[Harp-L] Introducing the GASKET-VALVE System

[bren@xxxxx]

Thanks Vern as always for your perceptive, scientific approach. Sorry,  
'combative' was the wrong word - your healthy scepticism is what any  
new idea making claims of improvement deserves, and we're lucky in the  
harmonica  scene to have you taking the time to do in-depth analysis  
for everyone's benefit.

Your point about gaskets or gasket-valves raising the reedplates is  
valid. Even a 0.1mm rise is enough for chromatics with the  
Suzuki-style slide assembly to put the front edge of the coverplates  
slightly higher than the rear edge of the mouthpiece, creating a  
perceptible lengthwise 'bump' at that point.

To overcome this the comb should be sanded down by the same thickness  
as the Gasket-valve or, in new models incorporating it, the design  
should take it into account.

As for overcoming valve slap or rattle: I think the main area to focus  
on is not so much the valve material as its shape, and the accuracy of  
placement over the slot. A tapered design reduces the valve footprint  
at the tip, where most of the 'slap' comes from. I'm still  
experimenting with the small details, but generally trimming the  
valves to the end of the slot and barely wider seems to get the best  
results in the normal harmonica range G3 and above. They still close  
off the air but are pretty quiet and don't stick. I'd say this  
shape/approach should work with Mylar too.

However for very low reeds (as in the bottom octave of the Lucky 13)  
I'm still getting some rattle, which is annoying! Today I'm going to  
try a wide range of valve shapes to see if I can overcome it.

Thanks for the wax suggestion - is that just to reduce sticking, or to  
give the valve a soft landing, to reduce slap/rattle?

At the moment I'm focused on diatonics and working everything out by  
trial and error. It would be great to film inside a comb chamber and  
then slow down the footage to see exactly what happens with different  
valve shapes and materials. I guess it could be possible by swapping  
the upper reedplate for perspex and filming through it - but  
condensation would quickly obscure everything! Filming outside valves  
would be simple enough, and maybe principles learned from them can be  
applied to inside valves too.

Harmonica valves are tiny things which can create problems way out of  
proportion to their size!  But I think the appliance of science (which  
is just trial and error done very systematically), a dash of intuitive  
guesswork and sheer dogged persistence can help us understand these  
pesky but useful little buggers and advance the state of the art in  
their design and use.

I'm finding it very engrossing anyway, and will report back on those  
low Lucky 13 reeds shortly.

Brendan


Vern <jevern at xxxxx>:

>> On Jun 12, 2019, at 3:47 AM, <bren at xxxxx>  
>> <bren at xxxxx> wrote:
>>
>> Hi Vern, David and Harp-L peeps,
>>
>
>> Thanks Vern for your typically sceptical, combative queries!
>>
> In the spirit of peer-review, I plead guilty to “sceptical”.  But  
> “combative”……never!
> I stand in awe of Brendan’s harmonica playing and would never  
> question a word he utters on that subject.
>
>> Most of your questions relate to chromatics, but for now we're only  
>> releasing the diatonic version. Chromatic Gasket-Valves for  
>> existing chroms would require all the in-situ valves to be pulled  
>> off and their glue patches thoroughly removed. That's a job most  
>> chrom players will not wish to do, I think! Tedious and rather  
>> pointless. For them it still makes more sense to replace individual  
>> valves as necessary.
>
> I agree.
>>
>> However I'm hoping in the future the Gasket-Valve idea will be  
>> licensed by one or more manufacturer, to be installed on chromatic  
>> harmonicas at the factory. It would save them a lot of time and  
>> cost, I believe. A couple of manufacturers are currently assessing  
>> it, so let's see what happens.
>
> GVs would be a boon to mfgrs  because one operation replaces 12 or 16.
>>
>> But anyway, to answer your chromatic Gasket-Valve questions:
>>
>> - The mouthpiece assemblies are made for a given height of the  
>> comb+plates.  Would not four GVs increase that height?
>> The GV material is about 0.1mm (.004”) thick. Assuming no extra  
>> spring material for two-part valves (not decided at this stage),  
>> that's only 0.1mm extra height on each reedplate, because the  
>> outside valve is a strip attached with double-sided tape behind the  
>> coverplates. If you had an extra spring part on the inner  
>> Gasket-Valve it would be thinner, maybe 0.05mm. So at the most  
>> 0.15mm extra height per side. I think exI attach some pictures for  
>> a test Seydel Saxony design to give you the idea.
>
> I understand.  I agree that most chromatics would tolerate that much  
> increase in plate and comb height.
>>
>> - If the GV material is stretchy (like Ultrasuede) would not  
>> alignment of all 12 or 16 valves be impossible?
>
>> It's not stretchy, it's stable. I don't want to reveal the material  
>> at this stage, but it is a food-safe polymer often used for drink  
>> bottles etc.
>
> OK it is not stretchy.
>>
>> - When one valve fails, does the repairman replace the whole  
>> (presumably expensive)  gasket/set?
>> Can do, or he/she could simply cut it out and replace with a single  
>> valve of a different type. I show how to cut out the valves with  
>> scissors in this video (12:41 - 14:03):
>> https://www.youtube.com/watch?v=nT7-ZAH0W9Q&t=45s  
>> <https://www.youtube.com/watch?v=nT7-ZAH0W9Q&t=45s>
>
> OK, I understand cutting out a failed GV valve.
>>
>> - What holds the outside GVs in place against the plate, glue?   
>> Longer screws with washers and nuts?
>
>> Double-sided tape. You can see me applying them in the same video  
>> on diatonics (egg at 7:18 - 7:58).
>
> OK, double-sided tape.  This is arguably a form of adhesive or glue.
>
>> - Because they get wet, more than 50% of valve replacements are  
>> outside on blow reeds.  Replacing one outside valve seems a lot  
>> easier and less costly than replacing the whole gasket set.
>> As stated before, there is no incompatibility between using the  
>> multiple-valve Gasket-Valve parts and replacing individual valves  
>> if you wish to.
>>
>> Incidentally, that test Seydel chrom with the single-piece  
>> Gasket-Valves (no extra valve spring) plays very well several weeks  
>> after I installed them, no valve issues so far. It's still early  
>> days with this new approach to valving harmonicas, but all the  
>> evidence from my own testing indicates the valves are stable and  
>> reliable over the long term. As well as playing extensively with  
>> Gasket-Valved harps at home over recent months, I've also done  
>> several gigs using them. Believe me, I would certainly not be  
>> releasing the Gasket-Valve system if I weren't confident they will  
>> work well for other players too - the repercussions in customer  
>> service issues would be too much of a disincentive!
>
> I don’t see how this differs much from Mylar of equal thickness  
> which is prone to sticking and popping.  However, the undisclosed  
> material may be different in some important way. It is  
> textured/bumpy and that may help. If it it performs well, then the  
> interesting question will arise as to what properties make it so.
>
> I make valves as close as I can get to 1/8” or 3.2mm.  Scaling from  
> your picture which shows perfect alignment, it appears that your  
> valves are tapered from about 3.8mm at the base to about 2.7mm at  
> the tip.  Assuming that the slot is 2.1mm, This allows only .3 mm  
> overlap along the sides at the tip.  This alignment accuracy would  
> be much harder to achieve over the length of a chromatic.
> l
>> I hope that answers your questions sufficiently.
>
> It does and thank you.
>
> One additional advantage shown in the picture is transparency.  You  
> can easily see (mis)alignment .  Also, you can backlight the plate  
> and see the reed-slot clearances.  Neither is possible with opaque  
> materials such as Ultrasuede.
>
> Wax on the plate helps regardless of reed material.
>
> Vern