Extended Tube Life

PrimaLuna was founded on the idea of eliminating tube maintenance. We do this by using a true and sophisticated Adaptive AutoBias system while running the tubes at the minimum dissipation (power) and giving more slam and bandwidth through superior output transformer design. 

There is no magic that allows a manufacturer to get more power output from a tube. It’s simple math, and everybody has to use the same formula. 

To get more output from a tube, you do it in two ways: 

Higher plate and screen voltage. Ask most manufacturers for that specification, and they will tell you it’s a trade secret, when in reality they don’t want you to know the truth. While PrimaLuna runs 417 volts, they may run 575 or even 625 volts in an effort to squeeze more power out of the tube. Even if it means that the customer runs greater risk of shorts resulting in major damage to the amp. It also means that the customer is locked into only one brand or tube type. Doesn’t seem like a big deal until you hear about some new tube or brand on the market and you can’t use them because you put your amp at risk. 

How the amp is biased. It’s also referred to as “idle current” because it is in essence like setting the idle on a car. Think of it like an engine with a red line of 6500 RPM, and though it’s best to set the idle 900 RPM, you set it at 5500 RPM. Yes, it’s below red line, but there is no doubt the engine will wear out faster or have a failure. We bias our tubes very easy, and we employ our exclusive Adaptive AutoBias to instantly put the amplifier into a "safe mode" in the unlikely event of a short. And a red LED will tell you there is a failure.

When you buy an amp that you know runs tubes hot, this is what’s going to happen. You won’t want to “waste hours” and you become nervous about leaving it on an extra hour or two here and there. Some tubes amps even have an hour meter built in! You’ll also worry because you know that they will need replacing in 12 or 18 months, but what about sonic degradation that occurs even before they are worn out? You are buying this to use it, hopefully every day. Not look at it while it sits silent.     

We run our tubes at the minimum dissipation per tube possible without going into crossover distortion. Forget replacement costs because it will happen rarely. And if one of the power output tubes wears “uneven” compared to its workmates, Adaptive AutoBias will work hard to ensure you never know it by allowing suboptimal tubes to sound their best. The result is customers have gone as long as ten years of regular use on one set of tubes!      

Can we prove it? Most brands quote 2000-2500 hour life on power tubes. This is a picture of a tube set left on 24 hours a day for over 5000 hours in a DiaLogue Premium power amp. Comparing the measurements after over 5000 hours of use, all of them test at least 90% of what they tested when new!     

One more note:  Never ever buy an amp with "Fake Auto Bias" also known as "Cathode Bias". Go to our Adaptive AutoBias page for a full explanation why.