Technical Question: Off-note Reed Windchest Design

Technical Question: Off-note Reed Windchest Design
Before I delve into the depths of another experimental making process, I’m asking assistance here from anyone with experience on this to save me the time in -*test*-('")ing. I’ve two designs in mind, but am not sure which would be the best way to go… The objective: To make a 22-note melody off-note trumpet windchest for my 49-kl Chiappa, sited on top of the instrument so as to be kept out of the sun, and be of a combined square boot block design so as to keep overall height to a minimum (as I’m limited here). I will also take advantage of a sound enhancement I’ve seen on square-booted German trumpets, which will incorporate a flap of leather to vibrate with the reed (in my case at the bottom of the reed block, with the air entering at the side). I was going to have my trumpets pointing upwards as usual, so the chest will be above the main pipework section obscured by the case, so that when the front is in place a decorative top cut out will reveal the wooden trumpet resonators only. Construction so far: The photos below show the reed block half assembled with the piece to hold each reed assembly to cover one end (leather will cover the other). You can also see in the background to the second picture the trumpets themselves, which use plastic boots at present which as well as looking awful don’t have the internal area for correct speech of the trumpets (not sure if I’ve made the new internal spaces big enough yet!). Typically there are also a few trumpets missing that I’ll need to make, along with some replacement shallots / tongues, so quite a bit to do yet. The wooden boot in the foreground of this picture by the way shows one of the replacement accompaniment trumpet boots I turned and bored out on the lathe, as these again have pipes missing completely that need to be made to complete the rank.

Windchest Design 1: The sketch below shows my proposal for this, using sprung pallets just like the original Chiappa chests in the instrument. Harder to make, but presumably a nice snappy action that should has similar timing to the rest of the chests. Will the push rod penetrating through the reed block affect the sound at all? Any better suggestions for this; should I have the action part completely separate from the reed box, just passing air to it rather than surrounding it?

Windchest Design 2: The sketch below shows my proposal for this simpler design, using standard round discs returned by air pressure and gravity. Will this action be quick enough for the job? Might weighted rods be better to improve the shut-off rate?

Any help will be most appreciated, and should ensure I get this right first time! I should just mention that these trumpets will be brought on with the ‘forte’ register (melody and accompaniment trumpets and bass trombones, as well as some percussion changes). There is a separate violin register, so they may be playing with just flutes, or with violins and (straight tuned) flutes as well. I haven’t thought about the possibility of piccolos yet as none were on the organ originally (anyone got a 22 G – F set lying around to save me some making time?!). From the (original but unusable) register box there was clearly going to be another rank somewhere, so I might decide to add these in for balance on the double rank constant-play flute chest on a leather valve register system and rig them so they only play when violin and forte registers are both off, or when they are both on (bearing in mind the glockenspiel will only be brought in when both registers are on). I’ll have to do a full diagram sometime to make the registers and ranks easier to explain, especially when you learn that for convenience and success of playing standard 48kl music without the additional 49th register hole present, the violin register is effectively ‘set off’ by this special key (so more of a ‘piano’ register I guess, with violins being the norm such that when the forte is set everything comes in). Dear me this is complex, but it makes the most logical sense from the music cutting point of view. Will explain this better later if you’re still lost! All the best, Nick

Hi Nick, I know little about offnote chests, but reading your posting reminded me of the extra register control that was incorporated into the 48 Key Richard Pawlyn which belonged to the late Jeff Bach (Now in Norfolk I think). When the bass drum sounded the organ would go into 'forte', so in effect an extra register could be activated the same time as the drum beat. The beauty is the bass drum hole in the music is cut slightly in advance of the beat, so in use register gives a prompt signal. The normal 'piano' key would cancel it as usual. So you could have a 48 keyless with three registers instead of two! (No 49th register hole!) Hope this makes sense. Robert Washington. :D

Thanks Robert for the idea. This is frequently used on 31-keyless organs to bring in a register control. It does unfortunately have one major limitation which is why I can’t use it here – if you use the bass drum to bring the register in, you can’t have any extra percussion effects that change with the registers, or else would forever be punching section in the music on the ‘cancel’ key to mirror the bass drum in the parts you didn’t want the register on! You’d probably need to do this anyway to most of the music at some points to get the ‘forte’ brought in at just the right places, not just when the bass drum starts. With my 49th note (already added to the tracker bar and an extra groove turned in the roller) the music doesn’t have to be any wider, it just uses the first fence edge note available to keyless organs (wouldn’t be room if it were a key), so is a good compromise to accommodate the extra register without extending the scale outwards or renewing each book. All the best, Nick

Hello Nick, I'd go for the second design of chest for simplicity & reliability. Rob.

Nick - what computer program do you use to create those nifty drawings ? Stephen.

