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  #1  
Old 02-06-2013, 01:58 AM
jyang jyang is offline
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Default Eleven Rack FX Loop - True Stereo Signal Flow?

Hey there,

I'm trying to use the Eleven Rack as an unbalancing amp, basically as an in-between unit between the sends of my console into some FX pedals - at the moment using some moogerfoogers.

Using direct connections, DI boxes in reverse, 11R OP to amp, line level shifters etc have proven to be problematic (with hum) due to the interfacing of balanced to unbalanced...

Going back the other way, i.e. feeding the console returns directly from the outputs of the pedals has been fine.

This is one working setup:

Console FX send -> Eleven Line In L (+4)
Eleven FX Loop Send L (stompbox mode) -> Moog 104M Delay Audio IN
Moog 104M Audio Out -> Console FX Return

I'm only using the FX sends as they are live, and not bothering to return through the Eleven.

The above scenario works perfectly, have routed the FX loop to the start of the chain so it passes the signal through without processing, only gain.

The issue:

I thought it would be cool to use one channel for one FX send, and the other channel for another FX send - thinking it would be a true stereo signal flow but it seems in either setting the Eleven sends whichever input is selected out both FX Loop channels...

So when the Input is selected as "Line in L", the same signal goes out both FX Loop L and Fx Loop R. And when the Input is "Line In R" the same thing happens. This is expected I guess. But when I set the Input to "Line In L+R" - the signal from both line inputs gets summed and is sent out both FX loop points simultaneously, not separately! So L+R goes out FXL, and FXR!

Sure - this is a different kind of usage to what was intended with the FX loop - but if I was sending a stereo signal into the Eleven for FX processing, I wouldn't want the right channel to go out the left FX loop point and vice versa, would rather it be treated as proper stereo!

Sorry for the long post - and hope it all makes sense - does anyone know whether there is a setting to get this sorted or is this a limitation?

Thanks!

Jeremy

And as an aside - do you guys have any experience with a reamp device that would act like the Eleven that could essentially do what it's doing? something like the radial x-amp or studio JCR reamp box?
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  #2  
Old 02-10-2013, 06:45 AM
musicman691 musicman691 is offline
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Default Re: Eleven Rack FX Loop - True Stereo Signal Flow?

Tremendous waste of the 11R's processing. You're not using any of it's processing are you? If not there's simpler ways of doing what you want.

First off:
Are you sure your console fx sends are balanced? Not all are. If they are you can get a balanced to unbalanced adapter cable. Simple and inexpensive. Or if you wanted to splurge you could get something from Radial but that would be unnecessary. Watch for any impedance matching problems as most guitar stompboxes are looking for high impedance on the input. Not too mention level matching (not overloading the stompbox input).
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  #3  
Old 02-10-2013, 11:12 AM
Darryl Ramm Darryl Ramm is offline
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Default Eleven Rack FX Loop - True Stereo Signal Flow?

Quote:
Originally Posted by jyang View Post
/snip/
So when the Input is selected as "Line in L", the same signal goes out both FX Loop L and Fx Loop R. And when the Input is "Line In R" the same thing happens. This is expected I guess. But when I set the Input to "Line In L+R" - the signal from both line inputs gets summed and is sent out both FX loop points simultaneously, not separately! So L+R goes out FXL, and FXR!

Sure - this is a different kind of usage to what was intended with the FX loop - but if I was sending a stereo signal into the Eleven for FX processing, I wouldn't want the right channel to go out the left FX loop point and vice versa, would rather it be treated as proper stereo!
/snip/
This is working exactly as designed and documented, and a shown in the rig view in the Eleven Rack Pro Tools GUI... notice the mono and stereo signal paths. The Eleven Rack virtual rig only has a mono input. The virtual rig only become stereo after processing by a stereo output block, like the stereo reverb. If you put the fx loop after that block you would have the stereo reverb correctly sent to the two different FX channels. But there is no way to get the rig input itself to be stereo. Not an important requirement since there are not many stereo guitars out there. And this would require running two amp and cab sims in parallel. which would be nice for other reasons, and we don't have that feature yet, and I would not be holding my breath for ever seeing that in an upgrade.

