Vactrol selection- rise time, ring mod

[blackieNYC]

So I became happy with this tremolo when I dropped the FET switching for a vactrol in series with the audio path.  With a cap switch in my LFO I had faux ring modulation going - I know I did.  But now the LFO peters out just when I get into ring mod territory.  I don't know how.   I coulda swore....  Anyway, I looked at the data sheet http://pdf.datasheetcatalog.com/datasheet/perkinelmer/VT500.pdf     And the Vtl5c3 has a turn off decay (to 100k ohms) of 35 ms where the vtl5c4 is 1.5 seconds (?!)  35 ms is 28hz, no? Does this mean a vtl5c3 should not be used for ring mod LFO ranges? Page 50.
There's a chart in page 45 that contradicts page 50 completely in response time comparison. But- it does say tthe faster vactrols have very large light history effect.  If you are ring modulating that thing, are you messing it up?

[PRR]

LDRs will *barely* get into lower audio frequencies.

The response rates are VERY dependent on impedance. Fast around 1K and takes forever to hit 10Meg. Try lower impedances around your LDR.