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General Discussion: Alpha - breath input has become erratic/not working

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written by: TheTechnobear

Thanks to Wayne @ Eigenlabs all fixed now , works better than ever.

as john diagnosed appears to have been a blocked pipe.

its great to have the breath pipe back in action, have missed it :o)

written by: TheTechnobear

Thu, 14 Nov 2013 23:29:38 +0000 GMT

Over the last few days my Alpha breath input seems to have gone very erratic.

to start with its seems to have become really insensitive, i know it requires quite a bit of pressure normally but now its almost impossible.

also, sometimes however much I blow, it doesn't work.

but today, ive also notice it seems to stick 'on' i.e. if you play the clarinet, it starts playing, but then even if you stop blowing , you can press keys and it will play notes :o(
if you 'suck' you can get it to stop.... (almost like you suck it back to a zero point)
but then as soon as blow again, it seems to stay on.

if it sticks on, even removing the pipe, will not cease the notes... thought they will stop after a few minutes.

ive not changed the O rings, as i can't really see this helping the 'sticking'

Apart from that everything else is fine.

Really hope its not something serious :o(

ok, some more experimenting...
the note only sticks on if breath compression is left at the default (0.3?). if i turn this to zero, then i cannot hear the note any more, though i can still hear the 'white noise/breath' - again, if I suck this disappears.
of course reducing the compression makes it even harder to get a note though :o(

written by: TheTechnobear

Thu, 14 Nov 2013 23:14:02 +0000 GMT

BTW, is the mechanism the same as the pico?
On the pico, if I remove the pipe and cover then end, then air comes out of the side holes.

but on my Alpha pipe, nothing comes out of the sides, i.e. if you block the end, its impossible to blow.... but perhaps works differently?

written by: john

Fri, 15 Nov 2013 07:59:22 +0000 GMT

The mechanism is the same in the Pico and the Alpha. It sounds to me like you may have experienced corrosion in the pipe, which has blocked the air space between the outer aluminium tube and inner tygon tube that carries the bypass air. That space carries the static pressure from the two mouth cavity pressure sensing ports on the mouthpiece, which is where the breath sensor gets it's signal, so if it's blocked then it cannot function. If you cannot blow some air through it when it is detached from the instrument this does mean that it is blocked - in normal use there is little to no airlflow through this path but detached it should flow, albeit slowly.

The outer tube is made of aluminium (for reasons of weight), which when raw is prone to corrosion. We coat this with a layer of epoxy (the same epoxy used to coat the inside of aluminium drinks cans in fact) and bake it in an oven to cure it. We have seen one failure so far of this tube, oddly just last week - Geert Bevin's died just before he was about to do a large performance and we had to emergency ship him a loaner breath pipe, my one in fact. I think it's possible that the epoxy might fail eventually for some people as the corrosive power of saliva has to be seen to be believed and does also differ from person to person substantially. Geert is of the opinion that his is particularly capable of melting metal and I am inclined to agree with him given that he has what looks like the first field failure of the epoxy.

There are several solutions to this. In the short term if you ship your breath pipe back ti us we can attempt to clean and refurbish it. There would be no charge for this, although we cannot guarantee that it's possible to repair it but we will give it our best shot. In the slightly longer term we have a new, mk 2 breathpipe coming out which uses a completely different inner coating, electroless plated nickel. This coating is much thinner and as a result allows for a more generous air path, resulting in much improved transient response. Given the corrosion issues that seem to be emerging in the long term with the epoxy coating, it is also to be hoped that it has a better lifetime. We tested a version of this with Geert, who played it every day for quite a few months, we then sectioned it and it was in excellent condition. We also had one tested using the standard industrial corrosion test which uses a fog of warm sulphuric acid, and it passed this with flying colours. However, I am now well aware of the astonishing abilities of human saliva to eat metals, so I have to say that we cannot really know until some years have passed whether or not it is a true final solution.

Wayne estimates that the new breathpipes should be available for sale in a few weeks at most, they've been in the process now for over six months and should return from final plating soon. In the meantime, send us your current pipe and we'll see what we can do.


written by: TheTechnobear

Fri, 15 Nov 2013 15:23:38 +0000 GMT

ok I'll try to organize return of my pipe.
If the new pipe is only going to be a few weeks, that may be as quick.
but would be good to have the old one as a backup if it's fixable.

I've looked at the raw data from the USB stack.
It's maxing at about 3400 ( as opposed to the normal 4096 I assume)
It then sticks at around 1700, only going below if I suck it
( then will drop to zero) but returns back to 1700 when you stop sucking.
Interestingly, if i then leave it for a few minutes, it suddenly drops to zero.

Is this expected ?

How does the air sensor work?
does it have a mid value, and sucking goes below this, and blowing above?
does it have a timeout, such that a certain period in the 'mid range' it turns off?
Is min 0, max 4095, mid 2048?

I'm a bit confused, why the sensor still reads after the pipe is removed,
I initially wondered if it was calibration.
Or is it something related to pressure due to block tube?

Thanks again for your quick response and help


written by: 0beron

Wed, 20 Nov 2013 04:59:20 +0000 GMT

I would also be interested in the Mark 2 breath pipe. The mouthpiece end of my Alpha breathpipe has been flaking off some of its outer layer for years now. I've been able to keep it going by cleaning out the side holes periodically (usually with a toothpick and then covering the end and blowing out the debris).
I also find that leaving the mouthpiece attached to the breathpipe is a quick way to ruin the O-rings, taking it off and letting the pieces dry out seems to keep it in much better condition.
The wider outer chamber and improved transient response sounds good as well.

written by: TheTechnobear

Thu, 5 Dec 2013 20:23:49 +0000 GMT

Thanks to Wayne @ Eigenlabs all fixed now , works better than ever.

as john diagnosed appears to have been a blocked pipe.

its great to have the breath pipe back in action, have missed it :o)

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