part value substitutions?

[tacobender]

So I recently got a big lot of old Cornell caps, the yellow ones. Not sure what material they are. Anyway the values for these caps are .02mfd. If they were .01's I figure I'd use them in some more tone Bender builds. So I'm wondering if it would make much of a difference, or do I need to change other part values to compensate for the higher value? ...or just find a completely different project?

[antonis]

You can always use a pair of them in series (if you build a custom made PCB) or modify resistor's respective values..

Are you sure that your caps values are 0.02mF..??
(because 20μF - or even 10μF are quite high values for Tone Benders - except perhaps of attack pot bypass)

[tacobender]

Isn't MFD just the old school way of saying uf? So they should be .02uf which would be twice the value of the .01uf caps tone Benders mostly use. So I'm not quite sure how to compinsate for the difference.

[LightSoundGeometry]

there are a tone of uses for 20nF and 10nF ..you can use those 20's where there is a need for a 22nF I bet they measure out pretty close  - the echoplex style preamp I been working on uses 22nF  poly caps.  From what I have seen so far those are pretty common used values for a lot of those pedal layouts floating all over the nets

[induction]

Isn't MFD just the old school way of saying uf? So they should be .02uf which would be twice the value of the .01uf caps tone Benders mostly use. So I'm not quite sure how to compinsate for the difference.

As antonis said, put them in series. Two 20n in series gives 10n.

[hymenoptera]

I have a LOT of these old CDE caps, sometimes called "lemon drops", in my stash. They were used in a lot of high end audio gear, like some of the Urei equipment, the 1176 compressors, and those silverface rackmount equalizers that go for cheap on the used market.

I'd hang onto them and use them where ever the actual value is within 5% or 10% of your target capacitance. As LightSoundGeometry said, a 0.02uF cap would work just about anywhere an 18nF, 20nF or 22nF cap is called for.

I believe the "WMF" on Cornell Dublier caps stands for "wound metalized film" or "metal film", but somebody correct me if I'm wrong, I think these would be mylar or polyester film.

Here's the datasheet
http://www.cde.com/resources/catalogs/WMF.pdf

Says they are polyester foil/film type. They are still in production today, but look slightly different.

[antonis]

And here comes the argument about using AGED capacitors...

[hymenoptera]

And here comes the argument about using AGED capacitors...

Is this even a problem for film types??

[antonis]

Is this even a problem for film types??

I presume that it is..

Mainly because of degradation of the encapsulation material which in turns leads to excessive moisture absorption..
(IMHO the epoxy laquer coating seem to be more "robost"..)

You can see that capacitor manufacturers follow relevant standards (i.e. IEC/EN 60384-x) concernig perfromace grading (Long life, general purpose e.t.c.) which mainly deal with aging in relation with moisture absorption..

[GibsonGM]

And here comes the argument about using AGED capacitors...

Oh, but the improvement in tone due to age, and the fact you're using REAL NOS PARTS...man, that can't be imitated! It's worth the risk!!    lol

[antonis]

It's worth the risk!!

I've to admit that I totally agree with you, Sir...

[duck_arse]

And here comes the argument about using AGED capacitors...

how old do they have to be, antonis?

there was a discussion a while back about old guitars sounded better, because the tone cap still had some old electricity in.

must be true ..... look at the price!

[hymenoptera]

there was a discussion a while back about old guitars sounded better, because the tone cap still had some old electricity in.

must be true ..... look at the price!

It's true! I once unplugged my ivory '68 Strat (formerly owned my Jimi Hendrix, of course) and when the tip momentarily touched the sleeve on the way out the jack, I could almost smell the mojo leaking out as the tone cap's plates were briefly shorted!

Now it just sounds like any other strat.  Bummer!

[tacobender]

Sorry been away on a short incarceration due to some over zealous coppers. Anyway back to the matter at hand, everything I've read so far says MFD is equivalent to UF, so am I miss informed or are these caps just older than anyone on this thread? I know Cornell cap's are good quality I'd realty like to use them in another Bender project if possible. In place of the .01uf caps.

[induction]

Sorry been away on a short incarceration due to some over zealous coppers.

Sorry to hear that.

everything I've read so far says MFD is equivalent to UF

Yup. Dumb, but true. Some folks with powdered wigs are rolling in their graves. "We do all this work to give you something slick, and this is how you treat it? This is why we can't have nice things."

[Granny Gremlin]

how old do they have to be, antonis?

there was a discussion a while back about old guitars sounded better, because the tone cap still had some old electricity in.

must be true ..... look at the price!

LOL.  Never heard that one.

[duck_arse]

this whole thread, but this is the post:

http://www.diystompboxes.com/smfforum/index.php?topic=104239.msg933243#msg933243

[hymenoptera]

Thanks! I enjoyed that!

Sounds like something you'd hear from a Guitar Center salesman.

I especially loved the part about storing your guitar cables tips-up so that the electrons don't fall out.

[tacobender]

Thanks for the laugh, I needed one. I think I'll build a Tesla style power generator for my rig. That should harvest some real mojo;)