Power Tube Help!

hochpt21
hochpt21 Posts: 5,423
If you had a tube amp with 4 KT120’s with around 200 hours, and one of them broke...what would you do and why?

Replace the broken one?
Replace a pair? (And what position)
Replace the quad?

Thanks,
Paul
2 ChannelTurntable - VPI Classic 2/Ortofon 2M BlueAmplification - Rogue Audio Cronus Magnum II, Parks Audio Budgie PhonoSpeakers - GoldenEar Triton 17.2 Home TheaterDenon AVR-X3300W; Rotel RMB-1066; Klipsch RP-280F's, Klipsch RP-450C, Polk FXi3's, Polk RC60i; Dual SVS PB 2000's; BenQ HT2050; Elite Screens 120"Man CaveTurntable - Pro-Ject 2.9 Wood/Grado GoldAmplification - Dared SL2000a, McCormack DNA 0.5 DeluxeCD: Cambridge AudioSpeakers - Wharfedale Linton 85th Anniversary; LSiM 703; SDA 2A

Comments

  • pitdogg2
    pitdogg2 Posts: 24,477
    I'd check bias. 200 hours is not a lot of time to be honest.
  • kharp1
    kharp1 Posts: 3,453
    I agree that 200 hrs is nothing time wise, but, a tube can go south for any number of reasons. I prefer to replace a pair and keep the odd one for backup.
  • michaeljhsda2
    michaeljhsda2 Posts: 2,165
    Just replace the one bad tube. Re bias all four after it's installed
    SDA SRS 1.2TL's
    SDA 1C's w/Clarity Cap ESA; PA, Mills, RD0194-1's
    SDA 2B TL's w/RD0198-1's
    Yaqin MC-30L integrated tube amp
    Yaqin MS-20L integrated tube amp
  • hochpt21
    hochpt21 Posts: 5,423
    I should have clarified. Tube was damaged during shipping. Nickle sized circle-ish crack...
    2 ChannelTurntable - VPI Classic 2/Ortofon 2M BlueAmplification - Rogue Audio Cronus Magnum II, Parks Audio Budgie PhonoSpeakers - GoldenEar Triton 17.2 Home TheaterDenon AVR-X3300W; Rotel RMB-1066; Klipsch RP-280F's, Klipsch RP-450C, Polk FXi3's, Polk RC60i; Dual SVS PB 2000's; BenQ HT2050; Elite Screens 120"Man CaveTurntable - Pro-Ject 2.9 Wood/Grado GoldAmplification - Dared SL2000a, McCormack DNA 0.5 DeluxeCD: Cambridge AudioSpeakers - Wharfedale Linton 85th Anniversary; LSiM 703; SDA 2A
  • hochpt21
    hochpt21 Posts: 5,423
    Just replace the one bad tube. Re bias all four after it's installed

    That would be ideal. So even with different hours, as long as the bias is checked every few months I should be good?
    2 ChannelTurntable - VPI Classic 2/Ortofon 2M BlueAmplification - Rogue Audio Cronus Magnum II, Parks Audio Budgie PhonoSpeakers - GoldenEar Triton 17.2 Home TheaterDenon AVR-X3300W; Rotel RMB-1066; Klipsch RP-280F's, Klipsch RP-450C, Polk FXi3's, Polk RC60i; Dual SVS PB 2000's; BenQ HT2050; Elite Screens 120"Man CaveTurntable - Pro-Ject 2.9 Wood/Grado GoldAmplification - Dared SL2000a, McCormack DNA 0.5 DeluxeCD: Cambridge AudioSpeakers - Wharfedale Linton 85th Anniversary; LSiM 703; SDA 2A
  • hochpt21
    hochpt21 Posts: 5,423
    kharp1 wrote: »
    I agree that 200 hrs is nothing time wise, but, a tube can go south for any number of reasons. I prefer to replace a pair and keep the odd one for backup.

    If I replaced a pair, does it matter what position they go in relative to the other ones?
    2 ChannelTurntable - VPI Classic 2/Ortofon 2M BlueAmplification - Rogue Audio Cronus Magnum II, Parks Audio Budgie PhonoSpeakers - GoldenEar Triton 17.2 Home TheaterDenon AVR-X3300W; Rotel RMB-1066; Klipsch RP-280F's, Klipsch RP-450C, Polk FXi3's, Polk RC60i; Dual SVS PB 2000's; BenQ HT2050; Elite Screens 120"Man CaveTurntable - Pro-Ject 2.9 Wood/Grado GoldAmplification - Dared SL2000a, McCormack DNA 0.5 DeluxeCD: Cambridge AudioSpeakers - Wharfedale Linton 85th Anniversary; LSiM 703; SDA 2A
  • mhardy6647
    mhardy6647 Posts: 32,926
    Probably. No idea what the amp's topology is, but if it is stereo(?) then there should be two push-pull pairs. The push and pull halves of one channel should be as identical as possible (in the best case). This is critical if the bias cannot be adjusted (as was often the case in many, even very fine, vintage amplifiers.