Thanks for the help Rob; I was favouring the simpler round pallet springless design for easy of making, but hadn’t thought of the reliability advantages too. You’ve made my mind up! This is now coming on great after a good evenings work, with the puff board and air transfer box well underway (as all those watching tonight’s WorkshopCam will have seen, see post under the general section for some images). Don’t forget to keep an eye on this forum for timings of the next live broadcast of the next stages of producing the chest later on Thursday! There will also be a ChiappaCam in a few days which we hope showing work as it happens with the key frame and primary chest being mounted along with the key frame motor, and then the tubing process. Regarding the software I used to draw the above images Stephen, I’m afraid it was nothing more than Microsoft Paint! (with a little imagination and a lot of patience!). :lol: All the best, Nick

This Chiappa melody trumpet chest is now well approaching the finished stage, though as ever with these types of jobs much of the time is spent setting clamps and waiting for glue to dry! This has given me time at least to get on with sorting the trumpet pipes to go in the chest, though still more reed blocks and resonators to make to complete the trumpet rank which came with the organ. Anyway, chest photos below (any ‘out of line’ holes you see will be the ones James drilled during his week here!):

Making push rods while the glue’s drying!

James signed his name on one of the cardboard discs, and amazingly by odds of 11/1 when I labled up the puffboard I found he’d signed it on note D for Dundon!

Almost forgot, does anyone have experience of which type of leather works best on trumpet boot holes? Thick? Thin? Or perhaps it doesn’t matter? I have a large skin of appalling quality medium thickness leather that I won’t use anywhere else (too poor for pneumatics) so perhaps this will suffice? The problem with it is this bad piece has tiny pinprick holes in it everywhere, so not greatly airtight, but perhaps a small quantity of escaping air from the pressure varying reed chamber might help push sound vibrations out the bottom as well as the top through the resonator? Else I have plenty of nice thick red leather which would look great but probably be too thick to vibrate efficiently. So any ideas before I decide what to use myself? It’s all a bit of an experiment this as I’ve never seen anything like a combined reed block with leather on the opposite ends, but am hoping my design will emulate the German fair organ trumpets (separate) which have air feed into the side of each boot and a leather covering the opposite end to the reed (i.e. on the top of the boot as German trumpets more often than not point downwards!). Hopefully it will be successful; we’ll know soon enough!

I went for some soft medium thickness leather in the end, as -*test*-('")s seemed to indicate this would be best. I’ve completed the chest now and barring the signal tubing it’s fitted into the roof of the case. Having -*test*-('")ed a few trumpets in the chest I’m pleased to say it’s making them sound much nicer than the usual white PVC plastic boots (no leather and air entering at the end) so my design of chest is a success! The leather end of the reed block really helps the speech of each reed, with a much cleaner start in the pronunciation of each note, just what I was aiming for. Some photos below, more to follow once I’ve completed and fitted the actual pipes!

Hello everyone, The Bruder that was owned by Ron Bowyer for many years (now sold, but where is it now?) had an extra trumpet rank that was on an upside down off note chest in the roof of the organ. I can't remember who made it for him, but they were old church organ trumpets made of pipe metal. I don't know why they were installed, as there would have been trumpets on the organ to start with. Rob.

Rob barker said: 'The Bruder that was owned by Ron Bowyer for many years (now sold, but where is it now?) had an extra trumpet rank that was on an upside down off note chest in the roof of the organ. I can't remember who made it for him, but they were old church organ trumpets made of pipe metal. I don't know why they were installed, as there would have been trumpets on the organ to start with.' The Bruder now resides 'up North' I believe, I remember a picture of it on Peter Griffiths website. (I even mentioned it to Ron at the time). The organ was originally barrel but was rather in poor condition so it was decided to convert it to 41 keyless book by Tony Cragg of Nottingham. I guess it was he who fitted the trumpets? It also had no percussion so drum cases had to be constructed as well. It was quite a stident sound for a small organ, typical German sound with all the reeds & flutes. Perhaps Peter can fill in some details? Regards Robert Washington :D

The Bruder photo is still on Peter Griffiths website homepage, I just had a look!! Robert Washington :D

After having some problems with some sticky notes on this melody trumpet windchest, I took no chances and removed the whole thing to modify the action. Whilst most did work without, all the pallets now have guide pins to ensure they seat closed in an airtight fashion. For completeness, here's how the inside of the chest looked before I sealed it back up again using that very out-of-date flowery wallpaper...

And here's the note I wrote inside the top lid of this chest first time around; I'm very glad it was me reading it this time, though I hadn't expected to be seeing it again so soon!

And a bit of a confesion if you look close enough, for some reason I used MDF :? . This is the only piece on the organ, and though I can't remember putting it on, the reason must have been so that the material could easily be bent off to gain access inside (thankfully!!!). It's not seen at all, as the top of this chest sits under the case, and at least I made this clear to whoever had to re-open the chest at any future point...

So am I the only organ builder who likes writing notes about construction material, histories, and anecdotes inside some of the sealed mechanism parts?! Just writing one’s name and date could prove facinating for those who discover in future generations, but perhaps taking it further than this with longer inscriptions could be even more fun for the person who discovers them. A sort of organ builder time capsule I suppose!

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