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Organ design and building including MIDI

 
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arthur nichols
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Joined: 23 Jun 2006
Posts: 8
Location: West Midlands UK

PostPosted: Wed Jul 05, 2006 9:11 pm    Post subject: Organ design and building including MIDI Reply with quote

Both of my organs are presently hand turned, my bigger one is about on the limit as to what I can reasonable crank. It can be motor driven which is ok for playing at home but would need a generator in other situations.
I am in the process of wanting to add extra pipe ranks on both but would like to become better informed as to what should be done when making additions.
They are roll playing 26 note Ian Alderman scale. The smaller is based on the Roy Norman plans which was for a 28note, it is built as a 28er except for the tracker bar which is 26 ( leaving two spare channels that might be used in the future).
The build of both is what I understand to be traditional, with primary motors operating on the RN to pouches and the big one to secondary motors and then palettes in bar chests.
The RN has had a MIDI manifold installed in parallel with the tracker bar and can be played via a John Wale board and Casio FD1.
The bigger organ has a solenoid bar which will operate directly onto the primary valves, lifting them mechanically. Both MIDI attachments can be added or removed with out interferring with how the organ plays pneumatically.
Whether or not I should be posting under hand turned I am not clear but if this thread develops the moderator might wish to move it or what ever.
I have several books on organs which I have read but maybe should have studied more and I have been unable to get answers as to what scale (size) rank I should make an additional rank of violins for my RN.
In practice I have made three sets of violin pipes but the scale has been too big, is there a rule of thumb to make a decision on?
Secondly in the absence of bleed screws and using sized holes how is the adjustment reached to get correct repetition. I am guessing trial and error but in my case the bleed holes are inside the chest which involves a lot of stripping and building back up?
Thirdly, balancing the wind on the pipe foot, is this done with a fairground or street organ? Pipes that I have seen from church organs seem to have much time spent on geting the correct balance.
Regarding MIDI, with me not being a trained musician I am not confident that I could transpose music to a 26 note scale so that it would sound good enough to be used in public. Could this mean that unless a MIDI playing organ is fully chromatic we could suffer from some poor sounding organs.
It is hoping that many of you will be champing at the bit to put me right and to either justify or otherwise the use of MIDI.
I am keen to get some answers to the above and am not motivated purely by getting some movement into the forum.

Arthur Nichols
West Midlands
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Dave Stubbs
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PostPosted: Wed Jul 05, 2006 11:28 pm    Post subject: Hi Arthur Reply with quote

Hi Arthur.

Yes, I think it would probably be better in the Hand Turned section, so I have taken the liberty of moving it.

Thanks for your posting, I hope it stimulates some responses!

Regarding transposing MIDI, a chromatic scale is easier to work with, but usually most organ scales (especially the smaller ones) have gaps, which make it much more difficult to transpose. You will end up with 'holes' in the music, which you can sometimes get away with, but other pieces just fall apart! This does of course depend on how you lay out the MIDI 'magnet driver' outputs.

It also depends on the music that you are planning to use. If you are using a General MIDI (GM) arrangement which you found on the Internet, you will have more difficulty making it fit a small scale.

You may even end up having to transpose each piece of music separately with a different number of semitones to suit the arrangement.

Apart from that, you need an organ expert for some constructive feedback!


Best regards,

Dave Stubbs (Site Admin)
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Peter Griffiths
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Joined: 29 Jun 2006
Posts: 5
Location: Cumbria UK

PostPosted: Thu Jul 06, 2006 9:27 pm    Post subject: Reply with quote

Hi there Arthur
Well you will certainly open a can of worms with this one!

Adding extra pipes to a small hand turned organ can be tricky. I would be fairly certain that the bellows would not be big enough to cope successfully with the increased demand for wind. If these pipes were used as a solo stop, then they would be OK, but if they are to be used to beef up the main melody line, then you could have problems.

There is no real rule of thumb for pipe scaling for a new rank. It all depends on the tone and volume of the present pipework, and the final sound you wish to achieve. The pressure of the organ will also make a difference - which brings us to voicing.

