I'm afraid I'm a bit of a Neanderthal when it comes to using gongs, JM - I just reach for the one that sounds good for a particular piece, and use it. But I can see what you're wanting is to very specifically notate the precise gong you want for your compositions. Of course notation books show you the specific symbols for the various gongs, but you're also wanting to be more familiar with what all the different gongs sound like. It's a completely new issue I've never seen anyone bring up, so I have nothing here at the Forum to which I can refer you.
There's this site I just now quickly Googled up. It has audio samples of 3 basic gong types, perhaps that can be a start:
http://www.percussionclinic.com/infoorc.htm
The way the gongs are named in GPO I think is a good example of "MIDI talk"--they aren't academically correct names, but rather descriptive. Here's a sound we'll describe as a "medium gong"--and here's another "medium gong." For most of us, more accurate names would be lost on us, we want to have some basic idea of what we're reaching for when we load one of the instruments.
I could be wrong, but it seems likely that when a live orchestra plays your music, the selection of gongs may be limited to what the percussionist has at hand. What one orchestra uses for your pieces will be different than what another orchestra uses - I'm not so sure getting so studiously accurate would really improve your score, since what will happen in an actuall performance situation will probably be unpredictable. But, as I said, my needs are simpler. If I want a gong, I can load one from the small collection of 4, choose a pitch, EQ it if I want, pitch shift even if I decide to reach for an outside pitch - I just need a metallic crashing sound with a ring to it.--
So - I do bet you could find more audio samples of all the different gongs with some searching online, and then you could experiment with what GPO has to approximate what you hear. The most crucial part for you, I think, will then be to look up the notation guides for the right symbols - And so forth.
It's the best I can do!
Randy
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