Plate Reverb Prototype Test.

Two day's ago i had the 1st opportunity to test out my prototype plate. The results were remarkable, as in it works, however it is not entirely pleasing.

As you can see in the picture's i soldered a contact microphone onto a terminal and then onto a guitar lead

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This lead was then placed into a di box and routed through a mixing desk into a hard disk recorder, the plate was then excited by being placed in front of a speaker with a track being played through it.

Here are two sample recordings, they start with the dry track, then are a full wet signal from the plate, then the wet and dry signals are mixed together.

When you here the tonality of the plate Reverb sound change, that is the effect of moving the positon of the plate in front of the speaker, i.e were on the plate the sound is being focused, the closer to the middle of the plate the higher the tonality.

In the second Plate sample you can hear a dominant frequency, this is because the tension across the plate was increased allowing certain frequencies to travel faster across the plate. This gave a better effect than the 1st test with less tension, although this dominant frequency (between 400 - 500 hz) is a problem, this is due to the size of the plate and is a similar effect to modes and standing waves with in a room.

My plan to get round this problem is to attach reeds to the back of the plate which will increase the surface area theoretically combating the effect of the dominant frequency.

Each of these reeds will be different lengths, therefore they will have different resonant frequencies which will hopefully colour the sound of the plate and help mask this dominant frequency, by introducing different standing waves and therefore there harmonic content.

I am also going to use a slightly larger plate, and attach two contact microphones for a stereo effect, i will also need a microphone to capture the effects of the reeds.

Another noticeable issue with these first tests is that the plate is very noisy, this is due to an earthing problem, this can be resolved by placing the plate and frame in a wooden box and earthing the box, however this is only one reason to the plates noise issue.

To capture any useful signal from the plate, gain structures need to be incredibly high which introduces noise into the signal, to help with this i am going to drive the plate with a very directional pieczo horn, this will make the plate more efficient by exciting the metal more efficiently plus this horn will also eliminate any low frequency resonance as most horns cannot reproduce frequencies below 1khz

On evaluation, this plate reverb does not entirely work as a plate 'reverb' but more as a stereo widening effect, it is not what i intended to do but could become a reasonable achievment.

However i am hoping with the suggested modifications i will be able to create a compact stereo reverb.