Church organ pipes tend to have the wind supply throttled in the foot of the pipe whilst voicing. The idea is to make a smooth start or 'attack' to the speech of the pipes. If you have a large windhole in the bottom of the pipe, the pipe will speak very quickly with almost a 'pop' as the wind rushes in. This is not wanted in most church organs. These pipes are designed for a low pressure wind supply, and use a fairly high volume of wind to improve the volume of sound.
Fair organ pipes tend to be on a higher pressure, and tend to be throttled by the slot between the cap and the block. These pipes need to speak extremely promptly, and so the pipe foot is not blocked up. There is not quite as much finesse used for these pipes, as volume tends to be the thing wanted.

Regarding the bleed holes, well I'm afraid fixed bleed holes are a pain in the ****. I would be very tempted to alter the organ to make the bleed holes adjustable. Whilst they may work perfectly well when the organ is new, over a period of time, adjustments do need to be made to the action to keep it on top form.

Arranging music - well there are already some abysmal arrangements out there when people take general MIDI arrangements and try to squash them down onto a small key size. OK, some people have done a good job, but as for the rest !!!!!!!!!!!!!
Really the arrangements have to be done specifically for the appropriate scale. The smaller the scale, the more difficult it can be to arrange well. Some people have the art, and some havn't. The useful thing with MIDI, is that it is so easy to try the arrangements out, and alter them if need be. If they are truly awful, then hitting DELETE can solve all problems.
Have a play around, and if you are not successful, then it has not cost you anything.

Cheers
Peter Griffiths
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arthur nichols
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Joined: 23 Jun 2006
Posts: 8
Location: West Midlands UK

PostPosted: Sat Jul 08, 2006 5:32 am    Post subject: Design and Building Reply with quote

Hi Peter
Thank you for your comments you make some interesting points.
Regarding the wind for additional pipe ranks. My first organ was built using Roy Norman plans and it has a plentiful wind supply, the first thing that I learnt when I became interested in building an organ was to ensure that the wind supply was adequate and that it worked OK without leaks. It was stressed that you can always shed any surplus wind but if you havn't got enough you have to work within those limits. It was fortunate that the design gave an adequate size of bellows and reservoir.
As you say it is imperative not to play too many registers at the same time. At times I am concerned that I have too much wind as the regulator sheds quite a lot, in fact in the colder weather I had a draft of air which cut across my knees whilst cranking, to avoid this I have added a small shield to deflect air from me. (The back of the organ is not normally fitted to enable interested parties to view what is going on.)
I presently have the melody pipes doubled up and playing in celeste, I am considering separating them and using one or two registers, this would enable some economy in use. I have also built a rank of violins which are on their own register. It is this rank that gave me some good practice in making pipes. The first two sets were too chunky (if that is the right word- sounded more like cellos than violins)
I should mention that the original design called for 6.5 inches wg, as it was intended to use the organ indoors or in fairly closed in areas I was advised that 4.5 in wg would be high enough. This advice was given early on in my building so I was able to voice the pipes on the pressure it was intended to use. This has also given me a mellow sounding instrument, which receives favourable comments.
Regarding my question about bleed holes, when first built it did have bleed screws which turned out to be too coarse a thread (whitworth thread form) too large a diameter 5/16inch and too short, such that air leaked around the threads, this particular size was used as it was to hand with experience I think I would use a finer thread and a smaller diameter and longer. These screws were replaced with a thick paper disk with a hole in it, which once set gave no means of adjustment. This change was made as it was the most expedient to get the organ playing when it was first tuned, perhaps a little short sighted at that time.
The organ has played to my satisfaction for three years until I tried a new roll of Ravel's Bolero this showed up that some notes were not repeatting, hence back to the drawing board. I am intending to refit screws hopefully without having to strip down the primary chest to do so.
This being my first organ build and starting with no previous experience of building an organ it has served me well. Then as time has gone on perhaps we have learned to listen more closely and can see where improvements might be made.
I hope that this discussion will encourage others who expect every thing to work perfectly first time and it dosn't, they are not alone.
Hopefully other points we can come back to later.
Finally it might be helpful to others to hear of things that have gone wrong as much it is to hear what went right.
Having stuck my head above the parapet perhaps others might do likewise.
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Last edited by arthur nichols on Sun Jul 09, 2006 7:09 am; edited 1 time in total
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Peter Griffiths
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Joined: 29 Jun 2006
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Location: Cumbria UK

