Basic cap types question

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Nathan, Jun 30, 2009.


  1. Nathan

    Nathan Member

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    How exactly do you know what kind of caps to use where? I realize the signal caps will have a greater effect on the tone, but how can you know when to use Orange Drops, Mallorys, PIO, etc?

    Also, couldn't you use non-electrolytics as filter caps if the voltage rating is high enough?
     
  2. oldhousescott

    oldhousescott Silver Supporting Member

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    For your first question, IMO it's a matter of accepted practice and personal preference.

    For the second, yes, you can use non-electros for filter caps, but in the capacities needed, they tend to get prohibitively large. One upside, if you have the room, is they should never need replacing.
     
  3. Nathan

    Nathan Member

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    Thanks man, but that "accepted practice" is what I want to know. I' still a newb at building with only 4 projects to my name, usually "paint-by-numbers" clones but I want to branch out.

    For example, why to you see silver mica caps on tone controls and nowhere else? Why are Mallory 150's so popular as coupling caps?

    Also, I have a stash of Vitamin Q's (many values) and I want to know if I should avoid using them in certain sections of an amp.
     
  4. SatelliteAmps

    SatelliteAmps Member

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    Take a simple amp design (i.e. a Champ) and try subbing in the different types of parts. It is all personal preference. If you sub them in and out, you will know what they sound like and their differences, rather than relying on someone else's opinions.
     
  5. dazco

    dazco Member

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    Well, it IS just preference. but the basics go like this...tone stack treble cap:silver mica, snubber caps:silver mica, signal caps in a marshall style amp:mallory, signal caps in a fender:eek:range drops, cathode bypass and filter caps:electrolytic. thats just how most people seem to do it, but likewas said it's personal preference. i personally have tried going outside those *"rules" before and so far i haven't found anything that sounded better than going by the rules. I found one thing that SEEMED better, but in the real world (in a band mix) they let me down. But i'm going by MY ears so you may have felt different.
     
  6. tommytomcat

    tommytomcat Member

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    The silver mica's in your amp are usually in 10-500pF (or .000010-.0005uF) range. These pass high frequencies and block mids and lows. .001 to .1uF are the most common values of film capacitors found in guitar amplifiers. The higher the number, the more mids and bass frequencies the cap will pass.

    Typical tone stack values are: Fender 250pF (treble), .047uF (middle), .1uF (bass) this emphasizes bass and treble, scooping the mids. Marshall's are typically 250-500pF (treb) .022uF (mid) .022uF (bass).. Mids are emphasized and the deep bass freq are cut.

    If there's not a tone stack between two gain stages/tubes, you'll see what's called a coupling cap.. They 'couple' the stages together sending an AC signal to the next tube grid. Typical values are .01 to .1 with .022uF being the most used.

    In general there are 2 cap types... Metalized film and film foil. The Mallory 150's are metalized polyester film.. Polyester caps are fairly neutral sounding. Good in bright circuits, like BF Fenders as a rule of thumb. The SBE OJ 715P are metalized polypropylene film... Polypropylene's are generally brighter, more hifi sounding.. IMO, these sound best in Tweed circuits. The OJ 716P is a polypropylene film/alum foil design. As a rule of thumb, film/foil's are going to be sonically richer. My favorite film/foil caps are either the Mojo Dijon or the Sozo standard series. These are close copies of the mustard cap found in early Marshall and Vox amps.

    The Vitamin Q's are paper in oil capacitors. Alum foil with an oil soaked paper diaelectric. This type of cap is what are found in the classic fender amps from the 50's and early 60's. To my ears, they pass a richer more 3D signal.

    All in all.. to the ear, most people/listeners/audience won't be able to tell the difference between an amp loaded with metalized film cap or PIO's.. and if building a solid lower cost amp is your goal, I would encourage you to use metalized film caps. If you're the kind of player who's always looking to improve your tone 2% here.. 4% there.. 1% here. Go with the PIO and/or film/foil caps.

    Vitamin Q's... I use my higher quality caps (PIO & film/foil) in the coupling positions and use the metalized films in the tone stack/tone ctl sections. Now that I have a nice collection of NOS Russian PIO's, that'll change to PIO's for couplers w/ film/foil's in the tone stacks. Make sure you Vitamin Q's are rated for 400vDC or more and you can use them everywhere.. But the benefits are most noticable when used as coupling caps.

    http://mojomusicalsupply.com (mojo dijon's)
    http://tubedepot.com (best prices on Sozo's & resistors, great service too)
    http://tubesandmore.com (have 10% off everything right now)
     
  7. go7

    go7 Member

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    Totally agree.
     
