POOR ELECTRONICS IN TAPE RECORDERS

 

Tim de Paravicini shares some sobering facts about the poor audio electronics in tape recorders…

Just to continue my saga on poor audio electronics in tape recorders. People would laugh their nuts off if this was a pre amplifier or power amplifier. It would be considered total unexceptable even for simple SE Teiode amps do much better.

First pic is stock Studer C37 record amp as the actual record current into record head it leaves a magnetic flux on tape precisely as show.

The second is my modified version.

The lower trace is input from generator. Second pic shows how little fall back on a20 HZ square wave. Indicating less than 10 degree phase shift at 20 HZ thus preserving the rhythm of the music.

Subsonic information is so important for timing in music. Now here is playback amplifiers complete with output transformers for 600 Ohm drive. The waveform I will show is with a dummy head. This is inductively coupled representing a perfect tape. 


These are at a 100 HZ as 20 HZ is extremely difficult. All these are CCIR as that is the only standard that had hypothetical no eq record current.

Hi pass filter which in effect a typical tape recorder is as any electronics engineer will know cause the bass to have advanced phase shift. The opposite to high frequencies.

I put it to people like this. When you pluck a string in an upright bass. The fundamental arrives ahead of the finger click sound.so you hear a dragging effect not a rushing effect as in music rhythm speak. Either the drummer is ahead the beat or dragging the beat.

So the better the bass response the better the beat sounds. The old Ampexs were worse that Studers by a long way back then. The ATR 100 series with loads of opamps got it very nearly right.