Why ‘Overhung Filament’?
Overhung filament is extremely difficult to manufacture as a tiny discrepancy in spacing, fixture and material characteristics under extreme temperature can lead to more possible ‘failure’ in production. Overall, tube factory will face a much higher rate of ‘scrap’ even before a tube reaches the product finishing line. This leads to eventually higher overall production cost. Many tube factories deliberately stay away from this filament design.
However, among tube manufacturers and audiophiles it also has a consensus that: A metal plate tube by default will sound more dynamic and transparent than a graphite plate tube; and when the same plate materials are used, a ‘overhung filament’ design by default will sound more delicate and refined than other filament design.
LINLAI 845-DG, 211-DG and 805-DG are made with graphite plate and overhung filament.
Another uniqueness of this ‘overhung filament’ model:
The large graphite plate has 3 side holes to let tube glow out. If you are a fan of 845 tube glowing, this is a great tube to look at while enjoying your tunes!
This tube is a nice upgrade from the commonly used stock 845B tubes from China in almost all new production 845 tube amps. The stock entry level Chinese 845/845B tubes tend to sound dry and harsh without much magic. The 845-DG upgrade tubes offer excellent ‘performance to price’ ratio, aka ‘bang for the buck’, with a unique overhang filament design, coupled with solid graphite plate.
Why is 845-DG not as popular as the more expensive metal plate E-845?
Besides the previously mentioned FOMO mindset, its reliability record is good but not as stellar as the E-845’s zero warranty record, we think the ‘dollar cost per listening day’ for 845-DG really isn’t much lower than E-845 – probably much less than a cup of java. Why not just ‘straight to the point’ could be some customers reason to opt for the E-845 instead.
We have been closely watching the warranty rate trend of 845-DG, and highly suspect some cases are related to users’ amps were not providing the right level of ‘load’ to these graphite plate high power tubes. Please note that ‘underload’ a graphite plate tube over a extended period of time can create excessive gas in the tube, eventually trigger an internal short tube failure. Users are strongly recommended to regularly check the amp bias and keep it in optimal range, besides keeping the amp’s power supply voltage stable with a proper power conditioning device.