GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Playback Listening
In the Thread: A playback and wrong notes.

Post Subject: All roads lead to rome ('the microphones are out-of-tune')Posted by Andy Simpson on: 2/25/2009

Romy the Cat wrote:

This weekend I discover interesting phenomena on which I did not pay attention before. The Montrealian Charles Dutoit conducted this weekend Boston symphony. I was listening the broadcast, recording it as usually. It was very bad. The BSO wind section butchered everything they could, particularly brasses that played 6 wrong notes out of any 10 notes. It might sound like a high-school Budweiser-loaded fun ….if it would not be coming for the most paid orchestra in US! Damn, it WAS disgusting! When they opened up with Rimsky-Korsakov Easter Overture I took for me a few seconds to figure out if they stat already to play or if they still keep tuning the orchestra…

Anyhow, after the broadcast I was doing something and ended up with Tannoy Reds connected. Since the Lavry was warmed I started to play the opened file off my hard drive with the Dutoit/BSO. In few minutes I realized that off-the pitch playing the BSO’s horns and trumpets did not bother me so much. I stopped the player and listen it again this time carefully. Sure, all wrong notes were there but total listening was near tolerable… I began to wonder….

The only difference between my initials very negative listening experience an my following tolerable experience was that first was “live” but second was off my DAW in 24/88. Also, the different was that the first I was listening Macondo (driven by Super Milq) and the second on Tannoy Reds (driven by full-range Milqs). I turned on the Super Milq, warmed it up and played the same file. Now, the “tolerable” effect went away and each single wrong note begun to scream about itself with the force of a thermonuclear exposure. A switched it back to the Reds and all wrong notes sunk into a smooth Tannoyness. Sure, they were still the wrong notes but they kind of did not bother me…

Interesting observations… I wonder what Macondo does that wrong pitches so much stick out the whole sound? Both speakers are driven with the same amps. So, what would it be? The drivers? The horns topology? The crossovers? Go figure..

What you describe sounds exactly like (bandwidth related reduction of) non-harmonic (intermodulation) distortion.

In other words, if we take a nonlinear system, any reduction of bandwidth will directly reduce intermodulation distortion - which products consist almost entirely of sharp/flat/out-of-key components.

Regarding the trumpets/brass, these instruments are often the most obvious at showing intermodulation distortion, which is perhaps related to their loud, harmonicly-rich & asymetrical output.

What you describe is almost the definition of 'musicality as a measure of intermodulation distortion'.

The interesting question is how do we relate this to your two systems? Bandwidth, linearity, both probably.

But wait, there is also the question of the nonlinearity of the microphones used in the recording. It may well be - in fact, almost certainly is the case - that the mics in question caused or enhanced the 'out-of-tune' sound by introducing inharmonic distortion products. It could be that this distortion is simply below the noise-floor or distortion floor of the tannoy system but not the main system, or it could be simple listening levels differing....or it could be a fascinating interaction, where nonlinear products fed into a secondary nonlinear stage give birth to further orders of nonlinear products. Oops.

Those microphones are out-of-tune. Not a joke. How much, depends on how loud the trumpets played.

Nonlinearity in transduction is responsible for more of the audio sins than might at first be expected.

Andy

Rerurn to Romy the Cat's Site