Capacitor questions.

[blester]

I am replacing the 23 year old electrolytic caps in an old effect and I have a few questions.

When using tantalums to replace on electrolytic NP caps I assume that the + lead should go to the pad with the highest voltage, is this correct?

When the DC voltage is identical should the + lead go towards the incoming signal or does the orientation not matter?

In the signal chain when is it OK to use a tantalum of film cap to replace an old electrolytic?  Are there any advantages to using another type of cap or is this just a fad?

In many cases the film caps are just too big to be used, is that the primary reason that pedal modders use tantalum's to replace electrolytics?

Thanks,

bl

[Barcode80]

In the signal chain when is it OK to use a tantalum of film cap to replace an old electrolytic?  Are there any advantages to using another type of cap or is this just a fad?

In many cases the film caps are just too big to be used, is that the primary reason that pedal modders use tantalum's to replace electrolytics?

Thanks,

bl

if replacing electros, why not use more electros? tants seem unnecessary. i'malso confused by your statement. most pedal modders DON'T use tantalums, or at least there isn't a predominant use of them.

[blester]

I've done a few mods using Monte Allum's kits and he uses 1uf tantalums to replace 1uf electrolytics.  I've also seen Keeley use them as well.  I think it may be a size issue as they are quite a bit smaller than the electrolytics.  The cost is much higher so I was curious as to any other advantage other than size.

bl

[Barcode80]

there is virtually no advantage. keely and monte CLAIM there is a sound difference with the tants and that it is better. I find it to be horse manure, and most on this forum will tell you tants don't sound as good as even cheap electros. the one advantage is space. the optimal replacement would be poly film or silver mica, these are the highest quality components available.

size is basically the only advantage, but the size difference is small enough between tants and electros that the benefit isn't really there.

[soulsonic]

If the cap was originally a Non-Polar cap, you should stick with an NP cap. Tantalums have a lower "Equivalent Series Resistance", and some people seem to think that automatically makes them better; but many tantalums have a significant amount of waveform distortion when coupling an AC signal. Maybe this distortion is what makes some people prefer them, but it some cases I've heard it sound bad. Also, the only tantalums I have personally liked the sound of are those fancy Sprague 150D type ones, and they're kinda too expensive to really be worth it - I got lucky and got a bunch in a grab bag, so I use them sometimes, but when I run out, I probably won't be buying any more at the regular price.

[blester]

Thanks to you all, good info for future builds and mods.

bl

[Exactopposite]

why are u replacing them? is there a problem with the pedal?

[blester]

I had an electrolytic that had leaked and had second one that was bad.  I changed out the caps that I had on hand and the pedal is back to 100%.  I thought it would be good to go through and replace the rest of the electrolytics.

[Gus]

It is not that simple, things can be measured that change with cap type.

For you rat owners try a rat with tants vs electros make sure to measure them to match the values.  The two at the feedback HP opamp part.  If I wanted to test this fast I would use a make before break switch and make two of the - input to ground networks(two caps and two resistors) match the resistors and caps turn the volume off to min the pop and switch them at the - input.

[blester]

I modded two Boss CE-2 pedals for a friend with the Monte Allums kits and had amazing results.  The kit had a couple of Panosonic film caps, a couple of tantalums and a few AVX box caps.  The two pedals sounded a bit different before the mods and sounded amazing and identical afterwards.   

My guess was that part of the improvement was due to the cap values that were changed and part was due to the quality of the parts used.  Not being a EE its all guess work to me as to what works and why.  I imagine that any new cap, regardless of type will improve the pedal if you are replacing an end of life tired electrolytic, and that is probably why the both CE-2s were identical in sound after the mods. 

It is great to be able to come to a forum like this and pick the brains of you folks that have so much experience with pedals.

bl

[Gus]

who posted about pan Vs years ago at Ampage?

[Paul Perry (Frostwave)]

There is one place that I use tantalums - when I need a high capacitance but a very low leakage.
Because, (at least in my experience) a tantalum has lower leakage than an equivalent value electrolytic.
http://en.wikipedia.org/wiki/Electrolytic_capacitor

[blester]

So are Polly Film caps the best choice for coupling if they will fit on the board?

[Gus]

Define BEST

[blester]

Best would be low noise and not color the audio signal beyond the design of RC network.  Also something that lasts and doesn't degenerate with time.  A cap with tight tolerances so that several effects of the same design sound alike.