Yes, it is something different than a Buchla low-pass gate. There's no ringing at all but a DSG, DTG, or TGO does act as a gate with low-pass characteristics, i.e., a gentle roll-off of the high frequency content of the signal.
You're correct that the Serge does not use vactrols in its VCAs or filters, as far as I know, but my Dual Phaser has some on the VC inputs and I imagine the single Phaser does, as well. Maybe others have spotted them elsewhere... This has nothing to do with the above topic vis a vis vactrols in gain elements but I thought I'd mention it just the same since I found the discovery interesting.
Matt
You're correct that the Serge does not use vactrols in its VCAs or filters, as far as I know, but my Dual Phaser has some on the VC inputs and I imagine the single Phaser does, as well. Maybe others have spotted them elsewhere... This has nothing to do with the above topic vis a vis vactrols in gain elements but I thought I'd mention it just the same since I found the discovery interesting.
Matt