[XLR8]

Simple really, of all Grado releases which has the largest cup volume?

 

[PETEREK]

What's the reason for you asking? There are users here that will make you a pair of cups from wood with a larger cup size. I don't know the answer to your question, I was just assuming you wanted the pair with more volume.

I was at a meet a couple weeks ago and can say that it appeared that the PS500's cups are bigger than the SR cups.

 

[XLR8]

I ask as the tuning of the cup plays a critical factor in sound signature from what I discovered. Curious if there is any exact science to the production of the cup or is it an aesthetic thing without research?

 

[PETEREK]

With most headphones the cups are designed around the driver. They would determine the best inner volume, design i.e. closed back, open, or semi-open, and then work on aesthetics after that. With Grado it seems they started that way innitially but then stuck with the same-ish design and just changed drivers. 

 

[Gagarin]

does cup volume matter when they're open headphones?
 
I really don't think it makes that much of a difference, but I'm not familiar with the technicalities.

 

[PETEREK]

It does if there's any kind of dampening materials in them, but mostly in open-air headphones the cup size could possibly be determined by the size of the pads the headphones need to have to get the proper sound. The cups will be bigger is the design is around ear rather than an on-ear design. 
 
Reference- Fidelio X1 vs. ATH-AD2000