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Not entirely correct. The cheaper Rogue tube amps need to be upgraded to Magnum status to take KT120s.
I have owned three Quicksilver amps; the 8417, the Silver 60s and I still own my GLA. I also own a Rogue Stereo 90 with Super Mag upgrade. The Quickie sound is very neutral with no major flaws anywhere. I find their house sound to be a little bland personally. The GLA is the only one I've kept for any length of time (I guess 6 years now). It was their entry level amp when new but I find it very satisfying. Both the 8417s and the Silver 60s were sold within a year of taking ownership. I was just looking for a bit more tube magic and 'ZIP' (Silver 60s) and more authority in the bass (8417s). I think I get both of those qualities with my Rogue Stereo 90. I'm very happy with the amp but I haven't yet tried the KT120s in it. Very soon, I hope. I had a slight issue with the 8417 once (don't remember exactly what happened, burnt resistor or similar) but I never had a single issue with the Silver 60s, GLA or Rogue amp...knock on wood!
The problem with the KT-120 is current filament draw is higher than 6550/KT88. Many power supplies simply can't handle it.
If you're not sure your amp can take the KT120 I have heard from a reliable source that you can pop them in and monitor the temp of the power transformer. If the tube pulls too much current for the power supply to handle the transformer will heat up. You can then turn it off and remove the tubes before any damage is done. Only do this if you're absolutely sure your amp can handle 6550s/KT88s. I don't know if I'd personally try this, maybe not all amps can safely run the KT120 for ANY length of time. But I thought I'd pass on the information. Don't kill the messenger if something bad happens....
Actually it is both...bias too low and it becomes and issue of too much idle current, bias too high and pop goes the transformers...Jim
Would not want to kill you..maybe just stick your tounge in a tube socket !!!
No. You are confusing bias current with filament current. Two different things. The problem with using KT-120's is that it draws more current, and some power supplies will not be able to handle the excess filament current.
Yes. I was trying to show the difference between DHT and KT-88 types.
Here is some (hopefully) clarifying explanation: " The KT120 has a taller glass bottle, longer internal plate structure, and much larger control grid cooling fins than current production KT88 tubes. Because the KT120 draws 100-300 mA more filament current than a standard 6550/KT88, check with your amp manufacturer to ensure you have the additional filament headroom to power these tubes. This new production Tung-Sol tube is manufactured in Russia for New Sensor. "
