MKT caps

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These three letters indicate the material that is used for dieelectricum:

MKT are polyester film caps and they are handy when your table is out of balance. Simply put one under the table foot that's causing the table to wobble. 🙁
MKC are polycarbonate film caps and better than MKT.
MKP are polypropylene film caps and the best of these three kinds.

There are some variants called FKC and FKP. These are meant for pulse applications but they are also good in audio.

Even better and rare are styroflex ( polystyrene ) and teflon film caps. Styroflex is hard to find and not available in large values ( I once saw a 220 nF and it had the size of a penlight battery ). Tube guys will advise you to use paper-in-oil caps. Technically I do not agree with that but sonically they can be the best.


Most shops can sell you MKT or MKP, the latter is a good choice for audio. You can also choose what metal the foil is made of. Generally aluminium is used for the foil. For instance Intertechnik ( Audyn cap ) makes MKP with tinfoil.Jensen makes paper on oil caps with copperfoil. Prices of these types are very high but if you want that last percents squeezed out of your gear then they are the right caps for you.
 
Well, it is true that a good film cap will generally have a higher dV/dt than an electrolytic, therefore increasing the pulse current capability of the system. However, this is true only insofar as the charge carrying capability of the (much smaller) film cap isn't exceeded. If we have a small high-frequency current demand on the system the impedance will remain low, but if the HF current demand increases the film cap will no longer present a low impedance. (we are assuming that the inductance of the electrolytic prevents it from helping much here)
 
hacknet said:
is it true that polyproplyene caps increase the charge rate of another bigger cap when put in parellel?
Your question in other words is; is it true that the charging current will be higher when a high quality PP cap is place in parallel to a larger (presumably lesser quality) cap then it would be for the larger cap by itself, with the same applied voltage?

The answer is yes. The magnitude of the initial charging current will be determined by the Equivalent Series Resistance (ESR) which will be lower in the higher quality cap. But as Tiroth indicates, ESR increases with increasing frequency.

Rodd Yamashita
 
hacknet said:
at 100hz... it should work rite? im a newbie... so spare me..
It depends on the circuit and the capacitors value. What do you want to use it for?

Rodd Yamashita

"Spare me" you say!
 

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hacknet said:
iz for a power supply.. to increase the charge rate of large 15000uf caps. since they were substandard... they dun work as well as elna caps...
The power supply will usually benefit from a bypass with film caps. Some amps are said to benefit more or less then others, but it certainly will not hurt. You don’t need to go crazy with the ultra high priced film capacitors. Most decent film capacitors should work fine. Read the Jung/Marsh article I posted earlier to help you make this selection.

Rodd Yamashita
 
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