Antique Sound Lab Hurricanes - Triode or Pentode ?


How do you run yours ? What are the sonic differences ? Do the amps need re-biasing when switching the mode ? What is preferred with 4 ohm speakers, like Magnepan 1.6s ?

All thoughts appreciated, as always !
dimitry
I am using 2.5 pairs of Hurricanes and another pair of ASL 845 (1009) to drive my Westlake HR7 speakers, single D-Box Mammouth subwoofer and a pair of super tweeters. My experience is that I always prefer connecting the ASL amp at 16ohm, irrespective of whether the speaker is 4ohm or otherwise. I've tried many times the triode mode but I always find the pentode mode better. Perhaps I am using my Hurricanes for base (400Hz and below) and super high (15,000Hz and above) so please take this into consideration. I also would like to hear others' experience.
Thanks for the information. Does the amp need to be re-biased when switching modes or is the bias preserved ?
I think the simple answer is just look at the numbers. I find 480 for each tube to be the best. So just make sure under all circumstances the number is around 480.
I will do so. My question was wether bias changes when going from triode to pentode. My concern was that the pentode bias would be much more than the triode bias, causing the tubes to run much greater than 480 on the first turn-on, perhaps resulting in lost tubes. I guess I will find out.
Some initial observations:

1. Bias goes up slightly when moving from triode to pentode - 480 became 500.
2. Substantially higher gain in pentode mode - at least 6db more and probably higher.
3. Better dynamics in pentode mode.
4. Better focus in pentode mode.
5. Slightly brighter balance in pentode mode.
6. Slightly more depth in triode mode.