Hey all,

I've been using Pure Data for about a year now. I originally installed in order to do some effects processing for my guitar but it took a while to get all the right hardware. Unfortunately I'm having trouble sending the signal back out of my laptop (new MacBook Pro) to my amp, and when i do manage it theres some serious crunchiness. Im using a Behringer Xenyx Q802 USB as a mixer and as an interface to send the guitar signal to the laptop. Is this wrong, or am i just missing some Pure Data setting? I've searched for forever but couldn't find a solution so any help would be very much appreciated.

Thanks

@TimelyRider Hello........ You could be overloading the [adc~] or the [dac~] ..... the audio level (the numbers passing through the "cords" should not be greater than +1/-1.
You could have a problem with the settings for the "soundcard" which is your Behringer in this case.
If you are using extended then you can look in the cords with "Edit" "MagicGlass". In vanilla you could use [print~]. Also try putting some VU meters in your patch to give a visual feedback of the levels...... [pvu~] and "put" "VU Meter"..........
David.

I never used a mixer (usb or not) to output signal to an guitar amp, but there could be a problem of signal level and/or impedance mismatch between the two. A "line level" output for instance is simply not suitable for such a connection, it results in a much too heavy signal coming into your amp pream stage, hence a distortion. If you listen to the output of pd with the headphones and the sound is clean, then the problem is located between pd and your gtr amp.

I personally do use pd as a effects processor using a "regular" soundcard (http://forum.pdpatchrepo.info/topic/9692/cubie-pd-pedal), but this is only possible because I have another guitar pedal that accepts "line" input signals, and has a the right output stage to "talk" to a guitar amp.

The keyword used when talking about sending line levels to guitar amps is "reamp(ing)", you can find passive or active reamping interfaces that do the job very well...but you'll pay for it I also think there exist soundcards with dedicated "to guitar amp" outputs, but I never tested it.

Nau

This is what i was afraid of. Im assuming it has to do with the mixer-laptop connection and not specifically PD because the same thing was happening when i tried it with garageband. I am pretty much figuring all this stuff out on my own so thank you for helping. I would prefer to avoid buying another piece of gear, but what can ya do. At least the mixer proved to be useful in other ways.

@TimelyRider You should trawl the threads for the mixer (google "problem") in that case, and at least check that the sample rates are set correctly..... I doubt they would have sold so many if the problems cannot be solved!........
David.