Hello, i have just joined FOPs but have been reading the forum pages for some time.
I got into Organs because my woodwork teacher built them. And has for 30 years or so. And knowing i could not afford to buy one i decided to build one.
So, i looked around and did research and found next to no info.
Finally i found the John Smith designs and settled on the Topsy 3 plans.
This is the reason for the post.
I am starting to look into making a few test pipes for my organ and i am intrigued by Johns pipe design with a step at the front.
I know it is to thicken the shelf to help shape the cut back. So i thought, why not build 3 different pipes to test.
One like Johns. One with a flat (thicker) shelf. And one with a sloping (thick shelf).
Research tells me there should be a slight difference in the sounds produced but........ as an engineer there's alway a but.........
does anyone have any idea of the optimum angle for the German Mouth! So far i have seen values of 10 degrees up to 30 degrees......
Does anyone have a favorite? Personally i think 15 degrees may be a good starter.
Any-how, i will let you all know how i get on later. Plus conclusions of course.
I will look forward to any thoughts, no matter how helpful
73 de Rose

Hi Rose, I would like to help but am struggling with your terminology.
John's pipes have a separate piece for the upper lip which slides over the front, this is simply to make it easy to set the 'cut up' or distance from the flue to upper lip while the pipes are on the organ. Personally I find it easier to use a single piece for the front, hold it on with rubber bands and slide it up and down, then glue when you find the correct place. The only issue with this is that you need to do this on a voicing machine, not while fitted to the organ, but there's not much involved in making one.

I'm not sure what you mean by the shelf, if you mean the upper lip then the angle is almost unimportant, I've experimented with a wide range and it makes no difference at all from say 10 to 45 degrees.

If you're talking about the top of the languid, sloped in some pipes, than I can't help as I've not yet experimented with anything but a flat languid.

Greg

Thank you Greg, yes, i am sorry, i was keeping things simple.
The Languid was the shelf i was speaking of.
If its at 90 degrees ( ie flat) i know this as a British mouth. It produces a more pure tone with less partials.
If at say 15 degrees ( sloped ) i know this as a German mouth. This should speak with more partials.
But, this normally applys to an open pipe. Stopped pipes naturally produce a different range of harmonics.
But i am unsure how much difference it will make overall as Johns pipes are small scale.
As for the extra piece of wood (step) i was talking about! It sits on the Languid at the front and is used to thicken the languid at that point.
This then allows enough depth to shape the underside of the Languid for the air to flow up the back of the lower Lip and form the Air Reed.
In all my research i have not come across this before.
Hence the post for Thoughts on pipes. as i am unsure how this step on the inside of the Languid affects pipe speech. On big bass pipes it probally can be ignored, but smaller pipes, well.......
But thank you Greg, your answer helps. And it looks like my experiments might help you a little as well. Once i have built some test pipes that is.
All the best Rose.

Hi Rose,
there's some confusion about what is an English or German mouth, Audsley in his lengthy work on pipe organs first states that a German mouth has the flue cut in the block AND has a sloping top to the block, backs this up with a drawing, then on another page contradicts himself by showing a drawing of a pipe with the flue cut in the block and a flat top, also labeling this as German. This latter drawing is most typical of fairground organ pipes.
I think it's really only safe to say that a German mouth has the flue cut in the block and an English mouth has it cut in the cap, the top of the block seems to be an unrelated variable which can be sloping in either type.

I've experimented with both ways to form the flue and found the English mouth has a sharper attack, possibly because the air is being directed slightly into the mouth rather than out of it, but that's only a theory. It's interesting to hear that a sloping block increases harmonics, I'll certainly give that a try.

Do you know that you can get spectrum analyzer programs for the PC that let you see' the harmonics?, I'm playing with Zelscope at the moment and it seems very useful. If you have a laptop with a microphone built in you just have to play the pipe in front of it.

I suspect the step you refer to is simply to allow the pipes to be made entirely of thin sheet material rather than a conventional block. Some people split the block into two, one for the languid and one for the foot, thus avoiding having to cut a V in the front, but they still make the languid thick enough for the front edge to be sloped gently to form a smooth flow of air. The key point seems to be that the air needs to form a smooth sheet flowing in a controlled direction towards the upper lip, if the languid is a very thin sheet this isn't necessarily going to be formed.

Regards
Greg

Hello Greg,
I've learnt something useful. I hadn't realised that Audsley contradicted himself but i am still reading through his writings on Organs.
I agree that names are confusing, German versus English when at the end of the day what we mean is flat or sloped. I suppose it no different with Enginnering as a Sky hook is a joke to one person and a very useful tool to someone else, but i digress.
I have studied quite a lot on pipes and have seen various ways of forming and directing the wind sheet. Different builders have different ideas but they all agree that the air reed needs to be directed across the mouth. Some prefer it slightly inside and others slightly out side!
It is all rather confusing as everybody contradicts every body else.....
.....anyhow, i am still a beginner and willing to learn.
Yes, i have a good pipe tuning program for when i need it. By Zeta!
Yes i know, i'll check for you and post a link a little later.
I also have a spectrum analyser program which i use for Radio and Electronics and it works at audio frequencys so i should be OK when i start building.
And the pipes are quite thin at 3mm so i would say that the step is to thicken and to shape the languid. But what that step will do to pipe speech is what started me out with this post!!!!!!
Thanks again Greg, speak to you later Rose.