Brass plosives can be massive, and it is a dangerous undertaking to use condenser mics -- especially
high-sensitivity vintage European condenser mics -- anywhere near loud brass instruments. In
many-mic recordings, my father always used ribbon mics on brass. He did some testing in the 1950s
and found that a muted trumpet could produce a blast of air that hit a U-47 hard enough to
momentarily short out the capsule. Not to mention that vintage mics often ring, and condenser mics
tend to ring in a way that brass blasts can trigger. And, brass blasts, especially trumpets and
trombones, tend to occur within the "presence peak" frequencies of vintage condenser mics and can
thus more easily overload a mic preamp.
-- Tom Fine
----- Original Message -----
From: "DAVID BURNHAM" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, September 30, 2014 11:09 AM
Subject: Re: [ARSCLIST] Distortion question
> As Lou points out, the distortion almost certainly occured in the mike preamp. Trumpets and
> Trombones, especially when muted, have a significantly larger positive excursion in the waveform
> compared to the negative half, perhaps as much as 20 dB, (an announcer's voice exhibits the same
> characteristic to a lesser degree). A mike, (or an ear), placed close to brass often just snips
> these spikes off but miked from a distance these spikes give the brass a presence which is very
> attractive on orchestral recordings, big band recordings or even jazz solo recordings.
> On Tuesday, September 30, 2014 10:07 AM, Bruce Whisler <[log in to unmask]> wrote:
> I am working with an old tape recording that has several instances of distortion that sound like
> clipping. When I view the waveform in my DAW, I see two things that are puzzling:
> 1. The waveform in the distorted areas is not at a higher amplitude than other undistorted
> 2. The waveform amplitude appears to be attenuated on the negative side of the waveform, but
> not on the positive side.
> The distorted sections usually last only about a second and do coincide with loud high notes from
> a trumpet soloist. The recordings are from live performances in the 1970s.
> Any thoughts on what I am dealing with? I have Izotope RX 3 Advanced, and have had little success
> in repairing this particular problem with the Declip, Decrackle, or Declick modules. I don't
> think there is enough tone left under the distortion to effectively repair it.
> Bruce Whisler