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cup tuning basics.

Jan 31, 2012 at 12:17 AM Post #106 of 294
back loaded horns also use the resonant frequencies to amplify and direct sound, so in that respect, they are not entirely dissimilar. Having an idea of what the nature of the sound waves a specific driver produces, can only help in fine tuning the size and shape of the cups. 
 
Jan 31, 2012 at 12:21 AM Post #108 of 294
please read what i wrote about that 'cove' which is just an indentation in the middle of the cup. where you see it dive in means the thickness there is thinner because the inside diameter is straight and the same. wherever you see a cove, that is where it's thinner.
 
 
also
i'm thinking the thinner the walls get, the longer i want the cup to be....does that have any correlation in your mind?
 

 
Jan 31, 2012 at 12:29 AM Post #109 of 294
Absolutely,
Think total volume of air in the cup, although it is open it is still the amount of air available for the magnet to move towards the film (rice paper) which creates the sound wave.
 
Jan 31, 2012 at 12:33 AM Post #110 of 294
I'll have to think about this - it would be very easy to end up with some pretty dramatic spikes in resonance (honking/pipe-organ pitching). And that is something we can avoid with a little planning... 
 
Jan 31, 2012 at 12:37 AM Post #111 of 294
well i can tell you from listening to that cup in teh picture, it's about as perfect a sound i've ever gotten, the only thing that may be missing is a touch of fullness.....and in my experiments it seemed that whenever i lengthened the cup, even by just a 1/4" it made the sound fuller. Now with the thicker walls i was using, it was a little too full sounding with the limba so i kept it at 1.25" but now with the thinner walls in the middle there,  i think i want to go back to 1.5" with the limba, i guess giving more internal air volume. I'm pretty certain that will be a sweet spot for this geometry and wood anyway....i will make it tomorrow.......
 
Jan 31, 2012 at 12:39 AM Post #112 of 294
Cool - keep us posted. I'll see if i can find some time to research a bit as well. Have a few things on the fire currently - so we'll see what happens.
 
Jan 31, 2012 at 12:55 AM Post #114 of 294
this also explains why the hf2 with it's endcap has that tight sound i mentioned in a past post. it is a kind of deadening feeling....i instantly recognized that quality when i put an end cap on a cup. and even more so when i compared it to a cup with no endcap.......turns out, we want the cup to move....i never would have thought this....i was trying to deaden it all this time with finish..........
 
Jan 31, 2012 at 1:23 AM Post #116 of 294
and then we need to start thinking about the way the gimbal attaches. maybe oversize the holes ever so slightly so that the gimbal doesn not prevent the cup from vibrating....again, i've been undersizing my holes to try and use the gimbal to keep the cup from vibrating....i suspect this was backwards thinking as well.........
 
Jan 31, 2012 at 1:44 AM Post #117 of 294
I've been listening to these coved cups more, and they are almost perfect. a little fuller which should happen tomorrow with the extra length and i think that will be the end of this......looking back, about the only thing i got right was the wood choice. I messed up the finish, the wall thickness, the way the gimbal attaches.........but all that matters is that we made it.......and i am almost certain, all we want for a finish is a very light non invasive violin type finish and these will be reference quaility...even what i'm listening to now in raw wood is damn near perfect. It's natural, even, instuments are true, bass is articulate and weighty, upper end is smooth midrange is not strident in the least, there is a ton of nuance and dynamics, totally fatigue free, the mids have just the right amount of air but still have some umph to them......I can't believe it......thanks to everyone who has helped me organize these things and guide the search. I really feel these are reference quality $1000 headphones at this point. I would not trade them for top of the line grado with those end caps that's for sure.
 
Jan 31, 2012 at 2:41 AM Post #120 of 294
Does this mean you are going to reconsider the importance of mounting the drivers properly? It makes sense to me that if you're looking to make the cup vibrate, you'd want the vibrations of the driver to contribute... maybe not 
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