Unison Research Simply Italy – how to know when it’s time to change the tubes?

[1980Nicola]

Hi everyone,

I’m using an Unison Research Simply Italy, a single-ended Class A tube integrated amplifier. It’s fitted with two Mullard NOS ECC82 tubes in the preamp stage and two EL34 tubes as power outputs.

I know that the ECC82 generally last much longer than the EL34, but I was wondering:

how can I tell when it’s time to replace the tubes?

Are there specific signs to watch out for (such as loss of dynamics, distortion, unusual noises, channel imbalance), or is it more of a gradual and subtle decline in sound quality?

Any advice or first-hand experience would be greatly appreciated!

Thanks in advance.

 

[Another Johnson]

The ECC82 will usually show their age by becoming noisier, often one side more so than the other. Ticks and pops may also begin.

The EL34 will show their age by literally red plating, motorboating, or blowing a fuse. Or they may become more difficult to bias.

On the way to these conditions, noise floor and dynamics may noticeably degrade, but degradation can be subtle and may not be quickly noticed.

You might want to contact the amp manufacturer and find out what their recommended replacement schedule is. Many people report that refreshing tubes before obvious degradation or failure is worthwhile and brings noticeable improvements.