Pennies from....uhm

Location
Melbourne
Equipment
Zoom H4N
Beta 58A and MkH60

What was supposed to be a simple short session at work to record some material for one of our current projects has turned out to be far more interesting.
Today at lunchtime I purchased a small bag of old Australian pennies. These have dates on them ranging from 1900, up to when we converted to metric money in the 1960’s. The bag of about 30 coins cost me about $7 so I guess they have increased in value pretty well.

I have recorded some regular coins in the past, but I really wanted something with a different sound. I was looking for something suitable to represent pirate treasure and giant gold coins. The pennies are made of a different metal to modern coins and are much larger; this allows them to produce a stronger ringing tone. I set up the H4N using both its internal microphones as well as the Beta 58A. I wanted the mics to be nice and close to the coins as I dropped them and bounced them on various surfaces. I made sure I monitored the levels carefully to make sure there was no chance of peaking the signal. I spent about 30 minutes playing with the coins on different surfaces, from modern laminate table top, to concrete and an old wooden table. In general I was quite happy with the types of sounds I could produce by dropping, bouncing, sliding and otherwise manipulating the coins singly and in a pile to produce various sounds.

Pennies

When transferred the sounds to my laptop I discovered that pretty much all the material was completely unusable. Even though I had been very careful to make sure non of the sounds had peaked, the extremely close proximity to the microphones had been an issue. The coins produced a very high frequency ping each time they impacted on any surface, and it seemed that this extremely high frequency sounds were a big issue for the mics to deal with at such a close range. All the material was effectively distorted even though the readout levels never came close to peaking. I have had a similar thing happen in the past when I tried to record some gongs and bells with my shotgun mic, and I placed the mic to close to the source. This is a behaviour I will need to look into and investigate its cause, and how best to deal with it. The obvious thing is to place the microphone further away from the source, but I still want to understand exactly what is going on so I can deal with it effectively rather than just guessing.  Keep an eye out for a later post on this issue as I try to find out what’s going on and redo the material I need.