The Fractal Axe FX can do closer to what you want (not to mention it has pretty good delay sims, which might just replace the Moog to start with), but you are still trying to screw a screw in with a hammer. The Eleven rack delay sims don't do it for you?

Darryl
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  #4  
Old 02-10-2013, 11:50 AM
musicman691 musicman691 is offline
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Default Re: Eleven Rack FX Loop - True Stereo Signal Flow?

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Originally Posted by Darryl Ramm View Post
The Eleven Rack virtual rig only has a mono input.


Darryl
If this is true than how do you account for being able to feed the rig with the stereo line input? I believe there are actually two rig chains but they are both set to the same amps and effects setups.
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Old 02-10-2013, 11:58 AM
Darryl Ramm Darryl Ramm is offline
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Default Eleven Rack FX Loop - True Stereo Signal Flow?

Quote:
Originally Posted by musicman691 View Post
If this is true than how do you account for being able to feed the rig with the stereo line input? I believe there are actually two rig chains but they are both set to the same amps and effects setups.
Ah you might want to carefully check what is happening, I will bet you are just feeding the L+R sum but still hearing a stereo soundstage due to stereo processing blocks downstream in the rig.

There is one mono input and a mostly mono rig (until it is split into stereo if at all). The input is mono, either one side of a stereo pair or the mono sum of a stereo pair, exactly as the OP noted.

Darryl
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Old 02-10-2013, 01:45 PM
musicman691 musicman691 is offline
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Default Re: Eleven Rack FX Loop - True Stereo Signal Flow?

Quote:
Originally Posted by Darryl Ramm View Post
Ah you might want to carefully check what is happening, I will bet you are just feeding the L+R sum but still hearing a stereo soundstage due to stereo processing blocks downstream in the rig.

There is one mono input and a mostly mono rig (until it is split into stereo if at all). The input is mono, either one side of a stereo pair or the mono sum of a stereo pair, exactly as the OP noted.

Darryl
I've read here where there are two processing streams in the 11R because someone asked about running two different amp sims/stream at the same time but were told because of the software it couldn't be done.

Where's Benoni when you need him? He'd know for sure.
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  #7  
Old 02-10-2013, 03:10 PM
Darryl Ramm Darryl Ramm is offline
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Default Eleven Rack FX Loop - True Stereo Signal Flow?

You don't need to ask somebody else. The input is documented as mono and behaves like a mono/stereo summing input. If you don't trust the documentation the test is trivial, feed it a stereo test signal and pan the signal hard left and hard right. In this case the stereo image will not pan on the outputs because it is being summed on the input. To be most convincing make the stereo test input L/R tracks identical so there is no signal change, just a level shift.

The most relevant discussion I can remember on DUC was where Chris Townsend commented/implied that there was probably enough DSP processing power in the Eleven Rack to allow running two amp sims... if Avid ever released the software to do that.

Jeez this is even question #1 in the Avid Eleven Rack FAQ http://avid.force.com/pkb/articles/en_US/FAQ/en359231

Darryl
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  #8  
Old 02-18-2013, 10:48 PM
jyang jyang is offline
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Default Re: Eleven Rack FX Loop - True Stereo Signal Flow?

hey guys,

sorry for the radio silence. was busy and totally forgot about this as we're testing lots of things.
thanks for all the points. confirmed what I suspected in the beginning.
not sure how i missed that question in the FAQ...

in response to musicman:

1. no not using any of the 11R's processing at the moment. understand it seems like a waste - but was more useful as a utility while it was not being used as a guitar sim! was plainly testing it's unbalancing capabilities.

2. the console's sends are definitely balanced. and we've tried balanced to unbalanced adapters - multiple configurations also, and there is hum every time. weird as the pedal can accept +4 line signal (although unbalanced TS connectors) - so would have thought a simple change to unbalanced would suffice but seems not.

testing out a reamp box today to see how that goes.
either way, the 11R works a treat with one signal, with or without the FX processing. was hoping for too much with the stereo flow.

and whether or not the delay sims do it for me the moog sounds awesome so want to use that!
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