Surround Effects

[Mark Hammer]

Hi everyone,

I am newbie here, is there surround effects that can play guitar notes all around you, like dolby 7.1?

Take a look here:  https://worldradiohistory.com/UK/Practical-Electronics/90s/Practical-Electronics-1990-02.pdf

[Rob Strand]

page 76 Holophonic Head

I thought if we record with two microphone, the brain would decode the effect. 

You need to read-up on HRTF's (Head Related Transfer Functions).

We identify the position of something from the frequency response and delays.   The left and right ears hear different things and our brain is trained to locate the source.

If you have a single source in front of you need to "undo" HRTF for an object in front of you then reapply the HRTF for an object at a different location (obviously the left and right ears get different signals).    Everyone has a different HRTF and that makes it difficult to get these things to work.   Moving an object from in front of you to behind you is one of the tests that things are on the right track.

This stuff is well known and documented these days.

If you build some sort of analog circuit with perhaps a BBD I suspect it's going to be a lot of circuit and disappointing end result.   If you get some HRTFs on-line and some HRTF software to run on your PC you will be up and running in no time and it will work reasonably well from the start.   The in-between solution is some sort of DSP platform.

Playback with headphones is easier.  Playback with speakers needs another level of processing.

[zbt]

https://www.researchgate.net/publication/200045100_Auditory_Scene_Analysis_The_Perceptual_Organization_of_Sound/link/54384e4d0cf24a6ddb934692/download

You gave me a wagyu steak Sir.

I tried to simulate it by playing

B               B               B
        E               E               E

B       B       B
    E       E       E

BBBBB
EEEEE

https://3diosound.com/ example of microphone

If you build some sort of analog circuit with perhaps a BBD I suspect it's going to be a lot of circuit and disappointing end result.   If you get some HRTFs on-line and some HRTF software to run on your PC you will be up and running in no time and it will work reasonably well from the start.   The in-between solution is some sort of DSP platform.

Playback with headphones is easier.  Playback with speakers needs another level of processing.

I try move speaker as far as possible 

http://spatialaudio.net/ssr/ with headphone

When I see some guitarists record using microphone, I think the speaker is part of it. So my thought why not put in the cabinet. Looks like digital is more feasible 

Thank you for the reference

Hi Iain,

The last time I tried, there seems to be oscillation. I also try, make it active by connecting it too collector Q1. My power supply is noisy, the filter cap 470uF not effective.
So I took 100 ohm resistor with 100uF capacitor for each RC on each transistor, works much better.  Lowering the gain of Q4 is quite nice, I make series the pot with R22, and connect 47uF positive to pin 2 of pot (center) and ground to ground, as sustain. 




Sorry for the late reply, and thank you.

[Mark Hammer]

Again, the question is : What do you want to achieve with "surround"?

With movies, 5.1 and other formats are used to position different sound sources in different locations.  So the footsteps of someone can be engineered to sound like they are behind you, and moving from one side to the other, or a car can sound like it is driving past you by changing where the engine and tire noise is coming from.

All of that is different than having a guitar sound "bigger" or thicker, the way that chorus does.  Some time back, I experimented with using two unsynchronized independent vibrato circuits (the "Magnavibe" circuit - a very simple one stage circuit), with each going to a separate amp.  It sounded incredible to my ears, because the independent LFOs, driving a subtle change, produced an "animated" sound that was unpredictable and had no particular pattern. Sometimes left was a little higher in pitch than right, sometimes right more than left, sometimes both higher, sometimes both lower.  And when both sides produced the exact same change in pitch, the similarity only lasted for a very brief moment before they were different again.  If the LFOs were perfectly synchronized, the effect would not have been as good.

Is that the sort of thing one could do with 3, 4, or 5 unsynchronized LFOs?  Maybe, and maybe it would sound beautiful.  Just remember that it would ultimately be listened to on a stereo sound system.

And Tom, now that I think about it, can one of the pins on your PIC be forfeited as a control input, and turned into a second output, so that a single pic could provide two asynchronous LFO outputs?  And if so, could there be an application for that?  I'll wager it could make for one helluva Dimension C chorus!

[PRR]

Pink Floyd, at some time, toured with a Quadraphonic sound system with a rotary panner which could put any signal (such as lead guitar) at any "virtual point" in the room. They mostly (I hear) used it "dynamic", spun the knob so the sound went "around the room". Probably just laying it left-rear and leaving it there would deafen part of the crowd and be unheard by others, and spinning or rocking spread similar effects to more paying customers.

In about the same decade (do not recall priority) I made a rotary panner for a dramatic production. It was not Don Giovanni being thrown down into hell, but a similar scene of chaos and noise. I know others did similar things. Mine was a holiday cookie tin, an Xmas lamp, and four photoresistors, carefully proportioned.

EDIT: Pink was way ahead of me.
https://www.wired.com/2009/05/dayintech-0512/
May 12, 1967: Pink Floyd Astounds With 'Sound in the Round'