Re: Compensating Systems on Tubas

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Posted by Patrick Sheridan on January 29, 2001 at 11:55:59:

In Reply to: Compensating Systems on Tubas posted by Tom B. on January 26, 2001 at 18:45:08:

There seems to be a gross misunderstanding about compensating systems.

Compensating systems are an alternative to a 5th valve (or 6th or 7th if you play an extremely out of tune F tuba). The theory behind the compensating tubing is that is approx. the same length as the 5th slide, BUT proportionately distributed amongst the 1st, 2nd and 3rd valves.

There are only 7 compensated notes on any compensating instrument if you play "traditional" fingerings.

Let's talk Eb tuba.

If you play Bb below the staff (BC) it is fingered 4th, thereby adding the length of the 4th slide to the bugle of the instrument. If you play the A a half step below (fingered 2-4) that you add the length of the 2nd slide, the 4th slide AND the 2nd valve compensating loop (quite short) to the length of the bugle. If you play the Ab (fingered 1-4) you add the length of the 1st slide, 4th slide and the 1st valve compensating loop to the length of the bugle. G (fingered 1-2-4) would add the length of the 1st slide, 2nd slide and 4th slide PLUS the 1st and 2nd valve compensating loops to the length of the bugle.

Etc, etc, etc...the more valves you depress IN CONJUCTION with the 4th valve, a greater length of tubing is added to the instrument thereby giving you the correct amount of length for the necessary pitch compensation. A 5th valve always gives you the same amount of tubing...thus the reason for the often ackward fingerings in the low register and the need to pull slides.

MYTH - if a horn has a compensating system on it, the whole horn is stuffier. WRONG - there are only 7 notes that engage the compensating system. If notes other than the compensated ones are stuffy, the problem lies elsewhere.

Do compensated notes blow differently than the same notes on a non-compensating instrument? YES! Differently, not worse. I used to believe this was the case, but in my 5 years of playing compensating instruments I have found that I have to change the speed and width of air column. Does this change our ability to produce huge sounds in the low register? NO! My ax, the Besson 983 Eb tuba has 17" bell on it with a significantly smaller taper on it than my CC Hirshbrunner with a slightly larger bell and much wider taper (and bore). It is unreasonable to assume that the Besson Eb will produce similar sounds in the low register as the CC tuba. However, this is often expected by many players and when their efforts fail, they blame it on the compensating system. This is an unreasonable expectation.

I have to agree with Gus Pratt regarding history and traditions! The massive efforts in marketing and development made by many manufacturers have dictated to players that CC and F tubas are traditionally not made with compensating systems. The amount of marketing and promotional dollars necessary to change these players minds far out weighs the gains, SO manufacturers make CC and F tuba that are non-compensated! Why buck the trend?

It is interesting to note however that on several occasions from 1890's - 1960's, Boosey &Hawkes (Besson) did in fact produce CC and F tubas with compensating systems in both a front-action and top action configuration. Why did these not catch on?? Don't know...

Hope this helps clear up any misconceptions about compensating systems.


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