    If it's a monoblock with four tubes, it's probably push pull parallel.

    In either case, if the bias can be adjusted for each tube individually, it's less of a factor than it would be in a fixed bias amplifier with no adjustment. Note, "fixed bias" simply means that there's a bias supply circuit (as opposed to, e.g., "cathode bias" in which the tube itself is actively involved in the bias circuit). A "fixed bias" amp can have adjustable bias, and nowadays many do! :)
  • pitdogg2
    pitdogg2 Posts: 24,477
    hochpt21 wrote: »
    I should have clarified. Tube was damaged during shipping. Nickle sized circle-ish crack...

    With this "new" info I'd say you may be replacing more sooner than later if it was rough handling. I'd find a pair.
  • hochpt21
    hochpt21 Posts: 5,423
    mhardy6647 wrote: »
    Probably. No idea what the amp's topology is, but if it is stereo(?) then there should be two push-pull pairs. The push and pull halves of one channel should be as identical as possible (in the best case). This is critical if the bias cannot be adjusted (as was often the case in many, even very fine, vintage amplifiers.

    If it's a monoblock with four tubes, it's probably push pull parallel.

    In either case, if the bias can be adjusted for each tube individually, it's less of a factor than it would be in a fixed bias amplifier with no adjustment. Note, "fixed bias" simply means that there's a bias supply circuit (as opposed to, e.g., "cathode bias" in which the tube itself is actively involved in the bias circuit). A "fixed bias" amp can have adjustable bias, and nowadays many do! :)

    Just changed my sig...Rogue Audio Cronus integrated amp. Bias is individual.
    2 ChannelTurntable - VPI Classic 2/Ortofon 2M BlueAmplification - Rogue Audio Cronus Magnum II, Parks Audio Budgie PhonoSpeakers - GoldenEar Triton 17.2 Home TheaterDenon AVR-X3300W; Rotel RMB-1066; Klipsch RP-280F's, Klipsch RP-450C, Polk FXi3's, Polk RC60i; Dual SVS PB 2000's; BenQ HT2050; Elite Screens 120"Man CaveTurntable - Pro-Ject 2.9 Wood/Grado GoldAmplification - Dared SL2000a, McCormack DNA 0.5 DeluxeCD: Cambridge AudioSpeakers - Wharfedale Linton 85th Anniversary; LSiM 703; SDA 2A
  • michaeljhsda2
    michaeljhsda2 Posts: 2,165
    hochpt21 wrote: »
    Just replace the one bad tube. Re bias all four after it's installed

    That would be ideal. So even with different hours, as long as the bias is checked every few months I should be good?

    Definitely
    SDA SRS 1.2TL's
    SDA 1C's w/Clarity Cap ESA; PA, Mills, RD0194-1's
    SDA 2B TL's w/RD0198-1's
    Yaqin MC-30L integrated tube amp
    Yaqin MS-20L integrated tube amp
  • hochpt21
    hochpt21 Posts: 5,423
    edited July 2018
    Just purchased a pair, and will keep one for back up.

    Does it matter what position I install them in?

    cpbgaj3gpy07.png
    2 ChannelTurntable - VPI Classic 2/Ortofon 2M BlueAmplification - Rogue Audio Cronus Magnum II, Parks Audio Budgie PhonoSpeakers - GoldenEar Triton 17.2 Home TheaterDenon AVR-X3300W; Rotel RMB-1066; Klipsch RP-280F's, Klipsch RP-450C, Polk FXi3's, Polk RC60i; Dual SVS PB 2000's; BenQ HT2050; Elite Screens 120"Man CaveTurntable - Pro-Ject 2.9 Wood/Grado GoldAmplification - Dared SL2000a, McCormack DNA 0.5 DeluxeCD: Cambridge AudioSpeakers - Wharfedale Linton 85th Anniversary; LSiM 703; SDA 2A
  • hochpt21
    hochpt21 Posts: 5,423
    edited July 2018
    .
    2 ChannelTurntable - VPI Classic 2/Ortofon 2M BlueAmplification - Rogue Audio Cronus Magnum II, Parks Audio Budgie PhonoSpeakers - GoldenEar Triton 17.2 Home TheaterDenon AVR-X3300W; Rotel RMB-1066; Klipsch RP-280F's, Klipsch RP-450C, Polk FXi3's, Polk RC60i; Dual SVS PB 2000's; BenQ HT2050; Elite Screens 120"Man CaveTurntable - Pro-Ject 2.9 Wood/Grado GoldAmplification - Dared SL2000a, McCormack DNA 0.5 DeluxeCD: Cambridge AudioSpeakers - Wharfedale Linton 85th Anniversary; LSiM 703; SDA 2A
  • michaeljhsda2
    michaeljhsda2 Posts: 2,165
    hochpt21 wrote: »
    Just purchased a pair, and will keep one for back up.

