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what about interconnecting two TC Electronic 3rd Dimension pedals to create a real dimension chorus?

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Short answer: nope, the sound quality is just too wretched to make this worth it.  I tried adjusting the bias trimmer on my sample unit: https://youtu.be/ucRMNt1bC2s ...and there seemed to be no way to get rid of the awful distortion, which is particularly audible on higher pitch single guitar notes. Still, in case anyone else wants to try this, I'll include all my notes and a video about how it would be done.  Maybe some TC units sound better than others: the NE571 compandor that they use is supposed to have external trimming to bring its sound quality up to the level of the NE570 used in the original Roland/Boss units, but TC Electronic skipped providing this trimmer.  Maybe some units happen to be closer to the ideal trim setting, given component tolerances and variations in the NE571 chips. https://youtu.be/9D7ya1y30Tc Here is my notebook entry, showing the changes needed to connect the two TC units. The modification is facilitated because the TC unit has a spare opam...
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Fail! The TC Electronic 3rd Dimension is not a dimension chorus!

https://youtu.be/V2Nq6mt4zaA Well, my TC pedal arrived today, and with great anticipation I set it up to run some test sounds, with my Vox Spitfire guitar and Fender Champ amp: should have been ideal clean tones to highlight a nice dimension chorus.  But the pedal sounded awful!  I think I'll return it.  It is nothing but a conventional analogue chorus, like the Boss CE-2, but with inferior sound quality.  I have no use for a unit like this, and I won't waste my time modding it, there is no hope of ever getting the sounds I'm seeking from this circuit.  There is no magic, no trickery, TC have not somehow found a way to make one delay line sound like the two in antiphase which define the dimension effect.  It's nothing but a plain vanilla chorus, dressed up and sold as if it were a clone of the Boss Dimension-C.  It's a scam.  What a disappointment. So.  Where does that leave us.  I really want to base my work on a unit which is still in ...
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the TC Electronic schematic

After much searching, I found this schematic online: https://postimg.cc/Wdn7WMD6 It is clearly not made by TC Electronic; however, it seems to correspond to some "gut shots" (photos of the internals) which I saw on another site, so maybe it is correct. http://www.modezero.com/tc-3rd-dim.htm NE571: compandor, similar to NE570 but cheaper and lower specs I am left with some questions.  Most importantly, there appears to only be one BBD delay line, with one clock generator.  This is implemented much like the delay lines in the Boss circuit, even down to the visual aspect of the two chips being located adjacent to each other with one flipped 180 degrees.  However, the second delay line appears to be missing (it's also not visible in the "gut shots"), and there is no associated inverting opamp to create the out-of-phase LFO signal.  I.e., to all appearances, this is merely a perfectly standard chorus circuit, not a dimension chorus at all!  Yet, it purports to be a r...
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the Boss schematic

I don't want to simply place a copy of the full Boss schematic here in this blog, because I'm not exactly sure about its copyright status.  However, it seems to be "freely available" online, such as from this link: https://www.audioservicemanuals.com/b/boss/boss-dc/329776-boss-dc-2-dimension-c-chorus-schematic Thank you to Boss for permitting, or at least not obstructing, this!  I wish TC Electronic would follow suit, but so far in my searches, it appears they have not done so. Identification of the significant, "non-obvious" chips in the Boss circuit: BA634: flip flop NE570: compandor MN3102: clock generator for analogue delay line MN3207: 1024-stage BBD delay line One thing that I note about the schematic (this is the Boss DC-2, i.e., the original Dimension-C, not the newer WazaCraft version).  Although this unit provides "stereo" outputs, there are still only two delay lines as far as I can tell.  I haven't extensively analyzed the schematic...
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overview of the work to be done

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  In the image above, I have copied the portion of the Boss Dimension-C schematic relevant to the pushbutton interface.  As you can see, the pushbuttons alter the resistance values of key parts of the circuit.  The switch contacts on the left affect the depth of the LFO signal; those on the right affect the rate (LFO frequency).  I have made a video on Youtube with more analysis of how these buttons function: https://www.youtube.com/watch?v=9X3oaw9NDnA The connection points between the main board and the switch board, 12 and 14 for the depth and 11 and 13 for the rate, would be obvious and convenient places to attach pots.  In fact, it wouldn't be necessary to disconnect the button interface in that case, because in preset 1, there are no components connected by either switch: it is basically the "null preset".  Thus, in preset 1, any connected pots would be the sole elements altering the resistances.  For that matter, by accessing the contacts associa...
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modifying the TC Electronic 3rd Dimension pedal

The TC Electronic 3rd Dimension pedal is essentially a clone of the Boss Dimension-C pedal.  These are so-called dimension chorus pedals.  The audio travels through two parallel BBD analogue delay lines.  The delay line clocks are modulated by a single LFO, but one delay line gets the direct LFO signal, and the other gets a 180-degree out-of-phase copy of the LFO signal.  Thus, when one delay line is at maximum delay time, the other is at minimum, and vice-versa.  These two delayed audio signals are then combined with the dry signal.  The result is something which sounds like a chorus effect, but the distinct "warble" from the LFO waveform which is clearly perceptible in most chorus pedals, is largely obscured.  This is thus called a "motionless" chorus.  It gives the shimmery ambiance associated with the chorus effect, but without the pulsating vibrato sound of the LFO.  It is a relatively subtle effect, which I have always found pleasing an...
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