Effect to eliminate a certain signal in stereo recording

shaman · 06-02-2008, 12:15 PM

Hi,

Basically two questions, where the first one should be easy to answer:

i have got two mono tracks (two microphones) and would like to turn them into one stereo track, how do i do that? i read somewhere that 'reaper does not share the concept of mono/stereo tracks' or something the like, but as a stereo wave pulled up in reaper shows up as a stereo track, there must be some switch i'm missing.

the second question is related to a plug i'm looking for:

with the stereo track, i want to eliminate (=make more quieter) a guitar that was picked up to enhance the drums that are also recorded on these 'room' mics. By putting an eq on the track i can surely make the git more quiet, but as it is a stereo track, there surely are some algorithms to identify the source in the stereo field and reduce the levels only for signals from that direction, right?

Thanks!

Lawrence · 06-02-2008, 01:18 PM

Quote:

Originally Posted by shaman

i have got two mono tracks (two microphones) and would like to turn them into one stereo track, how do i do that? i read somewhere that 'reaper does not share the concept of mono/stereo tracks' or something the like, but as a stereo wave pulled up in reaper shows up as a stereo track, there must be some switch i'm missing.

Mute everything but those two tracks (probably a better way to do this that a Reaper guru will tell you but..) and render a stereo mix and then import that file back in.

Stereo track.

P.S. I think there was an FR to render a stereo mix and have it automatically imported to a sample accurate position. If not there should be.

Quote:

with the stereo track, i want to eliminate (=make more quieter) a guitar that was picked up to enhance the drums that are also recorded on these 'room' mics. By putting an eq on the track i can surely make the git more quiet, but as it is a stereo track, there surely are some algorithms to identify the source in the stereo field and reduce the levels only for signals from that direction, right?

Not really. Cancellation tricks work sometimes but very tricky (duh! why they're called tricks...) and sometimes almost not possible.

Put your drum overheads at 0 and pan them dead center and remove any FX/EQ. Mute one of them, cross your fingers and ...

1. Send the guitar into the same channel as the drum part. Now the guitar and the drum "half" are playing through one channel. Turn off the master send on the guitar track. You should only be hearing those two parts from that one track.

2. Adjust the level of the guitar send so that it sounds relatively the same volume as the guitar bleed in that drum overhead side/track.

3. Now (the really tricky part) play around with the phase, send level and time position (the guitar bleed will not be sample accurate with the guitar track and also will be different sonically from the distance and the different mics). You *may* (if you do it right and get very, very lucky) get to a place where you can cancel *some* of the guitar bleed without affecting the drum track too much. If you do render it as OH L New (or R for right or whatever).

Mute that side and do the same with the other. If it works use the new overhead renders with (hopefully) less bleed.

Don't expect miracles.

I'd give it a 80-20 shot against making any difference at all.

P.S. If there is a gap in the drum track where the guitar bleed is there and the drums have paused, use that to time align the tracks.

Till · 06-02-2008, 01:20 PM

Q1: easy. create a track, righclick the track in the TCP and enable "Free Item Positioning Mode". drag both your mono items onto that track and sync them. in the item properties of each item pan one hard left and one hard right.

Q2: uh, that's tricky. hang on, i'll see if i can whip you up a nice JS for that.

fluffy · 06-02-2008, 02:14 PM

Have you tried Schwa's Spectro?
http://www.stillwellaudio.com/?page_id=32

It might be able to do what you're asking with regards to the drum tracks.

Till · 06-02-2008, 03:11 PM

ok, here ya go (attachment).

now this thing might work like a charm or just mess up stuff. i can't test it because i don't have any similar recordings.

put it on your stereo track. drag "reduction" down and adjust "direction" until the volume of the guitar reaches a minimum. you might have to search quite a bit for that, hold CTRL to finetune.

then adjust "Volume Pan" until the guitar reaches a minimum.

in theory this plugin can eliminate any direct sound from any source recorded with two mics of the same kind.

i'm afraid tho it's gonna cause do some nasty comb filtering on the drums.

and your guitar is probably not gonna be direct sound only.

halfway through programming this mind-twister i realized that it's probably not gonna sound good, but giving up? never!

please try it!

Staccato · 06-02-2008, 04:10 PM

Quote:

Originally Posted by shaman

Hi,

Basically two questions, where the first one should be easy to answer:

i have got two mono tracks (two microphones) and would like to turn them into one stereo track, how do i do that? i read somewhere that 'reaper does not share the concept of mono/stereo tracks' or something the like, but as a stereo wave pulled up in reaper shows up as a stereo track, there must be some switch i'm missing.

the second question is related to a plug i'm looking for:

with the stereo track, i want to eliminate (=make more quieter) a guitar that was picked up to enhance the drums that are also recorded on these 'room' mics. By putting an eq on the track i can surely make the git more quiet, but as it is a stereo track, there surely are some algorithms to identify the source in the stereo field and reduce the levels only for signals from that direction, right?