    Does it matter what position I install them in?

    cpbgaj3gpy07.png

    No
    SDA SRS 1.2TL's
    SDA 1C's w/Clarity Cap ESA; PA, Mills, RD0194-1's
    SDA 2B TL's w/RD0198-1's
    Yaqin MC-30L integrated tube amp
    Yaqin MS-20L integrated tube amp
  • hochpt21
    hochpt21 Posts: 5,423
    hochpt21 wrote: »
    Just purchased a pair, and will keep one for back up.

    Does it matter what position I install them in?

    cpbgaj3gpy07.png

    No

    Perfect, thank you.
    2 ChannelTurntable - VPI Classic 2/Ortofon 2M BlueAmplification - Rogue Audio Cronus Magnum II, Parks Audio Budgie PhonoSpeakers - GoldenEar Triton 17.2 Home TheaterDenon AVR-X3300W; Rotel RMB-1066; Klipsch RP-280F's, Klipsch RP-450C, Polk FXi3's, Polk RC60i; Dual SVS PB 2000's; BenQ HT2050; Elite Screens 120"Man CaveTurntable - Pro-Ject 2.9 Wood/Grado GoldAmplification - Dared SL2000a, McCormack DNA 0.5 DeluxeCD: Cambridge AudioSpeakers - Wharfedale Linton 85th Anniversary; LSiM 703; SDA 2A
  • hochpt21
    hochpt21 Posts: 5,423
    Got her up and running. Changed power tubes in 1 and 4. Bias set.

    Sounds beautiful.
    2 ChannelTurntable - VPI Classic 2/Ortofon 2M BlueAmplification - Rogue Audio Cronus Magnum II, Parks Audio Budgie PhonoSpeakers - GoldenEar Triton 17.2 Home TheaterDenon AVR-X3300W; Rotel RMB-1066; Klipsch RP-280F's, Klipsch RP-450C, Polk FXi3's, Polk RC60i; Dual SVS PB 2000's; BenQ HT2050; Elite Screens 120"Man CaveTurntable - Pro-Ject 2.9 Wood/Grado GoldAmplification - Dared SL2000a, McCormack DNA 0.5 DeluxeCD: Cambridge AudioSpeakers - Wharfedale Linton 85th Anniversary; LSiM 703; SDA 2A
  • jumpindick
    jumpindick Posts: 428
    If you ever want to roll tubes, the one in the middle (preamp) tube is that one to change. That is the one that has max impact on the overall sound coming out of that amp. I tried a few of them, but the best one, for me at least, was Psvane 12AU7 which is what you got..
  • nooshinjohn
    nooshinjohn Posts: 25,034
    The folks a Rogue would have replaced the damaged tube for free. I just lost a power tube on one of my amps, and after 7 years of faithful service, I am getting ready to replace all 12 KT120's.
    The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

    “When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
  • hochpt21
    hochpt21 Posts: 5,423
    I have a few tubes coming from @heiney9 , but the Psvanes sound pretty exceptional in there right now.
    2 ChannelTurntable - VPI Classic 2/Ortofon 2M BlueAmplification - Rogue Audio Cronus Magnum II, Parks Audio Budgie PhonoSpeakers - GoldenEar Triton 17.2 Home TheaterDenon AVR-X3300W; Rotel RMB-1066; Klipsch RP-280F's, Klipsch RP-450C, Polk FXi3's, Polk RC60i; Dual SVS PB 2000's; BenQ HT2050; Elite Screens 120"Man CaveTurntable - Pro-Ject 2.9 Wood/Grado GoldAmplification - Dared SL2000a, McCormack DNA 0.5 DeluxeCD: Cambridge AudioSpeakers - Wharfedale Linton 85th Anniversary; LSiM 703; SDA 2A