Hello,
Currently I'm building a Rod Elliot P3a, from Rods website sound.westhost.com. My problem is that I don't have enough knowledge about capacitors to chose the right one for its purpuse.
There are many different types of capacitors such as, elctrolytic, MKP, cermamic, etc. Could you please help me deciding wich type I should use at which place? I would like to know the main purposes en performance areas of the different types. Thanks in advance!
Currently I'm building a Rod Elliot P3a, from Rods website sound.westhost.com. My problem is that I don't have enough knowledge about capacitors to chose the right one for its purpuse.
There are many different types of capacitors such as, elctrolytic, MKP, cermamic, etc. Could you please help me deciding wich type I should use at which place? I would like to know the main purposes en performance areas of the different types. Thanks in advance!
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Some suggestions for starts:
C1: MKP or some would like Black Gate lytics
pf values: Polyestirene or MKP, for lower values you can also use Silver Mica.
nf values: MKP or Mylar films.
uf values (other than C1) use electolytics
In any case check the footprint of your selections to see if they match your PCB.
C1: MKP or some would like Black Gate lytics
pf values: Polyestirene or MKP, for lower values you can also use Silver Mica.
nf values: MKP or Mylar films.
uf values (other than C1) use electolytics
In any case check the footprint of your selections to see if they match your PCB.
Looks like C1 is polarized, doesn't that mean it has to be an electrolytic?
Oops, for the BOM
"C1 may be a standard electrolytic capacitor if desired. If a polarised electro is used for C1, the polarity is not shown on the overlay, but is clearly indicated on the overlay drawing.
"
Blessings Terry
Oops, for the BOM
"C1 may be a standard electrolytic capacitor if desired. If a polarised electro is used for C1, the polarity is not shown on the overlay, but is clearly indicated on the overlay drawing.
"
Blessings Terry
Hi,
C1 should be a non polar electrolytic or back to back polarised of double the capacitance value.
It would be far better to use a film cap here instead but MKP will be much larger and cost considerably more.
The builder decides!!!
Ceramic would never be used in the audio stages due to variable capacitance as the voltage varies. However they are unbeatable in decoupling of the hi frequency rubbish on the PSU etc where they see an almost constant (DC) voltage.
The film type usually perform better than any of the electros even black gate. Some film are better than others. Polypropylene, polystyrene and teflon are of the highest quality,
Polyethylene and polycarbonate are the next level down. Then there are a few others.
Try a search for a much more full report on capacitor quality
C1 should be a non polar electrolytic or back to back polarised of double the capacitance value.
It would be far better to use a film cap here instead but MKP will be much larger and cost considerably more.
The builder decides!!!
Ceramic would never be used in the audio stages due to variable capacitance as the voltage varies. However they are unbeatable in decoupling of the hi frequency rubbish on the PSU etc where they see an almost constant (DC) voltage.
The film type usually perform better than any of the electros even black gate. Some film are better than others. Polypropylene, polystyrene and teflon are of the highest quality,
Polyethylene and polycarbonate are the next level down. Then there are a few others.
Try a search for a much more full report on capacitor quality
Sander: Do _NOT_ use electrolytic as a C1. Use Polypropylene (Aydyn-Cap or similar) or better, Paper-In-Oil caps. It doesn't have to be 4,7µF, 1...2,2µF works fine. It won't fit on PCB, but who cares?
All electrolytics should (must, imo) be low-ESR types, Black Gate or something (OS-CON more preferably).
Mylar, MKP (Polypropylene), Silver-Mica or polystyrene for smaller ones.
That's how I would do it.
All electrolytics should (must, imo) be low-ESR types, Black Gate or something (OS-CON more preferably).
Mylar, MKP (Polypropylene), Silver-Mica or polystyrene for smaller ones.
That's how I would do it.
Hi Paulb,
you're claiming that transistor differences can be heard but on the other hand caps make no differenec to sound quality (for all but 0.1% of us). I am suprised at you conclusion.
I am glad that my first to third paragraghs in post 5 were worded as is and I will not waver from those statements. Any comeback?
you're claiming that transistor differences can be heard but on the other hand caps make no differenec to sound quality (for all but 0.1% of us). I am suprised at you conclusion.
I am glad that my first to third paragraghs in post 5 were worded as is and I will not waver from those statements. Any comeback?
I don't think I said capacitors make no difference to sound quality. I am saying that the "do not use" post (not by you) is a bunch of baloney and that the amp will sound excellent even with an electrolytic at the input. It's hard for beginners to sort out the difference between the important issues (like the ones you posted) versus the hype and overstatement. In general, the active devices make more difference than the passive ones. So don't go spending big bucks on a paper-in-oil input cap and use MJ2955/2N3055s on the outputs.
And amplifierguru shouldn't recommend people removing input coupling caps unless they know what they're doing.
And amplifierguru shouldn't recommend people removing input coupling caps unless they know what they're doing.
IMHO:
1. C1 can be eliminated if your source has an output cap or if you are sure that your source does not have any DC offset. Your amp will sound better without it. If I need it I would use a good quality polypropylene cap. The value depends on your chosen low frequency rolloff point, i.e. C = 1 / (2 x 3.1415 * f * R). Given the input impedance is set to 22k I personally would use something like 8.2uF. Lower is OK if you have a small speaker in which case you won't really tell any difference if you use anything like 1uF up.
2. For the 100pF I would use ceramic instead of polypropylene or polysteryn this is because at such a RF it is completely out of the audio band and the polys exhibite higher inductance that is no good for this application. Ceramic beats the polys in this case.
Regards,
Bill
1. C1 can be eliminated if your source has an output cap or if you are sure that your source does not have any DC offset. Your amp will sound better without it. If I need it I would use a good quality polypropylene cap. The value depends on your chosen low frequency rolloff point, i.e. C = 1 / (2 x 3.1415 * f * R). Given the input impedance is set to 22k I personally would use something like 8.2uF. Lower is OK if you have a small speaker in which case you won't really tell any difference if you use anything like 1uF up.
2. For the 100pF I would use ceramic instead of polypropylene or polysteryn this is because at such a RF it is completely out of the audio band and the polys exhibite higher inductance that is no good for this application. Ceramic beats the polys in this case.
Regards,
Bill
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