I'm fairly new to Pure Data, though I'm excited by what I've learned so far. I followed this tutorial -- http://designingsound.org/2013/04/pure-data-wavetable-synth-part-1/ -- up through the second-to-last step (with some adjustments for things that didn't quite work when I followed them in the tutorial), and then began modifying it to add more modulation and other features I wanted. I'm currently trying to implement what I'm thinking of as "suboscillators" that will be able to be tuned in relation to the main oscillator, mixed in with it, modulate pitch and amplitude, and take their own envelopes. I also want the suboscillators to be able to take modulation from either of the two "LFO"s [in quotes since the first LFO actually outputs in the audible range] (adding a second to what's specified in the tutorial, along with additional layers of LFOs below them), so I've been moving things around and redesigning the patch a little bit, breaking it off and on, and trying to get it working again.

While working on this, I noticed a behavior that's baffling me: the signal of the first LFO appears to distort when sent out through send~ and then back in through receive~. If I connect the output of the LFO directly to dac~, it sounds fine. Sent through send~ and back through receive~ and then to dac~ and it sounds louder and there are some other frequencies seemingly present, as if it's maybe clipping a little bit. I thought that send~ and receive~ were functionally the same as just using connector cords, so I'm seriously confused by this. For the purposes of the patch, having the LFO signal distort is not good, so I feel like I need to figure this out before I go forward with the features I want to implement. Being new, I imagine it's something simple I'm overlooking.

Here's a link to part of the patch where the problem is occurring: http://imgur.com/a/GkRUI I haven't tested yet to figure out if other send~ receive~ pairs are causing distortion. Any clarification or ideas about why this is happening would be much appreciated.

[edit: There's also apparently an error message going along with this: "consistency check failed: signal_free 3" I thought it was some other part of the larger patch generating the error, but I copied just the LFO generator section to a separate patch to play with, and that message still appears in the console. The weird distortion with receive~ still occurs too.]

Yes, I had a similar problem recently with throw~ and catch~. The signal gets quieter when two things are thrown to a catch~, but louder (the desired volume) when put directly into the dac~...

Huh, so this behavior seems to disappear if I take the guts out of the lfo1 subpatch and just have them in the top level patch. Now there's no noticeable difference in tone between the output of the former guts of the subpatch and a send~ and receive~ pair. Still curious if anyone has any idea what could have caused the problem in the first place and how I could avoid it. I'd rather have the guts in a subpatch to keep things visually simpler, but since this works I'll go with this for now.

@catkisser666 It would be better if you posted your patch on the forum...... The "imgur" picture is way too small for me (old) to read reliably....... and it would take a lot of time to build it again to see what is going on. Tell us your OS and version of Pure Data as well.
Zip the whole patch up and upload it....... you are more likely to get an answer......
David.

Here's the part of the patch that experiences the problem.
LFO Generator.zip

@catkisser666 Somehow you have managed to draw 2 audio patchcords....... one on top of the other..... which has doubled the volume, producing the distortion. If you delete one of them it solves the problem (the one underneath will remain).
When you connected directly to the [dac~] you only drew one.... which is correct. There was no way to spot this unless you uploaded the patch!

I will guess that originally you connected to both inlets of a [dac~].... and then renamed it [send~ $0-lfo1sig]...... and Pd connected both the cords to the only available inlet.
Happy patching!!
David.

Oh thank you! Boy that's a simple fix. I can't believe I didn't notice.