[warnerwh]

What I'd like to know is does it matter which one you use as long as it is the same value? Also does it matter if you increase the capacitance to say triple as long as the voltage stays the same. TIA

[NekoAudio]

Technically the parasitic characteristics of the three types will differ, but that may not be significant for your application. Likewise, depending on the purpose, increasing the capacitance may or may not matter. It will definitely matter if you're using them to create a filter of some sort.

[galyons]

Radial - Vertical cylinder. Both the leads come out the bottom of the cylinder along the radius.
Axial- Horizontal cylinder.  One lead end along the axis of the cylinder.
Disc - A Disc.   Leads come out on the bottom, generally following the circumference of the disc.

Radial is typically electrolytic.
Axial is typically electrolytic or film.
Disc is typically ceramic.

There are also mica and tantalum capatitors that are somewhat similar to discs, but the shape is more like a squarish bean.  Sliver mica comes in several form factors.

Upping the capacitance really depends on the use of the capacitor in the circuit.  Common electrolytic caps are typically 20%, film 10%, silver mica can be 1-5%. When you say "triple" do you mean go up 3 steps, such a .1uf to .22uf to .33uf or  47uf  to 150uf? Typically completely different circuit scenarios.

Hope this helps.

cheers,
Geary

[Æ]

What I'd like to know is does it matter which one you use as long as it is the same value? Also does it matter if you increase the capacitance to say triple as long as the voltage stays the same. TIA

The shape or style of a capacitor is what facilitates particular types of mounting. Some times you want them to stand up so that you can cram many of them close together. Other times you want them to lay down flat, low profile.
Some circuit boards are stuffed by hand-manually, while other circuit boards are stuffed mechanically, by high speed automation. The style of the package probably determines if high speed automation is applicable.

[Æ]

c.
Radial is typically electrolytic.
Axial is typically electrolytic or film.
Disc is typically ceramic.

Geary

Here is an example of both film and electrolytic axial. I would suppose that laying down an electrolytic, ultimately places less stress on the wire leads.

[warnerwh]

Geary: What I mean is as you said going up 3 steps. It was suggested to improve the audio on a tuner I have to at least double the capacitance on several caps.

My question regarding differences between the types of capacitors is to learn if it would be ok to use a disc where a lytic had been if the values are correct and if it will physically fit. I'm just learning and don't want to ruin any of my gear.

[Ethan Winer]

What I'd like to know is does it matter which one you use as long as it is the same value?

Maybe. It depends on how the cap will be used, and what sort of circuit it's in. Rolled up round caps have series inductance, so they're not suitable as bypass caps at the power pins for an IC op-amp. Disk ceramics have low series inductance, but they have high distortion for audio passing through them, so they're not suitable inline in an audio path. The capacitance of disk ceramics also drifts with temperature, and they can be microphonic, so you don't want them in an equalizer either. Mylar and polystyrene caps have low distortion, and are stable with temperature, but they're more expensive and they also have series inductance. And so forth.

--Ethan

[avahifi]

Use caution in changing capacitor values in a circuit.  Many capacitors used in audio circuits are in tuned circuits, designed to provide a specific frequency response characteristic.  Randomly changing capacitor values  can drive these circuits out of whack and ruin the performance of your unit.

One easy way to remember the lead placement of axial capacitors, is to think of them like car axles, with the ends protruding out on each side.

Most modern capacitors are radial lead to minimize circuit board space use.  Both film and electrolytic capacitors are available in radial and axial packages so this is not a sure fire way to determine which type of capacitor you are dealing with.

In general power supply capacitors will be electrolytic types because these can pack that most capacitance at a given voltage into the smallest space.  A film type 30,000 microfarad 250 volt film capacitor would be the size of a football or bigger. Their limitations is that most are polarized and will break down or even blow up if they see an opposite voltage at their terminals. They also tend to have poor very high frequency performance and tend to become resistive with age.  Old circuits being rejuvenated after long storage need to be brought up very slowly on an AC variac or the old electrolytics can fail catastrophically if they are hit with full voltage all at once.

Film capacitors are normally not polarized and have much better audio frequency performance.  However they have limitations in amount of capacitance and voltage they can supply  before becoming impractically large.

Be wary of substituting original parts with boutique type cylinder shaped spiral wound axial lead film capacitors.  These usually are spiral wound and have a substantial inductive effect.  This can change the operation of the circuit in unanticipated ways.  Soft spiral wound film caps also tend to be microphonic, adding a bit of low level "reverb" to the sound.  This can sound nice and make you think your high priced capacitors added ambiance.  Unfortunately often all they have added is reverb effects you can't turn off.

