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cap value

Discussion in 'Pickups & Electronics [BG]' started by GODSBASSMAN, Mar 26, 2014.


  1. GODSBASSMAN

    GODSBASSMAN

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    Feb 2, 2005
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    S. Carolina
    Messing around changing out capacitors went from .010 to .015 and was not expecting such a big change. Makes me wonder why is got that much deeper. It does not sound as deep as a .1 just so you know that was not the case of mistake value. It just got darker then expected. I wonder why it seems more so than .022 to .033 per se. any thoughts about this?
     
  2. bassliner50

    bassliner50

    Joined:
    Mar 20, 2012
    Very general rule of electronics is that a component tolerance of 10% is usually acceptable and would perform roughly equivalently. So, .010 mf plus 10% (.001mf) would be .011mf and would be hardly perceptible difference in high pass. Your .015 is actually a 50% bump up measured in mf, and I would expect an audible change from the original .010mf. BTW these are low cap values as far as I am concerned. My P's are loaded with .047, .078 and .1mf respectively...
     
  3. line6man

    line6man

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    I've never heard that before. 10% is not a good tolerance for many components in this day and age. What used to be 20%, 10% and even 5%, is now often 2%, 1% or 0.5%. With non-polarized capacitors, "good" is arguably around 5%.

    Note that ceramic capacitors are common for this application, and are pretty much the worst type of capacitor, tolerance-wise, with ratings as loose as 80% in some cases. If you have these, it is definitely a good idea to check the actual capacitance, rather than rely on a rating.
     
  4. bassliner50

    bassliner50

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    Mar 20, 2012
    You may never have heard that, but it was "rough" common knowledge among engineers and electronics technicians, as I used to be in a former life. Of course for precision analog circuits, you would choose 5% or 1% etc. tolerance, but for most general analog stuff, the 10% works well enough, is cheap and probably in line with the rest of the design. I just quoted it as a reasonable reference to Godsbassmans post. In essence: would you really hear a difference with a 10% bump up of high frequency to ground? I doubt it. But a 50% bump up of capacitance and hence high audio frequency to ground, I would expect to hear. Of course the association between cap value and tone is not necessarily a straight (linear) line. Go ahead experiment with various caps of close value and see...
     
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  6. line6man

    line6man

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    Again, it's not the way things work for modern componentry. Manufacturing has improved over what was commonplace twenty or thirty years ago. I suppose it really depends on what applications you are dealing with, however. Through-hole leaded PCB mount capacitors are rarely tightly spec'd, so you do still find 10% and worse.
     
  7. i_got_a_mohawk

    i_got_a_mohawk

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    Location:
    Edinburgh & Dundee, Scotland
    Still see some of the +80-20% ceramics about!
     
  8. line6man

    line6man

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    Jun 20, 2008
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    And there are few audio-related applications where that is touted as "good."
     
  9. i_got_a_mohawk

    i_got_a_mohawk

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    I'm not going to deny that!
     
  10. GODSBASSMAN

    GODSBASSMAN

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    Feb 2, 2005
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    S. Carolina
    :eyebrow: Well as usual I go checking this all out. Took computer, scanner and capacitor in question, scanned cap and zoomed to read labelling on said cap. Low and behold cap says 154j which is a .15uF NOT a .015uF capacitor according to on line charts. :eek:
    Sooo, off to sandpile, hide my head in the sand for embarrasment ... I,ve been duped. Good ting they are cheap buys.
     
  11. bassliner50

    bassliner50

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    Mar 20, 2012
    Yep, that would explain the tonal shift quite a bit...Your description of the cap value was off by a factor of 10! That cap will shunt plenty high and upper mid frequencies to ground
    where they will be lost from this universe forever...
     
  12. GODSBASSMAN

    GODSBASSMAN

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    OK, so...Playing around with capacitors the other day a .047 uF cap caused a very noticeable dead note on the A string at the D fret and it went away when I inserted a .022 uF capacitor. That note rang out as evenly as the others. This is strung with Rotosound PSD 99 strings and sports a .015 currently with no concerns with cap wired in parellel and pickup straight to jack.
    Anyone want to tackle this event and its causal explanation? :meh:
     
  13. bassliner50

    bassliner50

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    Mar 20, 2012
    I really cant think why *any cap* value or make up would affect just one string or one note. The physics dont add up. However, in order to reach and exchange the capacitor, you would have to remove or at least fully loosen your strings in order to remove the pickguard and get your hands on the cap. Are you sure you didn't disturb something through the physical process of accessing the cap? Maybe the setup changed as a result of string removal or loosening.... A .047 uf cap is a good value to use. I have used .047, .078 and .1 with satisfying results....I really doubt the cap you describe could cause that dead spot or string *directly*. Re do everything and retest. Change strings if you must. Let us know...
     
  14. john m

    john m Supporting Member

    Joined:
    Jan 15, 2006
    It's all about what works for the circuit.

    If it sounds good to you--- use it.
    There are lots of other areas in a circuit that add capacitance.

    I used to purchase military spec caps (+ or - 1%).
    Because they were used in analog timing that still have no digital equivalent, we had to hand test every cap and throw out all of them except the ones that were (- .5%), the ones that were + anything were NG, at about a buck each.
    Tossed out about 1000 pcs.
     
  15. bassliner50

    bassliner50

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    Mar 20, 2012
    Did you say you wired the cap in parallel to the pickup? Ummm, the cap should be in series with the "hot" side of the pickup (the tip of the 1/4" jack) and then in series with the tone pot then to ground. Then the tone pot can vary the path from the pickup though the cap which should only pass the higher frequencies to ground, resulting in attenuation of the highs...Did I miss understand you?
     
  16. petrus61

    petrus61 Supporting Member

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    I was comparing stated values between Sprague 225P's and 715P's which are supposedly at 5% and Mallory 150's (10%) at a friends and most tested within a couple digits of stated spec, with the Mallory's (10%) actually testing closer to spec on average than the Sprague "orange drops". Completely negligible tone wise, but I was surprised that the Mallory's were testing closer than the OD's with the tighter tolerance. The ceramics we tested were the .05 (503Z) commonly found in American Fender models and many of those tested out of spec, with some ranging as high as .1, which would certainly be audible in a bass/guitar circuit and would explain part of why two of the same model can sound so different. I'm guessing these ceramics were of the 80/20 tolerance, since they were brand new and stored in good conditions.
     
  17. GODSBASSMAN

    GODSBASSMAN

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    Feb 2, 2005
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    Thanks for responding , guys. This bass is custom built 6 string. No pots; just one P pick up and that wired to jack. This cap is soldered to the jack one leg to ground, one leg to signal. All access is on back control panel cavity cover. There is no pick guard to move nor are the strings touched to access "electrical components". This bass is passive. All I did was insert a .047 uF and then a .022uF to notice that dead D note on the A string. I thought is a strange event and wanted to share and see if anyone knew why this happened. I have not reinserted the .047uF cap to see if it happens again because it sounds the way I want it with a .015uF cap in this cavity. All EQ at amp.
     
  18. petrus61

    petrus61 Supporting Member

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    Dec 18, 2011
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    The deadspot was likely always there and still is, but since you're shunting less highs with the .01 and .022, it might be less obvious now. You're probably hearing the overtones that would have been bled off with the higher value cap.
     

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