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A.S.
05-09-2006, 09:53 PM
Many of us have a soft spot for analogue tape recorders, for their human ingenuity and design. There is a darker side though: the impossibility of recording flat in the bass region.

This shows the problem associated with the physics of the head design, tape speed, electronics design and wavelength of sound and it is not a pretty site: http://www.endino.com/graphs/

Please note that the red trace is at 30 inches per second and the blue trace at 15 ips i.e. the frequency response is flatter at the slower speed.

You will note that many of the problems are in the 30-200Hz region (an astonishingly wide range) which of course, covers the band where the speaker vent is contributing the most output. So, when deciding upon 'bass response' not only must we consider the characteristics of the woofer and the vent, we must also add-in that of the room at low frequencies and the recording machine itself.

I assume that with digital recordings that the frequency response is dead flat across the band, but is it any wonder that older analogue recordings sound so warm and lush when they have a bass boost and it would seem often a treble shelf or cut?

One of the machines I will - hopefully - one day get around to restoring is the Telefunken M15A; I have three and several Studers too, all ex-BBC. The most recent two M15A's I collected from BBC Broadcasting House in August 2006 and they came from studio B14, home of Radio 4 where they have been in daily service for about 20 years. The BBC has now gone completely digital. And yes, it sounds hard, and it does crash. But the running costs are low and it is extremely convenient. The world has (sadly) moved on.