Thanks!

Q1...just pan one track left, and one track right, or a combination thereof. I consider split mono superior to stereo since more control of the stereo width is retained!

Staccato · 06-02-2008, 04:12 PM

Quote:

Originally Posted by Till

ok, here ya go (attachment).

now this thing might work like a charm or just mess up stuff. i can't test it because i don't have any similar recordings.

put it on your stereo track. drag "reduction" down and adjust "direction" until the volume of the guitar reaches a minimum. you might have to search quite a bit for that, hold CTRL to finetune.

then adjust "Volume Pan" until the guitar reaches a minimum.

in theory this plugin can eliminate any direct sound from any source recorded with two mics of the same kind.

i'm afraid tho it's gonna cause do some nasty comb filtering on the drums.

and your guitar is probably not gonna be direct sound only.

halfway through programming this mind-twister i realized that it's probably not gonna sound good, but giving up? never!

please try it!

Maybe true, but still a creative innovation.....

nofish · 06-02-2008, 05:43 PM

Till,
just curious...
care to explain what your plug does technically?

I'd guess introducing some sort of phase reversed signal, or is it some more "geeky" stuff?

shaman · 06-02-2008, 11:46 PM

Thanks alot!

Lawrence: i was thinking the same (adding inverted phase signal for the guitar track) but guess what: it was not recorded on a separate track!! these are some very raw practiceroom recordings and sometimes we forget to plug a cable :P

Till: Thank you very much for your effort i'll try that as soon as i can (tomorrow propably) and report back.

fluffy: i'll add spectro to the chain as well, but i think its only mono isn't it? so this would just target a specific frequency rather than a stereo 'direction'

staccato: i guess i have to join them somehow to make a plugin able to process the stereo signal, no?

shockwave199 · 06-03-2008, 12:06 AM

You could also do whatever you need to do to the mono tracks and then put them in a folder, which creates a subgroup, and then render that folder track to stereo. I'm finding I like folders a bunch, especially for this task. Or you could render it as a stem.

Quote:

P.S. I think there was an FR to render a stereo mix and have it automatically imported to a sample accurate position. If not there should be.

I agree. There should just be an option to 'create a new track'. I don't see that in the rendering options.

Dan

shaman · 06-04-2008, 12:12 PM

Hey Till, your JS does something, not sure if its all good, because the stereo field seems to be 'decreased' somehow as well, but it also lowers (only) the unwanted guitar, so it does what it was intended for!

Thank you very much!

tweeksound · 06-04-2008, 12:27 PM

Wow, kudos Till!

todsandberg · 06-04-2008, 01:34 PM

to reduce the guitar (once you have a "stereo" signal) you could try ExtraBoy vst plugin.

Staccato · 06-04-2008, 02:13 PM

Quote:

Originally Posted by shaman

Thanks alot!

Lawrence: i was thinking the same (adding inverted phase signal for the guitar track) but guess what: it was not recorded on a separate track!! these are some very raw practiceroom recordings and sometimes we forget to plug a cable :P

Till: Thank you very much for your effort i'll try that as soon as i can (tomorrow propably) and report back.

fluffy: i'll add spectro to the chain as well, but i think its only mono isn't it? so this would just target a specific frequency rather than a stereo 'direction'

staccato: i guess i have to join them somehow to make a plugin able to process the stereo signal, no?

Yes, add a track and route the split mono to it. In the I/O of the original split mono's, remove the "master/parent" tick. Now the panning will be controlled by the original split mono's send pans.(or recieves of the new track,(buss)).

Blechi · 06-04-2008, 02:50 PM

Hi,

maybe this one ( http://www.celemony.com/cms/index.php?id=dna ) will help with the guitar problem. The downside: available in autumn 2008.

Regards
Blechi

Magicbuss · 06-05-2008, 06:56 AM

I would just use spectro to identify the guitar bleed and then reduce its volume.

The problem with bleed on stereo drum tracks is that the are truly FULL frequency (50hz - 20k) so any trickery will most definitely affect the drum sound. Your goal is to find a happy medium. Good luck

Till · 06-05-2008, 07:59 AM

wow, i'm glad it worked, but it messes with the drums, that's right.

how does it work?

well, it delays one channel (that's the first parameter), balances the channels (second parameter) creates a mid-side matrix from the two channels, turns down the mid-channel (third parameter), codes it back into left/right, restores the balance and reverses the delay (that's why it needs PDC).

so it's a space-time matrix, sweeeeeet.

I only did it for the idea

shaman, could you post a before/after sample?

and shockwave199: