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 Post subject: B flat slides
PostPosted: Wed Nov 26, 2008 11:19 am 
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Joined: Sat Nov 08, 2008 11:32 am
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This is a question essentially for Tony H.

Hi Tony, back in 1993 during a masterclass you told those playing paxmans to push their main slide in all the way and tune with the Bflat slide. Could you remind me of the science behind that and its effects. I seem to remember that it had a profound effect on top G but can't remember why. Does this apply to all instruments with a seperate Bflat slide us just we lucky few ;) .

Kind regards Jez


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 Post subject: Re: B flat slides
PostPosted: Wed Nov 26, 2008 2:33 pm 
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I don't wish to pre-empt the learned Prof, but I have to say that his advice works without question on my Paxman 25. (By the way, I think we're discussing Paxman 20/25 here.) When playing on the Bb side, with the main tuning slide fully home and the Bb slide pulled to get the correct pitch (and of course the F slide pulled also) notes above the stave are better defined, better "slotted" and - frankly - just easier to play, particularly the Ab. I can't say it affects the G much, if at all.

My only guess about the reason for this is that perhaps the nodes of the vibrating air column are shifted slightly. I don't know enough about the physics to be able to pin-point where the nodes fall and whether there is a joint or other slight obstruction involved. I do wonder why (if this is indeed an issue with this design) Paxman did not iron it out decades ago.


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 Post subject: Re: B flat slides
PostPosted: Wed Nov 26, 2008 3:34 pm 
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hello Jeremy and Observer,
The reasoning was first explained to me by the late Dick Merewether.
It has to do with keeping the integrity of the the bore of the first section of cylindrical tubing in the air-flow, that is, the main tuning slide.
Many years (over 40!) ago I took my then horn, an Alex 104, into Paxmans shop as I was convinced that the high register and the high Bb particularly, was VERY difficult and somehow 'stuffy'. Dick M looked at the horn and started chuckling, saying " I know exactly why it's like that! Close your eyes..."
I do so and unbeknown to me, Dick pushed the main slide at least 1.5 inches further in and pulled out the little Bb slide (which had been fully in) about 3/4 inch.
I was amazed to feel a very real improvement in the horn's high range, and a much more secure Bb.
Therefore, if the main slide is pulled out much more than at most 1 centimetre, the internal bore is widened TWICE of course at the ends of the tuning slide legs, giving a somehow impaired air-flow.
I know this isn't very 'scientific' but, in practice, it works very well to keep that slide in as far as possible.
Of course, that same bore-widening happens when the Bb and F slides are pulled out a fair distance, but for some reason, these enlargements happening further down the horn's length seem not to have such a profound effect on its performance.


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 Post subject: Re: B flat slides
PostPosted: Wed Nov 26, 2008 6:37 pm 
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Thanks to TH for the illuminating reply. It does seem to make a good deal of sense.

However, it leads to further questions. Why are the Paxman 40 designs (both older and current), where the leadpipe (i.e. the section preceding the first cylindrical section) passes through a valve in what is arguably an even more critical piece of tubing, where a smooth taper cannot possibly be maintained, not susceptible to similar problems?


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 Post subject: Re: B flat slides
PostPosted: Wed Nov 26, 2008 7:14 pm 
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Two thoughts:
Firstly, I found that a Vienna horn' which was playing sharp, responded much better intonation-wise to a longer crook than to pulling out the main slide which comes after the valve section - it seems that the length of that section before the valves is indeed the critical section.
Secondly, (as TonyH knows!) I have an old Alex 107 with a long leadpipe that has a slide in the taper. Certain notes (A, Bb B in the stave) play rather sharp but moving the slide out for tuning has quite dramatic effects on these certain notes. Keeping the leadpipe taper as smooth as possible seems critical to the intonation of the horn. Hopefully some work on the slide will sort it out.


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 Post subject: Re: B flat slides
PostPosted: Fri Nov 28, 2008 5:03 pm 
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Black magic! I too have heard some of this before - summed up as 'a dent in the leadpipe is more critical than a dent in the bell', i.e. a distortion in the initial taper has a disproportionate effect on the instrument. The reason the new mod 40 may not be affected as one poster noted is that the change valve makes only a short cylindrical section in the leadpipe. This probably does effect something, but perhaps less noticeably than a constriction (dent) or widening (gap at end of tuning slide) in this region.

The Vienna horn related comment above may relate to a different principle that I believe was another part of Merewether's 'system' - that the valves are best placed as late in the cylindrical section as possible. Pulling a tuning slide that comes after them will effectively make them appear 'earlier' in the total length of the instrument. Putting a longer crook works vice versa.

Tom


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 Post subject: Re: B flat slides
PostPosted: Sat Feb 21, 2009 8:35 pm 
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As I understand it the first leadpipe in your F/Bb horns is mathematically configured to work with your F horn. Most all F/Bb horns are F horn based and the Bb side is added and as such, mathmatic relations are compromised. This is partly why a single Bb horn is so different from a Double. The Bb single has a direct relationship between the Slides and the leadpipe.

But on a double horn you have to choose one or the other, or a compromise.

So, when you keep that Main tuning slide in it helps with the Bb because the more you pull it out or lengthen it the more you are moving away from the already compromised mathematic relationship(s). The Bb tuning slide itself is designed with the Bb slides in mind.

You mentioned the model 40 Paxman and the change valve and there not being enough lenth for a proper taper. The length here is more important than the taper. If you knew a really good technician who knew his math and physics you could have your leadpipe modified to work better with the Bb side of the horn and have a larger compromise on the F horn. Just last week I was talking to a friend who mentioned there was University professor who had his students play on the Bb side of the horns as much as possible, only rarely useing the F side. I wonder if he didn't also have them modify their equipment with a different leadpipe. I'll ask.


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 Post subject: Re: B flat slides
PostPosted: Fri Mar 13, 2009 10:51 pm 
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What is the best way to tune a horn with no separate Bb tuning slide? Do you suggest tuning the Bb side first and then use the F slides to tune the F side afterwards or tune the F side first?


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 Post subject: Re: B flat slides
PostPosted: Sat Mar 14, 2009 8:34 am 
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Quote:
tuning the Bb side first and then use the F slides to tune the F side afterwards

Yes of course, doing it the other way round would be illogical.


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 Post subject: Re: B flat slides
PostPosted: Sat Mar 14, 2009 8:58 am 
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Quote:
doing it the other way round would be illogical

it would be illogical only if you were a player who mostly uses the Bb horn. On the other hand if you played in the 'traditional' German/ American school :D as imported into the USA by e.g. Horner and continued by such as Chambers, Bloom and others, it would make sense to tune the F side first and then get the Bb side to match up with it. :geek:


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