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different choruses on separate path- DSP bug?
by robmartino on 2010-11-02 19:57:17

Hello,

I've been setting up patches for use with my Chapman Stick and been really happy with the sounds I'm getting, but I seem to have come across a bug in this patch- I have an Analog Chorus on the left and right signal paths, but only one of them seems to actually process sound (left channel).  I also assign EXP-1 to both chorus' mix but it only affects the left channel one.  Curious to get some thoughts on this...

Thanks,

Rob

http://robmartino.com



Re: different choruses on separate path- DSP bug?
by ozbadman on 2010-11-02 20:29:29

The problem in your patch is you've set your input 2 source to be AUX, instead of same.

Cheers,

David.



Re: different choruses on separate path- DSP bug?
by fester2000 on 2010-11-02 20:40:44

ozbadman wrote:

The problem in yiur patch is you've set your input 2 source to be AUX, instead of same.

Cheers,

David.

Well diagnosed, sir!

Cheers,

Fester2k



Re: different choruses on separate path- DSP bug?
by robmartino on 2010-11-02 21:11:18

Thanks for the response, but that is the way I have all my patches set up- the Stick has a stereo pickup so the bass and treble sides are processed differently (treble pickup to guitar input, bass pickup to Aux).  The other effects on the input 2 side seem to work fine (i.e. the compressor) and any other effect I add will work, but not that second Analog Chorus effect.  The mix knob seem to have no effect on the sound.



Re: different choruses on separate path- DSP bug?
by ozbadman on 2010-11-02 21:39:04

Ahh. Got you.

OK. I've had a bit of a look. The signal from the Analog chorus seems to be split in two. My guess is it's a stereo effect. The Mix has an effect, but it's tied in your patch to the Expression pedal. It looks like the dry output of the Analog chorus is the right channel, and the wet is the left. Therefore, when you put one path all left, and one all right, you get the first chorus working as you'd expect, but the second one is always dry. I'd have to think about the solution, but in the meantime you can hear the 2nd chorus working by panning it left instead of right. This uses the wet signal.

David.

ps: yep, it's a stereo effect. see this:

http://line6.com/community/docs/DOC-2099

Hmmm.Still doesn't explain the problem though, but it does narrow down where it is....

I must admit, it's feeling like a bug but trying to narrow it down beyond that is a little tricky.

Here's a simple test patch. Rotate the Path B pan knob left and right to hear it wet on the left, and dry on the right.

Some info about the Boss CE-1 though:

"When using only the mono jack, you get dry and wet out of that jack, but when you plug into the Stereo jack, the mono jack just gets wet and the stereo jack gets just dry."

Listening again, if you just have this device in line with a single path, and pan left and right, you get one dry and one wet. It seems like what Line 6 is doing is with multi path, if an effect is in the top path, they use the left side of a stereo signal and if it's down the bottom, they use the right side of the stereo signal. Hence the problem you are experiencing. Well no, that doesn't make sense either because the Pan A/B wouldn't have the effect it's having on the test patch if that's the case.

Perhaps some additional routing fleixibilty is required, or the ability to operate stereo effects in mono mode. I'd be interested in Line 6's opinion on this.



Re: different choruses on separate path- DSP bug?
by robmartino on 2010-11-03 08:04:48

Thanks ozbadman, I appreciate your help debugging this.  After experimenting more and looking at your test patch, it does seem the Left=wet, Right=dry behavior is being modeled (if indeed that's how a CE-1 worked).  This behavior doesn't seem useful in the context of dual path routing, but I did find a workaround- if I add a mono effect after the chorus on Path B, I can then keep path B panned full right and hear the chorus.

I suppose I could leave Path A and B panned center but in a typical mono live setup I prefer to have the bass and treble sides of the Stick going to separate channels on my Fishman Amp so I can have different EQ and reverb per channel.  If I was using a stereo amp setup, then it would make sense to leave Path A and B panned center to maintain stereo image of relevant effects, and run the L and R outputs to different amps.



Re: different choruses on separate path- DSP bug?
by ozbadman on 2010-11-03 09:35:37

Ahh. Good solution. So the mono effect must be mixing the stereo coming into it.

Cheers,

David.




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