  8. rmconner80

    rmconner80 Cantankerous Luddite Silver Supporting Member

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    Assuming you have metered out all the caps to be sure you are subbing with identical values.

    Most of these things have 10% tolerance or more. Aside from an extremely convincing argument for the placebo effect, differences in cap value probably comprise a significant contribution to any perceived tone differences.

    I still don't get why people use Orange Drops. They are radial caps, manufactured for PCB. Axial caps are manufactured for turret board construction.

    I use Mallory 150s because they are axial, cheap, abundant, and easy to source. It has nothing to do with "tone" differences. I honestly don't believe there is much of a tone difference between any two decent quality caps of identical value. Until there is a double blind recording test controlling for all other experimental variables (line voltage, mic placement, cabinet, cap tolerances, and re-amp of identical pre recorded guitar signals), no amount of personal taste testing will convince me otherwise.
     
  9. mbratch

    mbratch Member

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    Sort of. They come with long leads and are quite usable on turret and eyelet boards. And some people even like the way they sound. ;) It's also not uncommon to use axial caps on a PCB. Neither radial nor axial caps of this size are easily used on an automated PCB line, and are typically done manually. So the radial versus axial geometry difference is pretty minor with respect to utility in either application. Fender used radial caps in several of their eyelet board designs (the brown "turd" caps).
     
  10. hasserl

    hasserl Member

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    +1 And well put. Way too much emphasis is placed on cap brand and type with way too little scientific analysis and way too much hype. As always, a healthy dose of skepticism is called for whenever this discussion comes up. Me thinks the Emperor is a little under dressed. ;)
     
  11. donnyjaguar

    donnyjaguar Member

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    FWIW, I avoid orange drops in my hi-fi amplifier designs. They just don't sound as good as many others.
     
  12. mbratch

    mbratch Member

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    Funny thing about them, some seem to love 'em and some don't. Personally, I have them in a couple of amps and have no complaints, but haven't done any side by side comparison. I'm sure it depends upon the application, too.
     
  13. RockStarNick

    RockStarNick Supporting Member

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    So, if you wanted to reduce the bass even more, in a british circuit, would you go for a larger or smaller cap?

    From .022uf to ???

    What about adding/decreasing treble?
     
  14. mbratch

    mbratch Member

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    You might be interested in the TSC (Tone Stack Calculator).
     
  15. RockStarNick

    RockStarNick Supporting Member

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    i know, this looks awesome, but I'm running a MAC. :mad:

    UPDATE: Just got it to work with my virtual PC. HOLY CRAP this thing is awesome!!!!!!
     
  16. WailinGuy

    WailinGuy Supporting Member

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    No, these are polypropylene film/foil (not metallized). That's why they are fairly large for any given value. I think these sound fine for guitar amp applications.

    Also, a lot of techs (including myself now) don't like how silver mica caps sound in guitar amps, and use the traditional cheap ceramic disk caps instead. I can easily hear the difference. Sillver micas tend to sound brighter, and have a more extended (some might say cleaner), but sharper, sound. Ceramics seem to have a richer, more complex, "chalky" sound to them. They also seem to work better in circuits that generate or come after distortion because they tend to filter out the very upper harmonics that can sound harsh and fizzy. At least in Fender blackface style amps, I much prefer to use a ceramic disk for the 250p treble cap and the 10p cap (that bypasses the 3M3 resistor) in the reverb mix circuit. As usual, YMMV.
     
  17. Weldaar

    Weldaar Member

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    Axial vs Radial. What's recommended for guitars? I have Sprague Vitamin Q's in my guitars. Some said that they have to stand on end because they are axial. Can someone explain this to me? The leads come out of the ends, one on each side. They are paper in oil.
     
  18. HotBluePlates

    HotBluePlates Member

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    Whatever will fit.

    Really.

    If you want to use them & they will fit, knock yourself out. Doesn't matter what anyone says, only that they work for you.

    There's no explaining what other people say if they're wrong, or if you misquote them.

    Rather than expend energy on that, I offer you should just try the cap in your guitar (or wherever). If it does what you want it to do, it was a good choice.
     
  19. Weldaar

    Weldaar Member

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    Yeah, they have been in my guitar for 10 years and never a problem. i was just curious when someone stated that they should be standing up because they are axial caps. I never heard of that. That's all I needed to know.
     
  20. HotBluePlates

    HotBluePlates Member

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    That makes zero sense unless one is using an axial cap on a p.c. board to go where a radial cap previously went (because the holes in the board are closely spaced).

    Maybe they thought the oil would run out if you laid the cap down flat... :rolleyes:
     
    Weldaar likes this.

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