade tube candidates for improved sound quality and reliability.  While we often come across exquisite rare tubes, we are focused on tubes that are consistently available.  The RAY tubes are good examples of our curated tube upgrades.  

In production Tubes vs NOS tubes vs ZOTL tubes

NOS or New Old Stock tubes are some of the best tubes ever made. Production on most ended in the 60s, upon the arrival of the transistor. Our problem is that while they sound great, they are harder to get and they have more reliability issues as they are 50-70 years old.  We do use some tubes that we can get enough of and have a reputation for enhanced reliability. The majority of the tubes in production today come from Russia and China. Both countries have been making them for many years. There are no US manufacturers yet. Some of the Chinese tube manufacturers have made impressive progress in both quality and reliability.  For instance the Ray Tubes EL-34s actually are as good as the Mullard EL-34s.  We curate the tubes in all of our products and they are a mix of NOS and in-production vacuum tubes. Also, in some of our amplifier products we use 12 pin Compactron tubes that are excellent, but are difficult to use in amps with transformers. These are also hard to source because no one but LTA and Berning use them. SO most were thrown away over the years. We have lifetime supplies to ensure our customers always have them available. We are happy to supply you with an extra set.

What about Biasing Tubes

There are no bias adjustments. All LTA products with tubes have an auto bias circuit that optimizes the tube bias every time the unit is powered on.

What if I have a tube problem 

You might hear a rustling or rushing sound, or noticeable fluttering, or noise that doesn’t subside after startup. These are classic tube noise problems, typically only in one channel. Noise problems are noticed with nothing playing and do not trigger the protection system.

Your unit may have no sound output after turning on. This usually means something more drastic has happened and the protection circuit is activated. Our power amps and integrated amps all have sophisticated protection circuitry that monitors for tube issues, over current and a couple other things. If it detects a problem, it shuts down the power supply to protect the circuitry in your amp. 

We have a video about what to do.https://youtu.be/I2piuuPpYHs Most tube problems can be fixed with a new tube or pair of tubes. We have all replacements in stock and our tech support team can help you through the process. If you do not even want to deal with it, we will bring the under warranty unit back, test and replace whatever is the problem and return it to you all back to like new.

Tube Product Support  

Jacob is our tube expert with a decade of experience at LTA. You can ask him about recommendations, compatibility, or any issues you encounter.  He responds to emails promptly M-F, and tries to check once a day on weekends.