PostPosted: Sat Jul 08, 2006 11:00 pm    Post subject: Reply with quote

Hi again Arthur

If push comes to shove, you needn't have the bleed screws in the actual chest, though it is neater if you have. The bleed screws can be in a separate block added later. Make the block of bleed screws so that the tubes from the keyframe go into the block and go out the other side with a short length of tube into the primary chest. The bleed screws can be arranged to let air into each bore. Make sure that the air supply to the block comes from the primary chest itself. Block up the existing holes in the primary chest, and there you have it. It is easier to modify this arrangement than try messing with the main primary chest!

You seem to have thought out the wind supply. Always better to have too much than too little.

Cheers
Peter Griffiths
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arthur nichols
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Joined: 23 Jun 2006
Posts: 8
Location: West Midlands UK

PostPosted: Wed Jul 19, 2006 5:18 am    Post subject: Bleed screws Reply with quote

Thank you Peter for your reply, I will keep your suggestion in mind should the refitting of the screws not work out. As the primary chest is already drilled and tapped I will be trying longer screws.

A point I think worth mentioning is the actual positioning of the bleed screws, on my other organ they are accessible from above, this is OK for the ones on the ends but the ones immediately under the roll box are difficult to get at. The distance between the roll box and the top of the primary chest is minimal .
The holes to the primary motors are usually drilled horizontal with the bleed hole at right angles, my thoughts are to fit the bleed screws into the horizontal hole thus giving access from the rear and not from the top.
I notice that the holes into the primary chest are bigger than they need be, ie much larger than the holes in the paper discs, could this be a problem, requiring greater accuracy where the holes meet?

I need to learn a drawing programme, a picture would explain better than words.

Arthur
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arthur nichols
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Joined: 23 Jun 2006
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Location: West Midlands UK

PostPosted: Thu Jul 20, 2006 11:22 pm    Post subject: Organ Building Reply with quote

I see that the Organ Building messages have been viewed by 80 plus people.
It would be nice to know if the submissions are of any interest, surely some one could make a comment.
I am aware of three forums that seem to have died because no one is posting to them.
We do need to encourage and help each other by getting answers to our queries and letting others know of the pitfalls we have experienced.

A lot of work goes on in the background to set up and run a site, the organisers and moderators can best be encouraged by us posting our views.
May be you are all waiting for the dark nights to come!!!

Arthur
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Alan Roberts
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Joined: 27 Jun 2006
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Location: Wiltshire

PostPosted: Tue Aug 01, 2006 12:13 am    Post subject: Reply with quote

Hi Arhur,
I'm really getting the hang of this forum lark now!
Interesting to read yours and Peter Griffiths comments about adding extra ranks of pipes to a small organ and for me especially the part about midi useage.
I have arranged some 170 odd titles for our organ (a 69 keyless instument using the 'Odeon' system) and have found that down to say about 46 -48 key sizes and above it's all relatively plain sailing, as most, if not all, the required notes are there, or at least you can 'borrow' from a like sounding rank elsewhere.
The problem comes, as Dave quite rightly pointed out, when the actual scale of the organ is so limited as to make it terribly difficult to make a convincing arrangement of more complicated titles.
Simply writing a CAL (computor application language) programme to convert from a larger scale to a small one does not work for the reasons given above. In this case, it is simpler and more effective to actually arrange the title in that particular scale from the off.
I have succesefully converted our scale down to 54 key, and have sold some fifteen titles to an organ owner 'up north'. This gentleman also has a small organ and believ you me, it's very hard to get it to work; not impossible, but B....y hard !
But don't be put off; as Peter says, experiment. It only costs you time.
Sales Plug: my site is at www.mrgavioli.co.uk (sorry Dave!)
Alan
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