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 Low-G and Forked Eb intonation fixes
Author: joem5636 
Date:   2011-10-05 20:20

I am a good amateur bassoonist but have offered to try to get a local school's bassoon playing half-way decently and have little experience with, especially, intonation repairs. The instrument seems fairly "tight" but two notes in particular have serious intonation problems:

Low-G plays about 50 cents flat. I tried some tape on the top and (alternately) bottom sides of the F hole but that did not seem to help. I have had someone push the various keys on the butt while playing the G to see if some key is leaking but without success. I can lip this note up about 20 cents but it then switches to the middle G (which does play well).

The forked Eb is very sharp. I have cleaned all the tone holes and the bore. I have not tried tape on the inside of the D hole yet (and can never remember whether it should be on the top or bottom to correct which direction. I assume top makes it sharper?).

I have a call in to my own repair person, but hate to mooch too much.

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 Re: Low-G and Forked Eb intonation fixes
Author: Ian White 
Date:   2011-10-08 08:47

Low G - first thing is to check the opening of the F pad & E pads which should be about 4.5 mm. The opening of the bass joint keys also affects the tuning of other notes all over the instrument; again the C key should be about 4.5mm - so often these are set far too high which, counter-intuitively, lowers the pitch of G. Try playing the low G & slowly close the low D, C & B & see what effect this has. Have these as low as possible without affect the tuning & tone of other notes. A thicker cork under the end of the low B touchpiece nearest the pad key will close these down to suit.

Forked Eb - check that the Eb vent pad on the wing joint is sealing well (Key #17p on the chart in the resources section of the Fox web site). Also is the ring key of the boot joint (High G vent #25) closing tightly? Problems in these places can cause all sorts of tuning oddities.
Also do you use just LH 1 & 3 for this note? If so try adding the Bb key (L thumb) which is needed on most instruments to stabilise the Eb, despite what some fingering charts show.

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 Re: Low-G and Forked Eb intonation fixes
Author: joem5636 
Date:   2011-10-11 12:41

The suggestions were helpful. I am not sure what all helped reduce the problems (it was a Linton), but it now plays at least. One technique that seemed to help quite a bit was to paint around the tone holes with nail polish to build-up the seat (Linton had pretty flat seats mostly) and smooth the wood (most were very rough what with wood grain and the varnish Linton had applied).

The Eb seat was a mess as suggested. I scraped off the old varnish that was cracked and repainted that area with the nail polish (BTW, I used Hard as Nails as the clerk claimed it was the best -- it does seem to have worked pretty well with good build-up and hardness albeit it dries somewhat slowly for the same reasons).

I found some of the small tone holes somewhat clogged -- there are some tiny ones on the low G hole!

The Bb key's holes were also not sealing well. Again, building up the holes with nail polish and a little bending of the key helped.

The low G was still unstable but at least sounded in-tune when playing up/down scales and ignoring the meter. At least the low notes were sounding far better.

Many thanks for the suggestions. Holden McAleer also gave me some suggestions (mostly similar).



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