Summing or mixing 2 or more signals part 3

It may be done:


With resistors.


Hybrid transformers.


Nothing. Just connecting 2 signal voltage sources in series or parallel combinations. For example microphones.


Further nothing. By acoustic coexistence in the same space. All instruments in the same room very close to a mic?


In the above methods it is nature itself doing the summation. Electrons or molecules vibrating with the superimposition of each instrument vibration.


Advantages:


Almost infinite resolution.


No latency. Speed of light?


No power consumption,


No generation lost.


Almost infinite bandwidth.


Disadvantages:


Resistors will introduce some dB loss.


Hybrid transformers less dB loss. Less bandwidth. In fact this is an advantage, going for flat frequency response from instrument or voice chords to listener's brain. Instateneous peak limiting like magnetic tape recording and reproduction in real time. In fact this is an advantage too for getting a high average signal (loud).


By connecting signal voltage sources in series or parallel there is no dB loss but there is an increase or decrease in impedance. For example connecting together 4 microphones of 200Ω in a series parallel combination brings back the resultant impedance to 200Ω. At your own risk.


Adding instrument sounds by the acoustic waves themselves place very strict demands to the room or space. It is God or nature performing the addition but the acoustics play a very important role. Membrane bass absorbers should be used. Porous absorbers too. Or using outdoor or very large spaces.


In the 60's many of these principles must have been used by the nessesity of simplicity. Or by the quest for excellence.


Much passive connection was done just after the mic. For example the BBC or EMI using attenuators, summers too? just after the microphones or the internal mic prepreamps if it were a U47.


Acoustic leakage from each instrument was used to advantage for a big sound.


Handmade electron tube amplifiers, adders etc were made or made up from converted broadcast consoles.


Are these some reasons why 60's recording sound so great to our brain.


For example, This Girl's in Love - Dionne Warwick - produced by Phil Ramone


This post does not mean that great sounding music cannot be made with a laptop, for example Stepping Stone - Duffy.


References:


Discussion with Sean Davies on the use of passive circuitry just after the microphones by the BBC with no problems or no hiss or noise.


High Quality Sound Production and Reproduction - Hadden - BBC - Iliffe


Elements of Sound Recording - Frayne, Wolfe - University of California, Los Angeles - John Wiley & Sons


Motion Picture Sound Engineering - Research Council of the Academy of Motion Picture Arts and Sciences - D. Van Nostrand Company Inc.


Flat frequency response from singer's or actor's vocal chords to listener's brain, Sound Picture Recording and Reproducing Characteristis - Loye, Morgan - Journal of the Society of Motion Picture Engineers


(hybrid transformer adders), A Rerecording Console, Associated Circuits, and Constant B Equalizers - Miller, Kimball - JSMPE


Making Records - Phil Ramone


Acoustics for Radio and Television Studios - Gilford - BBC