Remember that the value of a capacitor is what it actually is, not the value printed on its case.  In changing capacitors to find the "best sounding" ones, be sure to use a capacitor meter and replace the part with a new one that measures exactly the same.  If you replace one 10 percent tolerance capacitor with another you may actually be changing the values by 20 percent.  This will make a difference in the sound of the unit you can actually hear, and has absolutely nothing to do with the so called musical quality of the part.

Finally don't be to quick to second guess the parts the manufacturer used.  In many applications we match capacitor values channel to channel to make sure that both channels of our equipment is exactly the same.  If you play the capacitor upgrade game and don't own a capacitor meter, and don't have access to a sufficient supply of the parts needed to make matched pairs, your changes will only make the equipment worse, not better.

Regards,

Frank Van Alstine

[Æ]

A film type 30,000 microfarad 250 volt film capacitor would be the size of a football or bigger.

Way bigger than a football. Probably about the size of a washing machine or refrigerator! 

[warnerwh]

Frank: Thank you very much. It sounds like I better take a class or 2 in electronics before I do anything without the help of expert advice. Sounds like changing capacitors gets more complicated than it at first appears.

I had swapped some caps in a tuner which did help the audio quality but I was told exactly what to do. The changes advised were to at least double the capacitance using the same voltage of 5 capacitors. This made me curious and I'm very glad you answered my question and explained some things I need to learn.

[avahifi]

Making power supply capacitors larger can be useful up to reasonable limits, but be very sure what part of the circuit you are working on.

Note that making the first power supply capacitor in a tube rectified circuit significantly larger can cause early failure of the rectifier tube.  The tube specifications will usually suggest the largest recommended capacitor value for safe operation of that tube type.

What you say?  Refer to specifications?  That's no fun.  Oh well.

One engineering design goal is to never have overlapping pole points; not allowing the rolloff characteristics of various parts of the circuit to all be at near the same frequency.  When this happens, stability is affected.  Making an input coupling capacitor or an interstage coupling capacitor, for example, a lot bigger, may have a negative effect on stability.  Be sure you know what the design intent was before replacing capacitors, and for sure test your work with a signal generator and scope, before and after, to make sure you have not turned your amplifier into an oscillator.

Frank Van Alstine

[warnerwh]

My intention to learn a about electronics has been something I've wanted to do for some time. It's only now that I am taking it more seriously. Hopefully I'll be able to take an electronics class in the near future.

My goal is to be able to freshen up some vintage gear before something bad happens to it. I'm not an engineer and respect their knowledge so will only do only what is advised.  I've been in this hobby since the early 70's. I believe in good engineering. There isn't any magic in electronics that I can tell.

I appreciate all of the information you have provided. Especially since I had planned on putting new caps today in a vintage tuner (Onkyo t4087) I have. You saved me from what would have been a major blunder so thank you again.

And thanks for everyone's input. You have made this thread educational and enjoyable for me.

[Æ]

My intention to learn a about electronics has been something I've wanted to do for some time. It's only now that I am taking it more seriously. Hopefully I'll be able to take an electronics class in the near future.

My goal is to be able to freshen up some vintage gear before something bad happens to it. I'm not an engineer and respect their knowledge so will only do only what is advised.  I've been in this hobby since the early 70's. I believe in good engineering. There isn't any magic in electronics that I can tell.

I appreciate all of the information you have provided. Especially since I had planned on putting new caps today in a vintage tuner (Onkyo t4087) I have. You saved me from what would have been a major blunder so thank you again.

And thanks for everyone's input. You have made this thread educational and enjoyable for me.

Electrolytic capacitors deteriorate (dry out) with age, either that or they leak all over and make a mess of the circuit board. Electrolytic capacitors are the ones most likely to fail. If the piece of equipment is really old, you might consider replacing each and every electrolytic capacitor. The only time you would increase or double up on the capacitance would be in the power supply section, the big filter capacitors, which are also electrolytic. Otherwise replace capacitors with the same value of capacitance, using the same rated voltage or higher. It never hurts to use a higher rated voltage capacitor, just as long as you are able to make it fit. Whenever you increase the capacitance or the voltage, the capacitor gets proportionally bigger/larger in size.

[srb]

Doubling up the capacitance on power supply capacitors isn't always a no-brainer.  If there is no current limiting, the greater inrush charging current might over-tax even a solid state rectifier and possibly even the transformer, depending upon the amplifier and its component capacity ratings.  Amplifiers that have muting circuits might also experience a pop at turn-on or turn-off that did not previously exist if the charging time is altered.
 
Steve

[Æ]

Doubling up the capacitance on power supply capacitors isn't always a no-brainer.  If there is no current limiting, the greater inrush charging current might over-tax even a solid state rectifier and possibly even the transformer, depending upon the amplifier and its component capacity ratings.  Amplifiers that have muting circuits might also experience a pop at turn-on or turn-off that did not previously exist if the charging time is altered.
 
Steve

It depends on how much ripple you are willing to accept on the smoothed DC.