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Blowers


David Coram

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Who's making what these days? I need to replace an inadequate Laukhuff unit 1 1/4HP which seems unable to drive a classical instrument of fewer than 20 stops through two generous wedge bellows. Even individual stops sag.

 

I've looked into Meidinger but they appear not to be making their own gear anymore.

 

We've had a BOB unit recently and not been very satisfied with it - bulky, extremely noisy.

 

We have 3-phase.

 

Where's the place to go?

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If individual stops 'sag', that should tell you that it's probably not the blower. There would obviously be ample wind for one stop. It's more likely a feature of the wind system itself. How are the wedge reservoirs controlled ? Check with a wind gauge for pressure drops. Are the trunks adequate ? Are the wedges weighted. If I remember my physics correctly, the mass of weights on a wedge reservoir will have a variable effect, depending on the opening angle of the wedge. Do the soundboards have 'local' schwimmer pans, supplied from the wedges ?

 

I would certainly recommend investigating causes very thoroughly before jumping in with a new blower, which may not solve the issue.

 

H

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If individual stops 'sag', that should tell you that it's probably not the blower. There would obviously be ample wind for one stop. It's more likely a feature of the wind system itself. How are the wedge reservoirs controlled ? Check with a wind gauge for pressure drops. Are the trunks adequate ? Are the wedges weighted. If I remember my physics correctly, the mass of weights on a wedge reservoir will have a variable effect, depending on the opening angle of the wedge. Do the soundboards have 'local' schwimmer pans, supplied from the wedges ?

 

I would certainly recommend investigating causes very thoroughly before jumping in with a new blower, which may not solve the issue.

 

H

 

Well, I thought that, but the wedgies drop very fast indeed. Trunks are ample sized rectangles, all very trad and solidly made. No schwimmers or concussions. Roller valves all working as well as can be expected and opening everything up about as far as it can go without crashing into the Swell action. The effect varies considerably depending how long the instrument has been switched on - and, possibly to some extent, the prevailing temperature - which has led us to suspect a seriously under-performing blower rather than the more obvious solution you suggest. According to people who've known the instrument for many years, it was all fine when the instrument was new.

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Well, I thought that, but the wedgies drop very fast indeed. Trunks are ample sized rectangles, all very trad and solidly made. No schwimmers or concussions. Roller valves all working as well as can be expected and opening everything up about as far as it can go without crashing into the Swell action. The effect varies considerably depending how long the instrument has been switched on - and, possibly to some extent, the prevailing temperature - which has led us to suspect a seriously under-performing blower rather than the more obvious solution you suggest. According to people who've known the instrument for many years, it was all fine when the instrument was new.

 

There may be a clue in that you have a 3-phase supply. A valued colleague picked me up on this point. Is it possible the blower is rotating in the wrong direction ?

 

I have experienced this several times. A 3 phase motor will run in either direction quite happily. If electricians have worked on church equipment (heating/lighting etc) they sometimes re-connect the phases differently. The lights and power circuits don't mind but the blower motor certainly will.

 

A blower running backwards can usually deliver near enough correct pressure but very little volume. That might explain your symptoms. If you find that it IS going backwards, it's usually a simple job to swap the phase wiring around and restore proper function.

 

Back to you...

 

H

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