MFOS VCF caps

[bunker]

Hi all.

I'm having some problems sourcing the 100pF polystyrene caps that are spec'd in the VCA schematic. They connect between the output of the LM13700 OTA, non inverting inputs of the TL082 op amps that make up each filter cell and ground. I can get hold of 150pF polystyrene's no problem so would I NEED to start re-scaling the resistors in the filter core too? Can anyone hazard a guess at what the result would be if I didn't re-scale resistors given the 50pF difference? It shouldn't be a big deal to rescale things to suit the bigger caps should it? Its not like I'm subbing the 100pF caps unto, say 1000pF.

Thanks

[bunker]

Thinking about it if the OTA is acting as the frequency setting resistor I'm assuming the 100pF cap is the C in the CR formula? In which case re-scaling the OTA shouldn't be required as its already the variable in the equation? So changing the value of the cap will just shift the cutoff frequency? Or am I barking up the wrong tree entirely?
Cheers!

[mrmrshoes]

i saw a link to a company over at muffs, it was in this thread.
(Polystyrene Capacitors: who stocks these??)
http://www.muffwiggler.com/forum/topic-98122-0-10.html


uk company and decent prices and stock.
https://www.rush-on-line.co.uk/cap_forums.html

haven't ordered from them but others have.

[bunker]

Most excellent links!! Thank you very muchly

[elmegil]