What does compensating mean?

Discussion in 'The Rehearsal Room' started by Pythagoras, Nov 14, 2005.

  1. Pythagoras

    Pythagoras Active Member

    I should probably know this, but what does it mean in adds for instruments when it says that valves are compensating?
  2. brassneck

    brassneck Active Member

  3. BeatTheSheep

    BeatTheSheep Member

    think I can answer that.

    valves lower the pitch of a note by an amount depending on the length of the instrument and the length of the valve tube proportional to that.

    However when you press a valve, the length of tubing gets longer, right? so the valve you press at the same time has to lengthen its tubing to stay in tune with its' now longer instrument. obviously this can' happen. The problem gets even worse with all three valves pressed, which is why C sharp on a cornet or horn is so out of tune.

    The solution to this is either triggers on the higher instruments or to increase the tubing by a system like compensating pistons, where when you press the third valve it takes the tubing around an extra path, adding tubing where necessary. There will be an extra slide on the other side of the 2nd and third (and 4th if applicable) for this on compensating instruments.

    This then works ok. There was an even better system called 'equisonant pistons' that was invented at the same time but it failed for the same reason that betamax failed against vhs i.e. expensive. It was also heavier.

    cornets and horns don't get compensation because apparently the extra weight would prove a problem. Who decided this!
  4. Aussie Tuba

    Aussie Tuba Member

    It definatly adds to correct tuning. lower register instuments tend to play better in tune with compensating valves, I wouldn't consider playing on anything less.
  5. Pythagoras

    Pythagoras Active Member

  6. brassneck

    brassneck Active Member

  7. Will the Sec

    Will the Sec Active Member

    "Compensating" comes from the Latin, and roughly translated means "Costing an extra £300 on a Euphonium, and up to an extra grand on a Bass".
  8. Chunky

    Chunky Active Member

    I thought it was basses having to play louder to compensate for others not playing loud enough :biggrin:
  9. postie

    postie Member

    Doesn't everything make more sense after a few cans!!!!!!!!!!!!!!!!!!!!
  10. madrich

    madrich Member

    You may or may not be interested to know that compensation is omited on horns and cornets not because of the extra weight but because the size of the extra slide required on the 1st certainly and possibly also the 3rd slides is too small to make a sensible slide. - Just look at how far the 1st valve trigger needs to move on a cornet and you'll see.

    Does anyone know if a horn has been designed with triggers? It would seem a sensible thing to at least prototype.
  11. brassneck

    brassneck Active Member

  12. starperformer

    starperformer Member

    Horn players prefer to keep "no triggers" in the excuses list.
  13. Ruthless

    Ruthless Member

    Don't they just make the usual "I'm a horn player" excuse?
  14. HBB

    HBB Active Member

    Ruth... :p
  15. skimbleshanks

    skimbleshanks Member

    So how about integrating a tuner into the instrument? Instead of driving a meter needle, feed the signal into a closed-loop control system that drives a stepping motor which moves the main tuning slide. Then you'd have an instrument that is always in tune!

    except that...
    • you'd need a power supply, either batteries (extra weight), or trailing wires
    • motor noise (wherrrr, wherrrr)
    • you'd need a main tuning slide like a trombone slide
    • problems of instability, overshoot and external interference in closed-loop control systems
    • you'd need a very quick response time
    • and if the response time was sufficiently good, you wouldn't be able to do vibrato!
    • if you were playing with an "unassisted" instrument, you wouldn't be able to lip it to match their imperfections.
    Did I just shoot myself down? I think so.
  16. Thirteen Ball

    Thirteen Ball Active Member

    Playing a non-compensating Tuba can be a serious danger to your sanity.None of the notes are where you think they are! Plus non-compensators are usually three-valves anyway, and they're AWFUL for tuning.

    I think that's why BB players started pedalling everything because when playing an octave below with the fourth valve in you can lip things up or down a semitone either way with no difficulty at all!

    But then, I did once hear Stuart Derrick playing a non-compensating euphonium when he was my conductor at YBS juniors, when our own euphs were missing. From stone cold to fully warmed up, he was bang in the middle of every note, every time, all night. Just goes to show you can have as many triggers and compensators as you like, but if you don't listen to the players around you, you're on a hiding to nothing.
  17. Jan H

    Jan H Moderator Staff Member

    These things could be improved considerably by including a "feed forward" loop in the control mechanism. This could be easily done by having a copy of the music on a small memory chip (a flash card or something), and connecting that to the electronics of the control system

  18. B'aht a band

    B'aht a band Member

    Back in my old band, I used to compensate by playing a bottom-stave E on 3rd instead of 1st and 2nd. It did wonders with my tuning, the other BBb bass tuning (the indefatigable Thirteen Ball) and the whole section's tuning.

    However, we used to have a player who's idea of compensating when playing a tricky run of quavers was just to waggle all his valves at once. He got a surprising amount of success out of that one........:sup

  19. starperformer

    starperformer Member

    If you ever play quavers or faster into a chromatic tuner, you'll know that current technology simply isn't anywhere near good enough to spot what notes you're trying to play let alone respond mechanically to pull them into tune.

    A more fundamental conceptual problem is that there is only such a thing as being "in tune" within the context of a tuning system - and in a brass band that varies depending on other players in the band, style of music, and key.

    Not to mention that most would agree that players whould be encouraged to use their ears and lips to tune themselves. And money spent on this sort of research would be better used on making better instruments with more consistent intonation.

    I think, but I could be wrong on this, that vibrato as applied by the best players is in fact purely a function of amplitude and can always be in tune. I don't think it's necessary to wobble in and out of tune to use the effect.
  20. FlugelD

    FlugelD Member

    Yeah - and a few more electrodes from the memory chip wired into the players' cheeks/lips/brain/central nervous system, and the conductor won't need a baton, just an 'ON' switch...

    :eek: :biggrin:

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