So the resonators arrived.
There is a circular plastic disk that you use to mount the resonator with three screws. Its got three holes on the perimeter or three holes close to the center, then there is a another hole you use to bolt the resonator to the disk.
thanks to the good DRodriquez for showing me this, its the details from someone else who made one of these and he shares his thoughts on why and how he made it.
"I made one. It cost less than the Eowave version and is closer to the Martenot original design.
Components (adjust to taste for local availability, I'm in Europe)
* Wuhan 60cm wind gong
* Monacor AR50 resonator
* some speaker cable (I used this
The AR50 is rated at 50W. It comes with a blastic disk that you are supposed to screw to a resonant wooden surface with three screws, then bolt to the resonator. I discarded this, drilled a hole in the gong (see below) and bolted the gong to the resonator. The wires from the resonator have crimp connections; i crimped on the speaker cable, and at the other end added connectors suitabkle for the amp. In my case that was a pair of 4mm banana plugs.
This needs an amp to drive it; I'm using an Alesis RA-150 which has 50W on two channels and a beefy power supply. The amp input is balanced; I use a Pulp Logic Exit Strategy but alternatives from Erthenvar or Vermona would work as well.
The Eowave Metallik uses the hanging holes at the top of the gong to suspend it, as does mine; the resonator is in turn hanging from the gong. A case isn't really needed; mine is suspended from a short cross-bar on a mic stand that I had handy. Note that this differs from the Metallique on the Ondes Martenot, where the resonator is bolted to a back brace on the cabinet and the gong is suspended from the resonator (which uses a beefy metal spider to bear the weight). Details in this post.
For the original Metallique, the mounting hole for the resonator is near the top, mabe 1/4 to 1/3 the way from the edge to the centre. But, remember that the gong is hanging from this so it is both the excitation point and the suspension point.
The Eowave Metallik uses a gong suspended from two holes, and places the resonator in a similar position to the original Ondes Martenot. But the suspension points are fixed and dampening points, so mounting close to these is sub optimal.
I hung my (undrilled) gong and experimented with tapping and hitting it. Close to the center is very boomy but rather dull. Close to the edge is sharp but thin. In between the suspension points is dull and thin. About 1/3 the way from the bottom edge to the centre has a good, rich, full sound with not too much treble and not too much bass, and a long resonance time. So that seemed like a good place to mount the exciter. But its a different place to both the Ondes Martenot and the Eowave, so I was hesitant.
Enter French Patent number FR1004397A, 15 April 1937 (so, now expired) by Maurice Martenot which describes this. Figure 1 shows a gong, suspended from two points at the top, and the bolt position for the exciter is on the midline and below the center - similar to the place I had found experimentally. So that is where I drilled. It works well.
I conclude that Martenot started with this design, but changed the exciter position when he went for a rigidly attached and braced exciter. The one he used was very heavy so would not have worked well suspended from the gong. And I conclude that Eowave simply copied the mounting point without thinking through the impact of their other changes (two-point top suspension, free hanging exciter)."
Looking at the resonator and mounting plate i kinda like the idea of just mounting the resonator directly to the gong like that guy did. have to wait till the gong gets here tomorrow to know for sure but I'll probably need a longer bolt than the one that come with the AR50....probably use some blue lok-tite on it, maybe I should do that regardless.
But i also kinda wonder if it would be better to have the larger contact area of the mounting plate? I also wonder if it would make more sense to mount the resonator of the "front" of the gong instead of the rear...would that change how the gong responds in any meaningful way...does it really matter where i put the resonator since I don't know if its going to have the same effect as hitting the gong with a mallet?? hmmmmmm, gong gets here tomorrow so i'll get to find the best sound that i like from hitting it with a mallet...don't know how good of an estimate i'll get from just holding the resonator against the gong to see how it sounds in different places? I'm assuming the gong is going to be thickest at the center, and thinner as it gets towards the edges, and thats probably going to be important in some way...