Tuesday, July 1, 2025

Recording the upright piano with 2 microphones one behind the other

 At your risk

This happened almost by chance trying in almost in vain to record a nice sound. 

So by instinct this unorthodox way came by.

Stand at the right of the piano by its side.

First mic a Unidyne B Mexico pointing at a angle to the cetre of the piano at 24in distance. Then on the same stand another Shure Unidyne B USA behind the other mic by 24in again. Both at the same line pointing towards the center of the piano. The 1st mic feeding the right channel, the 2nd mic feeding the left channel of Sony TC-D5M.

Interesting and promising result. Maybe the best recording i have done so far of a piano in a small living room.

So far my best piano recording may be one at Napier College church in Edinburg. A large church helps so much doing away the early reflections. 

A similar one mic behind the other setup in a bedroom with mics pointing at right angle sounded amazing with a Pleiades oscillator and glockenspiel recording, see previous post. Instruments were on top of of bed with Tempur matresse.




Pleiades BD139 Oscillator Schematic




At your risk. Take all safety precautions. A suitable fuse must be in series with any battery.




Another variable resistor can be added in the feedback path instead of the wire link.

This schematic naturally derived from the Pleiades 2N3053 single transistor audio power amplifier operating in class A (electrons flowing all the time). 

Most of this plus the original schematic (above) is derived from the electronic construction  game with springs Polycyclomatic 1002. Here is how it looks like:

https://www.radioerasitexnisam.gr/articles/15-%CF%80%CE%BF%CE%BB%CF%85%CE%BA%CF%85%CE%BA%CE%BB%CF%89%CE%BC%CE%B1%CF%84%CE%B9%CF%83%CF%84%CE%AE%CF%82-%CF%84%CE%BF-%CF%80%CE%B1%CE%B9%CF%87%CE%BD%CE%AF%CE%B4%CE%B9-%CF%84%CF%89%CE%BD-70s

Thank to a discussion on the beach with John and his Xenophon, both studying engineering there was encouragement to just convert one of the Pleiades single transistor prototypes. In just a few seconds a nice oscillator came up. Wago connectors made the modification possible so quickly. The 12V battery powered oscillator was feeding a Philips 8 in woofer. By adjusting the 2 variable resistors a bass sound repeated in tempo was created. The tempo can be changed by touching the cone of the speaker for current unknown reason. So there is much more flexibility as the pitch can also be affected.

2 Shure Unidyne B microphones, one behind the other at 24in were used to record in stereo the oscillator together with a glockenspiel. The result has some kind of magic from the natural reverberation of the glockenspiel together with the antithesis of the electron generated bass with harmonics sound. It was recorded on SONY TC-D5M.













The amazing Largo from F minor concerto by Bach

 



Here it's Glen Gould recording it in the famous orthodox church of 30th street used as a recording studio by CBS (Columbia Broadcasting System) engineers:






A Forest Recording?


 Malte Marten




A major 7th chord is nicely used. Key is F sharp minor. So D major 7th is beautifully used.



Wicked Game (cover) - London Grammar Using Shure SM7 Moving Coil Inside Magnetic Field Microphone

 


Notes originally written to my friend Markos:

When we talk about dynamic microphones we really mean a moving coil inside a magnetic field microphone. 

A similar mic to the SM57 (God Only Knows - Brian Wilson vocal, possibly uses the Shure Unidyne III which is really the same to SM57) is the SM7. SM stands for Studio Microphone.

Here is London Grammar on a cover using the SM7. Listen for what we were discussing on how humans sing the first few milliseconds of the note flat, and then good singers immediately raise pitch so that it sounds correct to listener's brain.

The singer is very close so the mic will receive spherical waves instead of plane wave fronts so there will be proximity effect, boost of bass and mid. They probably correct bass using a external electrical filter or they might use the filter inside the mic activated by a switch on the side.