Finding 3n9 or 4nf film cap in UK for muff tone control

[karesplat]

Hi all,

I'm building a black russian style big muff which uses a 3n9 / 3900pf cap for the high pass filter in the tone stage. I usually order my parts from Farnell with occassional bits from Maplin and various European websites whenever necessary. None of the places I've looked so far, including rs components and rapid, have a 3n9 cap. This is the last part I need to get it up and running and while I'm aware that I could put some lower values in parallel to make it up, I am building from Torchy's layout (thanks go to him if he ever reads this forum) and it just so happens to fit perfectly into an Eddystone 1590b enclosure. It would no longer fit at all if I broke off and started afresh with some new veroboard and added on the extra width needed to run another couple of caps in parallel. My ideal solution is a box style film cap with 5mm lead spacing.

Cheers for any pointers,

KS

[theehman]

 Easy to find as "greenies", but I don't know about as box caps.

[karesplat]

Thanks theehman, but even with greenies I'm stuck. Closest I'm able to get seems to be 3n3 which I think I'll probably go with and replace the 22k resistor with 27k to get back into the same frequency response ball park. Will give a more pronounced mid notch but I suppose I could compensate for that using a higher value resistor in conjunction with it in the filter.

KS

[Gurner]

Personally, I think cap tolerances are cack enough for you not to worry too much about 3.3nf vs 3.9nf), but how about these...

http://www.cricklewoodelectronics.com/Cricklewood/product.php?productid=1848&cat=0&page=1 ( 2.5mm pitch, but hey, beggars can't be choosers they're quite fair with their P&P charges to)

or if you want to push the boat out...

http://www.cricklewoodelectronics.com/Cricklewood/product.php?productid=20823&cat=0&page=1 (not sure what the body dimensions are but likely to be more suiitable pitch wise)

failing that a combination of two caps (in parallel, series...whatever you have to hand)

[karesplat]

Many thanks for looking around for me, Gurner. Your most important point is, by far, the fact that these components have tolerances and my obsessing over an exact match is kind of stupid! I forgot to come back and update this thread. I've ordered the 3n3 and will use a 27K resistor instead of 22K. Running various simulations I'm happy that the frequency response of this pairing is a good match for the original. I certainly don't have the ears to be able to detect the difference. Thanks to those who pitched in to help a fella out