Blog - Valve Heater

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Tungsol Electro Harmonix and Sovtek 12AX7 Valve Heater Glow

Everyone that loves the look of Glowing shiny valves sitting on a high end Hi Fi amp or visible behind a Guitar Valve amp Head will have mixed reactions regarding the new Generation Preamp tubes being produced from the Russian Factories. To the Dismay of the "we love the valve glow" fans they have modified most of the latest generation designs to improve Emissions efficiency which results in an all round better performing tube. The down side is a much tighter plate cage making it almost impossible to see that familiar red hot heater glowing from top, bottom and sometimes through the now vacant side holes.

We found on the Sovtek 12AX7LPS valve that you could not see any sign at all of any heater glow.  Some of the Electro harmonix valves are barely visible in darkened environment but again with the Tungsol valves we found it difficult to see the warm red heater glowing.

Manufacturers affected by not having a big bright heater glow are, Tungsol, Sovtek and Electro Harmonix preamp tubes.

So next time you invest in a brand new shiny pre amp tube for your beloved gear please note that a lack of glow is not indicative of a tube that is not working correctly but actually is likely to be a new generation valve.